primnodes.h

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

/*-------------------------------------------------------------------------
 *
 * primnodes.h
 *	  Definitions for "primitive" node types, those that are used in more
 *	  than one of the parse/plan/execute stages of the query pipeline.
 *	  Currently, these are mostly nodes for executable expressions
 *	  and join trees.
 *
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.109 2005/10/15 02:49:45 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef PRIMNODES_H
#define PRIMNODES_H

#include "access/attnum.h"
#include "nodes/pg_list.h"
#include "nodes/value.h"


/* ----------------------------------------------------------------
 *						node definitions
 * ----------------------------------------------------------------
 */

/*
 * Alias -
 *	  specifies an alias for a range variable; the alias might also
 *	  specify renaming of columns within the table.
 *
 * Note: colnames is a list of Value nodes (always strings).  In Alias structs
 * associated with RTEs, there may be entries corresponding to dropped
 * columns; these are normally empty strings ("").	See parsenodes.h for info.
 */
typedef struct Alias
{
	NodeTag		type;
	char	   *aliasname;		/* aliased rel name (never qualified) */
	List	   *colnames;		/* optional list of column aliases */
} Alias;

typedef enum InhOption
{
	INH_NO,						/* Do NOT scan child tables */
	INH_YES,					/* DO scan child tables */
	INH_DEFAULT					/* Use current SQL_inheritance option */
} InhOption;

/*
 * RangeVar - range variable, used in FROM clauses
 *
 * Also used to represent table names in utility statements; there, the alias
 * field is not used, and inhOpt shows whether to apply the operation
 * recursively to child tables.  In some contexts it is also useful to carry
 * a TEMP table indication here.
 */
typedef struct RangeVar
{
	NodeTag		type;
	char	   *catalogname;	/* the catalog (database) name, or NULL */
	char	   *schemaname;		/* the schema name, or NULL */
	char	   *relname;		/* the relation/sequence name */
	InhOption	inhOpt;			/* expand rel by inheritance? recursively act
								 * on children? */
	bool		istemp;			/* is this a temp relation/sequence? */
	Alias	   *alias;			/* table alias & optional column aliases */
} RangeVar;


/* ----------------------------------------------------------------
 *					node types for executable expressions
 * ----------------------------------------------------------------
 */

/*
 * Expr - generic superclass for executable-expression nodes
 *
 * All node types that are used in executable expression trees should derive
 * from Expr (that is, have Expr as their first field).  Since Expr only
 * contains NodeTag, this is a formality, but it is an easy form of
 * documentation.  See also the ExprState node types in execnodes.h.
 */
typedef struct Expr
{
	NodeTag		type;
} Expr;

/*
 * Var - expression node representing a variable (ie, a table column)
 *
 * Note: during parsing/planning, varnoold/varoattno are always just copies
 * of varno/varattno.  At the tail end of planning, Var nodes appearing in
 * upper-level plan nodes are reassigned to point to the outputs of their
 * subplans; for example, in a join node varno becomes INNER or OUTER and
 * varattno becomes the index of the proper element of that subplan's target
 * list.  But varnoold/varoattno continue to hold the original values.
 * The code doesn't really need varnoold/varoattno, but they are very useful
 * for debugging and interpreting completed plans, so we keep them around.
 */
#define    INNER		65000
#define    OUTER		65001

#define    PRS2_OLD_VARNO			1
#define    PRS2_NEW_VARNO			2

typedef struct Var
{
	Expr		xpr;
	Index		varno;			/* index of this var's relation in the range
								 * table (could also be INNER or OUTER) */
	AttrNumber	varattno;		/* attribute number of this var, or zero for
								 * all */
	Oid			vartype;		/* pg_type tuple OID for the type of this var */
	int32		vartypmod;		/* pg_attribute typmod value */
	Index		varlevelsup;

	/*
	 * for subquery variables referencing outer relations; 0 in a normal var,
	 * >0 means N levels up
	 */
	Index		varnoold;		/* original value of varno, for debugging */
	AttrNumber	varoattno;		/* original value of varattno */
} Var;

/*
 * Const
 */
typedef struct Const
{
	Expr		xpr;
	Oid			consttype;		/* PG_TYPE OID of the constant's datatype */
	int			constlen;		/* typlen of the constant's datatype */
	Datum		constvalue;		/* the constant's value */
	bool		constisnull;	/* whether the constant is null (if true,
								 * constvalue is undefined) */
	bool		constbyval;		/* whether this datatype is passed by value.
								 * If true, then all the information is stored
								 * in the Datum. If false, then the Datum
								 * contains a pointer to the information. */
} Const;

/* ----------------
 * Param
 *		paramkind - specifies the kind of parameter. The possible values
 *		for this field are specified in "params.h", and they are:
 *
 *		PARAM_NAMED: The parameter has a name, i.e. something
 *				like `$.salary' or `$.foobar'.
 *				In this case field `paramname' must be a valid name.
 *
 *		PARAM_NUM:	 The parameter has only a numeric identifier,
 *				i.e. something like `$1', `$2' etc.
 *				The number is contained in the `paramid' field.
 *
 *		PARAM_EXEC:  The parameter is an internal executor parameter.
 *				It has a number contained in the `paramid' field.
 * ----------------
 */
typedef struct Param
{
	Expr		xpr;
	int			paramkind;		/* kind of parameter. See above */
	AttrNumber	paramid;		/* numeric ID for parameter ("$1") */
	char	   *paramname;		/* name for parameter ("$.foo") */
	Oid			paramtype;		/* PG_TYPE OID of parameter's datatype */
} Param;

/*
 * Aggref
 */
typedef struct Aggref
{
	Expr		xpr;
	Oid			aggfnoid;		/* pg_proc Oid of the aggregate */
	Oid			aggtype;		/* type Oid of result of the aggregate */
	Expr	   *target;			/* expression we are aggregating on */
	Index		agglevelsup;	/* > 0 if agg belongs to outer query */
	bool		aggstar;		/* TRUE if argument was really '*' */
	bool		aggdistinct;	/* TRUE if it's agg(DISTINCT ...) */
} Aggref;

/* ----------------
 *	ArrayRef: describes an array subscripting operation
 *
 * An ArrayRef can describe fetching a single element from an array,
 * fetching a subarray (array slice), storing a single element into
 * an array, or storing a slice.  The "store" cases work with an
 * initial array value and a source value that is inserted into the
 * appropriate part of the array; the result of the operation is an
 * entire new modified array value.
 *
 * If reflowerindexpr = NIL, then we are fetching or storing a single array
 * element at the subscripts given by refupperindexpr.	Otherwise we are
 * fetching or storing an array slice, that is a rectangular subarray
 * with lower and upper bounds given by the index expressions.
 * reflowerindexpr must be the same length as refupperindexpr when it
 * is not NIL.
 *
 * Note: refrestype is NOT the element type, but the array type,
 * when doing subarray fetch or either type of store.
 * ----------------
 */
typedef struct ArrayRef
{
	Expr		xpr;
	Oid			refrestype;		/* type of the result of the ArrayRef
								 * operation */
	Oid			refarraytype;	/* type of the array proper */
	Oid			refelemtype;	/* type of the array elements */
	List	   *refupperindexpr;/* expressions that evaluate to upper array
								 * indexes */
	List	   *reflowerindexpr;/* expressions that evaluate to lower array
								 * indexes */
	Expr	   *refexpr;		/* the expression that evaluates to an array
								 * value */
	Expr	   *refassgnexpr;	/* expression for the source value, or NULL if
								 * fetch */
} ArrayRef;

/*
 * CoercionContext - distinguishes the allowed set of type casts
 *
 * NB: ordering of the alternatives is significant; later (larger) values
 * allow more casts than earlier ones.
 */
typedef enum CoercionContext
{
	COERCION_IMPLICIT,			/* coercion in context of expression */
	COERCION_ASSIGNMENT,		/* coercion in context of assignment */
	COERCION_EXPLICIT			/* explicit cast operation */
} CoercionContext;

/*
 * CoercionForm - information showing how to display a function-call node
 */
typedef enum CoercionForm
{
	COERCE_EXPLICIT_CALL,		/* display as a function call */
	COERCE_EXPLICIT_CAST,		/* display as an explicit cast */
	COERCE_IMPLICIT_CAST,		/* implicit cast, so hide it */
	COERCE_DONTCARE				/* special case for planner */
} CoercionForm;

/*
 * FuncExpr - expression node for a function call
 */
typedef struct FuncExpr
{
	Expr		xpr;
	Oid			funcid;			/* PG_PROC OID of the function */
	Oid			funcresulttype; /* PG_TYPE OID of result value */
	bool		funcretset;		/* true if function returns set */
	CoercionForm funcformat;	/* how to display this function call */
	List	   *args;			/* arguments to the function */
} FuncExpr;

/*
 * OpExpr - expression node for an operator invocation
 *
 * Semantically, this is essentially the same as a function call.
 *
 * Note that opfuncid is not necessarily filled in immediately on creation
 * of the node.  The planner makes sure it is valid before passing the node
 * tree to the executor, but during parsing/planning opfuncid is typically 0.
 */
typedef struct OpExpr
{
	Expr		xpr;
	Oid			opno;			/* PG_OPERATOR OID of the operator */
	Oid			opfuncid;		/* PG_PROC OID of underlying function */
	Oid			opresulttype;	/* PG_TYPE OID of result value */
	bool		opretset;		/* true if operator returns set */
	List	   *args;			/* arguments to the operator (1 or 2) */
} OpExpr;

/*
 * DistinctExpr - expression node for "x IS DISTINCT FROM y"
 *
 * Except for the nodetag, this is represented identically to an OpExpr
 * referencing the "=" operator for x and y.
 * We use "=", not the more obvious "<>", because more datatypes have "="
 * than "<>".  This means the executor must invert the operator result.
 * Note that the operator function won't be called at all if either input
 * is NULL, since then the result can be determined directly.
 */
typedef OpExpr DistinctExpr;

/*
 * ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
 *
 * The operator must yield boolean.  It is applied to the left operand
 * and each element of the righthand array, and the results are combined
 * with OR or AND (for ANY or ALL respectively).  The node representation
 * is almost the same as for the underlying operator, but we need a useOr
 * flag to remember whether it's ANY or ALL, and we don't have to store
 * the result type because it must be boolean.
 */
typedef struct ScalarArrayOpExpr
{
	Expr		xpr;
	Oid			opno;			/* PG_OPERATOR OID of the operator */
	Oid			opfuncid;		/* PG_PROC OID of underlying function */
	bool		useOr;			/* true for ANY, false for ALL */
	List	   *args;			/* the scalar and array operands */
} ScalarArrayOpExpr;

/*
 * BoolExpr - expression node for the basic Boolean operators AND, OR, NOT
 *