LCOV - code coverage report
Current view: top level - src/backend/executor - nodeForeignscan.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 100 142 70.4 %
Date: 2023-12-02 15:10:53 Functions: 9 14 64.3 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * nodeForeignscan.c
       4             :  *    Routines to support scans of foreign tables
       5             :  *
       6             :  * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *    src/backend/executor/nodeForeignscan.c
      12             :  *
      13             :  *-------------------------------------------------------------------------
      14             :  */
      15             : /*
      16             :  * INTERFACE ROUTINES
      17             :  *
      18             :  *      ExecForeignScan         scans a foreign table.
      19             :  *      ExecInitForeignScan     creates and initializes state info.
      20             :  *      ExecReScanForeignScan   rescans the foreign relation.
      21             :  *      ExecEndForeignScan      releases any resources allocated.
      22             :  */
      23             : #include "postgres.h"
      24             : 
      25             : #include "executor/executor.h"
      26             : #include "executor/nodeForeignscan.h"
      27             : #include "foreign/fdwapi.h"
      28             : #include "utils/memutils.h"
      29             : #include "utils/rel.h"
      30             : 
      31             : static TupleTableSlot *ForeignNext(ForeignScanState *node);
      32             : static bool ForeignRecheck(ForeignScanState *node, TupleTableSlot *slot);
      33             : 
      34             : 
      35             : /* ----------------------------------------------------------------
      36             :  *      ForeignNext
      37             :  *
      38             :  *      This is a workhorse for ExecForeignScan
      39             :  * ----------------------------------------------------------------
      40             :  */
      41             : static TupleTableSlot *
      42      140882 : ForeignNext(ForeignScanState *node)
      43             : {
      44             :     TupleTableSlot *slot;
      45      140882 :     ForeignScan *plan = (ForeignScan *) node->ss.ps.plan;
      46      140882 :     ExprContext *econtext = node->ss.ps.ps_ExprContext;
      47             :     MemoryContext oldcontext;
      48             : 
      49             :     /* Call the Iterate function in short-lived context */
      50      140882 :     oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
      51      140882 :     if (plan->operation != CMD_SELECT)
      52             :     {
      53             :         /*
      54             :          * direct modifications cannot be re-evaluated, so shouldn't get here
      55             :          * during EvalPlanQual processing
      56             :          */
      57             :         Assert(node->ss.ps.state->es_epq_active == NULL);
      58             : 
      59         836 :         slot = node->fdwroutine->IterateDirectModify(node);
      60             :     }
      61             :     else
      62      140046 :         slot = node->fdwroutine->IterateForeignScan(node);
      63      140856 :     MemoryContextSwitchTo(oldcontext);
      64             : 
      65             :     /*
      66             :      * Insert valid value into tableoid, the only actually-useful system
      67             :      * column.
      68             :      */
      69      140856 :     if (plan->fsSystemCol && !TupIsNull(slot))
      70        5038 :         slot->tts_tableOid = RelationGetRelid(node->ss.ss_currentRelation);
      71             : 
      72      140856 :     return slot;
      73             : }
      74             : 
      75             : /*
      76             :  * ForeignRecheck -- access method routine to recheck a tuple in EvalPlanQual
      77             :  */
      78             : static bool
      79           0 : ForeignRecheck(ForeignScanState *node, TupleTableSlot *slot)
      80             : {
      81           0 :     FdwRoutine *fdwroutine = node->fdwroutine;
      82             :     ExprContext *econtext;
      83             : 
      84             :     /*
      85             :      * extract necessary information from foreign scan node
      86             :      */
      87           0 :     econtext = node->ss.ps.ps_ExprContext;
      88             : 
      89             :     /* Does the tuple meet the remote qual condition? */
      90           0 :     econtext->ecxt_scantuple = slot;
      91             : 
      92           0 :     ResetExprContext(econtext);
      93             : 
      94             :     /*
      95             :      * If an outer join is pushed down, RecheckForeignScan may need to store a
      96             :      * different tuple in the slot, because a different set of columns may go
      97             :      * to NULL upon recheck.  Otherwise, it shouldn't need to change the slot
      98             :      * contents, just return true or false to indicate whether the quals still
      99             :      * pass.  For simple cases, setting fdw_recheck_quals may be easier than
     100             :      * providing this callback.
     101             :      */
     102           0 :     if (fdwroutine->RecheckForeignScan &&
     103           0 :         !fdwroutine->RecheckForeignScan(node, slot))
     104           0 :         return false;
     105             : 
     106           0 :     return ExecQual(node->fdw_recheck_quals, econtext);
     107             : }
     108             : 
     109             : /* ----------------------------------------------------------------
     110             :  *      ExecForeignScan(node)
     111             :  *
     112             :  *      Fetches the next tuple from the FDW, checks local quals, and
     113             :  *      returns it.
     114             :  *      We call the ExecScan() routine and pass it the appropriate
     115             :  *      access method functions.
     116             :  * ----------------------------------------------------------------
     117             :  */
     118             : static TupleTableSlot *
     119      122710 : ExecForeignScan(PlanState *pstate)
     120             : {
     121      122710 :     ForeignScanState *node = castNode(ForeignScanState, pstate);
     122      122710 :     ForeignScan *plan = (ForeignScan *) node->ss.ps.plan;
     123      122710 :     EState     *estate = node->ss.ps.state;
     124             : 
     125             :     /*
     126             :      * Ignore direct modifications when EvalPlanQual is active --- they are
     127             :      * irrelevant for EvalPlanQual rechecking
     128             :      */
     129      122710 :     if (estate->es_epq_active != NULL && plan->operation != CMD_SELECT)
     130           0 :         return NULL;
     131             : 
     132      122710 :     return ExecScan(&node->ss,
     133             :                     (ExecScanAccessMtd) ForeignNext,
     134             :                     (ExecScanRecheckMtd) ForeignRecheck);
     135             : }
     136             : 
     137             : 
     138             : /* ----------------------------------------------------------------
     139             :  *      ExecInitForeignScan
     140             :  * ----------------------------------------------------------------
     141             :  */
     142             : ForeignScanState *
     143        1916 : ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags)
     144             : {
     145             :     ForeignScanState *scanstate;
     146        1916 :     Relation    currentRelation = NULL;
     147        1916 :     Index       scanrelid = node->scan.scanrelid;
     148             :     int         tlistvarno;
     149             :     FdwRoutine *fdwroutine;
     150             : 
     151             :     /* check for unsupported flags */
     152             :     Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
     153             : 
     154             :     /*
     155             :      * create state structure
     156             :      */
     157        1916 :     scanstate = makeNode(ForeignScanState);
     158        1916 :     scanstate->ss.ps.plan = (Plan *) node;
     159        1916 :     scanstate->ss.ps.state = estate;
     160        1916 :     scanstate->ss.ps.ExecProcNode = ExecForeignScan;
     161             : 
     162             :     /*
     163             :      * Miscellaneous initialization
     164             :      *
     165             :      * create expression context for node
     166             :      */
     167        1916 :     ExecAssignExprContext(estate, &scanstate->ss.ps);
     168             : 
     169             :     /*
     170             :      * open the scan relation, if any; also acquire function pointers from the
     171             :      * FDW's handler
     172             :      */
     173        1916 :     if (scanrelid > 0)
     174             :     {
     175        1410 :         currentRelation = ExecOpenScanRelation(estate, scanrelid, eflags);
     176        1410 :         scanstate->ss.ss_currentRelation = currentRelation;
     177        1410 :         fdwroutine = GetFdwRoutineForRelation(currentRelation, true);
     178             :     }
     179             :     else
     180             :     {
     181             :         /* We can't use the relcache, so get fdwroutine the hard way */
     182         506 :         fdwroutine = GetFdwRoutineByServerId(node->fs_server);
     183             :     }
     184             : 
     185             :     /*
     186             :      * Determine the scan tuple type.  If the FDW provided a targetlist
     187             :      * describing the scan tuples, use that; else use base relation's rowtype.
     188             :      */
     189        1916 :     if (node->fdw_scan_tlist != NIL || currentRelation == NULL)
     190         506 :     {
     191             :         TupleDesc   scan_tupdesc;
     192             : 
     193         506 :         scan_tupdesc = ExecTypeFromTL(node->fdw_scan_tlist);
     194         506 :         ExecInitScanTupleSlot(estate, &scanstate->ss, scan_tupdesc,
     195             :                               &TTSOpsHeapTuple);
     196             :         /* Node's targetlist will contain Vars with varno = INDEX_VAR */
     197         506 :         tlistvarno = INDEX_VAR;
     198             :     }
     199             :     else
     200             :     {
     201             :         TupleDesc   scan_tupdesc;
     202             : 
     203             :         /* don't trust FDWs to return tuples fulfilling NOT NULL constraints */
     204        1410 :         scan_tupdesc = CreateTupleDescCopy(RelationGetDescr(currentRelation));
     205        1410 :         ExecInitScanTupleSlot(estate, &scanstate->ss, scan_tupdesc,
     206             :                               &TTSOpsHeapTuple);
     207             :         /* Node's targetlist will contain Vars with varno = scanrelid */
     208        1410 :         tlistvarno = scanrelid;
     209             :     }
     210             : 
     211             :     /* Don't know what an FDW might return */
     212        1916 :     scanstate->ss.ps.scanopsfixed = false;
     213        1916 :     scanstate->ss.ps.scanopsset = true;
     214             : 
     215             :     /*
     216             :      * Initialize result slot, type and projection.
     217             :      */
     218        1916 :     ExecInitResultTypeTL(&scanstate->ss.ps);
     219        1916 :     ExecAssignScanProjectionInfoWithVarno(&scanstate->ss, tlistvarno);
     220             : 
     221             :     /*
     222             :      * initialize child expressions
     223             :      */
     224        1916 :     scanstate->ss.ps.qual =
     225        1916 :         ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);
     226        1916 :     scanstate->fdw_recheck_quals =
     227        1916 :         ExecInitQual(node->fdw_recheck_quals, (PlanState *) scanstate);
     228             : 
     229             :     /*
     230             :      * Determine whether to scan the foreign relation asynchronously or not;
     231             :      * this has to be kept in sync with the code in ExecInitAppend().
     232             :      */
     233        2102 :     scanstate->ss.ps.async_capable = (((Plan *) node)->async_capable &&
     234         186 :                                       estate->es_epq_active == NULL);
     235             : 
     236             :     /*
     237             :      * Initialize FDW-related state.
     238             :      */
     239        1916 :     scanstate->fdwroutine = fdwroutine;
     240        1916 :     scanstate->fdw_state = NULL;
     241             : 
     242             :     /*
     243             :      * For the FDW's convenience, look up the modification target relation's
     244             :      * ResultRelInfo.  The ModifyTable node should have initialized it for us,
     245             :      * see ExecInitModifyTable.
     246             :      *
     247             :      * Don't try to look up the ResultRelInfo when EvalPlanQual is active,
     248             :      * though.  Direct modifications cannot be re-evaluated as part of
     249             :      * EvalPlanQual.  The lookup wouldn't work anyway because during
     250             :      * EvalPlanQual processing, EvalPlanQual only initializes the subtree
     251             :      * under the ModifyTable, and doesn't run ExecInitModifyTable.
     252             :      */
     253        1916 :     if (node->resultRelation > 0 && estate->es_epq_active == NULL)
     254             :     {
     255         208 :         if (estate->es_result_relations == NULL ||
     256         208 :             estate->es_result_relations[node->resultRelation - 1] == NULL)
     257             :         {
     258           0 :             elog(ERROR, "result relation not initialized");
     259             :         }
     260         208 :         scanstate->resultRelInfo = estate->es_result_relations[node->resultRelation - 1];
     261             :     }
     262             : 
     263             :     /* Initialize any outer plan. */
     264        1916 :     if (outerPlan(node))
     265          24 :         outerPlanState(scanstate) =
     266          24 :             ExecInitNode(outerPlan(node), estate, eflags);
     267             : 
     268             :     /*
     269             :      * Tell the FDW to initialize the scan.
     270             :      */
     271        1916 :     if (node->operation != CMD_SELECT)
     272             :     {
     273             :         /*
     274             :          * Direct modifications cannot be re-evaluated by EvalPlanQual, so
     275             :          * don't bother preparing the FDW.
     276             :          *
     277             :          * In case of an inherited UPDATE/DELETE with foreign targets there
     278             :          * can be direct-modify ForeignScan nodes in the EvalPlanQual subtree,
     279             :          * so we need to ignore such ForeignScan nodes during EvalPlanQual
     280             :          * processing.  See also ExecForeignScan/ExecReScanForeignScan.
     281             :          */
     282         208 :         if (estate->es_epq_active == NULL)
     283         208 :             fdwroutine->BeginDirectModify(scanstate, eflags);
     284             :     }
     285             :     else
     286        1708 :         fdwroutine->BeginForeignScan(scanstate, eflags);
     287             : 
     288        1900 :     return scanstate;
     289             : }
     290             : 
     291             : /* ----------------------------------------------------------------
     292             :  *      ExecEndForeignScan
     293             :  *
     294             :  *      frees any storage allocated through C routines.
     295             :  * ----------------------------------------------------------------
     296             :  */
     297             : void
     298        1848 : ExecEndForeignScan(ForeignScanState *node)
     299             : {
     300        1848 :     ForeignScan *plan = (ForeignScan *) node->ss.ps.plan;
     301        1848 :     EState     *estate = node->ss.ps.state;
     302             : 
     303             :     /* Let the FDW shut down */
     304        1848 :     if (plan->operation != CMD_SELECT)
     305             :     {
     306         192 :         if (estate->es_epq_active == NULL)
     307         192 :             node->fdwroutine->EndDirectModify(node);
     308             :     }
     309             :     else
     310        1656 :         node->fdwroutine->EndForeignScan(node);
     311             : 
     312             :     /* Shut down any outer plan. */
     313        1848 :     if (outerPlanState(node))
     314          24 :         ExecEndNode(outerPlanState(node));
     315        1848 : }
     316             : 
     317             : /* ----------------------------------------------------------------
     318             :  *      ExecReScanForeignScan
     319             :  *
     320             :  *      Rescans the relation.
     321             :  * ----------------------------------------------------------------
     322             :  */
     323             : void
     324         804 : ExecReScanForeignScan(ForeignScanState *node)
     325             : {
     326         804 :     ForeignScan *plan = (ForeignScan *) node->ss.ps.plan;
     327         804 :     EState     *estate = node->ss.ps.state;
     328         804 :     PlanState  *outerPlan = outerPlanState(node);
     329             : 
     330             :     /*
     331             :      * Ignore direct modifications when EvalPlanQual is active --- they are
     332             :      * irrelevant for EvalPlanQual rechecking
     333             :      */
     334         804 :     if (estate->es_epq_active != NULL && plan->operation != CMD_SELECT)
     335           0 :         return;
     336             : 
     337         804 :     node->fdwroutine->ReScanForeignScan(node);
     338             : 
     339             :     /*
     340             :      * If chgParam of subnode is not null then plan will be re-scanned by
     341             :      * first ExecProcNode.  outerPlan may also be NULL, in which case there is
     342             :      * nothing to rescan at all.
     343             :      */
     344         804 :     if (outerPlan != NULL && outerPlan->chgParam == NULL)
     345          20 :         ExecReScan(outerPlan);
     346             : 
     347         804 :     ExecScanReScan(&node->ss);
     348             : }
     349             : 
     350             : /* ----------------------------------------------------------------
     351             :  *      ExecForeignScanEstimate
     352             :  *
     353             :  *      Informs size of the parallel coordination information, if any
     354             :  * ----------------------------------------------------------------
     355             :  */
     356             : void
     357           0 : ExecForeignScanEstimate(ForeignScanState *node, ParallelContext *pcxt)
     358             : {
     359           0 :     FdwRoutine *fdwroutine = node->fdwroutine;
     360             : 
     361           0 :     if (fdwroutine->EstimateDSMForeignScan)
     362             :     {
     363           0 :         node->pscan_len = fdwroutine->EstimateDSMForeignScan(node, pcxt);
     364           0 :         shm_toc_estimate_chunk(&pcxt->estimator, node->pscan_len);
     365           0 :         shm_toc_estimate_keys(&pcxt->estimator, 1);
     366             :     }
     367           0 : }
     368             : 
     369             : /* ----------------------------------------------------------------
     370             :  *      ExecForeignScanInitializeDSM
     371             :  *
     372             :  *      Initialize the parallel coordination information
     373             :  * ----------------------------------------------------------------
     374             :  */
     375             : void
     376           0 : ExecForeignScanInitializeDSM(ForeignScanState *node, ParallelContext *pcxt)
     377             : {
     378           0 :     FdwRoutine *fdwroutine = node->fdwroutine;
     379             : 
     380           0 :     if (fdwroutine->InitializeDSMForeignScan)
     381             :     {
     382           0 :         int         plan_node_id = node->ss.ps.plan->plan_node_id;
     383             :         void       *coordinate;
     384             : 
     385           0 :         coordinate = shm_toc_allocate(pcxt->toc, node->pscan_len);
     386           0 :         fdwroutine->InitializeDSMForeignScan(node, pcxt, coordinate);
     387           0 :         shm_toc_insert(pcxt->toc, plan_node_id, coordinate);
     388             :     }
     389           0 : }
     390             : 
     391             : /* ----------------------------------------------------------------
     392             :  *      ExecForeignScanReInitializeDSM
     393             :  *
     394             :  *      Reset shared state before beginning a fresh scan.
     395             :  * ----------------------------------------------------------------
     396             :  */
     397             : void
     398           0 : ExecForeignScanReInitializeDSM(ForeignScanState *node, ParallelContext *pcxt)
     399             : {
     400           0 :     FdwRoutine *fdwroutine = node->fdwroutine;
     401             : 
     402           0 :     if (fdwroutine->ReInitializeDSMForeignScan)
     403             :     {
     404           0 :         int         plan_node_id = node->ss.ps.plan->plan_node_id;
     405             :         void       *coordinate;
     406             : 
     407           0 :         coordinate = shm_toc_lookup(pcxt->toc, plan_node_id, false);
     408           0 :         fdwroutine->ReInitializeDSMForeignScan(node, pcxt, coordinate);
     409             :     }
     410           0 : }
     411             : 
     412             : /* ----------------------------------------------------------------
     413             :  *      ExecForeignScanInitializeWorker
     414             :  *
     415             :  *      Initialization according to the parallel coordination information
     416             :  * ----------------------------------------------------------------
     417             :  */
     418             : void
     419           0 : ExecForeignScanInitializeWorker(ForeignScanState *node,
     420             :                                 ParallelWorkerContext *pwcxt)
     421             : {
     422           0 :     FdwRoutine *fdwroutine = node->fdwroutine;
     423             : 
     424           0 :     if (fdwroutine->InitializeWorkerForeignScan)
     425             :     {
     426           0 :         int         plan_node_id = node->ss.ps.plan->plan_node_id;
     427             :         void       *coordinate;
     428             : 
     429           0 :         coordinate = shm_toc_lookup(pwcxt->toc, plan_node_id, false);
     430           0 :         fdwroutine->InitializeWorkerForeignScan(node, pwcxt->toc, coordinate);
     431             :     }
     432           0 : }
     433             : 
     434             : /* ----------------------------------------------------------------
     435             :  *      ExecShutdownForeignScan
     436             :  *
     437             :  *      Gives FDW chance to stop asynchronous resource consumption
     438             :  *      and release any resources still held.
     439             :  * ----------------------------------------------------------------
     440             :  */
     441             : void
     442        1084 : ExecShutdownForeignScan(ForeignScanState *node)
     443             : {
     444        1084 :     FdwRoutine *fdwroutine = node->fdwroutine;
     445             : 
     446        1084 :     if (fdwroutine->ShutdownForeignScan)
     447           0 :         fdwroutine->ShutdownForeignScan(node);
     448        1084 : }
     449             : 
     450             : /* ----------------------------------------------------------------
     451             :  *      ExecAsyncForeignScanRequest
     452             :  *
     453             :  *      Asynchronously request a tuple from a designed async-capable node
     454             :  * ----------------------------------------------------------------
     455             :  */
     456             : void
     457       12150 : ExecAsyncForeignScanRequest(AsyncRequest *areq)
     458             : {
     459       12150 :     ForeignScanState *node = (ForeignScanState *) areq->requestee;
     460       12150 :     FdwRoutine *fdwroutine = node->fdwroutine;
     461             : 
     462             :     Assert(fdwroutine->ForeignAsyncRequest != NULL);
     463       12150 :     fdwroutine->ForeignAsyncRequest(areq);
     464       12150 : }
     465             : 
     466             : /* ----------------------------------------------------------------
     467             :  *      ExecAsyncForeignScanConfigureWait
     468             :  *
     469             :  *      In async mode, configure for a wait
     470             :  * ----------------------------------------------------------------
     471             :  */
     472             : void
     473         430 : ExecAsyncForeignScanConfigureWait(AsyncRequest *areq)
     474             : {
     475         430 :     ForeignScanState *node = (ForeignScanState *) areq->requestee;
     476         430 :     FdwRoutine *fdwroutine = node->fdwroutine;
     477             : 
     478             :     Assert(fdwroutine->ForeignAsyncConfigureWait != NULL);
     479         430 :     fdwroutine->ForeignAsyncConfigureWait(areq);
     480         428 : }
     481             : 
     482             : /* ----------------------------------------------------------------
     483             :  *      ExecAsyncForeignScanNotify
     484             :  *
     485             :  *      Callback invoked when a relevant event has occurred
     486             :  * ----------------------------------------------------------------
     487             :  */
     488             : void
     489         294 : ExecAsyncForeignScanNotify(AsyncRequest *areq)
     490             : {
     491         294 :     ForeignScanState *node = (ForeignScanState *) areq->requestee;
     492         294 :     FdwRoutine *fdwroutine = node->fdwroutine;
     493             : 
     494             :     Assert(fdwroutine->ForeignAsyncNotify != NULL);
     495         294 :     fdwroutine->ForeignAsyncNotify(areq);
     496         294 : }

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