LCOV - code coverage report
Current view: top level - src/backend/executor - nodeHashjoin.c (source / functions) Hit Total Coverage
Test: PostgreSQL 15devel Lines: 416 455 91.4 %
Date: 2021-12-03 03:09:03 Functions: 18 18 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * nodeHashjoin.c
       4             :  *    Routines to handle hash join nodes
       5             :  *
       6             :  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *    src/backend/executor/nodeHashjoin.c
      12             :  *
      13             :  * PARALLELISM
      14             :  *
      15             :  * Hash joins can participate in parallel query execution in several ways.  A
      16             :  * parallel-oblivious hash join is one where the node is unaware that it is
      17             :  * part of a parallel plan.  In this case, a copy of the inner plan is used to
      18             :  * build a copy of the hash table in every backend, and the outer plan could
      19             :  * either be built from a partial or complete path, so that the results of the
      20             :  * hash join are correspondingly either partial or complete.  A parallel-aware
      21             :  * hash join is one that behaves differently, coordinating work between
      22             :  * backends, and appears as Parallel Hash Join in EXPLAIN output.  A Parallel
      23             :  * Hash Join always appears with a Parallel Hash node.
      24             :  *
      25             :  * Parallel-aware hash joins use the same per-backend state machine to track
      26             :  * progress through the hash join algorithm as parallel-oblivious hash joins.
      27             :  * In a parallel-aware hash join, there is also a shared state machine that
      28             :  * co-operating backends use to synchronize their local state machines and
      29             :  * program counters.  The shared state machine is managed with a Barrier IPC
      30             :  * primitive.  When all attached participants arrive at a barrier, the phase
      31             :  * advances and all waiting participants are released.
      32             :  *
      33             :  * When a participant begins working on a parallel hash join, it must first
      34             :  * figure out how much progress has already been made, because participants
      35             :  * don't wait for each other to begin.  For this reason there are switch
      36             :  * statements at key points in the code where we have to synchronize our local
      37             :  * state machine with the phase, and then jump to the correct part of the
      38             :  * algorithm so that we can get started.
      39             :  *
      40             :  * One barrier called build_barrier is used to coordinate the hashing phases.
      41             :  * The phase is represented by an integer which begins at zero and increments
      42             :  * one by one, but in the code it is referred to by symbolic names as follows:
      43             :  *
      44             :  *   PHJ_BUILD_ELECTING              -- initial state
      45             :  *   PHJ_BUILD_ALLOCATING            -- one sets up the batches and table 0
      46             :  *   PHJ_BUILD_HASHING_INNER         -- all hash the inner rel
      47             :  *   PHJ_BUILD_HASHING_OUTER         -- (multi-batch only) all hash the outer
      48             :  *   PHJ_BUILD_DONE                  -- building done, probing can begin
      49             :  *
      50             :  * While in the phase PHJ_BUILD_HASHING_INNER a separate pair of barriers may
      51             :  * be used repeatedly as required to coordinate expansions in the number of
      52             :  * batches or buckets.  Their phases are as follows:
      53             :  *
      54             :  *   PHJ_GROW_BATCHES_ELECTING       -- initial state
      55             :  *   PHJ_GROW_BATCHES_ALLOCATING     -- one allocates new batches
      56             :  *   PHJ_GROW_BATCHES_REPARTITIONING -- all repartition
      57             :  *   PHJ_GROW_BATCHES_FINISHING      -- one cleans up, detects skew
      58             :  *
      59             :  *   PHJ_GROW_BUCKETS_ELECTING       -- initial state
      60             :  *   PHJ_GROW_BUCKETS_ALLOCATING     -- one allocates new buckets
      61             :  *   PHJ_GROW_BUCKETS_REINSERTING    -- all insert tuples
      62             :  *
      63             :  * If the planner got the number of batches and buckets right, those won't be
      64             :  * necessary, but on the other hand we might finish up needing to expand the
      65             :  * buckets or batches multiple times while hashing the inner relation to stay
      66             :  * within our memory budget and load factor target.  For that reason it's a
      67             :  * separate pair of barriers using circular phases.
      68             :  *
      69             :  * The PHJ_BUILD_HASHING_OUTER phase is required only for multi-batch joins,
      70             :  * because we need to divide the outer relation into batches up front in order
      71             :  * to be able to process batches entirely independently.  In contrast, the
      72             :  * parallel-oblivious algorithm simply throws tuples 'forward' to 'later'
      73             :  * batches whenever it encounters them while scanning and probing, which it
      74             :  * can do because it processes batches in serial order.
      75             :  *
      76             :  * Once PHJ_BUILD_DONE is reached, backends then split up and process
      77             :  * different batches, or gang up and work together on probing batches if there
      78             :  * aren't enough to go around.  For each batch there is a separate barrier
      79             :  * with the following phases:
      80             :  *
      81             :  *  PHJ_BATCH_ELECTING       -- initial state
      82             :  *  PHJ_BATCH_ALLOCATING     -- one allocates buckets
      83             :  *  PHJ_BATCH_LOADING        -- all load the hash table from disk
      84             :  *  PHJ_BATCH_PROBING        -- all probe
      85             :  *  PHJ_BATCH_DONE           -- end
      86             :  *
      87             :  * Batch 0 is a special case, because it starts out in phase
      88             :  * PHJ_BATCH_PROBING; populating batch 0's hash table is done during
      89             :  * PHJ_BUILD_HASHING_INNER so we can skip loading.
      90             :  *
      91             :  * Initially we try to plan for a single-batch hash join using the combined
      92             :  * hash_mem of all participants to create a large shared hash table.  If that
      93             :  * turns out either at planning or execution time to be impossible then we
      94             :  * fall back to regular hash_mem sized hash tables.
      95             :  *
      96             :  * To avoid deadlocks, we never wait for any barrier unless it is known that
      97             :  * all other backends attached to it are actively executing the node or have
      98             :  * already arrived.  Practically, that means that we never return a tuple
      99             :  * while attached to a barrier, unless the barrier has reached its final
     100             :  * state.  In the slightly special case of the per-batch barrier, we return
     101             :  * tuples while in PHJ_BATCH_PROBING phase, but that's OK because we use
     102             :  * BarrierArriveAndDetach() to advance it to PHJ_BATCH_DONE without waiting.
     103             :  *
     104             :  *-------------------------------------------------------------------------
     105             :  */
     106             : 
     107             : #include "postgres.h"
     108             : 
     109             : #include "access/htup_details.h"
     110             : #include "access/parallel.h"
     111             : #include "executor/executor.h"
     112             : #include "executor/hashjoin.h"
     113             : #include "executor/nodeHash.h"
     114             : #include "executor/nodeHashjoin.h"
     115             : #include "miscadmin.h"
     116             : #include "pgstat.h"
     117             : #include "utils/memutils.h"
     118             : #include "utils/sharedtuplestore.h"
     119             : 
     120             : 
     121             : /*
     122             :  * States of the ExecHashJoin state machine
     123             :  */
     124             : #define HJ_BUILD_HASHTABLE      1
     125             : #define HJ_NEED_NEW_OUTER       2
     126             : #define HJ_SCAN_BUCKET          3
     127             : #define HJ_FILL_OUTER_TUPLE     4
     128             : #define HJ_FILL_INNER_TUPLES    5
     129             : #define HJ_NEED_NEW_BATCH       6
     130             : 
     131             : /* Returns true if doing null-fill on outer relation */
     132             : #define HJ_FILL_OUTER(hjstate)  ((hjstate)->hj_NullInnerTupleSlot != NULL)
     133             : /* Returns true if doing null-fill on inner relation */
     134             : #define HJ_FILL_INNER(hjstate)  ((hjstate)->hj_NullOuterTupleSlot != NULL)
     135             : 
     136             : static TupleTableSlot *ExecHashJoinOuterGetTuple(PlanState *outerNode,
     137             :                                                  HashJoinState *hjstate,
     138             :                                                  uint32 *hashvalue);
     139             : static TupleTableSlot *ExecParallelHashJoinOuterGetTuple(PlanState *outerNode,
     140             :                                                          HashJoinState *hjstate,
     141             :                                                          uint32 *hashvalue);
     142             : static TupleTableSlot *ExecHashJoinGetSavedTuple(HashJoinState *hjstate,
     143             :                                                  BufFile *file,
     144             :                                                  uint32 *hashvalue,
     145             :                                                  TupleTableSlot *tupleSlot);
     146             : static bool ExecHashJoinNewBatch(HashJoinState *hjstate);
     147             : static bool ExecParallelHashJoinNewBatch(HashJoinState *hjstate);
     148             : static void ExecParallelHashJoinPartitionOuter(HashJoinState *node);
     149             : 
     150             : 
     151             : /* ----------------------------------------------------------------
     152             :  *      ExecHashJoinImpl
     153             :  *
     154             :  *      This function implements the Hybrid Hashjoin algorithm.  It is marked
     155             :  *      with an always-inline attribute so that ExecHashJoin() and
     156             :  *      ExecParallelHashJoin() can inline it.  Compilers that respect the
     157             :  *      attribute should create versions specialized for parallel == true and
     158             :  *      parallel == false with unnecessary branches removed.
     159             :  *
     160             :  *      Note: the relation we build hash table on is the "inner"
     161             :  *            the other one is "outer".
     162             :  * ----------------------------------------------------------------
     163             :  */
     164             : static pg_attribute_always_inline TupleTableSlot *
     165     7545090 : ExecHashJoinImpl(PlanState *pstate, bool parallel)
     166             : {
     167     7545090 :     HashJoinState *node = castNode(HashJoinState, pstate);
     168             :     PlanState  *outerNode;
     169             :     HashState  *hashNode;
     170             :     ExprState  *joinqual;
     171             :     ExprState  *otherqual;
     172             :     ExprContext *econtext;
     173             :     HashJoinTable hashtable;
     174             :     TupleTableSlot *outerTupleSlot;
     175             :     uint32      hashvalue;
     176             :     int         batchno;
     177             :     ParallelHashJoinState *parallel_state;
     178             : 
     179             :     /*
     180             :      * get information from HashJoin node
     181             :      */
     182     7545090 :     joinqual = node->js.joinqual;
     183     7545090 :     otherqual = node->js.ps.qual;
     184     7545090 :     hashNode = (HashState *) innerPlanState(node);
     185     7545090 :     outerNode = outerPlanState(node);
     186     7545090 :     hashtable = node->hj_HashTable;
     187     7545090 :     econtext = node->js.ps.ps_ExprContext;
     188     7545090 :     parallel_state = hashNode->parallel_state;
     189             : 
     190             :     /*
     191             :      * Reset per-tuple memory context to free any expression evaluation
     192             :      * storage allocated in the previous tuple cycle.
     193             :      */
     194     7545090 :     ResetExprContext(econtext);
     195             : 
     196             :     /*
     197             :      * run the hash join state machine
     198             :      */
     199             :     for (;;)
     200             :     {
     201             :         /*
     202             :          * It's possible to iterate this loop many times before returning a
     203             :          * tuple, in some pathological cases such as needing to move much of
     204             :          * the current batch to a later batch.  So let's check for interrupts
     205             :          * each time through.
     206             :          */
     207    29360986 :         CHECK_FOR_INTERRUPTS();
     208             : 
     209    29360986 :         switch (node->hj_JoinState)
     210             :         {
     211     1404926 :             case HJ_BUILD_HASHTABLE:
     212             : 
     213             :                 /*
     214             :                  * First time through: build hash table for inner relation.
     215             :                  */
     216             :                 Assert(hashtable == NULL);
     217             : 
     218             :                 /*
     219             :                  * If the outer relation is completely empty, and it's not
     220             :                  * right/full join, we can quit without building the hash
     221             :                  * table.  However, for an inner join it is only a win to
     222             :                  * check this when the outer relation's startup cost is less
     223             :                  * than the projected cost of building the hash table.
     224             :                  * Otherwise it's best to build the hash table first and see
     225             :                  * if the inner relation is empty.  (When it's a left join, we
     226             :                  * should always make this check, since we aren't going to be
     227             :                  * able to skip the join on the strength of an empty inner
     228             :                  * relation anyway.)
     229             :                  *
     230             :                  * If we are rescanning the join, we make use of information
     231             :                  * gained on the previous scan: don't bother to try the
     232             :                  * prefetch if the previous scan found the outer relation
     233             :                  * nonempty. This is not 100% reliable since with new
     234             :                  * parameters the outer relation might yield different
     235             :                  * results, but it's a good heuristic.
     236             :                  *
     237             :                  * The only way to make the check is to try to fetch a tuple
     238             :                  * from the outer plan node.  If we succeed, we have to stash
     239             :                  * it away for later consumption by ExecHashJoinOuterGetTuple.
     240             :                  */
     241     1404926 :                 if (HJ_FILL_INNER(node))
     242             :                 {
     243             :                     /* no chance to not build the hash table */
     244       11200 :                     node->hj_FirstOuterTupleSlot = NULL;
     245             :                 }
     246     1393726 :                 else if (parallel)
     247             :                 {
     248             :                     /*
     249             :                      * The empty-outer optimization is not implemented for
     250             :                      * shared hash tables, because no one participant can
     251             :                      * determine that there are no outer tuples, and it's not
     252             :                      * yet clear that it's worth the synchronization overhead
     253             :                      * of reaching consensus to figure that out.  So we have
     254             :                      * to build the hash table.
     255             :                      */
     256         216 :                     node->hj_FirstOuterTupleSlot = NULL;
     257             :                 }
     258     1393510 :                 else if (HJ_FILL_OUTER(node) ||
     259       10534 :                          (outerNode->plan->startup_cost < hashNode->ps.plan->total_cost &&
     260       10064 :                           !node->hj_OuterNotEmpty))
     261             :                 {
     262     1392262 :                     node->hj_FirstOuterTupleSlot = ExecProcNode(outerNode);
     263     1392262 :                     if (TupIsNull(node->hj_FirstOuterTupleSlot))
     264             :                     {
     265     1010504 :                         node->hj_OuterNotEmpty = false;
     266     1010504 :                         return NULL;
     267             :                     }
     268             :                     else
     269      381758 :                         node->hj_OuterNotEmpty = true;
     270             :                 }
     271             :                 else
     272        1248 :                     node->hj_FirstOuterTupleSlot = NULL;
     273             : 
     274             :                 /*
     275             :                  * Create the hash table.  If using Parallel Hash, then
     276             :                  * whoever gets here first will create the hash table and any
     277             :                  * later arrivals will merely attach to it.
     278             :                  */
     279      394422 :                 hashtable = ExecHashTableCreate(hashNode,
     280             :                                                 node->hj_HashOperators,
     281             :                                                 node->hj_Collations,
     282      394422 :                                                 HJ_FILL_INNER(node));
     283      394422 :                 node->hj_HashTable = hashtable;
     284             : 
     285             :                 /*
     286             :                  * Execute the Hash node, to build the hash table.  If using
     287             :                  * Parallel Hash, then we'll try to help hashing unless we
     288             :                  * arrived too late.
     289             :                  */
     290      394422 :                 hashNode->hashtable = hashtable;
     291      394422 :                 (void) MultiExecProcNode((PlanState *) hashNode);
     292             : 
     293             :                 /*
     294             :                  * If the inner relation is completely empty, and we're not
     295             :                  * doing a left outer join, we can quit without scanning the
     296             :                  * outer relation.
     297             :                  */
     298      394422 :                 if (hashtable->totalTuples == 0 && !HJ_FILL_OUTER(node))
     299         766 :                     return NULL;
     300             : 
     301             :                 /*
     302             :                  * need to remember whether nbatch has increased since we
     303             :                  * began scanning the outer relation
     304             :                  */
     305      393656 :                 hashtable->nbatch_outstart = hashtable->nbatch;
     306             : 
     307             :                 /*
     308             :                  * Reset OuterNotEmpty for scan.  (It's OK if we fetched a
     309             :                  * tuple above, because ExecHashJoinOuterGetTuple will
     310             :                  * immediately set it again.)
     311             :                  */
     312      393656 :                 node->hj_OuterNotEmpty = false;
     313             : 
     314      393656 :                 if (parallel)
     315             :                 {
     316             :                     Barrier    *build_barrier;
     317             : 
     318         216 :                     build_barrier = &parallel_state->build_barrier;
     319             :                     Assert(BarrierPhase(build_barrier) == PHJ_BUILD_HASHING_OUTER ||
     320             :                            BarrierPhase(build_barrier) == PHJ_BUILD_DONE);
     321         216 :                     if (BarrierPhase(build_barrier) == PHJ_BUILD_HASHING_OUTER)
     322             :                     {
     323             :                         /*
     324             :                          * If multi-batch, we need to hash the outer relation
     325             :                          * up front.
     326             :                          */
     327         152 :                         if (hashtable->nbatch > 1)
     328          86 :                             ExecParallelHashJoinPartitionOuter(node);
     329         152 :                         BarrierArriveAndWait(build_barrier,
     330             :                                              WAIT_EVENT_HASH_BUILD_HASH_OUTER);
     331             :                     }
     332             :                     Assert(BarrierPhase(build_barrier) == PHJ_BUILD_DONE);
     333             : 
     334             :                     /* Each backend should now select a batch to work on. */
     335         216 :                     hashtable->curbatch = -1;
     336         216 :                     node->hj_JoinState = HJ_NEED_NEW_BATCH;
     337             : 
     338         216 :                     continue;
     339             :                 }
     340             :                 else
     341      393440 :                     node->hj_JoinState = HJ_NEED_NEW_OUTER;
     342             : 
     343             :                 /* FALL THRU */
     344             : 
     345    14146336 :             case HJ_NEED_NEW_OUTER:
     346             : 
     347             :                 /*
     348             :                  * We don't have an outer tuple, try to get the next one
     349             :                  */
     350    14146336 :                 if (parallel)
     351             :                     outerTupleSlot =
     352     1200560 :                         ExecParallelHashJoinOuterGetTuple(outerNode, node,
     353             :                                                           &hashvalue);
     354             :                 else
     355             :                     outerTupleSlot =
     356    12945776 :                         ExecHashJoinOuterGetTuple(outerNode, node, &hashvalue);
     357             : 
     358    14146336 :                 if (TupIsNull(outerTupleSlot))
     359             :                 {
     360             :                     /* end of batch, or maybe whole join */
     361      394964 :                     if (HJ_FILL_INNER(node))
     362             :                     {
     363             :                         /* set up to scan for unmatched inner tuples */
     364       11162 :                         ExecPrepHashTableForUnmatched(node);
     365       11162 :                         node->hj_JoinState = HJ_FILL_INNER_TUPLES;
     366             :                     }
     367             :                     else
     368      383802 :                         node->hj_JoinState = HJ_NEED_NEW_BATCH;
     369      394964 :                     continue;
     370             :                 }
     371             : 
     372    13751372 :                 econtext->ecxt_outertuple = outerTupleSlot;
     373    13751372 :                 node->hj_MatchedOuter = false;
     374             : 
     375             :                 /*
     376             :                  * Find the corresponding bucket for this tuple in the main
     377             :                  * hash table or skew hash table.
     378             :                  */
     379    13751372 :                 node->hj_CurHashValue = hashvalue;
     380    13751372 :                 ExecHashGetBucketAndBatch(hashtable, hashvalue,
     381             :                                           &node->hj_CurBucketNo, &batchno);
     382    13751372 :                 node->hj_CurSkewBucketNo = ExecHashGetSkewBucket(hashtable,
     383             :                                                                  hashvalue);
     384    13751372 :                 node->hj_CurTuple = NULL;
     385             : 
     386             :                 /*
     387             :                  * The tuple might not belong to the current batch (where
     388             :                  * "current batch" includes the skew buckets if any).
     389             :                  */
     390    13751372 :                 if (batchno != hashtable->curbatch &&
     391      986528 :                     node->hj_CurSkewBucketNo == INVALID_SKEW_BUCKET_NO)
     392             :                 {
     393             :                     bool        shouldFree;
     394      986128 :                     MinimalTuple mintuple = ExecFetchSlotMinimalTuple(outerTupleSlot,
     395             :                                                                       &shouldFree);
     396             : 
     397             :                     /*
     398             :                      * Need to postpone this outer tuple to a later batch.
     399             :                      * Save it in the corresponding outer-batch file.
     400             :                      */
     401             :                     Assert(parallel_state == NULL);
     402             :                     Assert(batchno > hashtable->curbatch);
     403      986128 :                     ExecHashJoinSaveTuple(mintuple, hashvalue,
     404      986128 :                                           &hashtable->outerBatchFile[batchno]);
     405             : 
     406      986128 :                     if (shouldFree)
     407      986128 :                         heap_free_minimal_tuple(mintuple);
     408             : 
     409             :                     /* Loop around, staying in HJ_NEED_NEW_OUTER state */
     410      986128 :                     continue;
     411             :                 }
     412             : 
     413             :                 /* OK, let's scan the bucket for matches */
     414    12765244 :                 node->hj_JoinState = HJ_SCAN_BUCKET;
     415             : 
     416             :                 /* FALL THRU */
     417             : 
     418    16654314 :             case HJ_SCAN_BUCKET:
     419             : 
     420             :                 /*
     421             :                  * Scan the selected hash bucket for matches to current outer
     422             :                  */
     423    16654314 :                 if (parallel)
     424             :                 {
     425     2400032 :                     if (!ExecParallelScanHashBucket(node, econtext))
     426             :                     {
     427             :                         /* out of matches; check for possible outer-join fill */
     428     1200016 :                         node->hj_JoinState = HJ_FILL_OUTER_TUPLE;
     429     1200016 :                         continue;
     430             :                     }
     431             :                 }
     432             :                 else
     433             :                 {
     434    14254282 :                     if (!ExecScanHashBucket(node, econtext))
     435             :                     {
     436             :                         /* out of matches; check for possible outer-join fill */
     437     8490044 :                         node->hj_JoinState = HJ_FILL_OUTER_TUPLE;
     438     8490044 :                         continue;
     439             :                     }
     440             :                 }
     441             : 
     442             :                 /*
     443             :                  * We've got a match, but still need to test non-hashed quals.
     444             :                  * ExecScanHashBucket already set up all the state needed to
     445             :                  * call ExecQual.
     446             :                  *
     447             :                  * If we pass the qual, then save state for next call and have
     448             :                  * ExecProject form the projection, store it in the tuple
     449             :                  * table, and return the slot.
     450             :                  *
     451             :                  * Only the joinquals determine tuple match status, but all
     452             :                  * quals must pass to actually return the tuple.
     453             :                  */
     454     6964254 :                 if (joinqual == NULL || ExecQual(joinqual, econtext))
     455             :                 {
     456     6866696 :                     node->hj_MatchedOuter = true;
     457             : 
     458     6866696 :                     if (parallel)
     459             :                     {
     460             :                         /*
     461             :                          * Full/right outer joins are currently not supported
     462             :                          * for parallel joins, so we don't need to set the
     463             :                          * match bit.  Experiments show that it's worth
     464             :                          * avoiding the shared memory traffic on large
     465             :                          * systems.
     466             :                          */
     467             :                         Assert(!HJ_FILL_INNER(node));
     468             :                     }
     469             :                     else
     470             :                     {
     471             :                         /*
     472             :                          * This is really only needed if HJ_FILL_INNER(node),
     473             :                          * but we'll avoid the branch and just set it always.
     474             :                          */
     475     5666680 :                         HeapTupleHeaderSetMatch(HJTUPLE_MINTUPLE(node->hj_CurTuple));
     476             :                     }
     477             : 
     478             :                     /* In an antijoin, we never return a matched tuple */
     479     6866696 :                     if (node->js.jointype == JOIN_ANTI)
     480             :                     {
     481     1936186 :                         node->hj_JoinState = HJ_NEED_NEW_OUTER;
     482     1936186 :                         continue;
     483             :                     }
     484             : 
     485             :                     /*
     486             :                      * If we only need to join to the first matching inner
     487             :                      * tuple, then consider returning this one, but after that
     488             :                      * continue with next outer tuple.
     489             :                      */
     490     4930510 :                     if (node->js.single_match)
     491     1138950 :                         node->hj_JoinState = HJ_NEED_NEW_OUTER;
     492             : 
     493     4930510 :                     if (otherqual == NULL || ExecQual(otherqual, econtext))
     494     4854402 :                         return ExecProject(node->js.ps.ps_ProjInfo);
     495             :                     else
     496       76108 :                         InstrCountFiltered2(node, 1);
     497             :                 }
     498             :                 else
     499       97558 :                     InstrCountFiltered1(node, 1);
     500      173666 :                 break;
     501             : 
     502     9690060 :             case HJ_FILL_OUTER_TUPLE:
     503             : 
     504             :                 /*
     505             :                  * The current outer tuple has run out of matches, so check
     506             :                  * whether to emit a dummy outer-join tuple.  Whether we emit
     507             :                  * one or not, the next state is NEED_NEW_OUTER.
     508             :                  */
     509     9690060 :                 node->hj_JoinState = HJ_NEED_NEW_OUTER;
     510             : 
     511     9690060 :                 if (!node->hj_MatchedOuter &&
     512     6778098 :                     HJ_FILL_OUTER(node))
     513             :                 {
     514             :                     /*
     515             :                      * Generate a fake join tuple with nulls for the inner
     516             :                      * tuple, and return it if it passes the non-join quals.
     517             :                      */
     518     1696468 :                     econtext->ecxt_innertuple = node->hj_NullInnerTupleSlot;
     519             : 
     520     1696468 :                     if (otherqual == NULL || ExecQual(otherqual, econtext))
     521     1069716 :                         return ExecProject(node->js.ps.ps_ProjInfo);
     522             :                     else
     523      626752 :                         InstrCountFiltered2(node, 1);
     524             :                 }
     525     8620344 :                 break;
     526             : 
     527      228858 :             case HJ_FILL_INNER_TUPLES:
     528             : 
     529             :                 /*
     530             :                  * We have finished a batch, but we are doing right/full join,
     531             :                  * so any unmatched inner tuples in the hashtable have to be
     532             :                  * emitted before we continue to the next batch.
     533             :                  */
     534      228858 :                 if (!ExecScanHashTableForUnmatched(node, econtext))
     535             :                 {
     536             :                     /* no more unmatched tuples */
     537       11158 :                     node->hj_JoinState = HJ_NEED_NEW_BATCH;
     538       11158 :                     continue;
     539             :                 }
     540             : 
     541             :                 /*
     542             :                  * Generate a fake join tuple with nulls for the outer tuple,
     543             :                  * and return it if it passes the non-join quals.
     544             :                  */
     545      217700 :                 econtext->ecxt_outertuple = node->hj_NullOuterTupleSlot;
     546             : 
     547      217700 :                 if (otherqual == NULL || ExecQual(otherqual, econtext))
     548      215820 :                     return ExecProject(node->js.ps.ps_ProjInfo);
     549             :                 else
     550        1880 :                     InstrCountFiltered2(node, 1);
     551        1880 :                 break;
     552             : 
     553      395176 :             case HJ_NEED_NEW_BATCH:
     554             : 
     555             :                 /*
     556             :                  * Try to advance to next batch.  Done if there are no more.
     557             :                  */
     558      395176 :                 if (parallel)
     559             :                 {
     560         760 :                     if (!ExecParallelHashJoinNewBatch(node))
     561         216 :                         return NULL;    /* end of parallel-aware join */
     562             :                 }
     563             :                 else
     564             :                 {
     565      394416 :                     if (!ExecHashJoinNewBatch(node))
     566      393666 :                         return NULL;    /* end of parallel-oblivious join */
     567             :                 }
     568        1294 :                 node->hj_JoinState = HJ_NEED_NEW_OUTER;
     569        1294 :                 break;
     570             : 
     571           0 :             default:
     572           0 :                 elog(ERROR, "unrecognized hashjoin state: %d",
     573             :                      (int) node->hj_JoinState);
     574             :         }
     575             :     }
     576             : }
     577             : 
     578             : /* ----------------------------------------------------------------
     579             :  *      ExecHashJoin
     580             :  *
     581             :  *      Parallel-oblivious version.
     582             :  * ----------------------------------------------------------------
     583             :  */
     584             : static TupleTableSlot *         /* return: a tuple or NULL */
     585     6344858 : ExecHashJoin(PlanState *pstate)
     586             : {
     587             :     /*
     588             :      * On sufficiently smart compilers this should be inlined with the
     589             :      * parallel-aware branches removed.
     590             :      */
     591     6344858 :     return ExecHashJoinImpl(pstate, false);
     592             : }
     593             : 
     594             : /* ----------------------------------------------------------------
     595             :  *      ExecParallelHashJoin
     596             :  *
     597             :  *      Parallel-aware version.
     598             :  * ----------------------------------------------------------------
     599             :  */
     600             : static TupleTableSlot *         /* return: a tuple or NULL */
     601     1200232 : ExecParallelHashJoin(PlanState *pstate)
     602             : {
     603             :     /*
     604             :      * On sufficiently smart compilers this should be inlined with the
     605             :      * parallel-oblivious branches removed.
     606             :      */
     607     1200232 :     return ExecHashJoinImpl(pstate, true);
     608             : }
     609             : 
     610             : /* ----------------------------------------------------------------
     611             :  *      ExecInitHashJoin
     612             :  *
     613             :  *      Init routine for HashJoin node.
     614             :  * ----------------------------------------------------------------
     615             :  */
     616             : HashJoinState *
     617       46062 : ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
     618             : {
     619             :     HashJoinState *hjstate;
     620             :     Plan       *outerNode;
     621             :     Hash       *hashNode;
     622             :     TupleDesc   outerDesc,
     623             :                 innerDesc;
     624             :     const TupleTableSlotOps *ops;
     625             : 
     626             :     /* check for unsupported flags */
     627             :     Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
     628             : 
     629             :     /*
     630             :      * create state structure
     631             :      */
     632       46062 :     hjstate = makeNode(HashJoinState);
     633       46062 :     hjstate->js.ps.plan = (Plan *) node;
     634       46062 :     hjstate->js.ps.state = estate;
     635             : 
     636             :     /*
     637             :      * See ExecHashJoinInitializeDSM() and ExecHashJoinInitializeWorker()
     638             :      * where this function may be replaced with a parallel version, if we
     639             :      * managed to launch a parallel query.
     640             :      */
     641       46062 :     hjstate->js.ps.ExecProcNode = ExecHashJoin;
     642       46062 :     hjstate->js.jointype = node->join.jointype;
     643             : 
     644             :     /*
     645             :      * Miscellaneous initialization
     646             :      *
     647             :      * create expression context for node
     648             :      */
     649       46062 :     ExecAssignExprContext(estate, &hjstate->js.ps);
     650             : 
     651             :     /*
     652             :      * initialize child nodes
     653             :      *
     654             :      * Note: we could suppress the REWIND flag for the inner input, which
     655             :      * would amount to betting that the hash will be a single batch.  Not
     656             :      * clear if this would be a win or not.
     657             :      */
     658       46062 :     outerNode = outerPlan(node);
     659       46062 :     hashNode = (Hash *) innerPlan(node);
     660             : 
     661       46062 :     outerPlanState(hjstate) = ExecInitNode(outerNode, estate, eflags);
     662       46062 :     outerDesc = ExecGetResultType(outerPlanState(hjstate));
     663       46062 :     innerPlanState(hjstate) = ExecInitNode((Plan *) hashNode, estate, eflags);
     664       46062 :     innerDesc = ExecGetResultType(innerPlanState(hjstate));
     665             : 
     666             :     /*
     667             :      * Initialize result slot, type and projection.
     668             :      */
     669       46062 :     ExecInitResultTupleSlotTL(&hjstate->js.ps, &TTSOpsVirtual);
     670       46062 :     ExecAssignProjectionInfo(&hjstate->js.ps, NULL);
     671             : 
     672             :     /*
     673             :      * tuple table initialization
     674             :      */
     675       46062 :     ops = ExecGetResultSlotOps(outerPlanState(hjstate), NULL);
     676       46062 :     hjstate->hj_OuterTupleSlot = ExecInitExtraTupleSlot(estate, outerDesc,
     677             :                                                         ops);
     678             : 
     679             :     /*
     680             :      * detect whether we need only consider the first matching inner tuple
     681             :      */
     682       67266 :     hjstate->js.single_match = (node->join.inner_unique ||
     683       21204 :                                 node->join.jointype == JOIN_SEMI);
     684             : 
     685             :     /* set up null tuples for outer joins, if needed */
     686       46062 :     switch (node->join.jointype)
     687             :     {
     688       11152 :         case JOIN_INNER:
     689             :         case JOIN_SEMI:
     690       11152 :             break;
     691       23086 :         case JOIN_LEFT:
     692             :         case JOIN_ANTI:
     693       23086 :             hjstate->hj_NullInnerTupleSlot =
     694       23086 :                 ExecInitNullTupleSlot(estate, innerDesc, &TTSOpsVirtual);
     695       23086 :             break;
     696       11178 :         case JOIN_RIGHT:
     697       11178 :             hjstate->hj_NullOuterTupleSlot =
     698       11178 :                 ExecInitNullTupleSlot(estate, outerDesc, &TTSOpsVirtual);
     699       11178 :             break;
     700         646 :         case JOIN_FULL:
     701         646 :             hjstate->hj_NullOuterTupleSlot =
     702         646 :                 ExecInitNullTupleSlot(estate, outerDesc, &TTSOpsVirtual);
     703         646 :             hjstate->hj_NullInnerTupleSlot =
     704         646 :                 ExecInitNullTupleSlot(estate, innerDesc, &TTSOpsVirtual);
     705         646 :             break;
     706           0 :         default:
     707           0 :             elog(ERROR, "unrecognized join type: %d",
     708             :                  (int) node->join.jointype);
     709             :     }
     710             : 
     711             :     /*
     712             :      * now for some voodoo.  our temporary tuple slot is actually the result
     713             :      * tuple slot of the Hash node (which is our inner plan).  we can do this
     714             :      * because Hash nodes don't return tuples via ExecProcNode() -- instead
     715             :      * the hash join node uses ExecScanHashBucket() to get at the contents of
     716             :      * the hash table.  -cim 6/9/91
     717             :      */
     718             :     {
     719       46062 :         HashState  *hashstate = (HashState *) innerPlanState(hjstate);
     720       46062 :         TupleTableSlot *slot = hashstate->ps.ps_ResultTupleSlot;
     721             : 
     722       46062 :         hjstate->hj_HashTupleSlot = slot;
     723             :     }
     724             : 
     725             :     /*
     726             :      * initialize child expressions
     727             :      */
     728       46062 :     hjstate->js.ps.qual =
     729       46062 :         ExecInitQual(node->join.plan.qual, (PlanState *) hjstate);
     730       46062 :     hjstate->js.joinqual =
     731       46062 :         ExecInitQual(node->join.joinqual, (PlanState *) hjstate);
     732       46062 :     hjstate->hashclauses =
     733       46062 :         ExecInitQual(node->hashclauses, (PlanState *) hjstate);
     734             : 
     735             :     /*
     736             :      * initialize hash-specific info
     737             :      */
     738       46062 :     hjstate->hj_HashTable = NULL;
     739       46062 :     hjstate->hj_FirstOuterTupleSlot = NULL;
     740             : 
     741       46062 :     hjstate->hj_CurHashValue = 0;
     742       46062 :     hjstate->hj_CurBucketNo = 0;
     743       46062 :     hjstate->hj_CurSkewBucketNo = INVALID_SKEW_BUCKET_NO;
     744       46062 :     hjstate->hj_CurTuple = NULL;
     745             : 
     746       46062 :     hjstate->hj_OuterHashKeys = ExecInitExprList(node->hashkeys,
     747             :                                                  (PlanState *) hjstate);
     748       46062 :     hjstate->hj_HashOperators = node->hashoperators;
     749       46062 :     hjstate->hj_Collations = node->hashcollations;
     750             : 
     751       46062 :     hjstate->hj_JoinState = HJ_BUILD_HASHTABLE;
     752       46062 :     hjstate->hj_MatchedOuter = false;
     753       46062 :     hjstate->hj_OuterNotEmpty = false;
     754             : 
     755       46062 :     return hjstate;
     756             : }
     757             : 
     758             : /* ----------------------------------------------------------------
     759             :  *      ExecEndHashJoin
     760             :  *
     761             :  *      clean up routine for HashJoin node
     762             :  * ----------------------------------------------------------------
     763             :  */
     764             : void
     765       46022 : ExecEndHashJoin(HashJoinState *node)
     766             : {
     767             :     /*
     768             :      * Free hash table
     769             :      */
     770       46022 :     if (node->hj_HashTable)
     771             :     {
     772       37346 :         ExecHashTableDestroy(node->hj_HashTable);
     773       37346 :         node->hj_HashTable = NULL;
     774             :     }
     775             : 
     776             :     /*
     777             :      * Free the exprcontext
     778             :      */
     779       46022 :     ExecFreeExprContext(&node->js.ps);
     780             : 
     781             :     /*
     782             :      * clean out the tuple table
     783             :      */
     784       46022 :     ExecClearTuple(node->js.ps.ps_ResultTupleSlot);
     785       46022 :     ExecClearTuple(node->hj_OuterTupleSlot);
     786       46022 :     ExecClearTuple(node->hj_HashTupleSlot);
     787             : 
     788             :     /*
     789             :      * clean up subtrees
     790             :      */
     791       46022 :     ExecEndNode(outerPlanState(node));
     792       46022 :     ExecEndNode(innerPlanState(node));
     793       46022 : }
     794             : 
     795             : /*
     796             :  * ExecHashJoinOuterGetTuple
     797             :  *
     798             :  *      get the next outer tuple for a parallel oblivious hashjoin: either by
     799             :  *      executing the outer plan node in the first pass, or from the temp
     800             :  *      files for the hashjoin batches.
     801             :  *
     802             :  * Returns a null slot if no more outer tuples (within the current batch).
     803             :  *
     804             :  * On success, the tuple's hash value is stored at *hashvalue --- this is
     805             :  * either originally computed, or re-read from the temp file.
     806             :  */
     807             : static TupleTableSlot *
     808    12945776 : ExecHashJoinOuterGetTuple(PlanState *outerNode,
     809             :                           HashJoinState *hjstate,
     810             :                           uint32 *hashvalue)
     811             : {
     812    12945776 :     HashJoinTable hashtable = hjstate->hj_HashTable;
     813    12945776 :     int         curbatch = hashtable->curbatch;
     814             :     TupleTableSlot *slot;
     815             : 
     816    12945776 :     if (curbatch == 0)          /* if it is the first pass */
     817             :     {
     818             :         /*
     819             :          * Check to see if first outer tuple was already fetched by
     820             :          * ExecHashJoin() and not used yet.
     821             :          */
     822    11958898 :         slot = hjstate->hj_FirstOuterTupleSlot;
     823    11958898 :         if (!TupIsNull(slot))
     824      381422 :             hjstate->hj_FirstOuterTupleSlot = NULL;
     825             :         else
     826    11577476 :             slot = ExecProcNode(outerNode);
     827             : 
     828    11959418 :         while (!TupIsNull(slot))
     829             :         {
     830             :             /*
     831             :              * We have to compute the tuple's hash value.
     832             :              */
     833    11565748 :             ExprContext *econtext = hjstate->js.ps.ps_ExprContext;
     834             : 
     835    11565748 :             econtext->ecxt_outertuple = slot;
     836    11565748 :             if (ExecHashGetHashValue(hashtable, econtext,
     837             :                                      hjstate->hj_OuterHashKeys,
     838             :                                      true,  /* outer tuple */
     839    11565748 :                                      HJ_FILL_OUTER(hjstate),
     840             :                                      hashvalue))
     841             :             {
     842             :                 /* remember outer relation is not empty for possible rescan */
     843    11565228 :                 hjstate->hj_OuterNotEmpty = true;
     844             : 
     845    11565228 :                 return slot;
     846             :             }
     847             : 
     848             :             /*
     849             :              * That tuple couldn't match because of a NULL, so discard it and
     850             :              * continue with the next one.
     851             :              */
     852         520 :             slot = ExecProcNode(outerNode);
     853             :         }
     854             :     }
     855      986878 :     else if (curbatch < hashtable->nbatch)
     856             :     {
     857      986878 :         BufFile    *file = hashtable->outerBatchFile[curbatch];
     858             : 
     859             :         /*
     860             :          * In outer-join cases, we could get here even though the batch file
     861             :          * is empty.
     862             :          */
     863      986878 :         if (file == NULL)
     864           0 :             return NULL;
     865             : 
     866      986878 :         slot = ExecHashJoinGetSavedTuple(hjstate,
     867             :                                          file,
     868             :                                          hashvalue,
     869             :                                          hjstate->hj_OuterTupleSlot);
     870      986878 :         if (!TupIsNull(slot))
     871      986128 :             return slot;
     872             :     }
     873             : 
     874             :     /* End of this batch */
     875      394420 :     return NULL;
     876             : }
     877             : 
     878             : /*
     879             :  * ExecHashJoinOuterGetTuple variant for the parallel case.
     880             :  */
     881             : static TupleTableSlot *
     882     1200560 : ExecParallelHashJoinOuterGetTuple(PlanState *outerNode,
     883             :                                   HashJoinState *hjstate,
     884             :                                   uint32 *hashvalue)
     885             : {
     886     1200560 :     HashJoinTable hashtable = hjstate->hj_HashTable;
     887     1200560 :     int         curbatch = hashtable->curbatch;
     888             :     TupleTableSlot *slot;
     889             : 
     890             :     /*
     891             :      * In the Parallel Hash case we only run the outer plan directly for
     892             :      * single-batch hash joins.  Otherwise we have to go to batch files, even
     893             :      * for batch 0.
     894             :      */
     895     1200560 :     if (curbatch == 0 && hashtable->nbatch == 1)
     896             :     {
     897      480072 :         slot = ExecProcNode(outerNode);
     898             : 
     899      480072 :         while (!TupIsNull(slot))
     900             :         {
     901      480000 :             ExprContext *econtext = hjstate->js.ps.ps_ExprContext;
     902             : 
     903      480000 :             econtext->ecxt_outertuple = slot;
     904      480000 :             if (ExecHashGetHashValue(hashtable, econtext,
     905             :                                      hjstate->hj_OuterHashKeys,
     906             :                                      true,  /* outer tuple */
     907      480000 :                                      HJ_FILL_OUTER(hjstate),
     908             :                                      hashvalue))
     909      480000 :                 return slot;
     910             : 
     911             :             /*
     912             :              * That tuple couldn't match because of a NULL, so discard it and
     913             :              * continue with the next one.
     914             :              */
     915           0 :             slot = ExecProcNode(outerNode);
     916             :         }
     917             :     }
     918      720488 :     else if (curbatch < hashtable->nbatch)
     919             :     {
     920             :         MinimalTuple tuple;
     921             : 
     922      720488 :         tuple = sts_parallel_scan_next(hashtable->batches[curbatch].outer_tuples,
     923             :                                        hashvalue);
     924      720488 :         if (tuple != NULL)
     925             :         {
     926      720016 :             ExecForceStoreMinimalTuple(tuple,
     927             :                                        hjstate->hj_OuterTupleSlot,
     928             :                                        false);
     929      720016 :             slot = hjstate->hj_OuterTupleSlot;
     930      720016 :             return slot;
     931             :         }
     932             :         else
     933         472 :             ExecClearTuple(hjstate->hj_OuterTupleSlot);
     934             :     }
     935             : 
     936             :     /* End of this batch */
     937         544 :     return NULL;
     938             : }
     939             : 
     940             : /*
     941             :  * ExecHashJoinNewBatch
     942             :  *      switch to a new hashjoin batch
     943             :  *
     944             :  * Returns true if successful, false if there are no more batches.
     945             :  */
     946             : static bool
     947      394416 : ExecHashJoinNewBatch(HashJoinState *hjstate)
     948             : {
     949      394416 :     HashJoinTable hashtable = hjstate->hj_HashTable;
     950             :     int         nbatch;
     951             :     int         curbatch;
     952             :     BufFile    *innerFile;
     953             :     TupleTableSlot *slot;
     954             :     uint32      hashvalue;
     955             : 
     956      394416 :     nbatch = hashtable->nbatch;
     957      394416 :     curbatch = hashtable->curbatch;
     958             : 
     959      394416 :     if (curbatch > 0)
     960             :     {
     961             :         /*
     962             :          * We no longer need the previous outer batch file; close it right
     963             :          * away to free disk space.
     964             :          */
     965         750 :         if (hashtable->outerBatchFile[curbatch])
     966         750 :             BufFileClose(hashtable->outerBatchFile[curbatch]);
     967         750 :         hashtable->outerBatchFile[curbatch] = NULL;
     968             :     }
     969             :     else                        /* we just finished the first batch */
     970             :     {
     971             :         /*
     972             :          * Reset some of the skew optimization state variables, since we no
     973             :          * longer need to consider skew tuples after the first batch. The
     974             :          * memory context reset we are about to do will release the skew
     975             :          * hashtable itself.
     976             :          */
     977      393666 :         hashtable->skewEnabled = false;
     978      393666 :         hashtable->skewBucket = NULL;
     979      393666 :         hashtable->skewBucketNums = NULL;
     980      393666 :         hashtable->nSkewBuckets = 0;
     981      393666 :         hashtable->spaceUsedSkew = 0;
     982             :     }
     983             : 
     984             :     /*
     985             :      * We can always skip over any batches that are completely empty on both
     986             :      * sides.  We can sometimes skip over batches that are empty on only one
     987             :      * side, but there are exceptions:
     988             :      *
     989             :      * 1. In a left/full outer join, we have to process outer batches even if
     990             :      * the inner batch is empty.  Similarly, in a right/full outer join, we
     991             :      * have to process inner batches even if the outer batch is empty.
     992             :      *
     993             :      * 2. If we have increased nbatch since the initial estimate, we have to
     994             :      * scan inner batches since they might contain tuples that need to be
     995             :      * reassigned to later inner batches.
     996             :      *
     997             :      * 3. Similarly, if we have increased nbatch since starting the outer
     998             :      * scan, we have to rescan outer batches in case they contain tuples that
     999             :      * need to be reassigned.
    1000             :      */
    1001      394416 :     curbatch++;
    1002      394416 :     while (curbatch < nbatch &&
    1003         750 :            (hashtable->outerBatchFile[curbatch] == NULL ||
    1004         750 :             hashtable->innerBatchFile[curbatch] == NULL))
    1005             :     {
    1006           0 :         if (hashtable->outerBatchFile[curbatch] &&
    1007           0 :             HJ_FILL_OUTER(hjstate))
    1008           0 :             break;              /* must process due to rule 1 */
    1009           0 :         if (hashtable->innerBatchFile[curbatch] &&
    1010           0 :             HJ_FILL_INNER(hjstate))
    1011           0 :             break;              /* must process due to rule 1 */
    1012           0 :         if (hashtable->innerBatchFile[curbatch] &&
    1013           0 :             nbatch != hashtable->nbatch_original)
    1014           0 :             break;              /* must process due to rule 2 */
    1015           0 :         if (hashtable->outerBatchFile[curbatch] &&
    1016           0 :             nbatch != hashtable->nbatch_outstart)
    1017           0 :             break;              /* must process due to rule 3 */
    1018             :         /* We can ignore this batch. */
    1019             :         /* Release associated temp files right away. */
    1020           0 :         if (hashtable->innerBatchFile[curbatch])
    1021           0 :             BufFileClose(hashtable->innerBatchFile[curbatch]);
    1022           0 :         hashtable->innerBatchFile[curbatch] = NULL;
    1023           0 :         if (hashtable->outerBatchFile[curbatch])
    1024           0 :             BufFileClose(hashtable->outerBatchFile[curbatch]);
    1025           0 :         hashtable->outerBatchFile[curbatch] = NULL;
    1026           0 :         curbatch++;
    1027             :     }
    1028             : 
    1029      394416 :     if (curbatch >= nbatch)
    1030      393666 :         return false;           /* no more batches */
    1031             : 
    1032         750 :     hashtable->curbatch = curbatch;
    1033             : 
    1034             :     /*
    1035             :      * Reload the hash table with the new inner batch (which could be empty)
    1036             :      */
    1037         750 :     ExecHashTableReset(hashtable);
    1038             : 
    1039         750 :     innerFile = hashtable->innerBatchFile[curbatch];
    1040             : 
    1041         750 :     if (innerFile != NULL)
    1042             :     {
    1043         750 :         if (BufFileSeek(innerFile, 0, 0L, SEEK_SET))
    1044           0 :             ereport(ERROR,
    1045             :                     (errcode_for_file_access(),
    1046             :                      errmsg("could not rewind hash-join temporary file")));
    1047             : 
    1048     1567834 :         while ((slot = ExecHashJoinGetSavedTuple(hjstate,
    1049             :                                                  innerFile,
    1050             :                                                  &hashvalue,
    1051             :                                                  hjstate->hj_HashTupleSlot)))
    1052             :         {
    1053             :             /*
    1054             :              * NOTE: some tuples may be sent to future batches.  Also, it is
    1055             :              * possible for hashtable->nbatch to be increased here!
    1056             :              */
    1057     1567084 :             ExecHashTableInsert(hashtable, slot, hashvalue);
    1058             :         }
    1059             : 
    1060             :         /*
    1061             :          * after we build the hash table, the inner batch file is no longer
    1062             :          * needed
    1063             :          */
    1064         750 :         BufFileClose(innerFile);
    1065         750 :         hashtable->innerBatchFile[curbatch] = NULL;
    1066             :     }
    1067             : 
    1068             :     /*
    1069             :      * Rewind outer batch file (if present), so that we can start reading it.
    1070             :      */
    1071         750 :     if (hashtable->outerBatchFile[curbatch] != NULL)
    1072             :     {
    1073         750 :         if (BufFileSeek(hashtable->outerBatchFile[curbatch], 0, 0L, SEEK_SET))
    1074           0 :             ereport(ERROR,
    1075             :                     (errcode_for_file_access(),
    1076             :                      errmsg("could not rewind hash-join temporary file")));
    1077             :     }
    1078             : 
    1079         750 :     return true;
    1080             : }
    1081             : 
    1082             : /*
    1083             :  * Choose a batch to work on, and attach to it.  Returns true if successful,
    1084             :  * false if there are no more batches.
    1085             :  */
    1086             : static bool
    1087         760 : ExecParallelHashJoinNewBatch(HashJoinState *hjstate)
    1088             : {
    1089         760 :     HashJoinTable hashtable = hjstate->hj_HashTable;
    1090             :     int         start_batchno;
    1091             :     int         batchno;
    1092             : 
    1093             :     /*
    1094             :      * If we started up so late that the batch tracking array has been freed
    1095             :      * already by ExecHashTableDetach(), then we are finished.  See also
    1096             :      * ExecParallelHashEnsureBatchAccessors().
    1097             :      */
    1098         760 :     if (hashtable->batches == NULL)
    1099           0 :         return false;
    1100             : 
    1101             :     /*
    1102             :      * If we were already attached to a batch, remember not to bother checking
    1103             :      * it again, and detach from it (possibly freeing the hash table if we are
    1104             :      * last to detach).
    1105             :      */
    1106         760 :     if (hashtable->curbatch >= 0)
    1107             :     {
    1108         544 :         hashtable->batches[hashtable->curbatch].done = true;
    1109         544 :         ExecHashTableDetachBatch(hashtable);
    1110             :     }
    1111             : 
    1112             :     /*
    1113             :      * Search for a batch that isn't done.  We use an atomic counter to start
    1114             :      * our search at a different batch in every participant when there are
    1115             :      * more batches than participants.
    1116             :      */
    1117         760 :     batchno = start_batchno =
    1118         760 :         pg_atomic_fetch_add_u32(&hashtable->parallel_state->distributor, 1) %
    1119         760 :         hashtable->nbatch;
    1120             :     do
    1121             :     {
    1122             :         uint32      hashvalue;
    1123             :         MinimalTuple tuple;
    1124             :         TupleTableSlot *slot;
    1125             : 
    1126        1870 :         if (!hashtable->batches[batchno].done)
    1127             :         {
    1128             :             SharedTuplestoreAccessor *inner_tuples;
    1129        1080 :             Barrier    *batch_barrier =
    1130        1080 :             &hashtable->batches[batchno].shared->batch_barrier;
    1131             : 
    1132        1080 :             switch (BarrierAttach(batch_barrier))
    1133             :             {
    1134         376 :                 case PHJ_BATCH_ELECTING:
    1135             : 
    1136             :                     /* One backend allocates the hash table. */
    1137         376 :                     if (BarrierArriveAndWait(batch_barrier,
    1138             :                                              WAIT_EVENT_HASH_BATCH_ELECT))
    1139         376 :                         ExecParallelHashTableAlloc(hashtable, batchno);
    1140             :                     /* Fall through. */
    1141             : 
    1142             :                 case PHJ_BATCH_ALLOCATING:
    1143             :                     /* Wait for allocation to complete. */
    1144         378 :                     BarrierArriveAndWait(batch_barrier,
    1145             :                                          WAIT_EVENT_HASH_BATCH_ALLOCATE);
    1146             :                     /* Fall through. */
    1147             : 
    1148         396 :                 case PHJ_BATCH_LOADING:
    1149             :                     /* Start (or join in) loading tuples. */
    1150         396 :                     ExecParallelHashTableSetCurrentBatch(hashtable, batchno);
    1151         396 :                     inner_tuples = hashtable->batches[batchno].inner_tuples;
    1152         396 :                     sts_begin_parallel_scan(inner_tuples);
    1153      653514 :                     while ((tuple = sts_parallel_scan_next(inner_tuples,
    1154             :                                                            &hashvalue)))
    1155             :                     {
    1156      653118 :                         ExecForceStoreMinimalTuple(tuple,
    1157             :                                                    hjstate->hj_HashTupleSlot,
    1158             :                                                    false);
    1159      653118 :                         slot = hjstate->hj_HashTupleSlot;
    1160      653118 :                         ExecParallelHashTableInsertCurrentBatch(hashtable, slot,
    1161             :                                                                 hashvalue);
    1162             :                     }
    1163         396 :                     sts_end_parallel_scan(inner_tuples);
    1164         396 :                     BarrierArriveAndWait(batch_barrier,
    1165             :                                          WAIT_EVENT_HASH_BATCH_LOAD);
    1166             :                     /* Fall through. */
    1167             : 
    1168         544 :                 case PHJ_BATCH_PROBING:
    1169             : 
    1170             :                     /*
    1171             :                      * This batch is ready to probe.  Return control to
    1172             :                      * caller. We stay attached to batch_barrier so that the
    1173             :                      * hash table stays alive until everyone's finished
    1174             :                      * probing it, but no participant is allowed to wait at
    1175             :                      * this barrier again (or else a deadlock could occur).
    1176             :                      * All attached participants must eventually call
    1177             :                      * BarrierArriveAndDetach() so that the final phase
    1178             :                      * PHJ_BATCH_DONE can be reached.
    1179             :                      */
    1180         544 :                     ExecParallelHashTableSetCurrentBatch(hashtable, batchno);
    1181         544 :                     sts_begin_parallel_scan(hashtable->batches[batchno].outer_tuples);
    1182         544 :                     return true;
    1183             : 
    1184         536 :                 case PHJ_BATCH_DONE:
    1185             : 
    1186             :                     /*
    1187             :                      * Already done.  Detach and go around again (if any
    1188             :                      * remain).
    1189             :                      */
    1190         536 :                     BarrierDetach(batch_barrier);
    1191         536 :                     hashtable->batches[batchno].done = true;
    1192         536 :                     hashtable->curbatch = -1;
    1193         536 :                     break;
    1194             : 
    1195           0 :                 default:
    1196           0 :                     elog(ERROR, "unexpected batch phase %d",
    1197             :                          BarrierPhase(batch_barrier));
    1198             :             }
    1199             :         }
    1200        1326 :         batchno = (batchno + 1) % hashtable->nbatch;
    1201        1326 :     } while (batchno != start_batchno);
    1202             : 
    1203         216 :     return false;
    1204             : }
    1205             : 
    1206             : /*
    1207             :  * ExecHashJoinSaveTuple
    1208             :  *      save a tuple to a batch file.
    1209             :  *
    1210             :  * The data recorded in the file for each tuple is its hash value,
    1211             :  * then the tuple in MinimalTuple format.
    1212             :  *
    1213             :  * Note: it is important always to call this in the regular executor
    1214             :  * context, not in a shorter-lived context; else the temp file buffers
    1215             :  * will get messed up.
    1216             :  */
    1217             : void
    1218     2553212 : ExecHashJoinSaveTuple(MinimalTuple tuple, uint32 hashvalue,
    1219             :                       BufFile **fileptr)
    1220             : {
    1221     2553212 :     BufFile    *file = *fileptr;
    1222             : 
    1223     2553212 :     if (file == NULL)
    1224             :     {
    1225             :         /* First write to this batch file, so open it. */
    1226        1500 :         file = BufFileCreateTemp(false);
    1227        1500 :         *fileptr = file;
    1228             :     }
    1229             : 
    1230     2553212 :     BufFileWrite(file, (void *) &hashvalue, sizeof(uint32));
    1231     2553212 :     BufFileWrite(file, (void *) tuple, tuple->t_len);
    1232     2553212 : }
    1233             : 
    1234             : /*
    1235             :  * ExecHashJoinGetSavedTuple
    1236             :  *      read the next tuple from a batch file.  Return NULL if no more.
    1237             :  *
    1238             :  * On success, *hashvalue is set to the tuple's hash value, and the tuple
    1239             :  * itself is stored in the given slot.
    1240             :  */
    1241             : static TupleTableSlot *
    1242     2554712 : ExecHashJoinGetSavedTuple(HashJoinState *hjstate,
    1243             :                           BufFile *file,
    1244             :                           uint32 *hashvalue,
    1245             :                           TupleTableSlot *tupleSlot)
    1246             : {
    1247             :     uint32      header[2];
    1248             :     size_t      nread;
    1249             :     MinimalTuple tuple;
    1250             : 
    1251             :     /*
    1252             :      * We check for interrupts here because this is typically taken as an
    1253             :      * alternative code path to an ExecProcNode() call, which would include
    1254             :      * such a check.
    1255             :      */
    1256     2554712 :     CHECK_FOR_INTERRUPTS();
    1257             : 
    1258             :     /*
    1259             :      * Since both the hash value and the MinimalTuple length word are uint32,
    1260             :      * we can read them both in one BufFileRead() call without any type
    1261             :      * cheating.
    1262             :      */
    1263     2554712 :     nread = BufFileRead(file, (void *) header, sizeof(header));
    1264     2554712 :     if (nread == 0)             /* end of file */
    1265             :     {
    1266        1500 :         ExecClearTuple(tupleSlot);
    1267        1500 :         return NULL;
    1268             :     }
    1269     2553212 :     if (nread != sizeof(header))
    1270           0 :         ereport(ERROR,
    1271             :                 (errcode_for_file_access(),
    1272             :                  errmsg("could not read from hash-join temporary file: read only %zu of %zu bytes",
    1273             :                         nread, sizeof(header))));
    1274     2553212 :     *hashvalue = header[0];
    1275     2553212 :     tuple = (MinimalTuple) palloc(header[1]);
    1276     2553212 :     tuple->t_len = header[1];
    1277     2553212 :     nread = BufFileRead(file,
    1278             :                         (void *) ((char *) tuple + sizeof(uint32)),
    1279     2553212 :                         header[1] - sizeof(uint32));
    1280     2553212 :     if (nread != header[1] - sizeof(uint32))
    1281           0 :         ereport(ERROR,
    1282             :                 (errcode_for_file_access(),
    1283             :                  errmsg("could not read from hash-join temporary file: read only %zu of %zu bytes",
    1284             :                         nread, header[1] - sizeof(uint32))));
    1285     2553212 :     ExecForceStoreMinimalTuple(tuple, tupleSlot, true);
    1286     2553212 :     return tupleSlot;
    1287             : }
    1288             : 
    1289             : 
    1290             : void
    1291     1372906 : ExecReScanHashJoin(HashJoinState *node)
    1292             : {
    1293             :     /*
    1294             :      * In a multi-batch join, we currently have to do rescans the hard way,
    1295             :      * primarily because batch temp files may have already been released. But
    1296             :      * if it's a single-batch join, and there is no parameter change for the
    1297             :      * inner subnode, then we can just re-use the existing hash table without
    1298             :      * rebuilding it.
    1299             :      */
    1300     1372906 :     if (node->hj_HashTable != NULL)
    1301             :     {
    1302      357376 :         if (node->hj_HashTable->nbatch == 1 &&
    1303      357376 :             node->js.ps.righttree->chgParam == NULL)
    1304             :         {
    1305             :             /*
    1306             :              * Okay to reuse the hash table; needn't rescan inner, either.
    1307             :              *
    1308             :              * However, if it's a right/full join, we'd better reset the
    1309             :              * inner-tuple match flags contained in the table.
    1310             :              */
    1311         340 :             if (HJ_FILL_INNER(node))
    1312          20 :                 ExecHashTableResetMatchFlags(node->hj_HashTable);
    1313             : 
    1314             :             /*
    1315             :              * Also, we need to reset our state about the emptiness of the
    1316             :              * outer relation, so that the new scan of the outer will update
    1317             :              * it correctly if it turns out to be empty this time. (There's no
    1318             :              * harm in clearing it now because ExecHashJoin won't need the
    1319             :              * info.  In the other cases, where the hash table doesn't exist
    1320             :              * or we are destroying it, we leave this state alone because
    1321             :              * ExecHashJoin will need it the first time through.)
    1322             :              */
    1323         340 :             node->hj_OuterNotEmpty = false;
    1324             : 
    1325             :             /* ExecHashJoin can skip the BUILD_HASHTABLE step */
    1326         340 :             node->hj_JoinState = HJ_NEED_NEW_OUTER;
    1327             :         }
    1328             :         else
    1329             :         {
    1330             :             /* must destroy and rebuild hash table */
    1331      357036 :             HashState  *hashNode = castNode(HashState, innerPlanState(node));
    1332             : 
    1333             :             Assert(hashNode->hashtable == node->hj_HashTable);
    1334             :             /* accumulate stats from old hash table, if wanted */
    1335             :             /* (this should match ExecShutdownHash) */
    1336      357036 :             if (hashNode->ps.instrument && !hashNode->hinstrument)
    1337           0 :                 hashNode->hinstrument = (HashInstrumentation *)
    1338           0 :                     palloc0(sizeof(HashInstrumentation));
    1339      357036 :             if (hashNode->hinstrument)
    1340           0 :                 ExecHashAccumInstrumentation(hashNode->hinstrument,
    1341             :                                              hashNode->hashtable);
    1342             :             /* for safety, be sure to clear child plan node's pointer too */
    1343      357036 :             hashNode->hashtable = NULL;
    1344             : 
    1345      357036 :             ExecHashTableDestroy(node->hj_HashTable);
    1346      357036 :             node->hj_HashTable = NULL;
    1347      357036 :             node->hj_JoinState = HJ_BUILD_HASHTABLE;
    1348             : 
    1349             :             /*
    1350             :              * if chgParam of subnode is not null then plan will be re-scanned
    1351             :              * by first ExecProcNode.
    1352             :              */
    1353      357036 :             if (node->js.ps.righttree->chgParam == NULL)
    1354           0 :                 ExecReScan(node->js.ps.righttree);
    1355             :         }
    1356             :     }
    1357             : 
    1358             :     /* Always reset intra-tuple state */
    1359     1372906 :     node->hj_CurHashValue = 0;
    1360     1372906 :     node->hj_CurBucketNo = 0;
    1361     1372906 :     node->hj_CurSkewBucketNo = INVALID_SKEW_BUCKET_NO;
    1362     1372906 :     node->hj_CurTuple = NULL;
    1363             : 
    1364     1372906 :     node->hj_MatchedOuter = false;
    1365     1372906 :     node->hj_FirstOuterTupleSlot = NULL;
    1366             : 
    1367             :     /*
    1368             :      * if chgParam of subnode is not null then plan will be re-scanned by
    1369             :      * first ExecProcNode.
    1370             :      */
    1371     1372906 :     if (node->js.ps.lefttree->chgParam == NULL)
    1372        4986 :         ExecReScan(node->js.ps.lefttree);
    1373     1372906 : }
    1374             : 
    1375             : void
    1376       44106 : ExecShutdownHashJoin(HashJoinState *node)
    1377             : {
    1378       44106 :     if (node->hj_HashTable)
    1379             :     {
    1380             :         /*
    1381             :          * Detach from shared state before DSM memory goes away.  This makes
    1382             :          * sure that we don't have any pointers into DSM memory by the time
    1383             :          * ExecEndHashJoin runs.
    1384             :          */
    1385       37318 :         ExecHashTableDetachBatch(node->hj_HashTable);
    1386       37318 :         ExecHashTableDetach(node->hj_HashTable);
    1387             :     }
    1388       44106 : }
    1389             : 
    1390             : static void
    1391          86 : ExecParallelHashJoinPartitionOuter(HashJoinState *hjstate)
    1392             : {
    1393          86 :     PlanState  *outerState = outerPlanState(hjstate);
    1394          86 :     ExprContext *econtext = hjstate->js.ps.ps_ExprContext;
    1395          86 :     HashJoinTable hashtable = hjstate->hj_HashTable;
    1396             :     TupleTableSlot *slot;
    1397             :     uint32      hashvalue;
    1398             :     int         i;
    1399             : 
    1400             :     Assert(hjstate->hj_FirstOuterTupleSlot == NULL);
    1401             : 
    1402             :     /* Execute outer plan, writing all tuples to shared tuplestores. */
    1403             :     for (;;)
    1404             :     {
    1405      720102 :         slot = ExecProcNode(outerState);
    1406      720102 :         if (TupIsNull(slot))
    1407             :             break;
    1408      720016 :         econtext->ecxt_outertuple = slot;
    1409      720016 :         if (ExecHashGetHashValue(hashtable, econtext,
    1410             :                                  hjstate->hj_OuterHashKeys,
    1411             :                                  true,  /* outer tuple */
    1412      720016 :                                  HJ_FILL_OUTER(hjstate),
    1413             :                                  &hashvalue))
    1414             :         {
    1415             :             int         batchno;
    1416             :             int         bucketno;
    1417             :             bool        shouldFree;
    1418      720016 :             MinimalTuple mintup = ExecFetchSlotMinimalTuple(slot, &shouldFree);
    1419             : 
    1420      720016 :             ExecHashGetBucketAndBatch(hashtable, hashvalue, &bucketno,
    1421             :                                       &batchno);
    1422      720016 :             sts_puttuple(hashtable->batches[batchno].outer_tuples,
    1423             :                          &hashvalue, mintup);
    1424             : 
    1425      720016 :             if (shouldFree)
    1426      720016 :                 heap_free_minimal_tuple(mintup);
    1427             :         }
    1428      720016 :         CHECK_FOR_INTERRUPTS();
    1429             :     }
    1430             : 
    1431             :     /* Make sure all outer partitions are readable by any backend. */
    1432         766 :     for (i = 0; i < hashtable->nbatch; ++i)
    1433         680 :         sts_end_write(hashtable->batches[i].outer_tuples);
    1434          86 : }
    1435             : 
    1436             : void
    1437          64 : ExecHashJoinEstimate(HashJoinState *state, ParallelContext *pcxt)
    1438             : {
    1439          64 :     shm_toc_estimate_chunk(&pcxt->estimator, sizeof(ParallelHashJoinState));
    1440          64 :     shm_toc_estimate_keys(&pcxt->estimator, 1);
    1441          64 : }
    1442             : 
    1443             : void
    1444          64 : ExecHashJoinInitializeDSM(HashJoinState *state, ParallelContext *pcxt)
    1445             : {
    1446          64 :     int         plan_node_id = state->js.ps.plan->plan_node_id;
    1447             :     HashState  *hashNode;
    1448             :     ParallelHashJoinState *pstate;
    1449             : 
    1450             :     /*
    1451             :      * Disable shared hash table mode if we failed to create a real DSM
    1452             :      * segment, because that means that we don't have a DSA area to work with.
    1453             :      */
    1454          64 :     if (pcxt->seg == NULL)
    1455           0 :         return;
    1456             : 
    1457          64 :     ExecSetExecProcNode(&state->js.ps, ExecParallelHashJoin);
    1458             : 
    1459             :     /*
    1460             :      * Set up the state needed to coordinate access to the shared hash
    1461             :      * table(s), using the plan node ID as the toc key.
    1462             :      */
    1463          64 :     pstate = shm_toc_allocate(pcxt->toc, sizeof(ParallelHashJoinState));
    1464          64 :     shm_toc_insert(pcxt->toc, plan_node_id, pstate);
    1465             : 
    1466             :     /*
    1467             :      * Set up the shared hash join state with no batches initially.
    1468             :      * ExecHashTableCreate() will prepare at least one later and set nbatch
    1469             :      * and space_allowed.
    1470             :      */
    1471          64 :     pstate->nbatch = 0;
    1472          64 :     pstate->space_allowed = 0;
    1473          64 :     pstate->batches = InvalidDsaPointer;
    1474          64 :     pstate->old_batches = InvalidDsaPointer;
    1475          64 :     pstate->nbuckets = 0;
    1476          64 :     pstate->growth = PHJ_GROWTH_OK;
    1477          64 :     pstate->chunk_work_queue = InvalidDsaPointer;
    1478          64 :     pg_atomic_init_u32(&pstate->distributor, 0);
    1479          64 :     pstate->nparticipants = pcxt->nworkers + 1;
    1480          64 :     pstate->total_tuples = 0;
    1481          64 :     LWLockInitialize(&pstate->lock,
    1482             :                      LWTRANCHE_PARALLEL_HASH_JOIN);
    1483          64 :     BarrierInit(&pstate->build_barrier, 0);
    1484          64 :     BarrierInit(&pstate->grow_batches_barrier, 0);
    1485          64 :     BarrierInit(&pstate->grow_buckets_barrier, 0);
    1486             : 
    1487             :     /* Set up the space we'll use for shared temporary files. */
    1488          64 :     SharedFileSetInit(&pstate->fileset, pcxt->seg);
    1489             : 
    1490             :     /* Initialize the shared state in the hash node. */
    1491          64 :     hashNode = (HashState *) innerPlanState(state);
    1492          64 :     hashNode->parallel_state = pstate;
    1493             : }
    1494             : 
    1495             : /* ----------------------------------------------------------------
    1496             :  *      ExecHashJoinReInitializeDSM
    1497             :  *
    1498             :  *      Reset shared state before beginning a fresh scan.
    1499             :  * ----------------------------------------------------------------
    1500             :  */
    1501             : void
    1502          32 : ExecHashJoinReInitializeDSM(HashJoinState *state, ParallelContext *cxt)
    1503             : {
    1504          32 :     int         plan_node_id = state->js.ps.plan->plan_node_id;
    1505             :     ParallelHashJoinState *pstate =
    1506          32 :     shm_toc_lookup(cxt->toc, plan_node_id, false);
    1507             : 
    1508             :     /*
    1509             :      * It would be possible to reuse the shared hash table in single-batch
    1510             :      * cases by resetting and then fast-forwarding build_barrier to
    1511             :      * PHJ_BUILD_DONE and batch 0's batch_barrier to PHJ_BATCH_PROBING, but
    1512             :      * currently shared hash tables are already freed by now (by the last
    1513             :      * participant to detach from the batch).  We could consider keeping it
    1514             :      * around for single-batch joins.  We'd also need to adjust
    1515             :      * finalize_plan() so that it doesn't record a dummy dependency for
    1516             :      * Parallel Hash nodes, preventing the rescan optimization.  For now we
    1517             :      * don't try.
    1518             :      */
    1519             : 
    1520             :     /* Detach, freeing any remaining shared memory. */
    1521          32 :     if (state->hj_HashTable != NULL)
    1522             :     {
    1523           0 :         ExecHashTableDetachBatch(state->hj_HashTable);
    1524           0 :         ExecHashTableDetach(state->hj_HashTable);
    1525             :     }
    1526             : 
    1527             :     /* Clear any shared batch files. */
    1528          32 :     SharedFileSetDeleteAll(&pstate->fileset);
    1529             : 
    1530             :     /* Reset build_barrier to PHJ_BUILD_ELECTING so we can go around again. */
    1531          32 :     BarrierInit(&pstate->build_barrier, 0);
    1532          32 : }
    1533             : 
    1534             : void
    1535         172 : ExecHashJoinInitializeWorker(HashJoinState *state,
    1536             :                              ParallelWorkerContext *pwcxt)
    1537             : {
    1538             :     HashState  *hashNode;
    1539         172 :     int         plan_node_id = state->js.ps.plan->plan_node_id;
    1540             :     ParallelHashJoinState *pstate =
    1541         172 :     shm_toc_lookup(pwcxt->toc, plan_node_id, false);
    1542             : 
    1543             :     /* Attach to the space for shared temporary files. */
    1544         172 :     SharedFileSetAttach(&pstate->fileset, pwcxt->seg);
    1545             : 
    1546             :     /* Attach to the shared state in the hash node. */
    1547         172 :     hashNode = (HashState *) innerPlanState(state);
    1548         172 :     hashNode->parallel_state = pstate;
    1549             : 
    1550         172 :     ExecSetExecProcNode(&state->js.ps, ExecParallelHashJoin);
    1551         172 : }

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