analyze.c

关系型数据库 Postgresql 6.5.2

	extras_before = blist;
	extras_after = ilist;

	return q;
}	/* transformCreateStmt() */

/*
 * transformIndexStmt -
 *	  transforms the qualification of the index statement
 */
static Query *
transformIndexStmt(ParseState *pstate, IndexStmt *stmt)
{
	Query	   *qry;

	qry = makeNode(Query);
	qry->commandType = CMD_UTILITY;

	/* take care of the where clause */
	stmt->whereClause = transformWhereClause(pstate, stmt->whereClause, NULL);
	qry->hasSubLinks = pstate->p_hasSubLinks;

	stmt->rangetable = pstate->p_rtable;

	qry->utilityStmt = (Node *) stmt;

	return qry;
}

/*
 * transformExtendStmt -
 *	  transform the qualifications of the Extend Index Statement
 *
 */
static Query *
transformExtendStmt(ParseState *pstate, ExtendStmt *stmt)
{
	Query	   *qry;

	qry = makeNode(Query);
	qry->commandType = CMD_UTILITY;

	/* take care of the where clause */
	stmt->whereClause = transformWhereClause(pstate, stmt->whereClause, NULL);
	qry->hasSubLinks = pstate->p_hasSubLinks;

	stmt->rangetable = pstate->p_rtable;

	qry->utilityStmt = (Node *) stmt;
	return qry;
}

/*
 * transformRuleStmt -
 *	  transform a Create Rule Statement. The actions is a list of parse
 *	  trees which is transformed into a list of query trees.
 */
static Query *
transformRuleStmt(ParseState *pstate, RuleStmt *stmt)
{
	Query	   *qry;
	Query	   *action;
	List	   *actions;

	qry = makeNode(Query);
	qry->commandType = CMD_UTILITY;

	/*
	 * 'instead nothing' rules with a qualification need a query a
	 * rangetable so the rewrite handler can add the negated rule
	 * qualification to the original query. We create a query with the new
	 * command type CMD_NOTHING here that is treated special by the
	 * rewrite system.
	 */
	if (stmt->actions == NIL)
	{
		Query	   *nothing_qry = makeNode(Query);

		nothing_qry->commandType = CMD_NOTHING;

		addRangeTableEntry(pstate, stmt->object->relname, "*CURRENT*",
						   FALSE, FALSE);
		addRangeTableEntry(pstate, stmt->object->relname, "*NEW*",
						   FALSE, FALSE);

		nothing_qry->rtable = pstate->p_rtable;

		stmt->actions = lappend(NIL, nothing_qry);
	}

	actions = stmt->actions;

	/*
	 * transform each statment, like parse_analyze()
	 */
	while (actions != NIL)
	{

		/*
		 * NOTE: 'CURRENT' must always have a varno equal to 1 and 'NEW'
		 * equal to 2.
		 */
		addRangeTableEntry(pstate, stmt->object->relname, "*CURRENT*",
						   FALSE, FALSE);
		addRangeTableEntry(pstate, stmt->object->relname, "*NEW*",
						   FALSE, FALSE);

		pstate->p_last_resno = 1;
		pstate->p_is_rule = true;		/* for expand all */
		pstate->p_hasAggs = false;

		action = (Query *) lfirst(actions);
		if (action->commandType != CMD_NOTHING)
			lfirst(actions) = transformStmt(pstate, lfirst(actions));
		actions = lnext(actions);
	}

	/* take care of the where clause */
	stmt->whereClause = transformWhereClause(pstate, stmt->whereClause, NULL);
	qry->hasSubLinks = pstate->p_hasSubLinks;

	qry->utilityStmt = (Node *) stmt;
	return qry;
}


/*
 * transformSelectStmt -
 *	  transforms a Select Statement
 *
 */
static Query *
transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
{
	Query	   *qry = makeNode(Query);
	Node	   *qual;

	qry->commandType = CMD_SELECT;

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

	qry->uniqueFlag = stmt->unique;

	qry->into = stmt->into;
	qry->isTemp = stmt->istemp;
	qry->isPortal = FALSE;

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

	qry->qual = transformWhereClause(pstate, stmt->whereClause, qual);

	/*
	 * 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;

	qry->sortClause = transformSortClause(pstate,
										  stmt->sortClause,
										  NIL,
										  qry->targetList,
										  qry->uniqueFlag);

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

	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;
}

/*
 * transformUpdateStmt -
 *	  transforms an update statement
 *
 */
static Query *
transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt)
{
	Query	   *qry = makeNode(Query);

	qry->commandType = CMD_UPDATE;
	pstate->p_is_update = true;

	/*
	 * the FROM clause is non-standard SQL syntax. We used to be able to
	 * do this with REPLACE in POSTQUEL so we keep the feature.
	 */
	makeRangeTable(pstate, stmt->relname, stmt->fromClause, NULL);

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

	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;
}

/*
 * transformCursorStmt -
 *	  transform a Create Cursor Statement
 *
 */
static Query *
transformCursorStmt(ParseState *pstate, SelectStmt *stmt)
{
	Query	   *qry;

	qry = transformSelectStmt(pstate, stmt);

	qry->into = stmt->portalname;
	qry->isTemp = stmt->istemp;
	qry->isPortal = TRUE;
	qry->isBinary = stmt->binary;		/* internal portal */

	return qry;
}

/***S*I***/
/* This function steps through the tree
 * built up by the select_w_o_sort rule
 * and builds a list of all SelectStmt Nodes found
 * The built up list is handed back in **select_list.
 * If one of the SelectStmt Nodes has the 'unionall' flag
 * set to true *unionall_present hands back 'true' */
void
create_select_list(Node *ptr, List **select_list, bool *unionall_present)
{
	if (IsA(ptr, SelectStmt))
	{
		*select_list = lappend(*select_list, ptr);
		if (((SelectStmt *) ptr)->unionall == TRUE)
			*unionall_present = TRUE;
		return;
	}

	/* Recursively call for all arguments. A NOT expr has no lexpr! */
	if (((A_Expr *) ptr)->lexpr != NULL)
		create_select_list(((A_Expr *) ptr)->lexpr, select_list, unionall_present);
	create_select_list(((A_Expr *) ptr)->rexpr, select_list, unionall_present);
}

/* Changes the A_Expr Nodes to Expr Nodes and exchanges ANDs and ORs.
 * The reason for the exchange is easy: We implement INTERSECTs and EXCEPTs
 * by rewriting these queries to semantically equivalent queries that use
 * IN and NOT IN subselects. To be able to use all three operations
 * (UNIONs INTERSECTs and EXCEPTs) in one complex query we have to
 * translate the queries into Disjunctive Normal Form (DNF). Unfortunately
 * there is no function 'dnfify' but there is a function 'cnfify'
 * which produces DNF when we exchange ANDs and ORs before calling
 * 'cnfify' and exchange them back in the result.
 *
 * If an EXCEPT or INTERSECT is present *intersect_present
 * hands back 'true' */
Node *
A_Expr_to_Expr(Node *ptr, bool *intersect_present)
{
	Node	   *result = NULL;

	switch (nodeTag(ptr))
	{
		case T_A_Expr:
			{
				A_Expr	   *a = (A_Expr *) ptr;

				switch (a->oper)
				{
					case AND:
						{
							Expr	   *expr = makeNode(Expr);
							Node	   *lexpr = A_Expr_to_Expr(((A_Expr *) ptr)->lexpr, intersect_present);
							Node	   *rexpr = A_Expr_to_Expr(((A_Expr *) ptr)->rexpr, intersect_present);

							*intersect_present = TRUE;

							expr->typeOid = BOOLOID;
							expr->opType = OR_EXPR;
							expr->args = makeList(lexpr, rexpr, -1);
							result = (Node *) expr;
							break;
						}
					case OR:
						{
							Expr	   *expr = makeNode(Expr);
							Node	   *lexpr = A_Expr_to_Expr(((A_Expr *) ptr)->lexpr, intersect_present);
							Node	   *rexpr = A_Expr_to_Expr(((A_Expr *) ptr)->rexpr, intersect_present);

							expr->typeOid = BOOLOID;
							expr->opType = AND_EXPR;
							expr->args = makeList(lexpr, rexpr, -1);
							result = (Node *) expr;
							break;
						}
					case NOT:
						{
							Expr	   *expr = makeNode(Expr);
							Node	   *rexpr = A_Expr_to_Expr(((A_Expr *) ptr)->rexpr, intersect_present);

							expr->typeOid = BOOLOID;
							expr->opType = NOT_EXPR;
							expr->args = makeList(rexpr, -1);
							result = (Node *) expr;
							break;
						}
				}
				break;
			}
		default:
			result = ptr;
	}
	return result;
}

void
CheckSelectForUpdate(Query *qry)
{
	if (qry->unionClause != NULL)
		elog(ERROR, "SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT clause");
	if (qry->uniqueFlag != NULL)
		elog(ERROR, "SELECT FOR UPDATE is not allowed with DISTINCT clause");
	if (qry->groupClause != NULL)
		elog(ERROR, "SELECT FOR UPDATE is not allowed with GROUP BY clause");
	if (qry->hasAggs)
		elog(ERROR, "SELECT FOR UPDATE is not allowed with AGGREGATE");
}

static void
transformForUpdate(Query *qry, List *forUpdate)
{
	List	   *rowMark = NULL;
	RowMark    *newrm;
	List	   *l;
	Index		i;

	CheckSelectForUpdate(qry);

	if (lfirst(forUpdate) == NULL)		/* all tables */
	{
		i = 1;
		foreach(l, qry->rtable)
		{
			newrm = makeNode(RowMark);
			newrm->rti = i++;
			newrm->info = ROW_MARK_FOR_UPDATE | ROW_ACL_FOR_UPDATE;
			rowMark = lappend(rowMark, newrm);
		}
		qry->rowMark = nconc(qry->rowMark, rowMark);
		return;
	}

	foreach(l, forUpdate)
	{
		List	   *l2;
		List	   *l3;

		i = 1;
		foreach(l2, qry->rtable)
		{
			if (strcmp(((RangeTblEntry *) lfirst(l2))->refname, lfirst(l)) == 0)
			{
				foreach(l3, rowMark)
				{
					if (((RowMark *) lfirst(l3))->rti == i)		/* duplicate */
						break;
				}
				if (l3 == NULL)
				{
					newrm = makeNode(RowMark);
					newrm->rti = i;
					newrm->info = ROW_MARK_FOR_UPDATE | ROW_ACL_FOR_UPDATE;
					rowMark = lappend(rowMark, newrm);
				}
				break;
			}
			i++;
		}
		if (l2 == NULL)
			elog(ERROR, "FOR UPDATE: relation %s not found in FROM clause", lfirst(l));
	}

	qry->rowMark = rowMark;
	return;
}