execnodes.h

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/*-------------------------------------------------------------------------
 *
 * execnodes.h
 *	  definitions for executor state nodes
 *
 *
 * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.161.2.2 2007/04/26 23:24:57 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef EXECNODES_H
#define EXECNODES_H

#include "access/relscan.h"
#include "nodes/params.h"
#include "nodes/plannodes.h"
#include "nodes/tidbitmap.h"
#include "utils/hsearch.h"
#include "utils/tuplestore.h"


/* ----------------
 *	  IndexInfo information
 *
 *		this struct holds the information needed to construct new index
 *		entries for a particular index.  Used for both index_build and
 *		retail creation of index entries.
 *
 *		NumIndexAttrs		number of columns in this index
 *		KeyAttrNumbers		underlying-rel attribute numbers used as keys
 *							(zeroes indicate expressions)
 *		Expressions			expr trees for expression entries, or NIL if none
 *		ExpressionsState	exec state for expressions, or NIL if none
 *		Predicate			partial-index predicate, or NIL if none
 *		PredicateState		exec state for predicate, or NIL if none
 *		Unique				is it a unique index?
 *		Concurrent			are we doing a concurrent index build?
 * ----------------
 */
typedef struct IndexInfo
{
	NodeTag		type;
	int			ii_NumIndexAttrs;
	AttrNumber	ii_KeyAttrNumbers[INDEX_MAX_KEYS];
	List	   *ii_Expressions; /* list of Expr */
	List	   *ii_ExpressionsState;	/* list of ExprState */
	List	   *ii_Predicate;	/* list of Expr */
	List	   *ii_PredicateState;		/* list of ExprState */
	bool		ii_Unique;
	bool		ii_Concurrent;
} IndexInfo;

/* ----------------
 *	  ExprContext_CB
 *
 *		List of callbacks to be called at ExprContext shutdown.
 * ----------------
 */
typedef void (*ExprContextCallbackFunction) (Datum arg);

typedef struct ExprContext_CB
{
	struct ExprContext_CB *next;
	ExprContextCallbackFunction function;
	Datum		arg;
} ExprContext_CB;

/* ----------------
 *	  ExprContext
 *
 *		This class holds the "current context" information
 *		needed to evaluate expressions for doing tuple qualifications
 *		and tuple projections.	For example, if an expression refers
 *		to an attribute in the current inner tuple then we need to know
 *		what the current inner tuple is and so we look at the expression
 *		context.
 *
 *	There are two memory contexts associated with an ExprContext:
 *	* ecxt_per_query_memory is a query-lifespan context, typically the same
 *	  context the ExprContext node itself is allocated in.	This context
 *	  can be used for purposes such as storing function call cache info.
 *	* ecxt_per_tuple_memory is a short-term context for expression results.
 *	  As the name suggests, it will typically be reset once per tuple,
 *	  before we begin to evaluate expressions for that tuple.  Each
 *	  ExprContext normally has its very own per-tuple memory context.
 *
 *	CurrentMemoryContext should be set to ecxt_per_tuple_memory before
 *	calling ExecEvalExpr() --- see ExecEvalExprSwitchContext().
 * ----------------
 */
typedef struct ExprContext
{
	NodeTag		type;

	/* Tuples that Var nodes in expression may refer to */
	TupleTableSlot *ecxt_scantuple;
	TupleTableSlot *ecxt_innertuple;
	TupleTableSlot *ecxt_outertuple;

	/* Memory contexts for expression evaluation --- see notes above */
	MemoryContext ecxt_per_query_memory;
	MemoryContext ecxt_per_tuple_memory;

	/* Values to substitute for Param nodes in expression */
	ParamExecData *ecxt_param_exec_vals;		/* for PARAM_EXEC params */
	ParamListInfo ecxt_param_list_info; /* for other param types */

	/* Values to substitute for Aggref nodes in expression */
	Datum	   *ecxt_aggvalues; /* precomputed values for Aggref nodes */
	bool	   *ecxt_aggnulls;	/* null flags for Aggref nodes */

	/* Value to substitute for CaseTestExpr nodes in expression */
	Datum		caseValue_datum;
	bool		caseValue_isNull;

	/* Value to substitute for CoerceToDomainValue nodes in expression */
	Datum		domainValue_datum;
	bool		domainValue_isNull;

	/* Link to containing EState (NULL if a standalone ExprContext) */
	struct EState *ecxt_estate;

	/* Functions to call back when ExprContext is shut down */
	ExprContext_CB *ecxt_callbacks;
} ExprContext;

/*
 * Set-result status returned by ExecEvalExpr()
 */
typedef enum
{
	ExprSingleResult,			/* expression does not return a set */
	ExprMultipleResult,			/* this result is an element of a set */
	ExprEndResult				/* there are no more elements in the set */
} ExprDoneCond;

/*
 * Return modes for functions returning sets.  Note values must be chosen
 * as separate bits so that a bitmask can be formed to indicate supported
 * modes.
 */
typedef enum
{
	SFRM_ValuePerCall = 0x01,	/* one value returned per call */
	SFRM_Materialize = 0x02		/* result set instantiated in Tuplestore */
} SetFunctionReturnMode;

/*
 * When calling a function that might return a set (multiple rows),
 * a node of this type is passed as fcinfo->resultinfo to allow
 * return status to be passed back.  A function returning set should
 * raise an error if no such resultinfo is provided.
 */
typedef struct ReturnSetInfo
{
	NodeTag		type;
	/* values set by caller: */
	ExprContext *econtext;		/* context function is being called in */
	TupleDesc	expectedDesc;	/* tuple descriptor expected by caller */
	int			allowedModes;	/* bitmask: return modes caller can handle */
	/* result status from function (but pre-initialized by caller): */
	SetFunctionReturnMode returnMode;	/* actual return mode */
	ExprDoneCond isDone;		/* status for ValuePerCall mode */
	/* fields filled by function in Materialize return mode: */
	Tuplestorestate *setResult; /* holds the complete returned tuple set */
	TupleDesc	setDesc;		/* actual descriptor for returned tuples */
} ReturnSetInfo;

/* ----------------
 *		ProjectionInfo node information
 *
 *		This is all the information needed to perform projections ---
 *		that is, form new tuples by evaluation of targetlist expressions.
 *		Nodes which need to do projections create one of these.
 *
 *		ExecProject() evaluates the tlist, forms a tuple, and stores it
 *		in the given slot.	Note that the result will be a "virtual" tuple
 *		unless ExecMaterializeSlot() is then called to force it to be
 *		converted to a physical tuple.	The slot must have a tupledesc
 *		that matches the output of the tlist!
 *
 *		The planner very often produces tlists that consist entirely of
 *		simple Var references (lower levels of a plan tree almost always
 *		look like that).  So we have an optimization to handle that case
 *		with minimum overhead.
 *
 *		targetlist		target list for projection
 *		exprContext		expression context in which to evaluate targetlist
 *		slot			slot to place projection result in
 *		itemIsDone		workspace for ExecProject
 *		isVarList		TRUE if simple-Var-list optimization applies
 *		varSlotOffsets	array indicating which slot each simple Var is from
 *		varNumbers		array indicating attr numbers of simple Vars
 *		lastInnerVar	highest attnum from inner tuple slot (0 if none)
 *		lastOuterVar	highest attnum from outer tuple slot (0 if none)
 *		lastScanVar		highest attnum from scan tuple slot (0 if none)
 * ----------------
 */
typedef struct ProjectionInfo
{
	NodeTag		type;
	List	   *pi_targetlist;
	ExprContext *pi_exprContext;
	TupleTableSlot *pi_slot;
	ExprDoneCond *pi_itemIsDone;
	bool		pi_isVarList;
	int		   *pi_varSlotOffsets;
	int		   *pi_varNumbers;
	int			pi_lastInnerVar;
	int			pi_lastOuterVar;
	int			pi_lastScanVar;
} ProjectionInfo;

/* ----------------
 *	  JunkFilter
 *
 *	  This class is used to store information regarding junk attributes.
 *	  A junk attribute is an attribute in a tuple that is needed only for
 *	  storing intermediate information in the executor, and does not belong
 *	  in emitted tuples.  For example, when we do an UPDATE query,
 *	  the planner adds a "junk" entry to the targetlist so that the tuples
 *	  returned to ExecutePlan() contain an extra attribute: the ctid of
 *	  the tuple to be updated.	This is needed to do the update, but we
 *	  don't want the ctid to be part of the stored new tuple!  So, we
 *	  apply a "junk filter" to remove the junk attributes and form the
 *	  real output tuple.
 *
 *	  targetList:		the original target list (including junk attributes).
 *	  cleanTupType:		the tuple descriptor for the "clean" tuple (with
 *						junk attributes removed).
 *	  cleanMap:			A map with the correspondence between the non-junk
 *						attribute numbers of the "original" tuple and the
 *						attribute numbers of the "clean" tuple.
 *	  resultSlot:		tuple slot used to hold cleaned tuple.
 * ----------------
 */
typedef struct JunkFilter
{
	NodeTag		type;
	List	   *jf_targetList;
	TupleDesc	jf_cleanTupType;
	AttrNumber *jf_cleanMap;
	TupleTableSlot *jf_resultSlot;
} JunkFilter;

/* ----------------
 *	  ResultRelInfo information
 *
 *		Whenever we update an existing relation, we have to
 *		update indices on the relation, and perhaps also fire triggers.
 *		The ResultRelInfo class is used to hold all the information needed
 *		about a result relation, including indices.. -cim 10/15/89
 *
 *		RangeTableIndex			result relation's range table index
 *		RelationDesc			relation descriptor for result relation
 *		NumIndices				# of indices existing on result relation
 *		IndexRelationDescs		array of relation descriptors for indices
 *		IndexRelationInfo		array of key/attr info for indices
 *		TrigDesc				triggers to be fired, if any
 *		TrigFunctions			cached lookup info for trigger functions
 *		TrigInstrument			optional runtime measurements for triggers
 *		ConstraintExprs			array of constraint-checking expr states
 *		junkFilter				for removing junk attributes from tuples
 *		projectReturning		for computing a RETURNING list
 * ----------------
 */
typedef struct ResultRelInfo
{
	NodeTag		type;
	Index		ri_RangeTableIndex;
	Relation	ri_RelationDesc;
	int			ri_NumIndices;
	RelationPtr ri_IndexRelationDescs;
	IndexInfo **ri_IndexRelationInfo;
	TriggerDesc *ri_TrigDesc;
	FmgrInfo   *ri_TrigFunctions;
	struct Instrumentation *ri_TrigInstrument;
	List	  **ri_ConstraintExprs;
	JunkFilter *ri_junkFilter;
	ProjectionInfo *ri_projectReturning;
} ResultRelInfo;

/* ----------------
 *	  EState information
 *
 * Master working state for an Executor invocation
 * ----------------
 */
typedef struct EState
{
	NodeTag		type;

	/* Basic state for all query types: */
	ScanDirection es_direction; /* current scan direction */
	Snapshot	es_snapshot;	/* time qual to use */
	Snapshot	es_crosscheck_snapshot; /* crosscheck time qual for RI */
	List	   *es_range_table; /* List of RangeTableEntrys */

	/* Info about target table for insert/update/delete queries: */
	ResultRelInfo *es_result_relations; /* array of ResultRelInfos */
	int			es_num_result_relations;		/* length of array */
	ResultRelInfo *es_result_relation_info;		/* currently active array elt */
	JunkFilter *es_junkFilter;	/* currently active junk filter */

	TupleTableSlot *es_trig_tuple_slot; /* for trigger output tuples */

	Relation	es_into_relation_descriptor;	/* for SELECT INTO */
	bool		es_into_relation_use_wal;

	/* Parameter info: */
	ParamListInfo es_param_list_info;	/* values of external params */
	ParamExecData *es_param_exec_vals;	/* values of internal params */

	/* Other working state: */
	MemoryContext es_query_cxt; /* per-query context in which EState lives */

	TupleTable	es_tupleTable;	/* Array of TupleTableSlots */

	uint32		es_processed;	/* # of tuples processed */
	Oid			es_lastoid;		/* last oid processed (by INSERT) */
	List	   *es_rowMarks;	/* not good place, but there is no other */

	bool		es_is_subquery;	/* true if subquery (es_query_cxt not mine) */

	bool		es_instrument;	/* true requests runtime instrumentation */
	bool		es_select_into; /* true if doing SELECT INTO */
	bool		es_into_oids;	/* true to generate OIDs in SELECT INTO */

	List	   *es_exprcontexts;	/* List of ExprContexts within EState */

	/*
	 * this ExprContext is for per-output-tuple operations, such as constraint
	 * checks and index-value computations.  It will be reset for each output
	 * tuple.  Note that it will be created only if needed.
	 */
	ExprContext *es_per_tuple_exprcontext;

	/* Below is to re-evaluate plan qual in READ COMMITTED mode */
	Plan	   *es_topPlan;		/* link to top of plan tree */
	struct evalPlanQual *es_evalPlanQual;		/* chain of PlanQual states */
	bool	   *es_evTupleNull; /* local array of EPQ status */
	HeapTuple  *es_evTuple;		/* shared array of EPQ substitute tuples */
	bool		es_useEvalPlan; /* evaluating EPQ tuples? */
} EState;