executils.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

/*-------------------------------------------------------------------------
 *
 * execUtils.c
 *	  miscellaneous executor utility routines
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/executor/execUtils.c,v 1.126.2.3 2005/11/23 20:28:04 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
/*
 * INTERFACE ROUTINES
 *		CreateExecutorState		Create/delete executor working state
 *		FreeExecutorState
 *		CreateExprContext
 *		FreeExprContext
 *		ReScanExprContext
 *
 *		ExecAssignExprContext	Common code for plan node init routines.
 *		ExecAssignResultType
 *		etc
 *
 *		ExecOpenIndices			\
 *		ExecCloseIndices		 | referenced by InitPlan, EndPlan,
 *		ExecInsertIndexTuples	/  ExecInsert, ExecUpdate
 *
 *		RegisterExprContextCallback    Register function shutdown callback
 *		UnregisterExprContextCallback  Deregister function shutdown callback
 *
 *	 NOTES
 *		This file has traditionally been the place to stick misc.
 *		executor support stuff that doesn't really go anyplace else.
 */

#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "catalog/index.h"
#include "catalog/catalog.h"
#include "catalog/pg_index.h"
#include "executor/execdebug.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/memutils.h"
#include "utils/relcache.h"
#include "utils/syscache.h"


/* ----------------------------------------------------------------
 *		global counters for number of tuples processed, retrieved,
 *		appended, replaced, deleted.
 * ----------------------------------------------------------------
 */
int			NTupleProcessed;
int			NTupleRetrieved;
int			NTupleReplaced;
int			NTupleAppended;
int			NTupleDeleted;
int			NIndexTupleInserted;
extern int	NIndexTupleProcessed;		/* have to be defined in the access
										 * method level so that the
										 * cinterface.a will link ok. */


static void ShutdownExprContext(ExprContext *econtext);


/* ----------------------------------------------------------------
 *						statistic functions
 * ----------------------------------------------------------------
 */

/* ----------------------------------------------------------------
 *		ResetTupleCount
 * ----------------------------------------------------------------
 */
#ifdef NOT_USED
void
ResetTupleCount(void)
{
	NTupleProcessed = 0;
	NTupleRetrieved = 0;
	NTupleAppended = 0;
	NTupleDeleted = 0;
	NTupleReplaced = 0;
	NIndexTupleProcessed = 0;
}
#endif

/* ----------------------------------------------------------------
 *		PrintTupleCount
 * ----------------------------------------------------------------
 */
#ifdef NOT_USED
void
DisplayTupleCount(FILE *statfp)
{
	if (NTupleProcessed > 0)
		fprintf(statfp, "!\t%d tuple%s processed, ", NTupleProcessed,
				(NTupleProcessed == 1) ? "" : "s");
	else
	{
		fprintf(statfp, "!\tno tuples processed.\n");
		return;
	}
	if (NIndexTupleProcessed > 0)
		fprintf(statfp, "%d indextuple%s processed, ", NIndexTupleProcessed,
				(NIndexTupleProcessed == 1) ? "" : "s");
	if (NIndexTupleInserted > 0)
		fprintf(statfp, "%d indextuple%s inserted, ", NIndexTupleInserted,
				(NIndexTupleInserted == 1) ? "" : "s");
	if (NTupleRetrieved > 0)
		fprintf(statfp, "%d tuple%s retrieved. ", NTupleRetrieved,
				(NTupleRetrieved == 1) ? "" : "s");
	if (NTupleAppended > 0)
		fprintf(statfp, "%d tuple%s appended. ", NTupleAppended,
				(NTupleAppended == 1) ? "" : "s");
	if (NTupleDeleted > 0)
		fprintf(statfp, "%d tuple%s deleted. ", NTupleDeleted,
				(NTupleDeleted == 1) ? "" : "s");
	if (NTupleReplaced > 0)
		fprintf(statfp, "%d tuple%s replaced. ", NTupleReplaced,
				(NTupleReplaced == 1) ? "" : "s");
	fprintf(statfp, "\n");
}
#endif


/* ----------------------------------------------------------------
 *				 Executor state and memory management functions
 * ----------------------------------------------------------------
 */

/* ----------------
 *		CreateExecutorState
 *
 *		Create and initialize an EState node, which is the root of
 *		working storage for an entire Executor invocation.
 *
 * Principally, this creates the per-query memory context that will be
 * used to hold all working data that lives till the end of the query.
 * Note that the per-query context will become a child of the caller's
 * CurrentMemoryContext.
 * ----------------
 */
EState *
CreateExecutorState(void)
{
	EState	   *estate;
	MemoryContext qcontext;
	MemoryContext oldcontext;

	/*
	 * Create the per-query context for this Executor run.
	 */
	qcontext = AllocSetContextCreate(CurrentMemoryContext,
									 "ExecutorState",
									 ALLOCSET_DEFAULT_MINSIZE,
									 ALLOCSET_DEFAULT_INITSIZE,
									 ALLOCSET_DEFAULT_MAXSIZE);

	/*
	 * Make the EState node within the per-query context.  This way, we don't
	 * need a separate pfree() operation for it at shutdown.
	 */
	oldcontext = MemoryContextSwitchTo(qcontext);

	estate = makeNode(EState);

	/*
	 * Initialize all fields of the Executor State structure
	 */
	estate->es_direction = ForwardScanDirection;
	estate->es_snapshot = SnapshotNow;
	estate->es_crosscheck_snapshot = InvalidSnapshot;	/* no crosscheck */
	estate->es_range_table = NIL;

	estate->es_result_relations = NULL;
	estate->es_num_result_relations = 0;
	estate->es_result_relation_info = NULL;

	estate->es_junkFilter = NULL;

	estate->es_trig_tuple_slot = NULL;

	estate->es_into_relation_descriptor = NULL;
	estate->es_into_relation_use_wal = false;

	estate->es_param_list_info = NULL;
	estate->es_param_exec_vals = NULL;

	estate->es_query_cxt = qcontext;

	estate->es_tupleTable = NULL;

	estate->es_processed = 0;
	estate->es_lastoid = InvalidOid;
	estate->es_rowMarks = NIL;
	estate->es_forUpdate = false;
	estate->es_rowNoWait = false;

	estate->es_instrument = false;
	estate->es_select_into = false;
	estate->es_into_oids = false;

	estate->es_exprcontexts = NIL;

	estate->es_per_tuple_exprcontext = NULL;

	estate->es_topPlan = NULL;
	estate->es_evalPlanQual = NULL;
	estate->es_evTupleNull = NULL;
	estate->es_evTuple = NULL;
	estate->es_useEvalPlan = false;

	/*
	 * Return the executor state structure
	 */
	MemoryContextSwitchTo(oldcontext);

	return estate;
}

/* ----------------
 *		FreeExecutorState
 *
 *		Release an EState along with all remaining working storage.
 *
 * Note: this is not responsible for releasing non-memory resources,
 * such as open relations or buffer pins.  But it will shut down any
 * still-active ExprContexts within the EState.  That is sufficient
 * cleanup for situations where the EState has only been used for expression
 * evaluation, and not to run a complete Plan.
 *
 * This can be called in any memory context ... so long as it's not one
 * of the ones to be freed.
 * ----------------
 */
void
FreeExecutorState(EState *estate)
{
	/*
	 * Shut down and free any remaining ExprContexts.  We do this explicitly
	 * to ensure that any remaining shutdown callbacks get called (since they
	 * might need to release resources that aren't simply memory within the
	 * per-query memory context).
	 */
	while (estate->es_exprcontexts)
	{
		/*
		 * XXX: seems there ought to be a faster way to implement this than
		 * repeated list_delete(), no?
		 */
		FreeExprContext((ExprContext *) linitial(estate->es_exprcontexts));
		/* FreeExprContext removed the list link for us */
	}

	/*
	 * Free the per-query memory context, thereby releasing all working
	 * memory, including the EState node itself.
	 */
	MemoryContextDelete(estate->es_query_cxt);
}

/* ----------------
 *		CreateExprContext
 *
 *		Create a context for expression evaluation within an EState.
 *
 * An executor run may require multiple ExprContexts (we usually make one
 * for each Plan node, and a separate one for per-output-tuple processing
 * such as constraint checking).  Each ExprContext has its own "per-tuple"
 * memory context.
 *
 * Note we make no assumption about the caller's memory context.
 * ----------------
 */
ExprContext *
CreateExprContext(EState *estate)
{
	ExprContext *econtext;
	MemoryContext oldcontext;

	/* Create the ExprContext node within the per-query memory context */
	oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

	econtext = makeNode(ExprContext);

	/* Initialize fields of ExprContext */
	econtext->ecxt_scantuple = NULL;
	econtext->ecxt_innertuple = NULL;
	econtext->ecxt_outertuple = NULL;

	econtext->ecxt_per_query_memory = estate->es_query_cxt;

	/*
	 * Create working memory for expression evaluation in this context.
	 */
	econtext->ecxt_per_tuple_memory =
		AllocSetContextCreate(estate->es_query_cxt,
							  "ExprContext",
							  ALLOCSET_DEFAULT_MINSIZE,
							  ALLOCSET_DEFAULT_INITSIZE,
							  ALLOCSET_DEFAULT_MAXSIZE);

	econtext->ecxt_param_exec_vals = estate->es_param_exec_vals;
	econtext->ecxt_param_list_info = estate->es_param_list_info;

	econtext->ecxt_aggvalues = NULL;
	econtext->ecxt_aggnulls = NULL;

	econtext->caseValue_datum = (Datum) 0;
	econtext->caseValue_isNull = true;

	econtext->domainValue_datum = (Datum) 0;
	econtext->domainValue_isNull = true;

	econtext->ecxt_estate = estate;

	econtext->ecxt_callbacks = NULL;

	/*
	 * Link the ExprContext into the EState to ensure it is shut down when the
	 * EState is freed.  Because we use lcons(), shutdowns will occur in
	 * reverse order of creation, which may not be essential but can't hurt.
	 */
	estate->es_exprcontexts = lcons(econtext, estate->es_exprcontexts);

	MemoryContextSwitchTo(oldcontext);

	return econtext;
}

/* ----------------
 *		FreeExprContext
 *
 *		Free an expression context, including calling any remaining
 *		shutdown callbacks.
 *
 * Since we free the temporary context used for expression evaluation,
 * any previously computed pass-by-reference expression result will go away!
 *
 * Note we make no assumption about the caller's memory context.
 * ----------------
 */
void
FreeExprContext(ExprContext *econtext)
{
	EState	   *estate;

	/* Call any registered callbacks */
	ShutdownExprContext(econtext);
	/* And clean up the memory used */
	MemoryContextDelete(econtext->ecxt_per_tuple_memory);
	/* Unlink self from owning EState */
	estate = econtext->ecxt_estate;
	estate->es_exprcontexts = list_delete_ptr(estate->es_exprcontexts, econtext);
	/* And delete the ExprContext node */
	pfree(econtext);
}

/*
 * ReScanExprContext
 *
 *		Reset an expression context in preparation for a rescan of its
 *		plan node.	This requires calling any registered shutdown callbacks,
 *		since any partially complete set-returning-functions must be canceled.
 *
 * Note we make no assumption about the caller's memory context.
 */
void
ReScanExprContext(ExprContext *econtext)
{
	/* Call any registered callbacks */
	ShutdownExprContext(econtext);
	/* And clean up the memory used */
	MemoryContextReset(econtext->ecxt_per_tuple_memory);
}

/*
 * Build a per-output-tuple ExprContext for an EState.
 *
 * This is normally invoked via GetPerTupleExprContext() macro,
 * not directly.
 */
ExprContext *
MakePerTupleExprContext(EState *estate)
{
	if (estate->es_per_tuple_exprcontext == NULL)
		estate->es_per_tuple_exprcontext = CreateExprContext(estate);

	return estate->es_per_tuple_exprcontext;
}


/* ----------------------------------------------------------------
 *				 miscellaneous node-init support functions
 *
 * Note: all of these are expected to be called with CurrentMemoryContext
 * equal to the per-query memory context.
 * ----------------------------------------------------------------
 */

/* ----------------
 *		ExecAssignExprContext
 *
 *		This initializes the ps_ExprContext field.	It is only necessary
 *		to do this for nodes which use ExecQual or ExecProject
 *		because those routines require an econtext. Other nodes that
 *		don't have to evaluate expressions don't need to do this.
 * ----------------
 */
void
ExecAssignExprContext(EState *estate, PlanState *planstate)
{
	planstate->ps_ExprContext = CreateExprContext(estate);
}

/* ----------------
 *		ExecAssignResultType
 * ----------------
 */
void
ExecAssignResultType(PlanState *planstate,
					 TupleDesc tupDesc, bool shouldFree)
{
	TupleTableSlot *slot = planstate->ps_ResultTupleSlot;

	ExecSetSlotDescriptor(slot, tupDesc, shouldFree);
}

/* ----------------
 *		ExecAssignResultTypeFromTL
 * ----------------
 */
void
ExecAssignResultTypeFromTL(PlanState *planstate)
{
	bool		hasoid;
	TupleDesc	tupDesc;

	if (ExecContextForcesOids(planstate, &hasoid))
	{
		/* context forces OID choice; hasoid is now set correctly */
	}
	else
	{
		/* given free choice, don't leave space for OIDs in result tuples */
		hasoid = false;
	}

	/*
	 * ExecTypeFromTL needs the parse-time representation of the tlist, not a
	 * list of ExprStates.	This is good because some plan nodes don't bother
	 * to set up planstate->targetlist ...
	 */
	tupDesc = ExecTypeFromTL(planstate->plan->targetlist, hasoid);
	ExecAssignResultType(planstate, tupDesc, true);
}

/* ----------------
 *		ExecGetResultType
 * ----------------
 */
TupleDesc
ExecGetResultType(PlanState *planstate)
{
	TupleTableSlot *slot = planstate->ps_ResultTupleSlot;

	return slot->tts_tupleDescriptor;
}

/* ----------------
 *		ExecBuildProjectionInfo
 *
 * Build a ProjectionInfo node for evaluating the given tlist in the given
 * econtext, and storing the result into the tuple slot.  (Caller must have
 * ensured that tuple slot has a descriptor matching the tlist!)  Note that
 * the given tlist should be a list of ExprState nodes, not Expr nodes.
 * ----------------
 */
ProjectionInfo *
ExecBuildProjectionInfo(List *targetList,
						ExprContext *econtext,
						TupleTableSlot *slot)
{
	ProjectionInfo *projInfo = makeNode(ProjectionInfo);
	int			len;
	bool		isVarList;
	ListCell   *tl;

	len = ExecTargetListLength(targetList);

	projInfo->pi_targetlist = targetList;
	projInfo->pi_exprContext = econtext;
	projInfo->pi_slot = slot;

	/*
	 * Determine whether the target list consists entirely of simple Var
	 * references (ie, references to non-system attributes).  If so, we can
	 * use the simpler ExecVariableList instead of ExecTargetList.
	 */
	isVarList = true;
	foreach(tl, targetList)
	{
		GenericExprState *gstate = (GenericExprState *) lfirst(tl);
		Var		   *variable = (Var *) gstate->arg->expr;

		if (variable == NULL ||
			!IsA(variable, Var) ||
			variable->varattno <= 0)
		{
			isVarList = false;
			break;
		}
	}
	projInfo->pi_isVarList = isVarList;

	if (isVarList)
	{
		int		   *varSlotOffsets;