LCOV - code coverage report
Current view: top level - src/backend/executor - nodeHashjoin.c (source / functions) Hit Total Coverage
Test: PostgreSQL 13devel Lines: 401 436 92.0 %
Date: 2019-09-19 02:07:14 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) 1996-2019, 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             :  * work_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 work_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     7072314 : ExecHashJoinImpl(PlanState *pstate, bool parallel)
     166             : {
     167     7072314 :     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     7072314 :     joinqual = node->js.joinqual;
     183     7072314 :     otherqual = node->js.ps.qual;
     184     7072314 :     hashNode = (HashState *) innerPlanState(node);
     185     7072314 :     outerNode = outerPlanState(node);
     186     7072314 :     hashtable = node->hj_HashTable;
     187     7072314 :     econtext = node->js.ps.ps_ExprContext;
     188     7072314 :     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     7072314 :     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    42282674 :         CHECK_FOR_INTERRUPTS();
     208             : 
     209    24677494 :         switch (node->hj_JoinState)
     210             :         {
     211             :             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     1083392 :                 if (HJ_FILL_INNER(node))
     242             :                 {
     243             :                     /* no chance to not build the hash table */
     244        3866 :                     node->hj_FirstOuterTupleSlot = NULL;
     245             :                 }
     246     1079526 :                 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         224 :                     node->hj_FirstOuterTupleSlot = NULL;
     257             :                 }
     258     1090292 :                 else if (HJ_FILL_OUTER(node) ||
     259       21702 :                          (outerNode->plan->startup_cost < hashNode->ps.plan->total_cost &&
     260       10712 :                           !node->hj_OuterNotEmpty))
     261             :                 {
     262     1078342 :                     node->hj_FirstOuterTupleSlot = ExecProcNode(outerNode);
     263     1331126 :                     if (TupIsNull(node->hj_FirstOuterTupleSlot))
     264             :                     {
     265      825558 :                         node->hj_OuterNotEmpty = false;
     266      825558 :                         return NULL;
     267             :                     }
     268             :                     else
     269      252784 :                         node->hj_OuterNotEmpty = true;
     270             :                 }
     271             :                 else
     272         960 :                     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      257834 :                 hashtable = ExecHashTableCreate(hashNode,
     280             :                                                 node->hj_HashOperators,
     281             :                                                 node->hj_Collations,
     282      257834 :                                                 HJ_FILL_INNER(node));
     283      257834 :                 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      257834 :                 hashNode->hashtable = hashtable;
     291      257834 :                 (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      257834 :                 if (hashtable->totalTuples == 0 && !HJ_FILL_OUTER(node))
     299        1822 :                     return NULL;
     300             : 
     301             :                 /*
     302             :                  * need to remember whether nbatch has increased since we
     303             :                  * began scanning the outer relation
     304             :                  */
     305      256012 :                 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      256012 :                 node->hj_OuterNotEmpty = false;
     313             : 
     314      256012 :                 if (parallel)
     315             :                 {
     316             :                     Barrier    *build_barrier;
     317             : 
     318         224 :                     build_barrier = &parallel_state->build_barrier;
     319             :                     Assert(BarrierPhase(build_barrier) == PHJ_BUILD_HASHING_OUTER ||
     320             :                            BarrierPhase(build_barrier) == PHJ_BUILD_DONE);
     321         224 :                     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         160 :                         if (hashtable->nbatch > 1)
     328          94 :                             ExecParallelHashJoinPartitionOuter(node);
     329         160 :                         BarrierArriveAndWait(build_barrier,
     330             :                                              WAIT_EVENT_HASH_BUILD_HASHING_OUTER);
     331             :                     }
     332             :                     Assert(BarrierPhase(build_barrier) == PHJ_BUILD_DONE);
     333             : 
     334             :                     /* Each backend should now select a batch to work on. */
     335         224 :                     hashtable->curbatch = -1;
     336         224 :                     node->hj_JoinState = HJ_NEED_NEW_BATCH;
     337             : 
     338         224 :                     continue;
     339             :                 }
     340             :                 else
     341      255788 :                     node->hj_JoinState = HJ_NEED_NEW_OUTER;
     342             : 
     343             :                 /* FALL THRU */
     344             : 
     345             :             case HJ_NEED_NEW_OUTER:
     346             : 
     347             :                 /*
     348             :                  * We don't have an outer tuple, try to get the next one
     349             :                  */
     350    10760230 :                 if (parallel)
     351     1200580 :                     outerTupleSlot =
     352             :                         ExecParallelHashJoinOuterGetTuple(outerNode, node,
     353             :                                                           &hashvalue);
     354             :                 else
     355     9559650 :                     outerTupleSlot =
     356             :                         ExecHashJoinOuterGetTuple(outerNode, node, &hashvalue);
     357             : 
     358    10760230 :                 if (TupIsNull(outerTupleSlot))
     359             :                 {
     360             :                     /* end of batch, or maybe whole join */
     361      257208 :                     if (HJ_FILL_INNER(node))
     362             :                     {
     363             :                         /* set up to scan for unmatched inner tuples */
     364        3676 :                         ExecPrepHashTableForUnmatched(node);
     365        3676 :                         node->hj_JoinState = HJ_FILL_INNER_TUPLES;
     366             :                     }
     367             :                     else
     368      253532 :                         node->hj_JoinState = HJ_NEED_NEW_BATCH;
     369      257208 :                     continue;
     370             :                 }
     371             : 
     372    10503022 :                 econtext->ecxt_outertuple = outerTupleSlot;
     373    10503022 :                 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    10503022 :                 node->hj_CurHashValue = hashvalue;
     380    10503022 :                 ExecHashGetBucketAndBatch(hashtable, hashvalue,
     381             :                                           &node->hj_CurBucketNo, &batchno);
     382    10503022 :                 node->hj_CurSkewBucketNo = ExecHashGetSkewBucket(hashtable,
     383             :                                                                  hashvalue);
     384    10503022 :                 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    11489550 :                 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     9516894 :                 node->hj_JoinState = HJ_SCAN_BUCKET;
     415             : 
     416             :                 /* FALL THRU */
     417             : 
     418             :             case HJ_SCAN_BUCKET:
     419             : 
     420             :                 /*
     421             :                  * Scan the selected hash bucket for matches to current outer
     422             :                  */
     423    14430468 :                 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    12030436 :                     if (!ExecScanHashBucket(node, econtext))
     435             :                     {
     436             :                         /* out of matches; check for possible outer-join fill */
     437     6512144 :                         node->hj_JoinState = HJ_FILL_OUTER_TUPLE;
     438     6512144 :                         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     6718308 :                 if (joinqual == NULL || ExecQual(joinqual, econtext))
     455             :                 {
     456     6632696 :                     node->hj_MatchedOuter = true;
     457     6632696 :                     HeapTupleHeaderSetMatch(HJTUPLE_MINTUPLE(node->hj_CurTuple));
     458             : 
     459             :                     /* In an antijoin, we never return a matched tuple */
     460     6632696 :                     if (node->js.jointype == JOIN_ANTI)
     461             :                     {
     462     1445658 :                         node->hj_JoinState = HJ_NEED_NEW_OUTER;
     463     1445658 :                         continue;
     464             :                     }
     465             : 
     466             :                     /*
     467             :                      * If we only need to join to the first matching inner
     468             :                      * tuple, then consider returning this one, but after that
     469             :                      * continue with next outer tuple.
     470             :                      */
     471     5187038 :                     if (node->js.single_match)
     472      359036 :                         node->hj_JoinState = HJ_NEED_NEW_OUTER;
     473             : 
     474     5250972 :                     if (otherqual == NULL || ExecQual(otherqual, econtext))
     475     5123104 :                         return ExecProject(node->js.ps.ps_ProjInfo);
     476             :                     else
     477       63934 :                         InstrCountFiltered2(node, 1);
     478             :                 }
     479             :                 else
     480       85612 :                     InstrCountFiltered1(node, 1);
     481      149546 :                 break;
     482             : 
     483             :             case HJ_FILL_OUTER_TUPLE:
     484             : 
     485             :                 /*
     486             :                  * The current outer tuple has run out of matches, so check
     487             :                  * whether to emit a dummy outer-join tuple.  Whether we emit
     488             :                  * one or not, the next state is NEED_NEW_OUTER.
     489             :                  */
     490     7712160 :                 node->hj_JoinState = HJ_NEED_NEW_OUTER;
     491             : 
     492    11465948 :                 if (!node->hj_MatchedOuter &&
     493     3753788 :                     HJ_FILL_OUTER(node))
     494             :                 {
     495             :                     /*
     496             :                      * Generate a fake join tuple with nulls for the inner
     497             :                      * tuple, and return it if it passes the non-join quals.
     498             :                      */
     499     1166842 :                     econtext->ecxt_innertuple = node->hj_NullInnerTupleSlot;
     500             : 
     501     1166842 :                     if (otherqual == NULL || ExecQual(otherqual, econtext))
     502      663574 :                         return ExecProject(node->js.ps.ps_ProjInfo);
     503             :                     else
     504      503268 :                         InstrCountFiltered2(node, 1);
     505             :                 }
     506     7048586 :                 break;
     507             : 
     508             :             case HJ_FILL_INNER_TUPLES:
     509             : 
     510             :                 /*
     511             :                  * We have finished a batch, but we are doing right/full join,
     512             :                  * so any unmatched inner tuples in the hashtable have to be
     513             :                  * emitted before we continue to the next batch.
     514             :                  */
     515      206498 :                 if (!ExecScanHashTableForUnmatched(node, econtext))
     516             :                 {
     517             :                     /* no more unmatched tuples */
     518        3672 :                     node->hj_JoinState = HJ_NEED_NEW_BATCH;
     519        3672 :                     continue;
     520             :                 }
     521             : 
     522             :                 /*
     523             :                  * Generate a fake join tuple with nulls for the outer tuple,
     524             :                  * and return it if it passes the non-join quals.
     525             :                  */
     526      202826 :                 econtext->ecxt_outertuple = node->hj_NullOuterTupleSlot;
     527             : 
     528      202826 :                 if (otherqual == NULL || ExecQual(otherqual, econtext))
     529      202274 :                     return ExecProject(node->js.ps.ps_ProjInfo);
     530             :                 else
     531         552 :                     InstrCountFiltered2(node, 1);
     532         552 :                 break;
     533             : 
     534             :             case HJ_NEED_NEW_BATCH:
     535             : 
     536             :                 /*
     537             :                  * Try to advance to next batch.  Done if there are no more.
     538             :                  */
     539      257428 :                 if (parallel)
     540             :                 {
     541         788 :                     if (!ExecParallelHashJoinNewBatch(node))
     542         224 :                         return NULL;    /* end of parallel-aware join */
     543             :                 }
     544             :                 else
     545             :                 {
     546      256640 :                     if (!ExecHashJoinNewBatch(node))
     547      255758 :                         return NULL;    /* end of parallel-oblivious join */
     548             :                 }
     549        1446 :                 node->hj_JoinState = HJ_NEED_NEW_OUTER;
     550        1446 :                 break;
     551             : 
     552             :             default:
     553           0 :                 elog(ERROR, "unrecognized hashjoin state: %d",
     554             :                      (int) node->hj_JoinState);
     555             :         }
     556             :     }
     557             : }
     558             : 
     559             : /* ----------------------------------------------------------------
     560             :  *      ExecHashJoin
     561             :  *
     562             :  *      Parallel-oblivious version.
     563             :  * ----------------------------------------------------------------
     564             :  */
     565             : static TupleTableSlot *         /* return: a tuple or NULL */
     566     5872074 : ExecHashJoin(PlanState *pstate)
     567             : {
     568             :     /*
     569             :      * On sufficiently smart compilers this should be inlined with the
     570             :      * parallel-aware branches removed.
     571             :      */
     572     5872074 :     return ExecHashJoinImpl(pstate, false);
     573             : }
     574             : 
     575             : /* ----------------------------------------------------------------
     576             :  *      ExecParallelHashJoin
     577             :  *
     578             :  *      Parallel-aware version.
     579             :  * ----------------------------------------------------------------
     580             :  */
     581             : static TupleTableSlot *         /* return: a tuple or NULL */
     582     1200240 : ExecParallelHashJoin(PlanState *pstate)
     583             : {
     584             :     /*
     585             :      * On sufficiently smart compilers this should be inlined with the
     586             :      * parallel-oblivious branches removed.
     587             :      */
     588     1200240 :     return ExecHashJoinImpl(pstate, true);
     589             : }
     590             : 
     591             : /* ----------------------------------------------------------------
     592             :  *      ExecInitHashJoin
     593             :  *
     594             :  *      Init routine for HashJoin node.
     595             :  * ----------------------------------------------------------------
     596             :  */
     597             : HashJoinState *
     598       26618 : ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
     599             : {
     600             :     HashJoinState *hjstate;
     601             :     Plan       *outerNode;
     602             :     Hash       *hashNode;
     603             :     TupleDesc   outerDesc,
     604             :                 innerDesc;
     605             :     const TupleTableSlotOps *ops;
     606             : 
     607             :     /* check for unsupported flags */
     608             :     Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
     609             : 
     610             :     /*
     611             :      * create state structure
     612             :      */
     613       26618 :     hjstate = makeNode(HashJoinState);
     614       26618 :     hjstate->js.ps.plan = (Plan *) node;
     615       26618 :     hjstate->js.ps.state = estate;
     616             : 
     617             :     /*
     618             :      * See ExecHashJoinInitializeDSM() and ExecHashJoinInitializeWorker()
     619             :      * where this function may be replaced with a parallel version, if we
     620             :      * managed to launch a parallel query.
     621             :      */
     622       26618 :     hjstate->js.ps.ExecProcNode = ExecHashJoin;
     623       26618 :     hjstate->js.jointype = node->join.jointype;
     624             : 
     625             :     /*
     626             :      * Miscellaneous initialization
     627             :      *
     628             :      * create expression context for node
     629             :      */
     630       26618 :     ExecAssignExprContext(estate, &hjstate->js.ps);
     631             : 
     632             :     /*
     633             :      * initialize child nodes
     634             :      *
     635             :      * Note: we could suppress the REWIND flag for the inner input, which
     636             :      * would amount to betting that the hash will be a single batch.  Not
     637             :      * clear if this would be a win or not.
     638             :      */
     639       26618 :     outerNode = outerPlan(node);
     640       26618 :     hashNode = (Hash *) innerPlan(node);
     641             : 
     642       26618 :     outerPlanState(hjstate) = ExecInitNode(outerNode, estate, eflags);
     643       26618 :     outerDesc = ExecGetResultType(outerPlanState(hjstate));
     644       26618 :     innerPlanState(hjstate) = ExecInitNode((Plan *) hashNode, estate, eflags);
     645       26618 :     innerDesc = ExecGetResultType(innerPlanState(hjstate));
     646             : 
     647             :     /*
     648             :      * Initialize result slot, type and projection.
     649             :      */
     650       26618 :     ExecInitResultTupleSlotTL(&hjstate->js.ps, &TTSOpsVirtual);
     651       26618 :     ExecAssignProjectionInfo(&hjstate->js.ps, NULL);
     652             : 
     653             :     /*
     654             :      * tuple table initialization
     655             :      */
     656       26618 :     ops = ExecGetResultSlotOps(outerPlanState(hjstate), NULL);
     657       26618 :     hjstate->hj_OuterTupleSlot = ExecInitExtraTupleSlot(estate, outerDesc,
     658             :                                                         ops);
     659             : 
     660             :     /*
     661             :      * detect whether we need only consider the first matching inner tuple
     662             :      */
     663       42428 :     hjstate->js.single_match = (node->join.inner_unique ||
     664       15810 :                                 node->join.jointype == JOIN_SEMI);
     665             : 
     666             :     /* set up null tuples for outer joins, if needed */
     667       26618 :     switch (node->join.jointype)
     668             :     {
     669             :         case JOIN_INNER:
     670             :         case JOIN_SEMI:
     671       12332 :             break;
     672             :         case JOIN_LEFT:
     673             :         case JOIN_ANTI:
     674       10100 :             hjstate->hj_NullInnerTupleSlot =
     675       10100 :                 ExecInitNullTupleSlot(estate, innerDesc, &TTSOpsVirtual);
     676       10100 :             break;
     677             :         case JOIN_RIGHT:
     678        3804 :             hjstate->hj_NullOuterTupleSlot =
     679        3804 :                 ExecInitNullTupleSlot(estate, outerDesc, &TTSOpsVirtual);
     680        3804 :             break;
     681             :         case JOIN_FULL:
     682         382 :             hjstate->hj_NullOuterTupleSlot =
     683         382 :                 ExecInitNullTupleSlot(estate, outerDesc, &TTSOpsVirtual);
     684         382 :             hjstate->hj_NullInnerTupleSlot =
     685         382 :                 ExecInitNullTupleSlot(estate, innerDesc, &TTSOpsVirtual);
     686         382 :             break;
     687             :         default:
     688           0 :             elog(ERROR, "unrecognized join type: %d",
     689             :                  (int) node->join.jointype);
     690             :     }
     691             : 
     692             :     /*
     693             :      * now for some voodoo.  our temporary tuple slot is actually the result
     694             :      * tuple slot of the Hash node (which is our inner plan).  we can do this
     695             :      * because Hash nodes don't return tuples via ExecProcNode() -- instead
     696             :      * the hash join node uses ExecScanHashBucket() to get at the contents of
     697             :      * the hash table.  -cim 6/9/91
     698             :      */
     699             :     {
     700       26618 :         HashState  *hashstate = (HashState *) innerPlanState(hjstate);
     701       26618 :         TupleTableSlot *slot = hashstate->ps.ps_ResultTupleSlot;
     702             : 
     703       26618 :         hjstate->hj_HashTupleSlot = slot;
     704             :     }
     705             : 
     706             :     /*
     707             :      * initialize child expressions
     708             :      */
     709       26618 :     hjstate->js.ps.qual =
     710       26618 :         ExecInitQual(node->join.plan.qual, (PlanState *) hjstate);
     711       26618 :     hjstate->js.joinqual =
     712       26618 :         ExecInitQual(node->join.joinqual, (PlanState *) hjstate);
     713       26618 :     hjstate->hashclauses =
     714       26618 :         ExecInitQual(node->hashclauses, (PlanState *) hjstate);
     715             : 
     716             :     /*
     717             :      * initialize hash-specific info
     718             :      */
     719       26618 :     hjstate->hj_HashTable = NULL;
     720       26618 :     hjstate->hj_FirstOuterTupleSlot = NULL;
     721             : 
     722       26618 :     hjstate->hj_CurHashValue = 0;
     723       26618 :     hjstate->hj_CurBucketNo = 0;
     724       26618 :     hjstate->hj_CurSkewBucketNo = INVALID_SKEW_BUCKET_NO;
     725       26618 :     hjstate->hj_CurTuple = NULL;
     726             : 
     727       26618 :     hjstate->hj_OuterHashKeys = ExecInitExprList(node->hashkeys,
     728             :                                                  (PlanState *) hjstate);
     729       26618 :     hjstate->hj_HashOperators = node->hashoperators;
     730       26618 :     hjstate->hj_Collations = node->hashcollations;
     731             : 
     732       26618 :     hjstate->hj_JoinState = HJ_BUILD_HASHTABLE;
     733       26618 :     hjstate->hj_MatchedOuter = false;
     734       26618 :     hjstate->hj_OuterNotEmpty = false;
     735             : 
     736       26618 :     return hjstate;
     737             : }
     738             : 
     739             : /* ----------------------------------------------------------------
     740             :  *      ExecEndHashJoin
     741             :  *
     742             :  *      clean up routine for HashJoin node
     743             :  * ----------------------------------------------------------------
     744             :  */
     745             : void
     746       26582 : ExecEndHashJoin(HashJoinState *node)
     747             : {
     748             :     /*
     749             :      * Free hash table
     750             :      */
     751       26582 :     if (node->hj_HashTable)
     752             :     {
     753       16242 :         ExecHashTableDestroy(node->hj_HashTable);
     754       16242 :         node->hj_HashTable = NULL;
     755             :     }
     756             : 
     757             :     /*
     758             :      * Free the exprcontext
     759             :      */
     760       26582 :     ExecFreeExprContext(&node->js.ps);
     761             : 
     762             :     /*
     763             :      * clean out the tuple table
     764             :      */
     765       26582 :     ExecClearTuple(node->js.ps.ps_ResultTupleSlot);
     766       26582 :     ExecClearTuple(node->hj_OuterTupleSlot);
     767       26582 :     ExecClearTuple(node->hj_HashTupleSlot);
     768             : 
     769             :     /*
     770             :      * clean up subtrees
     771             :      */
     772       26582 :     ExecEndNode(outerPlanState(node));
     773       26582 :     ExecEndNode(innerPlanState(node));
     774       26582 : }
     775             : 
     776             : /*
     777             :  * ExecHashJoinOuterGetTuple
     778             :  *
     779             :  *      get the next outer tuple for a parallel oblivious hashjoin: either by
     780             :  *      executing the outer plan node in the first pass, or from the temp
     781             :  *      files for the hashjoin batches.
     782             :  *
     783             :  * Returns a null slot if no more outer tuples (within the current batch).
     784             :  *
     785             :  * On success, the tuple's hash value is stored at *hashvalue --- this is
     786             :  * either originally computed, or re-read from the temp file.
     787             :  */
     788             : static TupleTableSlot *
     789     9559650 : ExecHashJoinOuterGetTuple(PlanState *outerNode,
     790             :                           HashJoinState *hjstate,
     791             :                           uint32 *hashvalue)
     792             : {
     793     9559650 :     HashJoinTable hashtable = hjstate->hj_HashTable;
     794     9559650 :     int         curbatch = hashtable->curbatch;
     795             :     TupleTableSlot *slot;
     796             : 
     797     9559650 :     if (curbatch == 0)          /* if it is the first pass */
     798             :     {
     799             :         /*
     800             :          * Check to see if first outer tuple was already fetched by
     801             :          * ExecHashJoin() and not used yet.
     802             :          */
     803     8572640 :         slot = hjstate->hj_FirstOuterTupleSlot;
     804     8572640 :         if (!TupIsNull(slot))
     805      251444 :             hjstate->hj_FirstOuterTupleSlot = NULL;
     806             :         else
     807     8321196 :             slot = ExecProcNode(outerNode);
     808             : 
     809    17145744 :         while (!TupIsNull(slot))
     810             :         {
     811             :             /*
     812             :              * We have to compute the tuple's hash value.
     813             :              */
     814     8317342 :             ExprContext *econtext = hjstate->js.ps.ps_ExprContext;
     815             : 
     816     8317342 :             econtext->ecxt_outertuple = slot;
     817     8317342 :             if (ExecHashGetHashValue(hashtable, econtext,
     818             :                                      hjstate->hj_OuterHashKeys,
     819             :                                      true,  /* outer tuple */
     820     8317342 :                                      HJ_FILL_OUTER(hjstate),
     821             :                                      hashvalue))
     822             :             {
     823             :                 /* remember outer relation is not empty for possible rescan */
     824     8316878 :                 hjstate->hj_OuterNotEmpty = true;
     825             : 
     826     8316878 :                 return slot;
     827             :             }
     828             : 
     829             :             /*
     830             :              * That tuple couldn't match because of a NULL, so discard it and
     831             :              * continue with the next one.
     832             :              */
     833         464 :             slot = ExecProcNode(outerNode);
     834             :         }
     835             :     }
     836      987010 :     else if (curbatch < hashtable->nbatch)
     837             :     {
     838      987010 :         BufFile    *file = hashtable->outerBatchFile[curbatch];
     839             : 
     840             :         /*
     841             :          * In outer-join cases, we could get here even though the batch file
     842             :          * is empty.
     843             :          */
     844      987010 :         if (file == NULL)
     845           0 :             return NULL;
     846             : 
     847      987010 :         slot = ExecHashJoinGetSavedTuple(hjstate,
     848             :                                          file,
     849             :                                          hashvalue,
     850             :                                          hjstate->hj_OuterTupleSlot);
     851      987010 :         if (!TupIsNull(slot))
     852      986128 :             return slot;
     853             :     }
     854             : 
     855             :     /* End of this batch */
     856      256644 :     return NULL;
     857             : }
     858             : 
     859             : /*
     860             :  * ExecHashJoinOuterGetTuple variant for the parallel case.
     861             :  */
     862             : static TupleTableSlot *
     863     1200580 : ExecParallelHashJoinOuterGetTuple(PlanState *outerNode,
     864             :                                   HashJoinState *hjstate,
     865             :                                   uint32 *hashvalue)
     866             : {
     867     1200580 :     HashJoinTable hashtable = hjstate->hj_HashTable;
     868     1200580 :     int         curbatch = hashtable->curbatch;
     869             :     TupleTableSlot *slot;
     870             : 
     871             :     /*
     872             :      * In the Parallel Hash case we only run the outer plan directly for
     873             :      * single-batch hash joins.  Otherwise we have to go to batch files, even
     874             :      * for batch 0.
     875             :      */
     876     1200652 :     if (curbatch == 0 && hashtable->nbatch == 1)
     877             :     {
     878      480072 :         slot = ExecProcNode(outerNode);
     879             : 
     880      960144 :         while (!TupIsNull(slot))
     881             :         {
     882      480000 :             ExprContext *econtext = hjstate->js.ps.ps_ExprContext;
     883             : 
     884      480000 :             econtext->ecxt_outertuple = slot;
     885      480000 :             if (ExecHashGetHashValue(hashtable, econtext,
     886             :                                      hjstate->hj_OuterHashKeys,
     887             :                                      true,  /* outer tuple */
     888      480000 :                                      HJ_FILL_OUTER(hjstate),
     889             :                                      hashvalue))
     890      480000 :                 return slot;
     891             : 
     892             :             /*
     893             :              * That tuple couldn't match because of a NULL, so discard it and
     894             :              * continue with the next one.
     895             :              */
     896           0 :             slot = ExecProcNode(outerNode);
     897             :         }
     898             :     }
     899      720508 :     else if (curbatch < hashtable->nbatch)
     900             :     {
     901             :         MinimalTuple tuple;
     902             : 
     903      720508 :         tuple = sts_parallel_scan_next(hashtable->batches[curbatch].outer_tuples,
     904             :                                        hashvalue);
     905      720508 :         if (tuple != NULL)
     906             :         {
     907      720016 :             ExecForceStoreMinimalTuple(tuple,
     908             :                                        hjstate->hj_OuterTupleSlot,
     909             :                                        false);
     910      720016 :             slot = hjstate->hj_OuterTupleSlot;
     911      720016 :             return slot;
     912             :         }
     913             :         else
     914         492 :             ExecClearTuple(hjstate->hj_OuterTupleSlot);
     915             :     }
     916             : 
     917             :     /* End of this batch */
     918         564 :     return NULL;
     919             : }
     920             : 
     921             : /*
     922             :  * ExecHashJoinNewBatch
     923             :  *      switch to a new hashjoin batch
     924             :  *
     925             :  * Returns true if successful, false if there are no more batches.
     926             :  */
     927             : static bool
     928      256640 : ExecHashJoinNewBatch(HashJoinState *hjstate)
     929             : {
     930      256640 :     HashJoinTable hashtable = hjstate->hj_HashTable;
     931             :     int         nbatch;
     932             :     int         curbatch;
     933             :     BufFile    *innerFile;
     934             :     TupleTableSlot *slot;
     935             :     uint32      hashvalue;
     936             : 
     937      256640 :     nbatch = hashtable->nbatch;
     938      256640 :     curbatch = hashtable->curbatch;
     939             : 
     940      256640 :     if (curbatch > 0)
     941             :     {
     942             :         /*
     943             :          * We no longer need the previous outer batch file; close it right
     944             :          * away to free disk space.
     945             :          */
     946         882 :         if (hashtable->outerBatchFile[curbatch])
     947         882 :             BufFileClose(hashtable->outerBatchFile[curbatch]);
     948         882 :         hashtable->outerBatchFile[curbatch] = NULL;
     949             :     }
     950             :     else                        /* we just finished the first batch */
     951             :     {
     952             :         /*
     953             :          * Reset some of the skew optimization state variables, since we no
     954             :          * longer need to consider skew tuples after the first batch. The
     955             :          * memory context reset we are about to do will release the skew
     956             :          * hashtable itself.
     957             :          */
     958      255758 :         hashtable->skewEnabled = false;
     959      255758 :         hashtable->skewBucket = NULL;
     960      255758 :         hashtable->skewBucketNums = NULL;
     961      255758 :         hashtable->nSkewBuckets = 0;
     962      255758 :         hashtable->spaceUsedSkew = 0;
     963             :     }
     964             : 
     965             :     /*
     966             :      * We can always skip over any batches that are completely empty on both
     967             :      * sides.  We can sometimes skip over batches that are empty on only one
     968             :      * side, but there are exceptions:
     969             :      *
     970             :      * 1. In a left/full outer join, we have to process outer batches even if
     971             :      * the inner batch is empty.  Similarly, in a right/full outer join, we
     972             :      * have to process inner batches even if the outer batch is empty.
     973             :      *
     974             :      * 2. If we have increased nbatch since the initial estimate, we have to
     975             :      * scan inner batches since they might contain tuples that need to be
     976             :      * reassigned to later inner batches.
     977             :      *
     978             :      * 3. Similarly, if we have increased nbatch since starting the outer
     979             :      * scan, we have to rescan outer batches in case they contain tuples that
     980             :      * need to be reassigned.
     981             :      */
     982      256640 :     curbatch++;
     983      514162 :     while (curbatch < nbatch &&
     984        1764 :            (hashtable->outerBatchFile[curbatch] == NULL ||
     985         882 :             hashtable->innerBatchFile[curbatch] == NULL))
     986             :     {
     987           0 :         if (hashtable->outerBatchFile[curbatch] &&
     988           0 :             HJ_FILL_OUTER(hjstate))
     989           0 :             break;              /* must process due to rule 1 */
     990           0 :         if (hashtable->innerBatchFile[curbatch] &&
     991           0 :             HJ_FILL_INNER(hjstate))
     992           0 :             break;              /* must process due to rule 1 */
     993           0 :         if (hashtable->innerBatchFile[curbatch] &&
     994           0 :             nbatch != hashtable->nbatch_original)
     995           0 :             break;              /* must process due to rule 2 */
     996           0 :         if (hashtable->outerBatchFile[curbatch] &&
     997           0 :             nbatch != hashtable->nbatch_outstart)
     998           0 :             break;              /* must process due to rule 3 */
     999             :         /* We can ignore this batch. */
    1000             :         /* Release associated temp files right away. */
    1001           0 :         if (hashtable->innerBatchFile[curbatch])
    1002           0 :             BufFileClose(hashtable->innerBatchFile[curbatch]);
    1003           0 :         hashtable->innerBatchFile[curbatch] = NULL;
    1004           0 :         if (hashtable->outerBatchFile[curbatch])
    1005           0 :             BufFileClose(hashtable->outerBatchFile[curbatch]);
    1006           0 :         hashtable->outerBatchFile[curbatch] = NULL;
    1007           0 :         curbatch++;
    1008             :     }
    1009             : 
    1010      256640 :     if (curbatch >= nbatch)
    1011      255758 :         return false;           /* no more batches */
    1012             : 
    1013         882 :     hashtable->curbatch = curbatch;
    1014             : 
    1015             :     /*
    1016             :      * Reload the hash table with the new inner batch (which could be empty)
    1017             :      */
    1018         882 :     ExecHashTableReset(hashtable);
    1019             : 
    1020         882 :     innerFile = hashtable->innerBatchFile[curbatch];
    1021             : 
    1022         882 :     if (innerFile != NULL)
    1023             :     {
    1024         882 :         if (BufFileSeek(innerFile, 0, 0L, SEEK_SET))
    1025           0 :             ereport(ERROR,
    1026             :                     (errcode_for_file_access(),
    1027             :                      errmsg("could not rewind hash-join temporary file: %m")));
    1028             : 
    1029     1815328 :         while ((slot = ExecHashJoinGetSavedTuple(hjstate,
    1030             :                                                  innerFile,
    1031             :                                                  &hashvalue,
    1032             :                                                  hjstate->hj_HashTupleSlot)))
    1033             :         {
    1034             :             /*
    1035             :              * NOTE: some tuples may be sent to future batches.  Also, it is
    1036             :              * possible for hashtable->nbatch to be increased here!
    1037             :              */
    1038     1813564 :             ExecHashTableInsert(hashtable, slot, hashvalue);
    1039             :         }
    1040             : 
    1041             :         /*
    1042             :          * after we build the hash table, the inner batch file is no longer
    1043             :          * needed
    1044             :          */
    1045         882 :         BufFileClose(innerFile);
    1046         882 :         hashtable->innerBatchFile[curbatch] = NULL;
    1047             :     }
    1048             : 
    1049             :     /*
    1050             :      * Rewind outer batch file (if present), so that we can start reading it.
    1051             :      */
    1052         882 :     if (hashtable->outerBatchFile[curbatch] != NULL)
    1053             :     {
    1054         882 :         if (BufFileSeek(hashtable->outerBatchFile[curbatch], 0, 0L, SEEK_SET))
    1055           0 :             ereport(ERROR,
    1056             :                     (errcode_for_file_access(),
    1057             :                      errmsg("could not rewind hash-join temporary file: %m")));
    1058             :     }
    1059             : 
    1060         882 :     return true;
    1061             : }
    1062             : 
    1063             : /*
    1064             :  * Choose a batch to work on, and attach to it.  Returns true if successful,
    1065             :  * false if there are no more batches.
    1066             :  */
    1067             : static bool
    1068         788 : ExecParallelHashJoinNewBatch(HashJoinState *hjstate)
    1069             : {
    1070         788 :     HashJoinTable hashtable = hjstate->hj_HashTable;
    1071             :     int         start_batchno;
    1072             :     int         batchno;
    1073             : 
    1074             :     /*
    1075             :      * If we started up so late that the batch tracking array has been freed
    1076             :      * already by ExecHashTableDetach(), then we are finished.  See also
    1077             :      * ExecParallelHashEnsureBatchAccessors().
    1078             :      */
    1079         788 :     if (hashtable->batches == NULL)
    1080           0 :         return false;
    1081             : 
    1082             :     /*
    1083             :      * If we were already attached to a batch, remember not to bother checking
    1084             :      * it again, and detach from it (possibly freeing the hash table if we are
    1085             :      * last to detach).
    1086             :      */
    1087         788 :     if (hashtable->curbatch >= 0)
    1088             :     {
    1089         564 :         hashtable->batches[hashtable->curbatch].done = true;
    1090         564 :         ExecHashTableDetachBatch(hashtable);
    1091             :     }
    1092             : 
    1093             :     /*
    1094             :      * Search for a batch that isn't done.  We use an atomic counter to start
    1095             :      * our search at a different batch in every participant when there are
    1096             :      * more batches than participants.
    1097             :      */
    1098         788 :     batchno = start_batchno =
    1099        1576 :         pg_atomic_fetch_add_u32(&hashtable->parallel_state->distributor, 1) %
    1100         788 :         hashtable->nbatch;
    1101             :     do
    1102             :     {
    1103             :         uint32      hashvalue;
    1104             :         MinimalTuple tuple;
    1105             :         TupleTableSlot *slot;
    1106             : 
    1107        1982 :         if (!hashtable->batches[batchno].done)
    1108             :         {
    1109             :             SharedTuplestoreAccessor *inner_tuples;
    1110        1120 :             Barrier    *batch_barrier =
    1111        1120 :             &hashtable->batches[batchno].shared->batch_barrier;
    1112             : 
    1113        1120 :             switch (BarrierAttach(batch_barrier))
    1114             :             {
    1115             :                 case PHJ_BATCH_ELECTING:
    1116             : 
    1117             :                     /* One backend allocates the hash table. */
    1118         392 :                     if (BarrierArriveAndWait(batch_barrier,
    1119             :                                              WAIT_EVENT_HASH_BATCH_ELECTING))
    1120         392 :                         ExecParallelHashTableAlloc(hashtable, batchno);
    1121             :                     /* Fall through. */
    1122             : 
    1123             :                 case PHJ_BATCH_ALLOCATING:
    1124             :                     /* Wait for allocation to complete. */
    1125         394 :                     BarrierArriveAndWait(batch_barrier,
    1126             :                                          WAIT_EVENT_HASH_BATCH_ALLOCATING);
    1127             :                     /* Fall through. */
    1128             : 
    1129             :                 case PHJ_BATCH_LOADING:
    1130             :                     /* Start (or join in) loading tuples. */
    1131         400 :                     ExecParallelHashTableSetCurrentBatch(hashtable, batchno);
    1132         400 :                     inner_tuples = hashtable->batches[batchno].inner_tuples;
    1133         400 :                     sts_begin_parallel_scan(inner_tuples);
    1134      655164 :                     while ((tuple = sts_parallel_scan_next(inner_tuples,
    1135             :                                                            &hashvalue)))
    1136             :                     {
    1137      654364 :                         ExecForceStoreMinimalTuple(tuple,
    1138             :                                                    hjstate->hj_HashTupleSlot,
    1139             :                                                    false);
    1140      654364 :                         slot = hjstate->hj_HashTupleSlot;
    1141      654364 :                         ExecParallelHashTableInsertCurrentBatch(hashtable, slot,
    1142             :                                                                 hashvalue);
    1143             :                     }
    1144         400 :                     sts_end_parallel_scan(inner_tuples);
    1145         400 :                     BarrierArriveAndWait(batch_barrier,
    1146             :                                          WAIT_EVENT_HASH_BATCH_LOADING);
    1147             :                     /* Fall through. */
    1148             : 
    1149             :                 case PHJ_BATCH_PROBING:
    1150             : 
    1151             :                     /*
    1152             :                      * This batch is ready to probe.  Return control to
    1153             :                      * caller. We stay attached to batch_barrier so that the
    1154             :                      * hash table stays alive until everyone's finished
    1155             :                      * probing it, but no participant is allowed to wait at
    1156             :                      * this barrier again (or else a deadlock could occur).
    1157             :                      * All attached participants must eventually call
    1158             :                      * BarrierArriveAndDetach() so that the final phase
    1159             :                      * PHJ_BATCH_DONE can be reached.
    1160             :                      */
    1161         564 :                     ExecParallelHashTableSetCurrentBatch(hashtable, batchno);
    1162         564 :                     sts_begin_parallel_scan(hashtable->batches[batchno].outer_tuples);
    1163         564 :                     return true;
    1164             : 
    1165             :                 case PHJ_BATCH_DONE:
    1166             : 
    1167             :                     /*
    1168             :                      * Already done.  Detach and go around again (if any
    1169             :                      * remain).
    1170             :                      */
    1171         556 :                     BarrierDetach(batch_barrier);
    1172         556 :                     hashtable->batches[batchno].done = true;
    1173         556 :                     hashtable->curbatch = -1;
    1174         556 :                     break;
    1175             : 
    1176             :                 default:
    1177           0 :                     elog(ERROR, "unexpected batch phase %d",
    1178             :                          BarrierPhase(batch_barrier));
    1179             :             }
    1180             :         }
    1181        1418 :         batchno = (batchno + 1) % hashtable->nbatch;
    1182        1418 :     } while (batchno != start_batchno);
    1183             : 
    1184         224 :     return false;
    1185             : }
    1186             : 
    1187             : /*
    1188             :  * ExecHashJoinSaveTuple
    1189             :  *      save a tuple to a batch file.
    1190             :  *
    1191             :  * The data recorded in the file for each tuple is its hash value,
    1192             :  * then the tuple in MinimalTuple format.
    1193             :  *
    1194             :  * Note: it is important always to call this in the regular executor
    1195             :  * context, not in a shorter-lived context; else the temp file buffers
    1196             :  * will get messed up.
    1197             :  */
    1198             : void
    1199     2799692 : ExecHashJoinSaveTuple(MinimalTuple tuple, uint32 hashvalue,
    1200             :                       BufFile **fileptr)
    1201             : {
    1202     2799692 :     BufFile    *file = *fileptr;
    1203             :     size_t      written;
    1204             : 
    1205     2799692 :     if (file == NULL)
    1206             :     {
    1207             :         /* First write to this batch file, so open it. */
    1208        1764 :         file = BufFileCreateTemp(false);
    1209        1764 :         *fileptr = file;
    1210             :     }
    1211             : 
    1212     2799692 :     written = BufFileWrite(file, (void *) &hashvalue, sizeof(uint32));
    1213     2799692 :     if (written != sizeof(uint32))
    1214           0 :         ereport(ERROR,
    1215             :                 (errcode_for_file_access(),
    1216             :                  errmsg("could not write to hash-join temporary file: %m")));
    1217             : 
    1218     2799692 :     written = BufFileWrite(file, (void *) tuple, tuple->t_len);
    1219     2799692 :     if (written != tuple->t_len)
    1220           0 :         ereport(ERROR,
    1221             :                 (errcode_for_file_access(),
    1222             :                  errmsg("could not write to hash-join temporary file: %m")));
    1223     2799692 : }
    1224             : 
    1225             : /*
    1226             :  * ExecHashJoinGetSavedTuple
    1227             :  *      read the next tuple from a batch file.  Return NULL if no more.
    1228             :  *
    1229             :  * On success, *hashvalue is set to the tuple's hash value, and the tuple
    1230             :  * itself is stored in the given slot.
    1231             :  */
    1232             : static TupleTableSlot *
    1233     2801456 : ExecHashJoinGetSavedTuple(HashJoinState *hjstate,
    1234             :                           BufFile *file,
    1235             :                           uint32 *hashvalue,
    1236             :                           TupleTableSlot *tupleSlot)
    1237             : {
    1238             :     uint32      header[2];
    1239             :     size_t      nread;
    1240             :     MinimalTuple tuple;
    1241             : 
    1242             :     /*
    1243             :      * We check for interrupts here because this is typically taken as an
    1244             :      * alternative code path to an ExecProcNode() call, which would include
    1245             :      * such a check.
    1246             :      */
    1247     2801456 :     CHECK_FOR_INTERRUPTS();
    1248             : 
    1249             :     /*
    1250             :      * Since both the hash value and the MinimalTuple length word are uint32,
    1251             :      * we can read them both in one BufFileRead() call without any type
    1252             :      * cheating.
    1253             :      */
    1254     2801456 :     nread = BufFileRead(file, (void *) header, sizeof(header));
    1255     2801456 :     if (nread == 0)             /* end of file */
    1256             :     {
    1257        1764 :         ExecClearTuple(tupleSlot);
    1258        1764 :         return NULL;
    1259             :     }
    1260     2799692 :     if (nread != sizeof(header))
    1261           0 :         ereport(ERROR,
    1262             :                 (errcode_for_file_access(),
    1263             :                  errmsg("could not read from hash-join temporary file: %m")));
    1264     2799692 :     *hashvalue = header[0];
    1265     2799692 :     tuple = (MinimalTuple) palloc(header[1]);
    1266     2799692 :     tuple->t_len = header[1];
    1267     2799692 :     nread = BufFileRead(file,
    1268             :                         (void *) ((char *) tuple + sizeof(uint32)),
    1269     2799692 :                         header[1] - sizeof(uint32));
    1270     2799692 :     if (nread != header[1] - sizeof(uint32))
    1271           0 :         ereport(ERROR,
    1272             :                 (errcode_for_file_access(),
    1273             :                  errmsg("could not read from hash-join temporary file: %m")));
    1274     2799692 :     ExecForceStoreMinimalTuple(tuple, tupleSlot, true);
    1275     2799692 :     return tupleSlot;
    1276             : }
    1277             : 
    1278             : 
    1279             : void
    1280     1065668 : ExecReScanHashJoin(HashJoinState *node)
    1281             : {
    1282             :     /*
    1283             :      * In a multi-batch join, we currently have to do rescans the hard way,
    1284             :      * primarily because batch temp files may have already been released. But
    1285             :      * if it's a single-batch join, and there is no parameter change for the
    1286             :      * inner subnode, then we can just re-use the existing hash table without
    1287             :      * rebuilding it.
    1288             :      */
    1289     1065668 :     if (node->hj_HashTable != NULL)
    1290             :     {
    1291      483272 :         if (node->hj_HashTable->nbatch == 1 &&
    1292      241636 :             node->js.ps.righttree->chgParam == NULL)
    1293             :         {
    1294             :             /*
    1295             :              * Okay to reuse the hash table; needn't rescan inner, either.
    1296             :              *
    1297             :              * However, if it's a right/full join, we'd better reset the
    1298             :              * inner-tuple match flags contained in the table.
    1299             :              */
    1300          76 :             if (HJ_FILL_INNER(node))
    1301          20 :                 ExecHashTableResetMatchFlags(node->hj_HashTable);
    1302             : 
    1303             :             /*
    1304             :              * Also, we need to reset our state about the emptiness of the
    1305             :              * outer relation, so that the new scan of the outer will update
    1306             :              * it correctly if it turns out to be empty this time. (There's no
    1307             :              * harm in clearing it now because ExecHashJoin won't need the
    1308             :              * info.  In the other cases, where the hash table doesn't exist
    1309             :              * or we are destroying it, we leave this state alone because
    1310             :              * ExecHashJoin will need it the first time through.)
    1311             :              */
    1312          76 :             node->hj_OuterNotEmpty = false;
    1313             : 
    1314             :             /* ExecHashJoin can skip the BUILD_HASHTABLE step */
    1315          76 :             node->hj_JoinState = HJ_NEED_NEW_OUTER;
    1316             :         }
    1317             :         else
    1318             :         {
    1319             :             /* must destroy and rebuild hash table */
    1320      241560 :             ExecHashTableDestroy(node->hj_HashTable);
    1321      241560 :             node->hj_HashTable = NULL;
    1322      241560 :             node->hj_JoinState = HJ_BUILD_HASHTABLE;
    1323             : 
    1324             :             /*
    1325             :              * if chgParam of subnode is not null then plan will be re-scanned
    1326             :              * by first ExecProcNode.
    1327             :              */
    1328      241560 :             if (node->js.ps.righttree->chgParam == NULL)
    1329           0 :                 ExecReScan(node->js.ps.righttree);
    1330             :         }
    1331             :     }
    1332             : 
    1333             :     /* Always reset intra-tuple state */
    1334     1065668 :     node->hj_CurHashValue = 0;
    1335     1065668 :     node->hj_CurBucketNo = 0;
    1336     1065668 :     node->hj_CurSkewBucketNo = INVALID_SKEW_BUCKET_NO;
    1337     1065668 :     node->hj_CurTuple = NULL;
    1338             : 
    1339     1065668 :     node->hj_MatchedOuter = false;
    1340     1065668 :     node->hj_FirstOuterTupleSlot = NULL;
    1341             : 
    1342             :     /*
    1343             :      * if chgParam of subnode is not null then plan will be re-scanned by
    1344             :      * first ExecProcNode.
    1345             :      */
    1346     1065668 :     if (node->js.ps.lefttree->chgParam == NULL)
    1347        1216 :         ExecReScan(node->js.ps.lefttree);
    1348     1065668 : }
    1349             : 
    1350             : void
    1351       25598 : ExecShutdownHashJoin(HashJoinState *node)
    1352             : {
    1353       25598 :     if (node->hj_HashTable)
    1354             :     {
    1355             :         /*
    1356             :          * Detach from shared state before DSM memory goes away.  This makes
    1357             :          * sure that we don't have any pointers into DSM memory by the time
    1358             :          * ExecEndHashJoin runs.
    1359             :          */
    1360       16538 :         ExecHashTableDetachBatch(node->hj_HashTable);
    1361       16538 :         ExecHashTableDetach(node->hj_HashTable);
    1362             :     }
    1363       25598 : }
    1364             : 
    1365             : static void
    1366          94 : ExecParallelHashJoinPartitionOuter(HashJoinState *hjstate)
    1367             : {
    1368          94 :     PlanState  *outerState = outerPlanState(hjstate);
    1369          94 :     ExprContext *econtext = hjstate->js.ps.ps_ExprContext;
    1370          94 :     HashJoinTable hashtable = hjstate->hj_HashTable;
    1371             :     TupleTableSlot *slot;
    1372             :     uint32      hashvalue;
    1373             :     int         i;
    1374             : 
    1375             :     Assert(hjstate->hj_FirstOuterTupleSlot == NULL);
    1376             : 
    1377             :     /* Execute outer plan, writing all tuples to shared tuplestores. */
    1378             :     for (;;)
    1379             :     {
    1380     1440126 :         slot = ExecProcNode(outerState);
    1381      720110 :         if (TupIsNull(slot))
    1382             :             break;
    1383      720016 :         econtext->ecxt_outertuple = slot;
    1384      720016 :         if (ExecHashGetHashValue(hashtable, econtext,
    1385             :                                  hjstate->hj_OuterHashKeys,
    1386             :                                  true,  /* outer tuple */
    1387      720016 :                                  HJ_FILL_OUTER(hjstate),
    1388             :                                  &hashvalue))
    1389             :         {
    1390             :             int         batchno;
    1391             :             int         bucketno;
    1392             :             bool        shouldFree;
    1393      720016 :             MinimalTuple mintup = ExecFetchSlotMinimalTuple(slot, &shouldFree);
    1394             : 
    1395      720016 :             ExecHashGetBucketAndBatch(hashtable, hashvalue, &bucketno,
    1396             :                                       &batchno);
    1397      720016 :             sts_puttuple(hashtable->batches[batchno].outer_tuples,
    1398             :                          &hashvalue, mintup);
    1399             : 
    1400      720016 :             if (shouldFree)
    1401      720016 :                 heap_free_minimal_tuple(mintup);
    1402             :         }
    1403      720016 :         CHECK_FOR_INTERRUPTS();
    1404             :     }
    1405             : 
    1406             :     /* Make sure all outer partitions are readable by any backend. */
    1407         862 :     for (i = 0; i < hashtable->nbatch; ++i)
    1408         768 :         sts_end_write(hashtable->batches[i].outer_tuples);
    1409          94 : }
    1410             : 
    1411             : void
    1412          64 : ExecHashJoinEstimate(HashJoinState *state, ParallelContext *pcxt)
    1413             : {
    1414          64 :     shm_toc_estimate_chunk(&pcxt->estimator, sizeof(ParallelHashJoinState));
    1415          64 :     shm_toc_estimate_keys(&pcxt->estimator, 1);
    1416          64 : }
    1417             : 
    1418             : void
    1419          64 : ExecHashJoinInitializeDSM(HashJoinState *state, ParallelContext *pcxt)
    1420             : {
    1421          64 :     int         plan_node_id = state->js.ps.plan->plan_node_id;
    1422             :     HashState  *hashNode;
    1423             :     ParallelHashJoinState *pstate;
    1424             : 
    1425             :     /*
    1426             :      * Disable shared hash table mode if we failed to create a real DSM
    1427             :      * segment, because that means that we don't have a DSA area to work with.
    1428             :      */
    1429          64 :     if (pcxt->seg == NULL)
    1430           0 :         return;
    1431             : 
    1432          64 :     ExecSetExecProcNode(&state->js.ps, ExecParallelHashJoin);
    1433             : 
    1434             :     /*
    1435             :      * Set up the state needed to coordinate access to the shared hash
    1436             :      * table(s), using the plan node ID as the toc key.
    1437             :      */
    1438          64 :     pstate = shm_toc_allocate(pcxt->toc, sizeof(ParallelHashJoinState));
    1439          64 :     shm_toc_insert(pcxt->toc, plan_node_id, pstate);
    1440             : 
    1441             :     /*
    1442             :      * Set up the shared hash join state with no batches initially.
    1443             :      * ExecHashTableCreate() will prepare at least one later and set nbatch
    1444             :      * and space_allowed.
    1445             :      */
    1446          64 :     pstate->nbatch = 0;
    1447          64 :     pstate->space_allowed = 0;
    1448          64 :     pstate->batches = InvalidDsaPointer;
    1449          64 :     pstate->old_batches = InvalidDsaPointer;
    1450          64 :     pstate->nbuckets = 0;
    1451          64 :     pstate->growth = PHJ_GROWTH_OK;
    1452          64 :     pstate->chunk_work_queue = InvalidDsaPointer;
    1453          64 :     pg_atomic_init_u32(&pstate->distributor, 0);
    1454          64 :     pstate->nparticipants = pcxt->nworkers + 1;
    1455          64 :     pstate->total_tuples = 0;
    1456          64 :     LWLockInitialize(&pstate->lock,
    1457             :                      LWTRANCHE_PARALLEL_HASH_JOIN);
    1458          64 :     BarrierInit(&pstate->build_barrier, 0);
    1459          64 :     BarrierInit(&pstate->grow_batches_barrier, 0);
    1460          64 :     BarrierInit(&pstate->grow_buckets_barrier, 0);
    1461             : 
    1462             :     /* Set up the space we'll use for shared temporary files. */
    1463          64 :     SharedFileSetInit(&pstate->fileset, pcxt->seg);
    1464             : 
    1465             :     /* Initialize the shared state in the hash node. */
    1466          64 :     hashNode = (HashState *) innerPlanState(state);
    1467          64 :     hashNode->parallel_state = pstate;
    1468             : }
    1469             : 
    1470             : /* ----------------------------------------------------------------
    1471             :  *      ExecHashJoinReInitializeDSM
    1472             :  *
    1473             :  *      Reset shared state before beginning a fresh scan.
    1474             :  * ----------------------------------------------------------------
    1475             :  */
    1476             : void
    1477          32 : ExecHashJoinReInitializeDSM(HashJoinState *state, ParallelContext *cxt)
    1478             : {
    1479          32 :     int         plan_node_id = state->js.ps.plan->plan_node_id;
    1480          32 :     ParallelHashJoinState *pstate =
    1481          32 :     shm_toc_lookup(cxt->toc, plan_node_id, false);
    1482             : 
    1483             :     /*
    1484             :      * It would be possible to reuse the shared hash table in single-batch
    1485             :      * cases by resetting and then fast-forwarding build_barrier to
    1486             :      * PHJ_BUILD_DONE and batch 0's batch_barrier to PHJ_BATCH_PROBING, but
    1487             :      * currently shared hash tables are already freed by now (by the last
    1488             :      * participant to detach from the batch).  We could consider keeping it
    1489             :      * around for single-batch joins.  We'd also need to adjust
    1490             :      * finalize_plan() so that it doesn't record a dummy dependency for
    1491             :      * Parallel Hash nodes, preventing the rescan optimization.  For now we
    1492             :      * don't try.
    1493             :      */
    1494             : 
    1495             :     /* Detach, freeing any remaining shared memory. */
    1496          32 :     if (state->hj_HashTable != NULL)
    1497             :     {
    1498           0 :         ExecHashTableDetachBatch(state->hj_HashTable);
    1499           0 :         ExecHashTableDetach(state->hj_HashTable);
    1500             :     }
    1501             : 
    1502             :     /* Clear any shared batch files. */
    1503          32 :     SharedFileSetDeleteAll(&pstate->fileset);
    1504             : 
    1505             :     /* Reset build_barrier to PHJ_BUILD_ELECTING so we can go around again. */
    1506          32 :     BarrierInit(&pstate->build_barrier, 0);
    1507          32 : }
    1508             : 
    1509             : void
    1510         180 : ExecHashJoinInitializeWorker(HashJoinState *state,
    1511             :                              ParallelWorkerContext *pwcxt)
    1512             : {
    1513             :     HashState  *hashNode;
    1514         180 :     int         plan_node_id = state->js.ps.plan->plan_node_id;
    1515         180 :     ParallelHashJoinState *pstate =
    1516         180 :     shm_toc_lookup(pwcxt->toc, plan_node_id, false);
    1517             : 
    1518             :     /* Attach to the space for shared temporary files. */
    1519         180 :     SharedFileSetAttach(&pstate->fileset, pwcxt->seg);
    1520             : 
    1521             :     /* Attach to the shared state in the hash node. */
    1522         180 :     hashNode = (HashState *) innerPlanState(state);
    1523         180 :     hashNode->parallel_state = pstate;
    1524             : 
    1525         180 :     ExecSetExecProcNode(&state->js.ps, ExecParallelHashJoin);
    1526         180 : }

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