analyze.c

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * analyze.c
 *	  transform the parse tree into a query tree
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *	$Id: analyze.c,v 1.110.2.1 1999/08/15 06:50:22 thomas Exp $
 *
 *-------------------------------------------------------------------------
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

#include "postgres.h"
#include "access/heapam.h"
#include "nodes/makefuncs.h"
#include "nodes/memnodes.h"
#include "nodes/pg_list.h"
#include "parser/analyze.h"
#include "parser/parse_agg.h"
#include "parser/parse_clause.h"
#include "parser/parse_node.h"
#include "parser/parse_relation.h"
#include "parser/parse_target.h"
/***S*I***/
#include "parser/parse_expr.h"
#include "catalog/pg_type.h"
#include "parse.h"

#include "utils/builtins.h"
#include "utils/mcxt.h"

static Query *transformStmt(ParseState *pstate, Node *stmt);
static Query *transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt);
static Query *transformInsertStmt(ParseState *pstate, InsertStmt *stmt);
static Query *transformIndexStmt(ParseState *pstate, IndexStmt *stmt);
static Query *transformExtendStmt(ParseState *pstate, ExtendStmt *stmt);
static Query *transformRuleStmt(ParseState *query, RuleStmt *stmt);
static Query *transformSelectStmt(ParseState *pstate, SelectStmt *stmt);
static Query *transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt);
static Query *transformCursorStmt(ParseState *pstate, SelectStmt *stmt);
static Query *transformCreateStmt(ParseState *pstate, CreateStmt *stmt);

static void transformForUpdate(Query *qry, List *forUpdate);
void		CheckSelectForUpdate(Query *qry);

List	   *extras_before = NIL;
List	   *extras_after = NIL;

/*
 * parse_analyze -
 *	  analyze a list of parse trees and transform them if necessary.
 *
 * Returns a list of transformed parse trees. Optimizable statements are
 * all transformed to Query while the rest stays the same.
 *
 */
List *
parse_analyze(List *pl, ParseState *parentParseState)
{
	List	   *result = NIL;
	ParseState *pstate;
	Query	   *parsetree;

	while (pl != NIL)
	{
		pstate = make_parsestate(parentParseState);
		parsetree = transformStmt(pstate, lfirst(pl));
		if (pstate->p_target_relation != NULL)
			heap_close(pstate->p_target_relation);

		while (extras_before != NIL)
		{
			result = lappend(result,
						   transformStmt(pstate, lfirst(extras_before)));
			if (pstate->p_target_relation != NULL)
				heap_close(pstate->p_target_relation);
			extras_before = lnext(extras_before);
		}

		result = lappend(result, parsetree);

		while (extras_after != NIL)
		{
			result = lappend(result,
							 transformStmt(pstate, lfirst(extras_after)));
			if (pstate->p_target_relation != NULL)
				heap_close(pstate->p_target_relation);
			extras_after = lnext(extras_after);
		}

		pl = lnext(pl);
		pfree(pstate);
	}

	return result;
}

/*
 * transformStmt -
 *	  transform a Parse tree. If it is an optimizable statement, turn it
 *	  into a Query tree.
 */
static Query *
transformStmt(ParseState *pstate, Node *parseTree)
{
	Query	   *result = NULL;

	switch (nodeTag(parseTree))
	{
			/*------------------------
			 *	Non-optimizable statements
			 *------------------------
			 */
		case T_CreateStmt:
			result = transformCreateStmt(pstate, (CreateStmt *) parseTree);
			break;

		case T_IndexStmt:
			result = transformIndexStmt(pstate, (IndexStmt *) parseTree);
			break;

		case T_ExtendStmt:
			result = transformExtendStmt(pstate, (ExtendStmt *) parseTree);
			break;

		case T_RuleStmt:
			result = transformRuleStmt(pstate, (RuleStmt *) parseTree);
			break;

		case T_ViewStmt:
			{
				ViewStmt   *n = (ViewStmt *) parseTree;

				n->query = (Query *) transformStmt(pstate, (Node *) n->query);
				result = makeNode(Query);
				result->commandType = CMD_UTILITY;
				result->utilityStmt = (Node *) n;
			}
			break;

		case T_VacuumStmt:
			{
				MemoryContext oldcontext;

				/*
				 * make sure that this Query is allocated in TopMemory
				 * context because vacuum spans transactions and we don't
				 * want to lose the vacuum Query due to end-of-transaction
				 * free'ing
				 */
				oldcontext = MemoryContextSwitchTo(TopMemoryContext);
				result = makeNode(Query);
				result->commandType = CMD_UTILITY;
				result->utilityStmt = (Node *) parseTree;
				MemoryContextSwitchTo(oldcontext);
				break;

			}
		case T_ExplainStmt:
			{
				ExplainStmt *n = (ExplainStmt *) parseTree;

				result = makeNode(Query);
				result->commandType = CMD_UTILITY;
				n->query = transformStmt(pstate, (Node *) n->query);
				result->utilityStmt = (Node *) parseTree;
			}
			break;

			/*------------------------
			 *	Optimizable statements
			 *------------------------
			 */
		case T_InsertStmt:
			result = transformInsertStmt(pstate, (InsertStmt *) parseTree);
			break;

		case T_DeleteStmt:
			result = transformDeleteStmt(pstate, (DeleteStmt *) parseTree);
			break;

		case T_UpdateStmt:
			result = transformUpdateStmt(pstate, (UpdateStmt *) parseTree);
			break;

		case T_SelectStmt:
			if (!((SelectStmt *) parseTree)->portalname)
			{
				result = transformSelectStmt(pstate, (SelectStmt *) parseTree);
				result->limitOffset = ((SelectStmt *) parseTree)->limitOffset;
				result->limitCount = ((SelectStmt *) parseTree)->limitCount;
			}
			else
				result = transformCursorStmt(pstate, (SelectStmt *) parseTree);
			break;

		default:

			/*
			 * other statments don't require any transformation-- just
			 * return the original parsetree, yea!
			 */
			result = makeNode(Query);
			result->commandType = CMD_UTILITY;
			result->utilityStmt = (Node *) parseTree;
			break;
	}
	return result;
}

/*
 * transformDeleteStmt -
 *	  transforms a Delete Statement
 */
static Query *
transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt)
{
	Query	   *qry = makeNode(Query);

	qry->commandType = CMD_DELETE;

	/* set up a range table */
	makeRangeTable(pstate, stmt->relname, NULL, NULL);

	qry->uniqueFlag = NULL;

	/* fix where clause */
	qry->qual = transformWhereClause(pstate, stmt->whereClause, NULL);
	qry->hasSubLinks = pstate->p_hasSubLinks;

	qry->rtable = pstate->p_rtable;
	qry->resultRelation = refnameRangeTablePosn(pstate, stmt->relname, NULL);

	qry->hasAggs = pstate->p_hasAggs;
	if (pstate->p_hasAggs)
		parseCheckAggregates(pstate, qry);

	return (Query *) qry;
}

/*
 * transformInsertStmt -
 *	  transform an Insert Statement
 */
static Query *
transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
{
	Query	   *qry = makeNode(Query);	/* make a new query tree */
	List	   *icolumns;

	qry->commandType = CMD_INSERT;
	pstate->p_is_insert = true;

	/* set up a range table */
	makeRangeTable(pstate, stmt->relname, stmt->fromClause, NULL);

	qry->uniqueFlag = stmt->unique;

	/* fix the target list */
	icolumns = pstate->p_insert_columns = makeTargetNames(pstate, stmt->cols);

	qry->targetList = transformTargetList(pstate, stmt->targetList);

	/* DEFAULT handling */
	if (length(qry->targetList) < pstate->p_target_relation->rd_att->natts &&
		pstate->p_target_relation->rd_att->constr &&
		pstate->p_target_relation->rd_att->constr->num_defval > 0)
	{
		Form_pg_attribute *att = pstate->p_target_relation->rd_att->attrs;
		AttrDefault *defval = pstate->p_target_relation->rd_att->constr->defval;
		int			ndef = pstate->p_target_relation->rd_att->constr->num_defval;

		/*
		 * if stmt->cols == NIL then makeTargetNames returns list of all
		 * attrs. May have to shorten icolumns list...
		 */
		if (stmt->cols == NIL)
		{
			List	   *extrl;
			int			i = length(qry->targetList);

			foreach(extrl, icolumns)
			{

				/*
				 * decrements first, so if we started with zero items it
				 * will now be negative
				 */
				if (--i <= 0)
					break;
			}

			/*
			 * this an index into the targetList, so make sure we had one
			 * to start...
			 */
			if (i >= 0)
			{
				freeList(lnext(extrl));
				lnext(extrl) = NIL;
			}
			else
				icolumns = NIL;
		}

		while (ndef-- > 0)
		{
			List	   *tl;
			Ident	   *id;
			TargetEntry *te;

			foreach(tl, icolumns)
			{
				id = (Ident *) lfirst(tl);
				if (namestrcmp(&(att[defval[ndef].adnum - 1]->attname), id->name) == 0)
					break;
			}
			if (tl != NIL)		/* something given for this attr */
				continue;

			/*
			 * Nothing given for this attr with DEFAULT expr, so add new
			 * TargetEntry to qry->targetList. Note, that we set resno to
			 * defval[ndef].adnum: it's what
			 * transformTargetList()->make_targetlist_expr() does for
			 * INSERT ... SELECT. But for INSERT ... VALUES
			 * pstate->p_last_resno is used. It doesn't matter for
			 * "normal" using (planner creates proper target list in
			 * preptlist.c), but may break RULEs in some way. It seems
			 * better to create proper target list here...
			 */
			te = makeTargetEntry(makeResdom(defval[ndef].adnum,
								   att[defval[ndef].adnum - 1]->atttypid,
								  att[defval[ndef].adnum - 1]->atttypmod,
			   pstrdup(nameout(&(att[defval[ndef].adnum - 1]->attname))),
											0, 0, false),
							  (Node *) stringToNode(defval[ndef].adbin));
			qry->targetList = lappend(qry->targetList, te);
		}
	}

	/* fix where clause */
	qry->qual = transformWhereClause(pstate, stmt->whereClause, NULL);

	/*
	 * The havingQual has a similar meaning as "qual" in the where
	 * statement. So we can easily use the code from the "where clause"
	 * with some additional traversals done in
	 * .../optimizer/plan/planner.c
	 */
	qry->havingQual = transformWhereClause(pstate, stmt->havingClause, NULL);

	qry->hasSubLinks = pstate->p_hasSubLinks;

	/* now the range table will not change */
	qry->rtable = pstate->p_rtable;
	qry->resultRelation = refnameRangeTablePosn(pstate, stmt->relname, NULL);

	qry->groupClause = transformGroupClause(pstate,
											stmt->groupClause,
											qry->targetList);

	/* fix order clause */
	qry->sortClause = transformSortClause(pstate,
										  NIL,
										  NIL,
										  qry->targetList,
										  qry->uniqueFlag);

	qry->hasAggs = pstate->p_hasAggs;
	if (pstate->p_hasAggs || qry->groupClause)
		parseCheckAggregates(pstate, qry);

	/*
	 * The INSERT INTO ... SELECT ... could have a UNION in child, so
	 * unionClause may be false ,
	 */
	qry->unionall = stmt->unionall;

	/***S*I***/

	/*
	 * Just hand through the unionClause and intersectClause. We will
	 * handle it in the function Except_Intersect_Rewrite()
	 */
	qry->unionClause = stmt->unionClause;
	qry->intersectClause = stmt->intersectClause;

	/*
	 * If there is a havingQual but there are no aggregates, then there is
	 * something wrong with the query because having must contain
	 * aggregates in its expressions! Otherwise the query could have been
	 * formulated using the where clause.
	 */
	if ((qry->hasAggs == false) && (qry->havingQual != NULL))
	{
		elog(ERROR, "SELECT/HAVING requires aggregates to be valid");
		return (Query *) NIL;
	}

	if (stmt->forUpdate != NULL)
		transformForUpdate(qry, stmt->forUpdate);

	return (Query *) qry;
}

/*
 *	makeObjectName()
 *
 *	Create a name for an implicitly created index, sequence, constraint, etc.
 *
 *	The parameters are: the original table name, the original field name, and
 *	a "type" string (such as "seq" or "pkey").  The field name and/or type
 *	can be NULL if not relevant.
 *
 *	The result is a palloc'd string.
 *
 *	The basic result we want is "name1_name2_type", omitting "_name2" or
 *	"_type" when those parameters are NULL.  However, we must generate
 *	a name with less than NAMEDATALEN characters!  So, we truncate one or
 *	both names if necessary to make a short-enough string.  The type part
 *	is never truncated (so it had better be reasonably short).
 *
 *	To reduce the probability of collisions, we might someday add more
 *	smarts to this routine, like including some "hash" characters computed
 *	from the truncated characters.  Currently it seems best to keep it simple,