調(diào)用關(guān)系：PortalRun ->?PortalRunSelect -> ExecutorRun

ExecutorRun，實(shí)際上會(huì)去運(yùn)行 standard_ExecutorRun ->ExecutePlan：

/* ----------------------------------------------------------------* ExecutorRun** This is the main routine of the executor module. It accepts* the query descriptor from the traffic cop and executes the* query plan.** ExecutorStart must have been called already.** If direction is NoMovementScanDirection then nothing is done* except to start up/shut down the destination. Otherwise,* we retrieve up to 'count' tuples in the specified direction.** Note: count = 0 is interpreted as no portal limit, i.e., run to* completion.** There is no return value, but output tuples (if any) are sent to* the destination receiver specified in the QueryDesc; and the number* of tuples processed at the top level can be found in* estate->es_processed.** We provide a function hook variable that lets loadable plugins* get control when ExecutorRun is called. Such a plugin would* normally call standard_ExecutorRun().** ----------------------------------------------------------------*/ void ExecutorRun(QueryDesc *queryDesc,ScanDirection direction, long count) {if (ExecutorRun_hook)(*ExecutorRun_hook) (queryDesc, direction, count);elsestandard_ExecutorRun(queryDesc, direction, count); }void standard_ExecutorRun(QueryDesc *queryDesc,ScanDirection direction, long count) {EState *estate;CmdType operation;DestReceiver *dest;bool sendTuples;MemoryContext oldcontext;/* sanity checks */Assert(queryDesc != NULL);estate = queryDesc->estate;Assert(estate != NULL);Assert(!(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));/** Switch into per-query memory context*/oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);/* Allow instrumentation of Executor overall runtime */if (queryDesc->totaltime)InstrStartNode(queryDesc->totaltime);/** extract information from the query descriptor and the query feature.*/operation = queryDesc->operation;dest = queryDesc->dest;/** startup tuple receiver, if we will be emitting tuples*/estate->es_processed = 0;estate->es_lastoid = InvalidOid;sendTuples = (operation == CMD_SELECT ||queryDesc->plannedstmt->hasReturning);if (sendTuples)(*dest->rStartup) (dest, operation, queryDesc->tupDesc);/** run plan*/if (!ScanDirectionIsNoMovement(direction)) ExecutePlan(estate,queryDesc->planstate,operation,sendTuples,count,direction,dest);/** shutdown tuple receiver, if we started it*/if (sendTuples)(*dest->rShutdown) (dest);if (queryDesc->totaltime)InstrStopNode(queryDesc->totaltime, estate->es_processed);MemoryContextSwitchTo(oldcontext); }

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