postgres/src/include/nodes/execnodes.h

/*-------------------------------------------------------------------------
 *
 * execnodes.h
 *	  definitions for executor state nodes
 *
 *
 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/nodes/execnodes.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef EXECNODES_H
#define EXECNODES_H

#include "access/genam.h"
#include "access/heapam.h"
#include "access/tupconvert.h"
#include "executor/instrument.h"
#include "lib/pairingheap.h"
#include "nodes/params.h"
#include "nodes/plannodes.h"
#include "utils/hsearch.h"
#include "utils/queryenvironment.h"
#include "utils/reltrigger.h"
#include "utils/sortsupport.h"
#include "utils/tuplestore.h"
#include "utils/tuplesort.h"
#include "nodes/tidbitmap.h"
#include "storage/condition_variable.h"


/* ----------------
 *		ExprState node
 *
 * ExprState is the top-level node for expression evaluation.
 * It contains instructions (in ->steps) to evaluate the expression.
 * ----------------
 */
struct ExprState;				/* forward references in this file */
struct ExprContext;
struct ExprEvalStep;			/* avoid including execExpr.h everywhere */

typedef Datum (*ExprStateEvalFunc) (struct ExprState *expression,
									struct ExprContext *econtext,
									bool *isNull);

/* Bits in ExprState->flags (see also execExpr.h for private flag bits): */
/* expression is for use with ExecQual() */
#define EEO_FLAG_IS_QUAL					(1 << 0)

typedef struct ExprState
{
	Node		tag;

	uint8		flags;			/* bitmask of EEO_FLAG_* bits, see above */

	/*
	 * Storage for result value of a scalar expression, or for individual
	 * column results within expressions built by ExecBuildProjectionInfo().
	 */
	bool		resnull;
	Datum		resvalue;

	/*
	 * If projecting a tuple result, this slot holds the result; else NULL.
	 */
	TupleTableSlot *resultslot;

	/*
	 * Instructions to compute expression's return value.
	 */
	struct ExprEvalStep *steps;

	/*
	 * Function that actually evaluates the expression.  This can be set to
	 * different values depending on the complexity of the expression.
	 */
	ExprStateEvalFunc evalfunc;

	/* original expression tree, for debugging only */
	Expr	   *expr;

	/*
	 * XXX: following only needed during "compilation", could be thrown away.
	 */

	int			steps_len;		/* number of steps currently */
	int			steps_alloc;	/* allocated length of steps array */

	Datum	   *innermost_caseval;
	bool	   *innermost_casenull;

	Datum	   *innermost_domainval;
	bool	   *innermost_domainnull;
} ExprState;


/* ----------------
 *	  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
 *		ExclusionOps		Per-column exclusion operators, or NULL if none
 *		ExclusionProcs		Underlying function OIDs for ExclusionOps
 *		ExclusionStrats		Opclass strategy numbers for ExclusionOps
 *		UniqueOps			Theses are like Exclusion*, but for unique indexes
 *		UniqueProcs
 *		UniqueStrats
 *		Unique				is it a unique index?
 *		ReadyForInserts		is it valid for inserts?
 *		Concurrent			are we doing a concurrent index build?
 *		BrokenHotChain		did we detect any broken HOT chains?
 *		AmCache				private cache area for index AM
 *		Context				memory context holding this IndexInfo
 *
 * ii_Concurrent and ii_BrokenHotChain are used only during index build;
 * they're conventionally set to false otherwise.
 * ----------------
 */
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 */
	ExprState  *ii_PredicateState;
	Oid		   *ii_ExclusionOps;	/* array with one entry per column */
	Oid		   *ii_ExclusionProcs;	/* array with one entry per column */
	uint16	   *ii_ExclusionStrats; /* array with one entry per column */
	Oid		   *ii_UniqueOps;	/* array with one entry per column */
	Oid		   *ii_UniqueProcs; /* array with one entry per column */
	uint16	   *ii_UniqueStrats;	/* array with one entry per column */
	bool		ii_Unique;
	bool		ii_ReadyForInserts;
	bool		ii_Concurrent;
	bool		ii_BrokenHotChain;
	void	   *ii_AmCache;
	MemoryContext ii_Context;
} 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 the expressions of an Agg
	 * node, or for WindowFunc nodes within a WindowAgg node.
	 */
	Datum	   *ecxt_aggvalues; /* precomputed values for aggs/windowfuncs */
	bool	   *ecxt_aggnulls;	/* null flags for aggs/windowfuncs */

	/* 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 or rescanned */
	ExprContext_CB *ecxt_callbacks;
} ExprContext;

/*
 * Set-result status used when evaluating functions potentially returning a
 * set.
 */
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.  SFRM_Materialize_Random and SFRM_Materialize_Preferred are
 * auxiliary flags about SFRM_Materialize mode, rather than separate modes.
 */
typedef enum
{
	SFRM_ValuePerCall = 0x01,	/* one value returned per call */
	SFRM_Materialize = 0x02,	/* result set instantiated in Tuplestore */
	SFRM_Materialize_Random = 0x04, /* Tuplestore needs randomAccess */
	SFRM_Materialize_Preferred = 0x08	/* caller prefers 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.
 *
 *		The target tuple slot is kept in ProjectionInfo->pi_state.resultslot.
 *		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!
 * ----------------
 */
typedef struct ProjectionInfo
{
	NodeTag		type;
	/* instructions to evaluate projection */
	ExprState	pi_state;
	/* expression context in which to evaluate expression */
	ExprContext *pi_exprContext;
} 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.  The junkfilter code also provides routines to
 *	  extract the values of the junk attribute(s) from the input 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.
 *	  junkAttNo:		not used by junkfilter code.  Can be used by caller
 *						to remember the attno of a specific junk attribute
 *						(nodeModifyTable.c keeps the "ctid" or "wholerow"
 *						attno here).
 * ----------------
 */
typedef struct JunkFilter
{
	NodeTag		type;
	List	   *jf_targetList;
	TupleDesc	jf_cleanTupType;
	AttrNumber *jf_cleanMap;
	TupleTableSlot *jf_resultSlot;
	AttrNumber	jf_junkAttNo;
} JunkFilter;

/*
 * ResultRelInfo
 *
 * Whenever we update an existing relation, we have to update indexes on the
 * relation, and perhaps also fire triggers.  ResultRelInfo holds all the
 * information needed about a result relation, including indexes.
 */
typedef struct ResultRelInfo
{
	NodeTag		type;

	/* result relation's range table index */
	Index		ri_RangeTableIndex;

	/* relation descriptor for result relation */
	Relation	ri_RelationDesc;

	/* # of indices existing on result relation */
	int			ri_NumIndices;

	/* array of relation descriptors for indices */
	RelationPtr ri_IndexRelationDescs;

	/* array of key/attr info for indices */
	IndexInfo **ri_IndexRelationInfo;

	/* triggers to be fired, if any */
	TriggerDesc *ri_TrigDesc;

	/* cached lookup info for trigger functions */
	FmgrInfo   *ri_TrigFunctions;

	/* array of trigger WHEN expr states */
	ExprState **ri_TrigWhenExprs;

	/* optional runtime measurements for triggers */
	Instrumentation *ri_TrigInstrument;

	/* FDW callback functions, if foreign table */
	struct FdwRoutine *ri_FdwRoutine;

	/* available to save private state of FDW */
	void	   *ri_FdwState;

	/* true when modifying foreign table directly */
	bool		ri_usesFdwDirectModify;

	/* list of WithCheckOption's to be checked */
	List	   *ri_WithCheckOptions;

	/* list of WithCheckOption expr states */
	List	   *ri_WithCheckOptionExprs;

	/* array of constraint-checking expr states */
	ExprState **ri_ConstraintExprs;

	/* for removing junk attributes from tuples */
	JunkFilter *ri_junkFilter;

	/* for computing a RETURNING list */
	ProjectionInfo *ri_projectReturning;

	/* for computing ON CONFLICT DO UPDATE SET */
	ProjectionInfo *ri_onConflictSetProj;

	/* list of ON CONFLICT DO UPDATE exprs (qual) */
	ExprState  *ri_onConflictSetWhere;

	/* partition check expression */
	List	   *ri_PartitionCheck;

	/* partition check expression state */
	ExprState  *ri_PartitionCheckExpr;

	/* relation descriptor for root partitioned table */
	Relation	ri_PartitionRoot;
} 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 RangeTblEntry */
	PlannedStmt *es_plannedstmt;	/* link to top of plan tree */
	const char *es_sourceText;	/* Source text from QueryDesc */

	JunkFilter *es_junkFilter;	/* top-level junk filter, if any */

	/* If query can insert/delete tuples, the command ID to mark them with */
	CommandId	es_output_cid;

	/* Info about target table(s) 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 */

	/*
	 * Info about the target partitioned target table root(s) for
	 * update/delete queries.  They required only to fire any per-statement
	 * triggers defined on the table.  It exists separately from
	 * es_result_relations, because partitioned tables don't appear in the
	 * plan tree for the update/delete cases.
	 */
	ResultRelInfo *es_root_result_relations;	/* array of ResultRelInfos */
	int			es_num_root_result_relations;	/* length of the array */

	/* Info about leaf partitions of partitioned table(s) for insert queries: */
	List	   *es_leaf_result_relations;	/* List of ResultRelInfos */

	/* Stuff used for firing triggers: */
	List	   *es_trig_target_relations;	/* trigger-only ResultRelInfos */
	TupleTableSlot *es_trig_tuple_slot; /* for trigger output tuples */
	TupleTableSlot *es_trig_oldtup_slot;	/* for TriggerEnabled */
	TupleTableSlot *es_trig_newtup_slot;	/* for TriggerEnabled */

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

	QueryEnvironment *es_queryEnv;	/* query environment */

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

	List	   *es_tupleTable;	/* List of TupleTableSlots */

	List	   *es_rowMarks;	/* List of ExecRowMarks */

	uint64		es_processed;	/* # of tuples processed */
	Oid			es_lastoid;		/* last oid processed (by INSERT) */

	int			es_top_eflags;	/* eflags passed to ExecutorStart */
	int			es_instrument;	/* OR of InstrumentOption flags */
	bool		es_finished;	/* true when ExecutorFinish is done */

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

	List	   *es_subplanstates;	/* List of PlanState for SubPlans */

	List	   *es_auxmodifytables; /* List of secondary ModifyTableStates */

	/*
	 * 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;

	/*
	 * These fields are for re-evaluating plan quals when an updated tuple is
	 * substituted in READ COMMITTED mode.  es_epqTuple[] contains tuples that
	 * scan plan nodes should return instead of whatever they'd normally
	 * return, or NULL if nothing to return; es_epqTupleSet[] is true if a
	 * particular array entry is valid; and es_epqScanDone[] is state to
	 * remember if the tuple has been returned already.  Arrays are of size
	 * list_length(es_range_table) and are indexed by scan node scanrelid - 1.
	 */
	HeapTuple  *es_epqTuple;	/* array of EPQ substitute tuples */
	bool	   *es_epqTupleSet; /* true if EPQ tuple is provided */
	bool	   *es_epqScanDone; /* true if EPQ tuple has been fetched */

	bool		es_use_parallel_mode; /* can we use parallel workers? */

	/* The per-query shared memory area to use for parallel execution. */
	struct dsa_area *es_query_dsa;
} EState;


/*
 * ExecRowMark -
 *	   runtime representation of FOR [KEY] UPDATE/SHARE clauses
 *
 * When doing UPDATE, DELETE, or SELECT FOR [KEY] UPDATE/SHARE, we will have an
 * ExecRowMark for each non-target relation in the query (except inheritance
 * parent RTEs, which can be ignored at runtime).  Virtual relations such as
 * subqueries-in-FROM will have an ExecRowMark with relation == NULL.  See
 * PlanRowMark for details about most of the fields.  In addition to fields
 * directly derived from PlanRowMark, we store an activity flag (to denote
 * inactive children of inheritance trees), curCtid, which is used by the
 * WHERE CURRENT OF code, and ermExtra, which is available for use by the plan
 * node that sources the relation (e.g., for a foreign table the FDW can use
 * ermExtra to hold information).
 *
 * EState->es_rowMarks is a list of these structs.
 */
typedef struct ExecRowMark
{
	Relation	relation;		/* opened and suitably locked relation */
	Oid			relid;			/* its OID (or InvalidOid, if subquery) */
	Index		rti;			/* its range table index */
	Index		prti;			/* parent range table index, if child */
	Index		rowmarkId;		/* unique identifier for resjunk columns */
	RowMarkType markType;		/* see enum in nodes/plannodes.h */
	LockClauseStrength strength;	/* LockingClause's strength, or LCS_NONE */
	LockWaitPolicy waitPolicy;	/* NOWAIT and SKIP LOCKED */
	bool		ermActive;		/* is this mark relevant for current tuple? */
	ItemPointerData curCtid;	/* ctid of currently locked tuple, if any */
	void	   *ermExtra;		/* available for use by relation source node */
} ExecRowMark;

/*
 * ExecAuxRowMark -
 *	   additional runtime representation of FOR [KEY] UPDATE/SHARE clauses
 *
 * Each LockRows and ModifyTable node keeps a list of the rowmarks it needs to
 * deal with.  In addition to a pointer to the related entry in es_rowMarks,
 * this struct carries the column number(s) of the resjunk columns associated
 * with the rowmark (see comments for PlanRowMark for more detail).  In the
 * case of ModifyTable, there has to be a separate ExecAuxRowMark list for
 * each child plan, because the resjunk columns could be at different physical
 * column positions in different subplans.
 */
typedef struct ExecAuxRowMark
{
	ExecRowMark *rowmark;		/* related entry in es_rowMarks */
	AttrNumber	ctidAttNo;		/* resno of ctid junk attribute, if any */
	AttrNumber	toidAttNo;		/* resno of tableoid junk attribute, if any */
	AttrNumber	wholeAttNo;		/* resno of whole-row junk attribute, if any */
} ExecAuxRowMark;


/* ----------------------------------------------------------------
 *				 Tuple Hash Tables
 *
 * All-in-memory tuple hash tables are used for a number of purposes.
 *
 * Note: tab_hash_funcs are for the key datatype(s) stored in the table,
 * and tab_eq_funcs are non-cross-type equality operators for those types.
 * Normally these are the only functions used, but FindTupleHashEntry()
 * supports searching a hashtable using cross-data-type hashing.  For that,
 * the caller must supply hash functions for the LHS datatype as well as
 * the cross-type equality operators to use.  in_hash_funcs and cur_eq_funcs
 * are set to point to the caller's function arrays while doing such a search.
 * During LookupTupleHashEntry(), they point to tab_hash_funcs and
 * tab_eq_funcs respectively.
 * ----------------------------------------------------------------
 */
typedef struct TupleHashEntryData *TupleHashEntry;
typedef struct TupleHashTableData *TupleHashTable;

typedef struct TupleHashEntryData
{
	MinimalTuple firstTuple;	/* copy of first tuple in this group */
	void	   *additional;		/* user data */
	uint32		status;			/* hash status */
	uint32		hash;			/* hash value (cached) */
} TupleHashEntryData;

/* define parameters necessary to generate the tuple hash table interface */
#define SH_PREFIX tuplehash
#define SH_ELEMENT_TYPE TupleHashEntryData
#define SH_KEY_TYPE MinimalTuple
#define SH_SCOPE extern
#define SH_DECLARE
#include "lib/simplehash.h"

typedef struct TupleHashTableData
{
	tuplehash_hash *hashtab;	/* underlying hash table */
	int			numCols;		/* number of columns in lookup key */
	AttrNumber *keyColIdx;		/* attr numbers of key columns */
	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
	MemoryContext tablecxt;		/* memory context containing table */
	MemoryContext tempcxt;		/* context for function evaluations */
	Size		entrysize;		/* actual size to make each hash entry */
	TupleTableSlot *tableslot;	/* slot for referencing table entries */
	/* The following fields are set transiently for each table search: */
	TupleTableSlot *inputslot;	/* current input tuple's slot */
	FmgrInfo   *in_hash_funcs;	/* hash functions for input datatype(s) */
	FmgrInfo   *cur_eq_funcs;	/* equality functions for input vs. table */
	uint32		hash_iv;		/* hash-function IV */
}			TupleHashTableData;

typedef tuplehash_iterator TupleHashIterator;

/*
 * Use InitTupleHashIterator/TermTupleHashIterator for a read/write scan.
 * Use ResetTupleHashIterator if the table can be frozen (in this case no
 * explicit scan termination is needed).
 */
#define InitTupleHashIterator(htable, iter) \
	tuplehash_start_iterate(htable->hashtab, iter)
#define TermTupleHashIterator(iter) \
	((void) 0)
#define ResetTupleHashIterator(htable, iter) \
	InitTupleHashIterator(htable, iter)
#define ScanTupleHashTable(htable, iter) \
	tuplehash_iterate(htable->hashtab, iter)


/* ----------------------------------------------------------------
 *				 Expression State Nodes
 *
 * Formerly, there was a separate executor expression state node corresponding
 * to each node in a planned expression tree.  That's no longer the case; for
 * common expression node types, all the execution info is embedded into
 * step(s) in a single ExprState node.  But we still have a few executor state
 * node types for selected expression node types, mostly those in which info
 * has to be shared with other parts of the execution state tree.
 * ----------------------------------------------------------------
 */

/* ----------------
 *		AggrefExprState node
 * ----------------
 */
typedef struct AggrefExprState
{
	NodeTag		type;
	Aggref	   *aggref;			/* expression plan node */
	int			aggno;			/* ID number for agg within its plan node */
} AggrefExprState;

/* ----------------
 *		WindowFuncExprState node
 * ----------------
 */
typedef struct WindowFuncExprState
{
	NodeTag		type;
	WindowFunc *wfunc;			/* expression plan node */
	List	   *args;			/* ExprStates for argument expressions */
	ExprState  *aggfilter;		/* FILTER expression */
	int			wfuncno;		/* ID number for wfunc within its plan node */
} WindowFuncExprState;


/* ----------------
 *		SetExprState node
 *
 * State for evaluating a potentially set-returning expression (like FuncExpr
 * or OpExpr).  In some cases, like some of the expressions in ROWS FROM(...)
 * the expression might not be a SRF, but nonetheless it uses the same
 * machinery as SRFs; it will be treated as a SRF returning a single row.
 * ----------------
 */
typedef struct SetExprState
{
	NodeTag		type;
	Expr	   *expr;			/* expression plan node */
	List	   *args;			/* ExprStates for argument expressions */

	/*
	 * In ROWS FROM, functions can be inlined, removing the FuncExpr normally
	 * inside.  In such a case this is the compiled expression (which cannot
	 * return a set), which'll be evaluated using regular ExecEvalExpr().
	 */
	ExprState  *elidedFuncState;

	/*
	 * Function manager's lookup info for the target function.  If func.fn_oid
	 * is InvalidOid, we haven't initialized it yet (nor any of the following
	 * fields, except funcReturnsSet).
	 */
	FmgrInfo	func;

	/*
	 * For a set-returning function (SRF) that returns a tuplestore, we keep
	 * the tuplestore here and dole out the result rows one at a time. The
	 * slot holds the row currently being returned.
	 */
	Tuplestorestate *funcResultStore;
	TupleTableSlot *funcResultSlot;

	/*
	 * In some cases we need to compute a tuple descriptor for the function's
	 * output.  If so, it's stored here.
	 */
	TupleDesc	funcResultDesc;
	bool		funcReturnsTuple;	/* valid when funcResultDesc isn't NULL */

	/*
	 * Remember whether the function is declared to return a set.  This is set
	 * by ExecInitExpr, and is valid even before the FmgrInfo is set up.
	 */
	bool		funcReturnsSet;

	/*
	 * setArgsValid is true when we are evaluating a set-returning function
	 * that uses value-per-call mode and we are in the middle of a call
	 * series; we want to pass the same argument values to the function again
	 * (and again, until it returns ExprEndResult).  This indicates that
	 * fcinfo_data already contains valid argument data.
	 */
	bool		setArgsValid;

	/*
	 * Flag to remember whether we have registered a shutdown callback for
	 * this SetExprState.  We do so only if funcResultStore or setArgsValid
	 * has been set at least once (since all the callback is for is to release
	 * the tuplestore or clear setArgsValid).
	 */
	bool		shutdown_reg;	/* a shutdown callback is registered */

	/*
	 * Call parameter structure for the function.  This has been initialized
	 * (by InitFunctionCallInfoData) if func.fn_oid is valid.  It also saves
	 * argument values between calls, when setArgsValid is true.
	 */
	FunctionCallInfoData fcinfo_data;
} SetExprState;

/* ----------------
 *		SubPlanState node
 * ----------------
 */
typedef struct SubPlanState
{
	NodeTag		type;
	SubPlan    *subplan;		/* expression plan node */
	struct PlanState *planstate;	/* subselect plan's state tree */
	struct PlanState *parent;	/* parent plan node's state tree */
	ExprState  *testexpr;		/* state of combining expression */
	List	   *args;			/* states of argument expression(s) */
	HeapTuple	curTuple;		/* copy of most recent tuple from subplan */
	Datum		curArray;		/* most recent array from ARRAY() subplan */
	/* these are used when hashing the subselect's output: */
	ProjectionInfo *projLeft;	/* for projecting lefthand exprs */
	ProjectionInfo *projRight;	/* for projecting subselect output */
	TupleHashTable hashtable;	/* hash table for no-nulls subselect rows */
	TupleHashTable hashnulls;	/* hash table for rows with null(s) */
	bool		havehashrows;	/* TRUE if hashtable is not empty */
	bool		havenullrows;	/* TRUE if hashnulls is not empty */
	MemoryContext hashtablecxt; /* memory context containing hash tables */
	MemoryContext hashtempcxt;	/* temp memory context for hash tables */
	ExprContext *innerecontext; /* econtext for computing inner tuples */
	AttrNumber *keyColIdx;		/* control data for hash tables */
	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
	FmgrInfo   *cur_eq_funcs;	/* equality functions for LHS vs. table */
} SubPlanState;

/* ----------------
 *		AlternativeSubPlanState node
 * ----------------
 */
typedef struct AlternativeSubPlanState
{
	NodeTag		type;
	AlternativeSubPlan *subplan;	/* expression plan node */
	List	   *subplans;		/* SubPlanStates of alternative subplans */
	int			active;			/* list index of the one we're using */
} AlternativeSubPlanState;

/*
 * DomainConstraintState - one item to check during CoerceToDomain
 *
 * Note: we consider this to be part of an ExprState tree, so we give it
 * a name following the xxxState convention.  But there's no directly
 * associated plan-tree node.
 */
typedef enum DomainConstraintType
{
	DOM_CONSTRAINT_NOTNULL,
	DOM_CONSTRAINT_CHECK
} DomainConstraintType;

typedef struct DomainConstraintState
{
	NodeTag		type;
	DomainConstraintType constrainttype;	/* constraint type */
	char	   *name;			/* name of constraint (for error msgs) */
	Expr	   *check_expr;		/* for CHECK, a boolean expression */
	ExprState  *check_exprstate;	/* check_expr's eval state, or NULL */
} DomainConstraintState;


/* ----------------------------------------------------------------
 *				 Executor State Trees
 *
 * An executing query has a PlanState tree paralleling the Plan tree
 * that describes the plan.
 * ----------------------------------------------------------------
 */

struct PlanState;

/* ----------------
 *	 ExecProcNodeMtd
 *
 * This is the method called by ExecProcNode to return the next tuple
 * from an executor node.  It returns NULL, or an empty TupleTableSlot,
 * if no more tuples are available.
 * ----------------
 */
typedef TupleTableSlot *(*ExecProcNodeMtd) (struct PlanState *pstate);

/* ----------------
 *		PlanState node
 *
 * We never actually instantiate any PlanState nodes; this is just the common
 * abstract superclass for all PlanState-type nodes.
 * ----------------
 */
typedef struct PlanState
{
	NodeTag		type;

	Plan	   *plan;			/* associated Plan node */

	EState	   *state;			/* at execution time, states of individual
								 * nodes point to one EState for the whole
								 * top-level plan */

	ExecProcNodeMtd ExecProcNode;	/* function to return next tuple */
	ExecProcNodeMtd ExecProcNodeReal;	/* actual function, if above is a
										 * wrapper */

	Instrumentation *instrument;	/* Optional runtime stats for this node */
	WorkerInstrumentation *worker_instrument;	/* per-worker instrumentation */

	/*
	 * Common structural data for all Plan types.  These links to subsidiary
	 * state trees parallel links in the associated plan tree (except for the
	 * subPlan list, which does not exist in the plan tree).
	 */
	ExprState  *qual;			/* boolean qual condition */
	struct PlanState *lefttree; /* input plan tree(s) */
	struct PlanState *righttree;
	List	   *initPlan;		/* Init SubPlanState nodes (un-correlated expr
								 * subselects) */
	List	   *subPlan;		/* SubPlanState nodes in my expressions */

	/*
	 * State for management of parameter-change-driven rescanning
	 */
	Bitmapset  *chgParam;		/* set of IDs of changed Params */

	/*
	 * Other run-time state needed by most if not all node types.
	 */
	TupleTableSlot *ps_ResultTupleSlot; /* slot for my result tuples */
	ExprContext *ps_ExprContext;	/* node's expression-evaluation context */
	ProjectionInfo *ps_ProjInfo;	/* info for doing tuple projection */
} PlanState;

/* ----------------
 *	these are defined to avoid confusion problems with "left"
 *	and "right" and "inner" and "outer".  The convention is that
 *	the "left" plan is the "outer" plan and the "right" plan is
 *	the inner plan, but these make the code more readable.
 * ----------------
 */
#define innerPlanState(node)		(((PlanState *)(node))->righttree)
#define outerPlanState(node)		(((PlanState *)(node))->lefttree)

/* Macros for inline access to certain instrumentation counters */
#define InstrCountFiltered1(node, delta) \
	do { \
		if (((PlanState *)(node))->instrument) \
			((PlanState *)(node))->instrument->nfiltered1 += (delta); \
	} while(0)
#define InstrCountFiltered2(node, delta) \
	do { \
		if (((PlanState *)(node))->instrument) \
			((PlanState *)(node))->instrument->nfiltered2 += (delta); \
	} while(0)

/*
 * EPQState is state for executing an EvalPlanQual recheck on a candidate
 * tuple in ModifyTable or LockRows.  The estate and planstate fields are
 * NULL if inactive.
 */
typedef struct EPQState
{
	EState	   *estate;			/* subsidiary EState */
	PlanState  *planstate;		/* plan state tree ready to be executed */
	TupleTableSlot *origslot;	/* original output tuple to be rechecked */
	Plan	   *plan;			/* plan tree to be executed */
	List	   *arowMarks;		/* ExecAuxRowMarks (non-locking only) */
	int			epqParam;		/* ID of Param to force scan node re-eval */
} EPQState;


/* ----------------
 *	 ResultState information
 * ----------------
 */
typedef struct ResultState
{
	PlanState	ps;				/* its first field is NodeTag */
	ExprState  *resconstantqual;
	bool		rs_done;		/* are we done? */
	bool		rs_checkqual;	/* do we need to check the qual? */
} ResultState;

/* ----------------
 *	 ProjectSetState information
 *
 * Note: at least one of the "elems" will be a SetExprState; the rest are
 * regular ExprStates.
 * ----------------
 */
typedef struct ProjectSetState
{
	PlanState	ps;				/* its first field is NodeTag */
	Node	  **elems;			/* array of expression states */
	ExprDoneCond *elemdone;		/* array of per-SRF is-done states */
	int			nelems;			/* length of elemdone[] array */
	bool		pending_srf_tuples; /* still evaluating srfs in tlist? */
	MemoryContext argcontext;	/* context for SRF arguments */
} ProjectSetState;

/* ----------------
 *	 ModifyTableState information
 * ----------------
 */
typedef struct ModifyTableState
{
	PlanState	ps;				/* its first field is NodeTag */
	CmdType		operation;		/* INSERT, UPDATE, or DELETE */
	bool		canSetTag;		/* do we set the command tag/es_processed? */
	bool		mt_done;		/* are we done? */
	PlanState **mt_plans;		/* subplans (one per target rel) */
	int			mt_nplans;		/* number of plans in the array */
	int			mt_whichplan;	/* which one is being executed (0..n-1) */
	ResultRelInfo *resultRelInfo;	/* per-subplan target relations */
	ResultRelInfo *rootResultRelInfo;	/* root target relation (partitioned
										 * table root) */
	List	  **mt_arowmarks;	/* per-subplan ExecAuxRowMark lists */
	EPQState	mt_epqstate;	/* for evaluating EvalPlanQual rechecks */
	bool		fireBSTriggers; /* do we need to fire stmt triggers? */
	OnConflictAction mt_onconflict; /* ON CONFLICT type */
	List	   *mt_arbiterindexes;	/* unique index OIDs to arbitrate taking
									 * alt path */
	TupleTableSlot *mt_existing;	/* slot to store existing target tuple in */
	List	   *mt_excludedtlist;	/* the excluded pseudo relation's tlist  */
	TupleTableSlot *mt_conflproj;	/* CONFLICT ... SET ... projection target */
	struct PartitionDispatchData **mt_partition_dispatch_info;
	/* Tuple-routing support info */
	int			mt_num_dispatch;	/* Number of entries in the above array */
	int			mt_num_partitions;	/* Number of members in the following
									 * arrays */
	ResultRelInfo **mt_partitions;	/* Per partition result relation pointers */
	TupleConversionMap **mt_partition_tupconv_maps;
	/* Per partition tuple conversion map */
	TupleTableSlot *mt_partition_tuple_slot;
	struct TransitionCaptureState *mt_transition_capture;
	/* controls transition table population for specified operation */
	struct TransitionCaptureState *mt_oc_transition_capture;
	/* controls transition table population for INSERT...ON CONFLICT UPDATE */
	TupleConversionMap **mt_transition_tupconv_maps;
	/* Per plan/partition tuple conversion */
} ModifyTableState;

/* ----------------
 *	 AppendState information
 *
 *		nplans			how many plans are in the array
 *		whichplan		which plan is being executed (0 .. n-1)
 * ----------------
 */
typedef struct AppendState
{
	PlanState	ps;				/* its first field is NodeTag */
	PlanState **appendplans;	/* array of PlanStates for my inputs */
	int			as_nplans;
	int			as_whichplan;
} AppendState;

/* ----------------
 *	 MergeAppendState information
 *
 *		nplans			how many plans are in the array
 *		nkeys			number of sort key columns
 *		sortkeys		sort keys in SortSupport representation
 *		slots			current output tuple of each subplan
 *		heap			heap of active tuples
 *		initialized		true if we have fetched first tuple from each subplan
 * ----------------
 */
typedef struct MergeAppendState
{
	PlanState	ps;				/* its first field is NodeTag */
	PlanState **mergeplans;		/* array of PlanStates for my inputs */
	int			ms_nplans;
	int			ms_nkeys;
	SortSupport ms_sortkeys;	/* array of length ms_nkeys */
	TupleTableSlot **ms_slots;	/* array of length ms_nplans */
	struct binaryheap *ms_heap; /* binary heap of slot indices */
	bool		ms_initialized; /* are subplans started? */
} MergeAppendState;

/* ----------------
 *	 RecursiveUnionState information
 *
 *		RecursiveUnionState is used for performing a recursive union.
 *
 *		recursing			T when we're done scanning the non-recursive term
 *		intermediate_empty	T if intermediate_table is currently empty
 *		working_table		working table (to be scanned by recursive term)
 *		intermediate_table	current recursive output (next generation of WT)
 * ----------------
 */
typedef struct RecursiveUnionState
{
	PlanState	ps;				/* its first field is NodeTag */
	bool		recursing;
	bool		intermediate_empty;
	Tuplestorestate *working_table;
	Tuplestorestate *intermediate_table;
	/* Remaining fields are unused in UNION ALL case */
	FmgrInfo   *eqfunctions;	/* per-grouping-field equality fns */
	FmgrInfo   *hashfunctions;	/* per-grouping-field hash fns */
	MemoryContext tempContext;	/* short-term context for comparisons */
	TupleHashTable hashtable;	/* hash table for tuples already seen */
	MemoryContext tableContext; /* memory context containing hash table */
} RecursiveUnionState;

/* ----------------
 *	 BitmapAndState information
 * ----------------
 */
typedef struct BitmapAndState
{
	PlanState	ps;				/* its first field is NodeTag */
	PlanState **bitmapplans;	/* array of PlanStates for my inputs */
	int			nplans;			/* number of input plans */
} BitmapAndState;

/* ----------------
 *	 BitmapOrState information
 * ----------------
 */
typedef struct BitmapOrState
{
	PlanState	ps;				/* its first field is NodeTag */
	PlanState **bitmapplans;	/* array of PlanStates for my inputs */
	int			nplans;			/* number of input plans */
} BitmapOrState;

/* ----------------------------------------------------------------
 *				 Scan State Information
 * ----------------------------------------------------------------
 */

/* ----------------
 *	 ScanState information
 *
 *		ScanState extends PlanState for node types that represent
 *		scans of an underlying relation.  It can also be used for nodes
 *		that scan the output of an underlying plan node --- in that case,
 *		only ScanTupleSlot is actually useful, and it refers to the tuple
 *		retrieved from the subplan.
 *
 *		currentRelation    relation being scanned (NULL if none)
 *		currentScanDesc    current scan descriptor for scan (NULL if none)
 *		ScanTupleSlot	   pointer to slot in tuple table holding scan tuple
 * ----------------
 */
typedef struct ScanState
{
	PlanState	ps;				/* its first field is NodeTag */
	Relation	ss_currentRelation;
	HeapScanDesc ss_currentScanDesc;
	TupleTableSlot *ss_ScanTupleSlot;
} ScanState;

/* ----------------
 *	 SeqScanState information
 * ----------------
 */
typedef struct SeqScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	Size		pscan_len;		/* size of parallel heap scan descriptor */
} SeqScanState;

/* ----------------
 *	 SampleScanState information
 * ----------------
 */
typedef struct SampleScanState
{
	ScanState	ss;
	List	   *args;			/* expr states for TABLESAMPLE params */
	ExprState  *repeatable;		/* expr state for REPEATABLE expr */
	/* use struct pointer to avoid including tsmapi.h here */
	struct TsmRoutine *tsmroutine;	/* descriptor for tablesample method */
	void	   *tsm_state;		/* tablesample method can keep state here */
	bool		use_bulkread;	/* use bulkread buffer access strategy? */
	bool		use_pagemode;	/* use page-at-a-time visibility checking? */
	bool		begun;			/* false means need to call BeginSampleScan */
	uint32		seed;			/* random seed */
} SampleScanState;

/*
 * These structs store information about index quals that don't have simple
 * constant right-hand sides.  See comments for ExecIndexBuildScanKeys()
 * for discussion.
 */
typedef struct
{
	ScanKey		scan_key;		/* scankey to put value into */
	ExprState  *key_expr;		/* expr to evaluate to get value */
	bool		key_toastable;	/* is expr's result a toastable datatype? */
} IndexRuntimeKeyInfo;

typedef struct
{
	ScanKey		scan_key;		/* scankey to put value into */
	ExprState  *array_expr;		/* expr to evaluate to get array value */
	int			next_elem;		/* next array element to use */
	int			num_elems;		/* number of elems in current array value */
	Datum	   *elem_values;	/* array of num_elems Datums */
	bool	   *elem_nulls;		/* array of num_elems is-null flags */
} IndexArrayKeyInfo;

/* ----------------
 *	 IndexScanState information
 *
 *		indexqualorig	   execution state for indexqualorig expressions
 *		indexorderbyorig   execution state for indexorderbyorig expressions
 *		ScanKeys		   Skey structures for index quals
 *		NumScanKeys		   number of ScanKeys
 *		OrderByKeys		   Skey structures for index ordering operators
 *		NumOrderByKeys	   number of OrderByKeys
 *		RuntimeKeys		   info about Skeys that must be evaluated at runtime
 *		NumRuntimeKeys	   number of RuntimeKeys
 *		RuntimeKeysReady   true if runtime Skeys have been computed
 *		RuntimeContext	   expr context for evaling runtime Skeys
 *		RelationDesc	   index relation descriptor
 *		ScanDesc		   index scan descriptor
 *
 *		ReorderQueue	   tuples that need reordering due to re-check
 *		ReachedEnd		   have we fetched all tuples from index already?
 *		OrderByValues	   values of ORDER BY exprs of last fetched tuple
 *		OrderByNulls	   null flags for OrderByValues
 *		SortSupport		   for reordering ORDER BY exprs
 *		OrderByTypByVals   is the datatype of order by expression pass-by-value?
 *		OrderByTypLens	   typlens of the datatypes of order by expressions
 *		pscan_len		   size of parallel index scan descriptor
 * ----------------
 */
typedef struct IndexScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	ExprState  *indexqualorig;
	List	   *indexorderbyorig;
	ScanKey		iss_ScanKeys;
	int			iss_NumScanKeys;
	ScanKey		iss_OrderByKeys;
	int			iss_NumOrderByKeys;
	IndexRuntimeKeyInfo *iss_RuntimeKeys;
	int			iss_NumRuntimeKeys;
	bool		iss_RuntimeKeysReady;
	ExprContext *iss_RuntimeContext;
	Relation	iss_RelationDesc;
	IndexScanDesc iss_ScanDesc;

	/* These are needed for re-checking ORDER BY expr ordering */
	pairingheap *iss_ReorderQueue;
	bool		iss_ReachedEnd;
	Datum	   *iss_OrderByValues;
	bool	   *iss_OrderByNulls;
	SortSupport iss_SortSupport;
	bool	   *iss_OrderByTypByVals;
	int16	   *iss_OrderByTypLens;
	Size		iss_PscanLen;
} IndexScanState;

/* ----------------
 *	 IndexOnlyScanState information
 *
 *		indexqual		   execution state for indexqual expressions
 *		ScanKeys		   Skey structures for index quals
 *		NumScanKeys		   number of ScanKeys
 *		OrderByKeys		   Skey structures for index ordering operators
 *		NumOrderByKeys	   number of OrderByKeys
 *		RuntimeKeys		   info about Skeys that must be evaluated at runtime
 *		NumRuntimeKeys	   number of RuntimeKeys
 *		RuntimeKeysReady   true if runtime Skeys have been computed
 *		RuntimeContext	   expr context for evaling runtime Skeys
 *		RelationDesc	   index relation descriptor
 *		ScanDesc		   index scan descriptor
 *		VMBuffer		   buffer in use for visibility map testing, if any
 *		HeapFetches		   number of tuples we were forced to fetch from heap
 *		ioss_PscanLen	   Size of parallel index-only scan descriptor
 * ----------------
 */
typedef struct IndexOnlyScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	ExprState  *indexqual;
	ScanKey		ioss_ScanKeys;
	int			ioss_NumScanKeys;
	ScanKey		ioss_OrderByKeys;
	int			ioss_NumOrderByKeys;
	IndexRuntimeKeyInfo *ioss_RuntimeKeys;
	int			ioss_NumRuntimeKeys;
	bool		ioss_RuntimeKeysReady;
	ExprContext *ioss_RuntimeContext;
	Relation	ioss_RelationDesc;
	IndexScanDesc ioss_ScanDesc;
	Buffer		ioss_VMBuffer;
	long		ioss_HeapFetches;
	Size		ioss_PscanLen;
} IndexOnlyScanState;

/* ----------------
 *	 BitmapIndexScanState information
 *
 *		result			   bitmap to return output into, or NULL
 *		ScanKeys		   Skey structures for index quals
 *		NumScanKeys		   number of ScanKeys
 *		RuntimeKeys		   info about Skeys that must be evaluated at runtime
 *		NumRuntimeKeys	   number of RuntimeKeys
 *		ArrayKeys		   info about Skeys that come from ScalarArrayOpExprs
 *		NumArrayKeys	   number of ArrayKeys
 *		RuntimeKeysReady   true if runtime Skeys have been computed
 *		RuntimeContext	   expr context for evaling runtime Skeys
 *		RelationDesc	   index relation descriptor
 *		ScanDesc		   index scan descriptor
 * ----------------
 */
typedef struct BitmapIndexScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	TIDBitmap  *biss_result;
	ScanKey		biss_ScanKeys;
	int			biss_NumScanKeys;
	IndexRuntimeKeyInfo *biss_RuntimeKeys;
	int			biss_NumRuntimeKeys;
	IndexArrayKeyInfo *biss_ArrayKeys;
	int			biss_NumArrayKeys;
	bool		biss_RuntimeKeysReady;
	ExprContext *biss_RuntimeContext;
	Relation	biss_RelationDesc;
	IndexScanDesc biss_ScanDesc;
} BitmapIndexScanState;

/* ----------------
 *	 SharedBitmapState information
 *
 *		BM_INITIAL		TIDBitmap creation is not yet started, so first worker
 *						to see this state will set the state to BM_INPROGRESS
 *						and that process will be responsible for creating
 *						TIDBitmap.
 *		BM_INPROGRESS	TIDBitmap creation is in progress; workers need to
 *						sleep until it's finished.
 *		BM_FINISHED		TIDBitmap creation is done, so now all workers can
 *						proceed to iterate over TIDBitmap.
 * ----------------
 */
typedef enum
{
	BM_INITIAL,
	BM_INPROGRESS,
	BM_FINISHED
} SharedBitmapState;

/* ----------------
 *	 ParallelBitmapHeapState information
 *		tbmiterator				iterator for scanning current pages
 *		prefetch_iterator		iterator for prefetching ahead of current page
 *		mutex					mutual exclusion for the prefetching variable
 *								and state
 *		prefetch_pages			# pages prefetch iterator is ahead of current
 *		prefetch_target			current target prefetch distance
 *		state					current state of the TIDBitmap
 *		cv						conditional wait variable
 *		phs_snapshot_data		snapshot data shared to workers
 * ----------------
 */
typedef struct ParallelBitmapHeapState
{
	dsa_pointer tbmiterator;
	dsa_pointer prefetch_iterator;
	slock_t		mutex;
	int			prefetch_pages;
	int			prefetch_target;
	SharedBitmapState state;
	ConditionVariable cv;
	char		phs_snapshot_data[FLEXIBLE_ARRAY_MEMBER];
} ParallelBitmapHeapState;

/* ----------------
 *	 BitmapHeapScanState information
 *
 *		bitmapqualorig	   execution state for bitmapqualorig expressions
 *		tbm				   bitmap obtained from child index scan(s)
 *		tbmiterator		   iterator for scanning current pages
 *		tbmres			   current-page data
 *		exact_pages		   total number of exact pages retrieved
 *		lossy_pages		   total number of lossy pages retrieved
 *		prefetch_iterator  iterator for prefetching ahead of current page
 *		prefetch_pages	   # pages prefetch iterator is ahead of current
 *		prefetch_target    current target prefetch distance
 *		prefetch_maximum   maximum value for prefetch_target
 *		pscan_len		   size of the shared memory for parallel bitmap
 *		initialized		   is node is ready to iterate
 *		shared_tbmiterator	   shared iterator
 *		shared_prefetch_iterator shared iterator for prefetching
 *		pstate			   shared state for parallel bitmap scan
 * ----------------
 */
typedef struct BitmapHeapScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	ExprState  *bitmapqualorig;
	TIDBitmap  *tbm;
	TBMIterator *tbmiterator;
	TBMIterateResult *tbmres;
	long		exact_pages;
	long		lossy_pages;
	TBMIterator *prefetch_iterator;
	int			prefetch_pages;
	int			prefetch_target;
	int			prefetch_maximum;
	Size		pscan_len;
	bool		initialized;
	TBMSharedIterator *shared_tbmiterator;
	TBMSharedIterator *shared_prefetch_iterator;
	ParallelBitmapHeapState *pstate;
} BitmapHeapScanState;

/* ----------------
 *	 TidScanState information
 *
 *		tidexprs	   list of TidExpr structs (see nodeTidscan.c)
 *		isCurrentOf    scan has a CurrentOfExpr qual
 *		NumTids		   number of tids in this scan
 *		TidPtr		   index of currently fetched tid
 *		TidList		   evaluated item pointers (array of size NumTids)
 *		htup		   currently-fetched tuple, if any
 * ----------------
 */
typedef struct TidScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	List	   *tss_tidexprs;
	bool		tss_isCurrentOf;
	int			tss_NumTids;
	int			tss_TidPtr;
	ItemPointerData *tss_TidList;
	HeapTupleData tss_htup;
} TidScanState;

/* ----------------
 *	 SubqueryScanState information
 *
 *		SubqueryScanState is used for scanning a sub-query in the range table.
 *		ScanTupleSlot references the current output tuple of the sub-query.
 * ----------------
 */
typedef struct SubqueryScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	PlanState  *subplan;
} SubqueryScanState;

/* ----------------
 *	 FunctionScanState information
 *
 *		Function nodes are used to scan the results of a
 *		function appearing in FROM (typically a function returning set).
 *
 *		eflags				node's capability flags
 *		ordinality			is this scan WITH ORDINALITY?
 *		simple				true if we have 1 function and no ordinality
 *		ordinal				current ordinal column value
 *		nfuncs				number of functions being executed
 *		funcstates			per-function execution states (private in
 *							nodeFunctionscan.c)
 *		argcontext			memory context to evaluate function arguments in
 * ----------------
 */
struct FunctionScanPerFuncState;

typedef struct FunctionScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	int			eflags;
	bool		ordinality;
	bool		simple;
	int64		ordinal;
	int			nfuncs;
	struct FunctionScanPerFuncState *funcstates;	/* array of length nfuncs */
	MemoryContext argcontext;
} FunctionScanState;

/* ----------------
 *	 ValuesScanState information
 *
 *		ValuesScan nodes are used to scan the results of a VALUES list
 *
 *		rowcontext			per-expression-list context
 *		exprlists			array of expression lists being evaluated
 *		array_len			size of array
 *		curr_idx			current array index (0-based)
 *
 *	Note: ss.ps.ps_ExprContext is used to evaluate any qual or projection
 *	expressions attached to the node.  We create a second ExprContext,
 *	rowcontext, in which to build the executor expression state for each
 *	Values sublist.  Resetting this context lets us get rid of expression
 *	state for each row, avoiding major memory leakage over a long values list.
 * ----------------
 */
typedef struct ValuesScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	ExprContext *rowcontext;
	List	  **exprlists;
	int			array_len;
	int			curr_idx;
} ValuesScanState;

/* ----------------
 *		TableFuncScanState node
 *
 * Used in table-expression functions like XMLTABLE.
 * ----------------
 */
typedef struct TableFuncScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	ExprState  *docexpr;		/* state for document expression */
	ExprState  *rowexpr;		/* state for row-generating expression */
	List	   *colexprs;		/* state for column-generating expression */
	List	   *coldefexprs;	/* state for column default expressions */
	List	   *ns_names;		/* list of str nodes with namespace names */
	List	   *ns_uris;		/* list of states of namespace uri exprs */
	Bitmapset  *notnulls;		/* nullability flag for each output column */
	void	   *opaque;			/* table builder private space */
	const struct TableFuncRoutine *routine; /* table builder methods */
	FmgrInfo   *in_functions;	/* input function for each column */
	Oid		   *typioparams;	/* typioparam for each column */
	int64		ordinal;		/* row number to be output next */
	MemoryContext perValueCxt;	/* short life context for value evaluation */
	Tuplestorestate *tupstore;	/* output tuple store */
} TableFuncScanState;

/* ----------------
 *	 CteScanState information
 *
 *		CteScan nodes are used to scan a CommonTableExpr query.
 *
 * Multiple CteScan nodes can read out from the same CTE query.  We use
 * a tuplestore to hold rows that have been read from the CTE query but
 * not yet consumed by all readers.
 * ----------------
 */
typedef struct CteScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	int			eflags;			/* capability flags to pass to tuplestore */
	int			readptr;		/* index of my tuplestore read pointer */
	PlanState  *cteplanstate;	/* PlanState for the CTE query itself */
	/* Link to the "leader" CteScanState (possibly this same node) */
	struct CteScanState *leader;
	/* The remaining fields are only valid in the "leader" CteScanState */
	Tuplestorestate *cte_table; /* rows already read from the CTE query */
	bool		eof_cte;		/* reached end of CTE query? */
} CteScanState;

/* ----------------
 *	 NamedTuplestoreScanState information
 *
 *		NamedTuplestoreScan nodes are used to scan a Tuplestore created and
 *		named prior to execution of the query.  An example is a transition
 *		table for an AFTER trigger.
 *
 * Multiple NamedTuplestoreScan nodes can read out from the same Tuplestore.
 * ----------------
 */
typedef struct NamedTuplestoreScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	int			readptr;		/* index of my tuplestore read pointer */
	TupleDesc	tupdesc;		/* format of the tuples in the tuplestore */
	Tuplestorestate *relation;	/* the rows */
} NamedTuplestoreScanState;

/* ----------------
 *	 WorkTableScanState information
 *
 *		WorkTableScan nodes are used to scan the work table created by
 *		a RecursiveUnion node.  We locate the RecursiveUnion node
 *		during executor startup.
 * ----------------
 */
typedef struct WorkTableScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	RecursiveUnionState *rustate;
} WorkTableScanState;

/* ----------------
 *	 ForeignScanState information
 *
 *		ForeignScan nodes are used to scan foreign-data tables.
 * ----------------
 */
typedef struct ForeignScanState
{
	ScanState	ss;				/* its first field is NodeTag */
	ExprState  *fdw_recheck_quals;	/* original quals not in ss.ps.qual */
	Size		pscan_len;		/* size of parallel coordination information */
	/* use struct pointer to avoid including fdwapi.h here */
	struct FdwRoutine *fdwroutine;
	void	   *fdw_state;		/* foreign-data wrapper can keep state here */
} ForeignScanState;

/* ----------------
 *	 CustomScanState information
 *
 *		CustomScan nodes are used to execute custom code within executor.
 *
 * Core code must avoid assuming that the CustomScanState is only as large as
 * the structure declared here; providers are allowed to make it the first
 * element in a larger structure, and typically would need to do so.  The
 * struct is actually allocated by the CreateCustomScanState method associated
 * with the plan node.  Any additional fields can be initialized there, or in
 * the BeginCustomScan method.
 * ----------------
 */
struct CustomExecMethods;

typedef struct CustomScanState
{
	ScanState	ss;
	uint32		flags;			/* mask of CUSTOMPATH_* flags, see
								 * nodes/extensible.h */
	List	   *custom_ps;		/* list of child PlanState nodes, if any */
	Size		pscan_len;		/* size of parallel coordination information */
	const struct CustomExecMethods *methods;
} CustomScanState;

/* ----------------------------------------------------------------
 *				 Join State Information
 * ----------------------------------------------------------------
 */

/* ----------------
 *	 JoinState information
 *
 *		Superclass for state nodes of join plans.
 * ----------------
 */
typedef struct JoinState
{
	PlanState	ps;
	JoinType	jointype;
	bool		single_match;	/* True if we should skip to next outer tuple
								 * after finding one inner match */
	ExprState  *joinqual;		/* JOIN quals (in addition to ps.qual) */
} JoinState;

/* ----------------
 *	 NestLoopState information
 *
 *		NeedNewOuter	   true if need new outer tuple on next call
 *		MatchedOuter	   true if found a join match for current outer tuple
 *		NullInnerTupleSlot prepared null tuple for left outer joins
 * ----------------
 */
typedef struct NestLoopState
{
	JoinState	js;				/* its first field is NodeTag */
	bool		nl_NeedNewOuter;
	bool		nl_MatchedOuter;
	TupleTableSlot *nl_NullInnerTupleSlot;
} NestLoopState;

/* ----------------
 *	 MergeJoinState information
 *
 *		NumClauses		   number of mergejoinable join clauses
 *		Clauses			   info for each mergejoinable clause
 *		JoinState		   current state of ExecMergeJoin state machine
 *		SkipMarkRestore    true if we may skip Mark and Restore operations
 *		ExtraMarks		   true to issue extra Mark operations on inner scan
 *		ConstFalseJoin	   true if we have a constant-false joinqual
 *		FillOuter		   true if should emit unjoined outer tuples anyway
 *		FillInner		   true if should emit unjoined inner tuples anyway
 *		MatchedOuter	   true if found a join match for current outer tuple
 *		MatchedInner	   true if found a join match for current inner tuple
 *		OuterTupleSlot	   slot in tuple table for cur outer tuple
 *		InnerTupleSlot	   slot in tuple table for cur inner tuple
 *		MarkedTupleSlot    slot in tuple table for marked tuple
 *		NullOuterTupleSlot prepared null tuple for right outer joins
 *		NullInnerTupleSlot prepared null tuple for left outer joins
 *		OuterEContext	   workspace for computing outer tuple's join values
 *		InnerEContext	   workspace for computing inner tuple's join values
 * ----------------
 */
/* private in nodeMergejoin.c: */
typedef struct MergeJoinClauseData *MergeJoinClause;

typedef struct MergeJoinState
{
	JoinState	js;				/* its first field is NodeTag */
	int			mj_NumClauses;
	MergeJoinClause mj_Clauses; /* array of length mj_NumClauses */
	int			mj_JoinState;
	bool		mj_SkipMarkRestore;
	bool		mj_ExtraMarks;
	bool		mj_ConstFalseJoin;
	bool		mj_FillOuter;
	bool		mj_FillInner;
	bool		mj_MatchedOuter;
	bool		mj_MatchedInner;
	TupleTableSlot *mj_OuterTupleSlot;
	TupleTableSlot *mj_InnerTupleSlot;
	TupleTableSlot *mj_MarkedTupleSlot;
	TupleTableSlot *mj_NullOuterTupleSlot;
	TupleTableSlot *mj_NullInnerTupleSlot;
	ExprContext *mj_OuterEContext;
	ExprContext *mj_InnerEContext;
} MergeJoinState;

/* ----------------
 *	 HashJoinState information
 *
 *		hashclauses				original form of the hashjoin condition
 *		hj_OuterHashKeys		the outer hash keys in the hashjoin condition
 *		hj_InnerHashKeys		the inner hash keys in the hashjoin condition
 *		hj_HashOperators		the join operators in the hashjoin condition
 *		hj_HashTable			hash table for the hashjoin
 *								(NULL if table not built yet)
 *		hj_CurHashValue			hash value for current outer tuple
 *		hj_CurBucketNo			regular bucket# for current outer tuple
 *		hj_CurSkewBucketNo		skew bucket# for current outer tuple
 *		hj_CurTuple				last inner tuple matched to current outer
 *								tuple, or NULL if starting search
 *								(hj_CurXXX variables are undefined if
 *								OuterTupleSlot is empty!)
 *		hj_OuterTupleSlot		tuple slot for outer tuples
 *		hj_HashTupleSlot		tuple slot for inner (hashed) tuples
 *		hj_NullOuterTupleSlot	prepared null tuple for right/full outer joins
 *		hj_NullInnerTupleSlot	prepared null tuple for left/full outer joins
 *		hj_FirstOuterTupleSlot	first tuple retrieved from outer plan
 *		hj_JoinState			current state of ExecHashJoin state machine
 *		hj_MatchedOuter			true if found a join match for current outer
 *		hj_OuterNotEmpty		true if outer relation known not empty
 * ----------------
 */

/* these structs are defined in executor/hashjoin.h: */
typedef struct HashJoinTupleData *HashJoinTuple;
typedef struct HashJoinTableData *HashJoinTable;

typedef struct HashJoinState
{
	JoinState	js;				/* its first field is NodeTag */
	ExprState  *hashclauses;
	List	   *hj_OuterHashKeys;	/* list of ExprState nodes */
	List	   *hj_InnerHashKeys;	/* list of ExprState nodes */
	List	   *hj_HashOperators;	/* list of operator OIDs */
	HashJoinTable hj_HashTable;
	uint32		hj_CurHashValue;
	int			hj_CurBucketNo;
	int			hj_CurSkewBucketNo;
	HashJoinTuple hj_CurTuple;
	TupleTableSlot *hj_OuterTupleSlot;
	TupleTableSlot *hj_HashTupleSlot;
	TupleTableSlot *hj_NullOuterTupleSlot;
	TupleTableSlot *hj_NullInnerTupleSlot;
	TupleTableSlot *hj_FirstOuterTupleSlot;
	int			hj_JoinState;
	bool		hj_MatchedOuter;
	bool		hj_OuterNotEmpty;
} HashJoinState;


/* ----------------------------------------------------------------
 *				 Materialization State Information
 * ----------------------------------------------------------------
 */

/* ----------------
 *	 MaterialState information
 *
 *		materialize nodes are used to materialize the results
 *		of a subplan into a temporary file.
 *
 *		ss.ss_ScanTupleSlot refers to output of underlying plan.
 * ----------------
 */
typedef struct MaterialState
{
	ScanState	ss;				/* its first field is NodeTag */
	int			eflags;			/* capability flags to pass to tuplestore */
	bool		eof_underlying; /* reached end of underlying plan? */
	Tuplestorestate *tuplestorestate;
} MaterialState;

/* ----------------
 *	 Shared memory container for per-worker sort information
 * ----------------
 */
typedef struct SharedSortInfo
{
	int			num_workers;
	TuplesortInstrumentation sinstrument[FLEXIBLE_ARRAY_MEMBER];
} SharedSortInfo;

/* ----------------
 *	 SortState information
 * ----------------
 */
typedef struct SortState
{
	ScanState	ss;				/* its first field is NodeTag */
	bool		randomAccess;	/* need random access to sort output? */
	bool		bounded;		/* is the result set bounded? */
	int64		bound;			/* if bounded, how many tuples are needed */
	bool		sort_Done;		/* sort completed yet? */
	bool		bounded_Done;	/* value of bounded we did the sort with */
	int64		bound_Done;		/* value of bound we did the sort with */
	void	   *tuplesortstate; /* private state of tuplesort.c */
	bool		am_worker;		/* are we a worker? */
	SharedSortInfo *shared_info;	/* one entry per worker */
} SortState;

/* ---------------------
 *	GroupState information
 * ---------------------
 */
typedef struct GroupState
{
	ScanState	ss;				/* its first field is NodeTag */
	FmgrInfo   *eqfunctions;	/* per-field lookup data for equality fns */
	bool		grp_done;		/* indicates completion of Group scan */
} GroupState;

/* ---------------------
 *	AggState information
 *
 *	ss.ss_ScanTupleSlot refers to output of underlying plan.
 *
 *	Note: ss.ps.ps_ExprContext contains ecxt_aggvalues and
 *	ecxt_aggnulls arrays, which hold the computed agg values for the current
 *	input group during evaluation of an Agg node's output tuple(s).  We
 *	create a second ExprContext, tmpcontext, in which to evaluate input
 *	expressions and run the aggregate transition functions.
 * ---------------------
 */
/* these structs are private in nodeAgg.c: */
typedef struct AggStatePerAggData *AggStatePerAgg;
typedef struct AggStatePerTransData *AggStatePerTrans;
typedef struct AggStatePerGroupData *AggStatePerGroup;
typedef struct AggStatePerPhaseData *AggStatePerPhase;
typedef struct AggStatePerHashData *AggStatePerHash;

typedef struct AggState
{
	ScanState	ss;				/* its first field is NodeTag */
	List	   *aggs;			/* all Aggref nodes in targetlist & quals */
	int			numaggs;		/* length of list (could be zero!) */
	int			numtrans;		/* number of pertrans items */
	AggStrategy aggstrategy;	/* strategy mode */
	AggSplit	aggsplit;		/* agg-splitting mode, see nodes.h */
	AggStatePerPhase phase;		/* pointer to current phase data */
	int			numphases;		/* number of phases (including phase 0) */
	int			current_phase;	/* current phase number */
	AggStatePerAgg peragg;		/* per-Aggref information */
	AggStatePerTrans pertrans;	/* per-Trans state information */
	ExprContext *hashcontext;	/* econtexts for long-lived data (hashtable) */
	ExprContext **aggcontexts;	/* econtexts for long-lived data (per GS) */
	ExprContext *tmpcontext;	/* econtext for input expressions */
	ExprContext *curaggcontext; /* currently active aggcontext */
	AggStatePerAgg curperagg;	/* currently active aggregate, if any */
	AggStatePerTrans curpertrans;	/* currently active trans state, if any */
	bool		input_done;		/* indicates end of input */
	bool		agg_done;		/* indicates completion of Agg scan */
	int			projected_set;	/* The last projected grouping set */
	int			current_set;	/* The current grouping set being evaluated */
	Bitmapset  *grouped_cols;	/* grouped cols in current projection */
	List	   *all_grouped_cols;	/* list of all grouped cols in DESC order */
	/* These fields are for grouping set phase data */
	int			maxsets;		/* The max number of sets in any phase */
	AggStatePerPhase phases;	/* array of all phases */
	Tuplesortstate *sort_in;	/* sorted input to phases > 1 */
	Tuplesortstate *sort_out;	/* input is copied here for next phase */
	TupleTableSlot *sort_slot;	/* slot for sort results */
	/* these fields are used in AGG_PLAIN and AGG_SORTED modes: */
	AggStatePerGroup pergroup;	/* per-Aggref-per-group working state */
	HeapTuple	grp_firstTuple; /* copy of first tuple of current group */
	/* these fields are used in AGG_HASHED and AGG_MIXED modes: */
	bool		table_filled;	/* hash table filled yet? */
	int			num_hashes;
	AggStatePerHash perhash;
	AggStatePerGroup *hash_pergroup;	/* array of per-group pointers */
	/* support for evaluation of agg input expressions: */
	ProjectionInfo *combinedproj;	/* projection machinery */
} AggState;

/* ----------------
 *	WindowAggState information
 * ----------------
 */
/* these structs are private in nodeWindowAgg.c: */
typedef struct WindowStatePerFuncData *WindowStatePerFunc;
typedef struct WindowStatePerAggData *WindowStatePerAgg;

typedef struct WindowAggState
{
	ScanState	ss;				/* its first field is NodeTag */

	/* these fields are filled in by ExecInitExpr: */
	List	   *funcs;			/* all WindowFunc nodes in targetlist */
	int			numfuncs;		/* total number of window functions */
	int			numaggs;		/* number that are plain aggregates */

	WindowStatePerFunc perfunc; /* per-window-function information */
	WindowStatePerAgg peragg;	/* per-plain-aggregate information */
	FmgrInfo   *partEqfunctions;	/* equality funcs for partition columns */
	FmgrInfo   *ordEqfunctions; /* equality funcs for ordering columns */
	Tuplestorestate *buffer;	/* stores rows of current partition */
	int			current_ptr;	/* read pointer # for current */
	int64		spooled_rows;	/* total # of rows in buffer */
	int64		currentpos;		/* position of current row in partition */
	int64		frameheadpos;	/* current frame head position */
	int64		frametailpos;	/* current frame tail position */
	/* use struct pointer to avoid including windowapi.h here */
	struct WindowObjectData *agg_winobj;	/* winobj for aggregate fetches */
	int64		aggregatedbase; /* start row for current aggregates */
	int64		aggregatedupto; /* rows before this one are aggregated */

	int			frameOptions;	/* frame_clause options, see WindowDef */
	ExprState  *startOffset;	/* expression for starting bound offset */
	ExprState  *endOffset;		/* expression for ending bound offset */
	Datum		startOffsetValue;	/* result of startOffset evaluation */
	Datum		endOffsetValue; /* result of endOffset evaluation */

	MemoryContext partcontext;	/* context for partition-lifespan data */
	MemoryContext aggcontext;	/* shared context for aggregate working data */
	MemoryContext curaggcontext;	/* current aggregate's working data */
	ExprContext *tmpcontext;	/* short-term evaluation context */

	bool		all_first;		/* true if the scan is starting */
	bool		all_done;		/* true if the scan is finished */
	bool		partition_spooled;	/* true if all tuples in current partition
									 * have been spooled into tuplestore */
	bool		more_partitions;	/* true if there's more partitions after
									 * this one */
	bool		framehead_valid;	/* true if frameheadpos is known up to
									 * date for current row */
	bool		frametail_valid;	/* true if frametailpos is known up to
									 * date for current row */

	TupleTableSlot *first_part_slot;	/* first tuple of current or next
										 * partition */

	/* temporary slots for tuples fetched back from tuplestore */
	TupleTableSlot *agg_row_slot;
	TupleTableSlot *temp_slot_1;
	TupleTableSlot *temp_slot_2;
} WindowAggState;

/* ----------------
 *	 UniqueState information
 *
 *		Unique nodes are used "on top of" sort nodes to discard
 *		duplicate tuples returned from the sort phase.  Basically
 *		all it does is compare the current tuple from the subplan
 *		with the previously fetched tuple (stored in its result slot).
 *		If the two are identical in all interesting fields, then
 *		we just fetch another tuple from the sort and try again.
 * ----------------
 */
typedef struct UniqueState
{
	PlanState	ps;				/* its first field is NodeTag */
	FmgrInfo   *eqfunctions;	/* per-field lookup data for equality fns */
	MemoryContext tempContext;	/* short-term context for comparisons */
} UniqueState;

/* ----------------
 * GatherState information
 *
 *		Gather nodes launch 1 or more parallel workers, run a subplan
 *		in those workers, and collect the results.
 * ----------------
 */
typedef struct GatherState
{
	PlanState	ps;				/* its first field is NodeTag */
	bool		initialized;	/* workers launched? */
	bool		need_to_scan_locally;	/* need to read from local plan? */
	int64		tuples_needed;	/* tuple bound, see ExecSetTupleBound */
	/* these fields are set up once: */
	TupleTableSlot *funnel_slot;
	struct ParallelExecutorInfo *pei;
	/* all remaining fields are reinitialized during a rescan: */
	int			nworkers_launched;	/* original number of workers */
	int			nreaders;		/* number of still-active workers */
	int			nextreader;		/* next one to try to read from */
	struct TupleQueueReader **reader;	/* array with nreaders active entries */
} GatherState;

/* ----------------
 * GatherMergeState information
 *
 *		Gather merge nodes launch 1 or more parallel workers, run a
 *		subplan which produces sorted output in each worker, and then
 *		merge the results into a single sorted stream.
 * ----------------
 */
struct GMReaderTupleBuffer;		/* private in nodeGatherMerge.c */

typedef struct GatherMergeState
{
	PlanState	ps;				/* its first field is NodeTag */
	bool		initialized;	/* workers launched? */
	bool		gm_initialized; /* gather_merge_init() done? */
	bool		need_to_scan_locally;	/* need to read from local plan? */
	int64		tuples_needed;	/* tuple bound, see ExecSetTupleBound */
	/* these fields are set up once: */
	TupleDesc	tupDesc;		/* descriptor for subplan result tuples */
	int			gm_nkeys;		/* number of sort columns */
	SortSupport gm_sortkeys;	/* array of length gm_nkeys */
	struct ParallelExecutorInfo *pei;
	/* all remaining fields are reinitialized during a rescan */
	/* (but the arrays are not reallocated, just cleared) */
	int			nworkers_launched;	/* original number of workers */
	int			nreaders;		/* number of active workers */
	TupleTableSlot **gm_slots;	/* array with nreaders+1 entries */
	struct TupleQueueReader **reader;	/* array with nreaders active entries */
	struct GMReaderTupleBuffer *gm_tuple_buffers;	/* nreaders tuple buffers */
	struct binaryheap *gm_heap; /* binary heap of slot indices */
} GatherMergeState;

/* ----------------
 *	 HashState information
 * ----------------
 */
typedef struct HashState
{
	PlanState	ps;				/* its first field is NodeTag */
	HashJoinTable hashtable;	/* hash table for the hashjoin */
	List	   *hashkeys;		/* list of ExprState nodes */
	/* hashkeys is same as parent's hj_InnerHashKeys */
} HashState;

/* ----------------
 *	 SetOpState information
 *
 *		Even in "sorted" mode, SetOp nodes are more complex than a simple
 *		Unique, since we have to count how many duplicates to return.  But
 *		we also support hashing, so this is really more like a cut-down
 *		form of Agg.
 * ----------------
 */
/* this struct is private in nodeSetOp.c: */
typedef struct SetOpStatePerGroupData *SetOpStatePerGroup;

typedef struct SetOpState
{
	PlanState	ps;				/* its first field is NodeTag */
	FmgrInfo   *eqfunctions;	/* per-grouping-field equality fns */
	FmgrInfo   *hashfunctions;	/* per-grouping-field hash fns */
	bool		setop_done;		/* indicates completion of output scan */
	long		numOutput;		/* number of dups left to output */
	MemoryContext tempContext;	/* short-term context for comparisons */
	/* these fields are used in SETOP_SORTED mode: */
	SetOpStatePerGroup pergroup;	/* per-group working state */
	HeapTuple	grp_firstTuple; /* copy of first tuple of current group */
	/* these fields are used in SETOP_HASHED mode: */
	TupleHashTable hashtable;	/* hash table with one entry per group */
	MemoryContext tableContext; /* memory context containing hash table */
	bool		table_filled;	/* hash table filled yet? */
	TupleHashIterator hashiter; /* for iterating through hash table */
} SetOpState;

/* ----------------
 *	 LockRowsState information
 *
 *		LockRows nodes are used to enforce FOR [KEY] UPDATE/SHARE locking.
 * ----------------
 */
typedef struct LockRowsState
{
	PlanState	ps;				/* its first field is NodeTag */
	List	   *lr_arowMarks;	/* List of ExecAuxRowMarks */
	EPQState	lr_epqstate;	/* for evaluating EvalPlanQual rechecks */
	HeapTuple  *lr_curtuples;	/* locked tuples (one entry per RT entry) */
	int			lr_ntables;		/* length of lr_curtuples[] array */
} LockRowsState;

/* ----------------
 *	 LimitState information
 *
 *		Limit nodes are used to enforce LIMIT/OFFSET clauses.
 *		They just select the desired subrange of their subplan's output.
 *
 * offset is the number of initial tuples to skip (0 does nothing).
 * count is the number of tuples to return after skipping the offset tuples.
 * If no limit count was specified, count is undefined and noCount is true.
 * When lstate == LIMIT_INITIAL, offset/count/noCount haven't been set yet.
 * ----------------
 */
typedef enum
{
	LIMIT_INITIAL,				/* initial state for LIMIT node */
	LIMIT_RESCAN,				/* rescan after recomputing parameters */
	LIMIT_EMPTY,				/* there are no returnable rows */
	LIMIT_INWINDOW,				/* have returned a row in the window */
	LIMIT_SUBPLANEOF,			/* at EOF of subplan (within window) */
	LIMIT_WINDOWEND,			/* stepped off end of window */
	LIMIT_WINDOWSTART			/* stepped off beginning of window */
} LimitStateCond;

typedef struct LimitState
{
	PlanState	ps;				/* its first field is NodeTag */
	ExprState  *limitOffset;	/* OFFSET parameter, or NULL if none */
	ExprState  *limitCount;		/* COUNT parameter, or NULL if none */
	int64		offset;			/* current OFFSET value */
	int64		count;			/* current COUNT, if any */
	bool		noCount;		/* if true, ignore count */
	LimitStateCond lstate;		/* state machine status, as above */
	int64		position;		/* 1-based index of last tuple returned */
	TupleTableSlot *subSlot;	/* tuple last obtained from subplan */
} LimitState;

#endif							/* EXECNODES_H */