parsenodes.h

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 * the item and set raw_default instead.  CONSTR_DEFAULT items
 * should not appear in any subsequent processing.
 */
typedef struct ColumnDef
{
	NodeTag		type;
	char	   *colname;		/* name of column */
	TypeName   *typename;		/* type of column */
	int			inhcount;		/* number of times column is inherited */
	bool		is_local;		/* column has local (non-inherited) def'n */
	bool		is_not_null;	/* NOT NULL constraint specified? */
	Node	   *raw_default;	/* default value (untransformed parse tree) */
	char	   *cooked_default; /* nodeToString representation */
	List	   *constraints;	/* other constraints on column */
} ColumnDef;

/*
 * inhRelation - Relations a CREATE TABLE is to inherit attributes of
 */
typedef struct InhRelation
{
	NodeTag		type;
	RangeVar   *relation;
	List	   *options;		/* integer List of CreateStmtLikeOption */
} InhRelation;

typedef enum CreateStmtLikeOption
{
	CREATE_TABLE_LIKE_INCLUDING_DEFAULTS,
	CREATE_TABLE_LIKE_EXCLUDING_DEFAULTS,
	CREATE_TABLE_LIKE_INCLUDING_CONSTRAINTS,
	CREATE_TABLE_LIKE_EXCLUDING_CONSTRAINTS,
	CREATE_TABLE_LIKE_INCLUDING_INDEXES,
	CREATE_TABLE_LIKE_EXCLUDING_INDEXES
} CreateStmtLikeOption;

/*
 * IndexElem - index parameters (used in CREATE INDEX)
 *
 * For a plain index attribute, 'name' is the name of the table column to
 * index, and 'expr' is NULL.  For an index expression, 'name' is NULL and
 * 'expr' is the expression tree.
 */
typedef struct IndexElem
{
	NodeTag		type;
	char	   *name;			/* name of attribute to index, or NULL */
	Node	   *expr;			/* expression to index, or NULL */
	List	   *opclass;		/* name of desired opclass; NIL = default */
} IndexElem;

/*
 * DefElem -
 *	  a definition (used in definition lists in the form of defname = arg)
 */
typedef struct DefElem
{
	NodeTag		type;
	char	   *defname;
	Node	   *arg;			/* a (Value *) or a (TypeName *) */
} DefElem;

/*
 * LockingClause - raw representation of FOR UPDATE/SHARE options
 *
 * Note: lockedRels == NIL means "all relations in query".	Otherwise it
 * is a list of String nodes giving relation eref names.
 */
typedef struct LockingClause
{
	NodeTag		type;
	List	   *lockedRels;		/* FOR UPDATE or FOR SHARE relations */
	bool		forUpdate;		/* true = FOR UPDATE, false = FOR SHARE */
	bool		noWait;			/* NOWAIT option */
} LockingClause;


/****************************************************************************
 *	Nodes for a Query tree
 ****************************************************************************/

/*--------------------
 * RangeTblEntry -
 *	  A range table is a List of RangeTblEntry nodes.
 *
 *	  A range table entry may represent a plain relation, a sub-select in
 *	  FROM, or the result of a JOIN clause.  (Only explicit JOIN syntax
 *	  produces an RTE, not the implicit join resulting from multiple FROM
 *	  items.  This is because we only need the RTE to deal with SQL features
 *	  like outer joins and join-output-column aliasing.)  Other special
 *	  RTE types also exist, as indicated by RTEKind.
 *
 *	  alias is an Alias node representing the AS alias-clause attached to the
 *	  FROM expression, or NULL if no clause.
 *
 *	  eref is the table reference name and column reference names (either
 *	  real or aliases).  Note that system columns (OID etc) are not included
 *	  in the column list.
 *	  eref->aliasname is required to be present, and should generally be used
 *	  to identify the RTE for error messages etc.
 *
 *	  In RELATION RTEs, the colnames in both alias and eref are indexed by
 *	  physical attribute number; this means there must be colname entries for
 *	  dropped columns.	When building an RTE we insert empty strings ("") for
 *	  dropped columns.	Note however that a stored rule may have nonempty
 *	  colnames for columns dropped since the rule was created (and for that
 *	  matter the colnames might be out of date due to column renamings).
 *	  The same comments apply to FUNCTION RTEs when the function's return type
 *	  is a named composite type.
 *
 *	  In JOIN RTEs, the colnames in both alias and eref are one-to-one with
 *	  joinaliasvars entries.  A JOIN RTE will omit columns of its inputs when
 *	  those columns are known to be dropped at parse time.	Again, however,
 *	  a stored rule might contain entries for columns dropped since the rule
 *	  was created.	(This is only possible for columns not actually referenced
 *	  in the rule.)  When loading a stored rule, we replace the joinaliasvars
 *	  items for any such columns with NULL Consts.	(We can't simply delete
 *	  them from the joinaliasvars list, because that would affect the attnums
 *	  of Vars referencing the rest of the list.)
 *
 *	  inh is TRUE for relation references that should be expanded to include
 *	  inheritance children, if the rel has any.  This *must* be FALSE for
 *	  RTEs other than RTE_RELATION entries.
 *
 *	  inFromCl marks those range variables that are listed in the FROM clause.
 *	  It's false for RTEs that are added to a query behind the scenes, such
 *	  as the NEW and OLD variables for a rule, or the subqueries of a UNION.
 *	  This flag is not used anymore during parsing, since the parser now uses
 *	  a separate "namespace" data structure to control visibility, but it is
 *	  needed by ruleutils.c to determine whether RTEs should be shown in
 *	  decompiled queries.
 *
 *	  requiredPerms and checkAsUser specify run-time access permissions
 *	  checks to be performed at query startup.	The user must have *all*
 *	  of the permissions that are OR'd together in requiredPerms (zero
 *	  indicates no permissions checking).  If checkAsUser is not zero,
 *	  then do the permissions checks using the access rights of that user,
 *	  not the current effective user ID.  (This allows rules to act as
 *	  setuid gateways.)
 *--------------------
 */
typedef enum RTEKind
{
	RTE_RELATION,				/* ordinary relation reference */
	RTE_SUBQUERY,				/* subquery in FROM */
	RTE_JOIN,					/* join */
	RTE_SPECIAL,				/* special rule relation (NEW or OLD) */
	RTE_FUNCTION,				/* function in FROM */
	RTE_VALUES					/* VALUES (<exprlist>), (<exprlist>), ... */
} RTEKind;

typedef struct RangeTblEntry
{
	NodeTag		type;

	RTEKind		rtekind;		/* see above */

	/*
	 * XXX the fields applicable to only some rte kinds should be merged into
	 * a union.  I didn't do this yet because the diffs would impact a lot of
	 * code that is being actively worked on.  FIXME later.
	 */

	/*
	 * Fields valid for a plain relation RTE (else zero):
	 */
	Oid			relid;			/* OID of the relation */

	/*
	 * Fields valid for a subquery RTE (else NULL):
	 */
	Query	   *subquery;		/* the sub-query */

	/*
	 * Fields valid for a function RTE (else NULL):
	 *
	 * If the function returns RECORD, funccoltypes lists the column types
	 * declared in the RTE's column type specification, and funccoltypmods
	 * lists their declared typmods.  Otherwise, both fields are NIL.
	 */
	Node	   *funcexpr;		/* expression tree for func call */
	List	   *funccoltypes;	/* OID list of column type OIDs */
	List	   *funccoltypmods; /* integer list of column typmods */

	/*
	 * Fields valid for a values RTE (else NIL):
	 */
	List	   *values_lists;	/* list of expression lists */

	/*
	 * Fields valid for a join RTE (else NULL/zero):
	 *
	 * joinaliasvars is a list of Vars or COALESCE expressions corresponding
	 * to the columns of the join result.  An alias Var referencing column K
	 * of the join result can be replaced by the K'th element of joinaliasvars
	 * --- but to simplify the task of reverse-listing aliases correctly, we
	 * do not do that until planning time.	In a Query loaded from a stored
	 * rule, it is also possible for joinaliasvars items to be NULL Consts,
	 * denoting columns dropped since the rule was made.
	 */
	JoinType	jointype;		/* type of join */
	List	   *joinaliasvars;	/* list of alias-var expansions */

	/*
	 * Fields valid in all RTEs:
	 */
	Alias	   *alias;			/* user-written alias clause, if any */
	Alias	   *eref;			/* expanded reference names */
	bool		inh;			/* inheritance requested? */
	bool		inFromCl;		/* present in FROM clause? */
	AclMode		requiredPerms;	/* bitmask of required access permissions */
	Oid			checkAsUser;	/* if valid, check access as this role */
} RangeTblEntry;

/*
 * SortClause -
 *	   representation of ORDER BY clauses
 *
 * tleSortGroupRef must match ressortgroupref of exactly one entry of the
 * associated targetlist; that is the expression to be sorted (or grouped) by.
 * sortop is the OID of the ordering operator.
 *
 * SortClauses are also used to identify targets that we will do a "Unique"
 * filter step on (for SELECT DISTINCT and SELECT DISTINCT ON).  The
 * distinctClause list is simply a copy of the relevant members of the
 * sortClause list.  Note that distinctClause can be a subset of sortClause,
 * but cannot have members not present in sortClause; and the members that
 * do appear must be in the same order as in sortClause.
 */
typedef struct SortClause
{
	NodeTag		type;
	Index		tleSortGroupRef;	/* reference into targetlist */
	Oid			sortop;			/* the sort operator to use */
} SortClause;

/*
 * GroupClause -
 *	   representation of GROUP BY clauses
 *
 * GroupClause is exactly like SortClause except for the nodetag value
 * (it's probably not even really necessary to have two different
 * nodetags...).  We have routines that operate interchangeably on both.
 */
typedef SortClause GroupClause;

/*
 * RowMarkClause -
 *	   representation of FOR UPDATE/SHARE clauses
 *
 * We create a separate RowMarkClause node for each target relation
 */
typedef struct RowMarkClause
{
	NodeTag		type;
	Index		rti;			/* range table index of target relation */
	bool		forUpdate;		/* true = FOR UPDATE, false = FOR SHARE */
	bool		noWait;			/* NOWAIT option */
} RowMarkClause;

/*****************************************************************************
 *		Optimizable Statements
 *****************************************************************************/

/* ----------------------
 *		Insert Statement
 *
 * The source expression is represented by SelectStmt for both the
 * SELECT and VALUES cases.  If selectStmt is NULL, then the query
 * is INSERT ... DEFAULT VALUES.
 * ----------------------
 */
typedef struct InsertStmt
{
	NodeTag		type;
	RangeVar   *relation;		/* relation to insert into */
	List	   *cols;			/* optional: names of the target columns */
	Node	   *selectStmt;		/* the source SELECT/VALUES, or NULL */
	List	   *returningList;	/* list of expressions to return */
} InsertStmt;

/* ----------------------
 *		Delete Statement
 * ----------------------
 */
typedef struct DeleteStmt
{
	NodeTag		type;
	RangeVar   *relation;		/* relation to delete from */
	List	   *usingClause;	/* optional using clause for more tables */
	Node	   *whereClause;	/* qualifications */
	List	   *returningList;	/* list of expressions to return */
} DeleteStmt;

/* ----------------------
 *		Update Statement
 * ----------------------
 */
typedef struct UpdateStmt
{
	NodeTag		type;
	RangeVar   *relation;		/* relation to update */
	List	   *targetList;		/* the target list (of ResTarget) */
	Node	   *whereClause;	/* qualifications */
	List	   *fromClause;		/* optional from clause for more tables */
	List	   *returningList;	/* list of expressions to return */
} UpdateStmt;

/* ----------------------
 *		Select Statement
 *
 * A "simple" SELECT is represented in the output of gram.y by a single
 * SelectStmt node; so is a VALUES construct.  A query containing set
 * operators (UNION, INTERSECT, EXCEPT) is represented by a tree of SelectStmt
 * nodes, in which the leaf nodes are component SELECTs and the internal nodes
 * represent UNION, INTERSECT, or EXCEPT operators.  Using the same node
 * type for both leaf and internal nodes allows gram.y to stick ORDER BY,
 * LIMIT, etc, clause values into a SELECT statement without worrying
 * whether it is a simple or compound SELECT.
 * ----------------------
 */
typedef enum SetOperation
{
	SETOP_NONE = 0,
	SETOP_UNION,
	SETOP_INTERSECT,
	SETOP_EXCEPT
} SetOperation;

typedef struct SelectStmt
{
	NodeTag		type;

	/*
	 * These fields are used only in "leaf" SelectStmts.
	 *
	 * into, intoColNames, intoOptions, intoOnCommit, and intoTableSpaceName
	 * are a kluge; they belong somewhere else...
	 */
	List	   *distinctClause; /* NULL, list of DISTINCT ON exprs, or
								 * lcons(NIL,NIL) for all (SELECT DISTINCT) */
	RangeVar   *into;			/* target table (for select into table) */
	List	   *intoColNames;	/* column names for into table */
	List	   *intoOptions;	/* options from WITH clause */
	OnCommitAction intoOnCommit;	/* what do we do at COMMIT? */
	char	   *intoTableSpaceName;		/* table space to use, or NULL */
	List	   *targetList;		/* the target list (of ResTarget) */
	List	   *fromClause;		/* the FROM clause */
	Node	   *whereClause;	/* WHERE qualification */
	List	   *groupClause;	/* GROUP BY clauses */
	Node	   *havingClause;	/* HAVING conditional-expression */

	/*
	 * In a "leaf" node representing a VALUES list, the above fields are all
	 * null, and instead this field is set.  Note that the elements of the
	 * sublists are just expressions, without ResTarget decoration. Also note
	 * that a list element can be DEFAULT (represented as a SetToDefault
	 * node), regardless of the context of the VALUES list. It's up to parse
	 * analysis to reject that where not valid.
	 */
	List	   *valuesLists;	/* untransformed list of expression lists */

	/*
	 * These fields are used in both "leaf" SelectStmts and upper-level
	 * SelectStmts.
	 */
	List	   *sortClause;		/* sort clause (a list of SortBy's) */
	Node	   *limitOffset;	/* # of result tuples to skip */
	Node	   *limitCount;		/* # of result tuples to return */
	List	   *lockingClause;	/* FOR UPDATE (list of LockingClause's) */

	/*
	 * These fields are used only in upper-level SelectStmts.
	 */
	SetOperation op;			/* type of set op */
	bool		all;			/* ALL specified? */
	struct SelectStmt *larg;	/* left child */
	struct SelectStmt *rarg;	/* right child */
	/* Eventually add fields for CORRESPONDING spec here */
} SelectStmt;


/* ----------------------
 *		Set Operation node for post-analysis query trees
 *
 * After parse analysis, a SELECT with set operations is represented by a
 * top-level Query node containing the leaf SELECTs as subqueries in its
 * range table.  Its setOperations field shows the tree of set operations,
 * with leaf SelectStmt nodes replaced by RangeTblRef nodes, and internal
 * nodes replaced by SetOperationStmt nodes.
 * ----------------------
 */
typedef struct SetOperationStmt