LCOV - code coverage report
Current view: top level - src/backend/executor - nodeMaterial.c (source / functions) Hit Total Coverage
Test: PostgreSQL 13devel Lines: 81 87 93.1 %
Date: 2019-11-22 06:06:53 Functions: 6 6 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * nodeMaterial.c
       4             :  *    Routines to handle materialization 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/nodeMaterial.c
      12             :  *
      13             :  *-------------------------------------------------------------------------
      14             :  */
      15             : /*
      16             :  * INTERFACE ROUTINES
      17             :  *      ExecMaterial            - materialize the result of a subplan
      18             :  *      ExecInitMaterial        - initialize node and subnodes
      19             :  *      ExecEndMaterial         - shutdown node and subnodes
      20             :  *
      21             :  */
      22             : #include "postgres.h"
      23             : 
      24             : #include "executor/executor.h"
      25             : #include "executor/nodeMaterial.h"
      26             : #include "miscadmin.h"
      27             : 
      28             : /* ----------------------------------------------------------------
      29             :  *      ExecMaterial
      30             :  *
      31             :  *      As long as we are at the end of the data collected in the tuplestore,
      32             :  *      we collect one new row from the subplan on each call, and stash it
      33             :  *      aside in the tuplestore before returning it.  The tuplestore is
      34             :  *      only read if we are asked to scan backwards, rescan, or mark/restore.
      35             :  *
      36             :  * ----------------------------------------------------------------
      37             :  */
      38             : static TupleTableSlot *         /* result tuple from subplan */
      39     9390336 : ExecMaterial(PlanState *pstate)
      40             : {
      41     9390336 :     MaterialState *node = castNode(MaterialState, pstate);
      42             :     EState     *estate;
      43             :     ScanDirection dir;
      44             :     bool        forward;
      45             :     Tuplestorestate *tuplestorestate;
      46             :     bool        eof_tuplestore;
      47             :     TupleTableSlot *slot;
      48             : 
      49     9390336 :     CHECK_FOR_INTERRUPTS();
      50             : 
      51             :     /*
      52             :      * get state info from node
      53             :      */
      54     9390336 :     estate = node->ss.ps.state;
      55     9390336 :     dir = estate->es_direction;
      56     9390336 :     forward = ScanDirectionIsForward(dir);
      57     9390336 :     tuplestorestate = node->tuplestorestate;
      58             : 
      59             :     /*
      60             :      * If first time through, and we need a tuplestore, initialize it.
      61             :      */
      62     9390336 :     if (tuplestorestate == NULL && node->eflags != 0)
      63             :     {
      64       38364 :         tuplestorestate = tuplestore_begin_heap(true, false, work_mem);
      65       38364 :         tuplestore_set_eflags(tuplestorestate, node->eflags);
      66       38364 :         if (node->eflags & EXEC_FLAG_MARK)
      67             :         {
      68             :             /*
      69             :              * Allocate a second read pointer to serve as the mark. We know it
      70             :              * must have index 1, so needn't store that.
      71             :              */
      72             :             int         ptrno PG_USED_FOR_ASSERTS_ONLY;
      73             : 
      74          60 :             ptrno = tuplestore_alloc_read_pointer(tuplestorestate,
      75             :                                                   node->eflags);
      76             :             Assert(ptrno == 1);
      77             :         }
      78       38364 :         node->tuplestorestate = tuplestorestate;
      79             :     }
      80             : 
      81             :     /*
      82             :      * If we are not at the end of the tuplestore, or are going backwards, try
      83             :      * to fetch a tuple from tuplestore.
      84             :      */
      85    18780542 :     eof_tuplestore = (tuplestorestate == NULL) ||
      86     9390206 :         tuplestore_ateof(tuplestorestate);
      87             : 
      88     9390336 :     if (!forward && eof_tuplestore)
      89             :     {
      90           8 :         if (!node->eof_underlying)
      91             :         {
      92             :             /*
      93             :              * When reversing direction at tuplestore EOF, the first
      94             :              * gettupleslot call will fetch the last-added tuple; but we want
      95             :              * to return the one before that, if possible. So do an extra
      96             :              * fetch.
      97             :              */
      98           0 :             if (!tuplestore_advance(tuplestorestate, forward))
      99           0 :                 return NULL;    /* the tuplestore must be empty */
     100             :         }
     101           8 :         eof_tuplestore = false;
     102             :     }
     103             : 
     104             :     /*
     105             :      * If we can fetch another tuple from the tuplestore, return it.
     106             :      */
     107     9390336 :     slot = node->ss.ps.ps_ResultTupleSlot;
     108     9390336 :     if (!eof_tuplestore)
     109             :     {
     110     9348908 :         if (tuplestore_gettupleslot(tuplestorestate, forward, false, slot))
     111     8663300 :             return slot;
     112      685608 :         if (forward)
     113      685600 :             eof_tuplestore = true;
     114             :     }
     115             : 
     116             :     /*
     117             :      * If necessary, try to fetch another row from the subplan.
     118             :      *
     119             :      * Note: the eof_underlying state variable exists to short-circuit further
     120             :      * subplan calls.  It's not optional, unfortunately, because some plan
     121             :      * node types are not robust about being called again when they've already
     122             :      * returned NULL.
     123             :      */
     124      727036 :     if (eof_tuplestore && !node->eof_underlying)
     125             :     {
     126             :         PlanState  *outerNode;
     127             :         TupleTableSlot *outerslot;
     128             : 
     129             :         /*
     130             :          * We can only get here with forward==true, so no need to worry about
     131             :          * which direction the subplan will go.
     132             :          */
     133       83846 :         outerNode = outerPlanState(node);
     134       83846 :         outerslot = ExecProcNode(outerNode);
     135       83846 :         if (TupIsNull(outerslot))
     136             :         {
     137       38256 :             node->eof_underlying = true;
     138       38256 :             return NULL;
     139             :         }
     140             : 
     141             :         /*
     142             :          * Append a copy of the returned tuple to tuplestore.  NOTE: because
     143             :          * the tuplestore is certainly in EOF state, its read position will
     144             :          * move forward over the added tuple.  This is what we want.
     145             :          */
     146       45590 :         if (tuplestorestate)
     147       45466 :             tuplestore_puttupleslot(tuplestorestate, outerslot);
     148             : 
     149       45590 :         ExecCopySlot(slot, outerslot);
     150       45590 :         return slot;
     151             :     }
     152             : 
     153             :     /*
     154             :      * Nothing left ...
     155             :      */
     156      643190 :     return ExecClearTuple(slot);
     157             : }
     158             : 
     159             : /* ----------------------------------------------------------------
     160             :  *      ExecInitMaterial
     161             :  * ----------------------------------------------------------------
     162             :  */
     163             : MaterialState *
     164        2760 : ExecInitMaterial(Material *node, EState *estate, int eflags)
     165             : {
     166             :     MaterialState *matstate;
     167             :     Plan       *outerPlan;
     168             : 
     169             :     /*
     170             :      * create state structure
     171             :      */
     172        2760 :     matstate = makeNode(MaterialState);
     173        2760 :     matstate->ss.ps.plan = (Plan *) node;
     174        2760 :     matstate->ss.ps.state = estate;
     175        2760 :     matstate->ss.ps.ExecProcNode = ExecMaterial;
     176             : 
     177             :     /*
     178             :      * We must have a tuplestore buffering the subplan output to do backward
     179             :      * scan or mark/restore.  We also prefer to materialize the subplan output
     180             :      * if we might be called on to rewind and replay it many times. However,
     181             :      * if none of these cases apply, we can skip storing the data.
     182             :      */
     183        2760 :     matstate->eflags = (eflags & (EXEC_FLAG_REWIND |
     184             :                                   EXEC_FLAG_BACKWARD |
     185             :                                   EXEC_FLAG_MARK));
     186             : 
     187             :     /*
     188             :      * Tuplestore's interpretation of the flag bits is subtly different from
     189             :      * the general executor meaning: it doesn't think BACKWARD necessarily
     190             :      * means "backwards all the way to start".  If told to support BACKWARD we
     191             :      * must include REWIND in the tuplestore eflags, else tuplestore_trim
     192             :      * might throw away too much.
     193             :      */
     194        2760 :     if (eflags & EXEC_FLAG_BACKWARD)
     195           8 :         matstate->eflags |= EXEC_FLAG_REWIND;
     196             : 
     197        2760 :     matstate->eof_underlying = false;
     198        2760 :     matstate->tuplestorestate = NULL;
     199             : 
     200             :     /*
     201             :      * Miscellaneous initialization
     202             :      *
     203             :      * Materialization nodes don't need ExprContexts because they never call
     204             :      * ExecQual or ExecProject.
     205             :      */
     206             : 
     207             :     /*
     208             :      * initialize child nodes
     209             :      *
     210             :      * We shield the child node from the need to support REWIND, BACKWARD, or
     211             :      * MARK/RESTORE.
     212             :      */
     213        2760 :     eflags &= ~(EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK);
     214             : 
     215        2760 :     outerPlan = outerPlan(node);
     216        2760 :     outerPlanState(matstate) = ExecInitNode(outerPlan, estate, eflags);
     217             : 
     218             :     /*
     219             :      * Initialize result type and slot. No need to initialize projection info
     220             :      * because this node doesn't do projections.
     221             :      *
     222             :      * material nodes only return tuples from their materialized relation.
     223             :      */
     224        2760 :     ExecInitResultTupleSlotTL(&matstate->ss.ps, &TTSOpsMinimalTuple);
     225        2760 :     matstate->ss.ps.ps_ProjInfo = NULL;
     226             : 
     227             :     /*
     228             :      * initialize tuple type.
     229             :      */
     230        2760 :     ExecCreateScanSlotFromOuterPlan(estate, &matstate->ss, &TTSOpsMinimalTuple);
     231             : 
     232        2760 :     return matstate;
     233             : }
     234             : 
     235             : /* ----------------------------------------------------------------
     236             :  *      ExecEndMaterial
     237             :  * ----------------------------------------------------------------
     238             :  */
     239             : void
     240        2696 : ExecEndMaterial(MaterialState *node)
     241             : {
     242             :     /*
     243             :      * clean out the tuple table
     244             :      */
     245        2696 :     ExecClearTuple(node->ss.ss_ScanTupleSlot);
     246             : 
     247             :     /*
     248             :      * Release tuplestore resources
     249             :      */
     250        2696 :     if (node->tuplestorestate != NULL)
     251        2434 :         tuplestore_end(node->tuplestorestate);
     252        2696 :     node->tuplestorestate = NULL;
     253             : 
     254             :     /*
     255             :      * shut down the subplan
     256             :      */
     257        2696 :     ExecEndNode(outerPlanState(node));
     258        2696 : }
     259             : 
     260             : /* ----------------------------------------------------------------
     261             :  *      ExecMaterialMarkPos
     262             :  *
     263             :  *      Calls tuplestore to save the current position in the stored file.
     264             :  * ----------------------------------------------------------------
     265             :  */
     266             : void
     267        4240 : ExecMaterialMarkPos(MaterialState *node)
     268             : {
     269             :     Assert(node->eflags & EXEC_FLAG_MARK);
     270             : 
     271             :     /*
     272             :      * if we haven't materialized yet, just return.
     273             :      */
     274        4240 :     if (!node->tuplestorestate)
     275           0 :         return;
     276             : 
     277             :     /*
     278             :      * copy the active read pointer to the mark.
     279             :      */
     280        4240 :     tuplestore_copy_read_pointer(node->tuplestorestate, 0, 1);
     281             : 
     282             :     /*
     283             :      * since we may have advanced the mark, try to truncate the tuplestore.
     284             :      */
     285        4240 :     tuplestore_trim(node->tuplestorestate);
     286             : }
     287             : 
     288             : /* ----------------------------------------------------------------
     289             :  *      ExecMaterialRestrPos
     290             :  *
     291             :  *      Calls tuplestore to restore the last saved file position.
     292             :  * ----------------------------------------------------------------
     293             :  */
     294             : void
     295       36024 : ExecMaterialRestrPos(MaterialState *node)
     296             : {
     297             :     Assert(node->eflags & EXEC_FLAG_MARK);
     298             : 
     299             :     /*
     300             :      * if we haven't materialized yet, just return.
     301             :      */
     302       36024 :     if (!node->tuplestorestate)
     303           0 :         return;
     304             : 
     305             :     /*
     306             :      * copy the mark to the active read pointer.
     307             :      */
     308       36024 :     tuplestore_copy_read_pointer(node->tuplestorestate, 1, 0);
     309             : }
     310             : 
     311             : /* ----------------------------------------------------------------
     312             :  *      ExecReScanMaterial
     313             :  *
     314             :  *      Rescans the materialized relation.
     315             :  * ----------------------------------------------------------------
     316             :  */
     317             : void
     318      692428 : ExecReScanMaterial(MaterialState *node)
     319             : {
     320      692428 :     PlanState  *outerPlan = outerPlanState(node);
     321             : 
     322      692428 :     ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
     323             : 
     324      692428 :     if (node->eflags != 0)
     325             :     {
     326             :         /*
     327             :          * If we haven't materialized yet, just return. If outerplan's
     328             :          * chgParam is not NULL then it will be re-scanned by ExecProcNode,
     329             :          * else no reason to re-scan it at all.
     330             :          */
     331      692424 :         if (!node->tuplestorestate)
     332        2438 :             return;
     333             : 
     334             :         /*
     335             :          * If subnode is to be rescanned then we forget previous stored
     336             :          * results; we have to re-read the subplan and re-store.  Also, if we
     337             :          * told tuplestore it needn't support rescan, we lose and must
     338             :          * re-read.  (This last should not happen in common cases; else our
     339             :          * caller lied by not passing EXEC_FLAG_REWIND to us.)
     340             :          *
     341             :          * Otherwise we can just rewind and rescan the stored output. The
     342             :          * state of the subnode does not change.
     343             :          */
     344     1344106 :         if (outerPlan->chgParam != NULL ||
     345      654120 :             (node->eflags & EXEC_FLAG_REWIND) == 0)
     346             :         {
     347       35866 :             tuplestore_end(node->tuplestorestate);
     348       35866 :             node->tuplestorestate = NULL;
     349       35866 :             if (outerPlan->chgParam == NULL)
     350           0 :                 ExecReScan(outerPlan);
     351       35866 :             node->eof_underlying = false;
     352             :         }
     353             :         else
     354      654120 :             tuplestore_rescan(node->tuplestorestate);
     355             :     }
     356             :     else
     357             :     {
     358             :         /* In this case we are just passing on the subquery's output */
     359             : 
     360             :         /*
     361             :          * if chgParam of subnode is not null then plan will be re-scanned by
     362             :          * first ExecProcNode.
     363             :          */
     364           4 :         if (outerPlan->chgParam == NULL)
     365           0 :             ExecReScan(outerPlan);
     366           4 :         node->eof_underlying = false;
     367             :     }
     368             : }

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