ruleutils.c

来自「PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统」· C语言 代码 · 共 2,434 行 · 第 1/5 页

	/* Add the FOR UPDATE/SHARE clause if present */
	if (query->rowMarks != NIL)
	{
		if (query->forUpdate)
			appendContextKeyword(context, " FOR UPDATE OF ",
								 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
		else
			appendContextKeyword(context, " FOR SHARE OF ",
								 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
		sep = "";
		foreach(l, query->rowMarks)
		{
			int			rtindex = lfirst_int(l);
			RangeTblEntry *rte = rt_fetch(rtindex, query->rtable);

			appendStringInfo(buf, "%s%s",
							 sep,
							 quote_identifier(rte->eref->aliasname));
			sep = ", ";
		}
		if (query->rowNoWait)
			appendStringInfo(buf, " NOWAIT");
	}
}

static void
get_basic_select_query(Query *query, deparse_context *context,
					   TupleDesc resultDesc)
{
	StringInfo	buf = context->buf;
	char	   *sep;
	ListCell   *l;
	int			colno;

	/*
	 * Build up the query string - first we say SELECT
	 */
	if (PRETTY_INDENT(context))
	{
		context->indentLevel += PRETTYINDENT_STD;
		appendStringInfoChar(buf, ' ');
	}
	appendStringInfo(buf, "SELECT");

	/* Add the DISTINCT clause if given */
	if (query->distinctClause != NIL)
	{
		if (has_distinct_on_clause(query))
		{
			appendStringInfo(buf, " DISTINCT ON (");
			sep = "";
			foreach(l, query->distinctClause)
			{
				SortClause *srt = (SortClause *) lfirst(l);

				appendStringInfoString(buf, sep);
				get_rule_sortgroupclause(srt, query->targetList,
										 false, context);
				sep = ", ";
			}
			appendStringInfo(buf, ")");
		}
		else
			appendStringInfo(buf, " DISTINCT");
	}

	/* Then we tell what to select (the targetlist) */
	sep = " ";
	colno = 0;
	foreach(l, query->targetList)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(l);
		char	   *colname;
		char	   *attname;

		if (tle->resjunk)
			continue;			/* ignore junk entries */

		appendStringInfoString(buf, sep);
		sep = ", ";
		colno++;

		/*
		 * We special-case Var nodes rather than using get_rule_expr.
		 * This is needed because get_rule_expr will display a whole-row Var
		 * as "foo.*", which is the preferred notation in most contexts, but
		 * at the top level of a SELECT list it's not right (the parser will
		 * expand that notation into multiple columns, yielding behavior
		 * different from a whole-row Var).  We want just "foo", instead.
		 */
		if (tle->expr && IsA(tle->expr, Var))
		{
			Var		   *var = (Var *) (tle->expr);
			char	   *schemaname;
			char	   *refname;

			get_names_for_var(var, 0, context,
							  &schemaname, &refname, &attname);
			if (refname && (context->varprefix || attname == NULL))
			{
				if (schemaname)
					appendStringInfo(buf, "%s.",
									 quote_identifier(schemaname));

				if (strcmp(refname, "*NEW*") == 0)
					appendStringInfoString(buf, "new");
				else if (strcmp(refname, "*OLD*") == 0)
					appendStringInfoString(buf, "old");
				else
					appendStringInfoString(buf, quote_identifier(refname));

				if (attname)
					appendStringInfoChar(buf, '.');
			}
			if (attname)
				appendStringInfoString(buf, quote_identifier(attname));
			else
			{
				/*
				 * In the whole-row Var case, refname is what the default AS
				 * name would be.
				 */
				attname = refname;
			}
		}
		else
		{
			get_rule_expr((Node *) tle->expr, context, true);
			/* We'll show the AS name unless it's this: */
			attname = "?column?";
		}

		/*
		 * Figure out what the result column should be called.	In the context
		 * of a view, use the view's tuple descriptor (so as to pick up the
		 * effects of any column RENAME that's been done on the view).
		 * Otherwise, just use what we can find in the TLE.
		 */
		if (resultDesc && colno <= resultDesc->natts)
			colname = NameStr(resultDesc->attrs[colno - 1]->attname);
		else
			colname = tle->resname;

		/* Show AS unless the column's name is correct as-is */
		if (colname)			/* resname could be NULL */
		{
			if (attname == NULL || strcmp(attname, colname) != 0)
				appendStringInfo(buf, " AS %s", quote_identifier(colname));
		}
	}

	/* Add the FROM clause if needed */
	get_from_clause(query, " FROM ", context);

	/* Add the WHERE clause if given */
	if (query->jointree->quals != NULL)
	{
		appendContextKeyword(context, " WHERE ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
		get_rule_expr(query->jointree->quals, context, false);
	}

	/* Add the GROUP BY clause if given */
	if (query->groupClause != NULL)
	{
		appendContextKeyword(context, " GROUP BY ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
		sep = "";
		foreach(l, query->groupClause)
		{
			GroupClause *grp = (GroupClause *) lfirst(l);

			appendStringInfoString(buf, sep);
			get_rule_sortgroupclause(grp, query->targetList,
									 false, context);
			sep = ", ";
		}
	}

	/* Add the HAVING clause if given */
	if (query->havingQual != NULL)
	{
		appendContextKeyword(context, " HAVING ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
		get_rule_expr(query->havingQual, context, false);
	}
}

static void
get_setop_query(Node *setOp, Query *query, deparse_context *context,
				TupleDesc resultDesc)
{
	StringInfo	buf = context->buf;
	bool		need_paren;

	if (IsA(setOp, RangeTblRef))
	{
		RangeTblRef *rtr = (RangeTblRef *) setOp;
		RangeTblEntry *rte = rt_fetch(rtr->rtindex, query->rtable);
		Query	   *subquery = rte->subquery;

		Assert(subquery != NULL);
		Assert(subquery->setOperations == NULL);
		/* Need parens if ORDER BY, FOR UPDATE, or LIMIT; see gram.y */
		need_paren = (subquery->sortClause ||
					  subquery->rowMarks ||
					  subquery->limitOffset ||
					  subquery->limitCount);
		if (need_paren)
			appendStringInfoChar(buf, '(');
		get_query_def(subquery, buf, context->namespaces, resultDesc,
					  context->prettyFlags, context->indentLevel);
		if (need_paren)
			appendStringInfoChar(buf, ')');
	}
	else if (IsA(setOp, SetOperationStmt))
	{
		SetOperationStmt *op = (SetOperationStmt *) setOp;

		/*
		 * We force parens whenever nesting two SetOperationStmts. There are
		 * some cases in which parens are needed around a leaf query too, but
		 * those are more easily handled at the next level down (see code
		 * above).
		 */
		need_paren = !IsA(op->larg, RangeTblRef);

		if (need_paren)
			appendStringInfoChar(buf, '(');
		get_setop_query(op->larg, query, context, resultDesc);
		if (need_paren)
			appendStringInfoChar(buf, ')');

		if (!PRETTY_INDENT(context))
			appendStringInfoChar(buf, ' ');
		switch (op->op)
		{
			case SETOP_UNION:
				appendContextKeyword(context, "UNION ",
									 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
				break;
			case SETOP_INTERSECT:
				appendContextKeyword(context, "INTERSECT ",
									 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
				break;
			case SETOP_EXCEPT:
				appendContextKeyword(context, "EXCEPT ",
									 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
				break;
			default:
				elog(ERROR, "unrecognized set op: %d",
					 (int) op->op);
		}
		if (op->all)
			appendStringInfo(buf, "ALL ");

		if (PRETTY_INDENT(context))
			appendContextKeyword(context, "", 0, 0, 0);

		need_paren = !IsA(op->rarg, RangeTblRef);

		if (need_paren)
			appendStringInfoChar(buf, '(');
		get_setop_query(op->rarg, query, context, resultDesc);
		if (need_paren)
			appendStringInfoChar(buf, ')');
	}
	else
	{
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(setOp));
	}
}

/*
 * Display a sort/group clause.
 *
 * Also returns the expression tree, so caller need not find it again.
 */
static Node *
get_rule_sortgroupclause(SortClause *srt, List *tlist, bool force_colno,
						 deparse_context *context)
{
	StringInfo	buf = context->buf;
	TargetEntry *tle;
	Node	   *expr;

	tle = get_sortgroupclause_tle(srt, tlist);
	expr = (Node *) tle->expr;

	/*
	 * Use column-number form if requested by caller or if expression is a
	 * constant --- a constant is ambiguous (and will be misinterpreted by
	 * findTargetlistEntry()) if we dump it explicitly.
	 */
	if (force_colno || (expr && IsA(expr, Const)))
	{
		Assert(!tle->resjunk);
		appendStringInfo(buf, "%d", tle->resno);
	}
	else
		get_rule_expr(expr, context, true);

	return expr;
}

/* ----------
 * get_insert_query_def			- Parse back an INSERT parsetree
 * ----------
 */
static void
get_insert_query_def(Query *query, deparse_context *context)
{
	StringInfo	buf = context->buf;
	RangeTblEntry *select_rte = NULL;
	RangeTblEntry *rte;
	char	   *sep;
	ListCell   *l;
	List	   *strippedexprs;

	/*
	 * If it's an INSERT ... SELECT there will be a single subquery RTE for
	 * the SELECT.
	 */
	foreach(l, query->rtable)
	{
		rte = (RangeTblEntry *) lfirst(l);
		if (rte->rtekind != RTE_SUBQUERY)
			continue;
		if (select_rte)
			elog(ERROR, "too many RTEs in INSERT");
		select_rte = rte;
	}

	/*
	 * Start the query with INSERT INTO relname
	 */
	rte = rt_fetch(query->resultRelation, query->rtable);
	Assert(rte->rtekind == RTE_RELATION);

	if (PRETTY_INDENT(context))
	{
		context->indentLevel += PRETTYINDENT_STD;
		appendStringInfoChar(buf, ' ');
	}
	appendStringInfo(buf, "INSERT INTO %s (",
					 generate_relation_name(rte->relid));

	/*
	 * Add the insert-column-names list, and make a list of the actual
	 * assignment source expressions.
	 */
	strippedexprs = NIL;
	sep = "";
	foreach(l, query->targetList)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(l);

		if (tle->resjunk)
			continue;			/* ignore junk entries */

		appendStringInfoString(buf, sep);
		sep = ", ";

		/*
		 * Put out name of target column; look in the catalogs, not at
		 * tle->resname, since resname will fail to track RENAME.
		 */
		appendStringInfoString(buf,
						quote_identifier(get_relid_attribute_name(rte->relid,
															   tle->resno)));

		/*
		 * Print any indirection needed (subfields or subscripts), and strip
		 * off the top-level nodes representing the indirection assignments.
		 */
		strippedexprs = lappend(strippedexprs,
								processIndirection((Node *) tle->expr,
												   context));
	}
	appendStringInfo(buf, ") ");

	/* Add the VALUES or the SELECT */
	if (select_rte == NULL)
	{
		appendContextKeyword(context, "VALUES (",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 2);
		get_rule_expr((Node *) strippedexprs, context, false);
		appendStringInfoChar(buf, ')');
	}
	else
		get_query_def(select_rte->subquery, buf, NIL, NULL,
					  context->prettyFlags, context->indentLevel);
}


/* ----------
 * get_update_query_def			- Parse back an UPDATE parsetree
 * ----------
 */
static void
get_update_query_def(Query *query, deparse_context *context)
{
	StringInfo	buf = context->buf;
	char	   *sep;
	RangeTblEntry *rte;
	ListCell   *l;

	/*
	 * Start the query with UPDATE relname SET
	 */
	rte = rt_fetch(query->resultRelation, query->rtable);
	Assert(rte->rtekind == RTE_RELATION);
	if (PRETTY_INDENT(context))
	{
		appendStringInfoChar(buf, ' ');
		context->indentLevel += PRETTYINDENT_STD;
	}
	appendStringInfo(buf, "UPDATE %s%s SET ",
					 only_marker(rte),
					 generate_relation_name(rte->relid));

	/* Add the comma separated list of 'attname = value' */
	sep = "";
	foreach(l, query->targetList)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(l);
		Node	   *expr;

		if (tle->resjunk)
			continue;			/* ignore junk entries */

		appendStringInfoString(buf, sep);
		sep = ", ";

		/*
		 * Put out name of target column; look in the catalogs, not at
		 * tle->resname, since resname will fail to track RENAME.
		 */
		appendStringInfoString(buf,
						quote_identifier(get_relid_attribute_name(rte->relid,
															   tle->resno)));

		/*
		 * Print any indirection needed (subfields or subscripts), and strip
		 * off the top-level nodes representing the indirection assignments.
		 */
		expr = processIndirection((Node *) tle->expr, context);

		appendStringInfo(buf, " = ");

		get_rule_expr(expr, context, false);
	}

	/* Add the FROM clause if needed */
	get_from_clause(query, " FROM ", context);

	/* Finally add a WHERE clause if given */
	if (query->jointree->quals != NULL)
	{
		appendContextKeyword(context, " WHERE ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
		get_rule_expr(query->jointree->quals, context, false);
	}
}


/* ----------
 * get_delete_query_def			- Parse back a DELETE parsetree
 * ----------
 */
static void
get_delete_query_def(Query *query, deparse_context *context)
{
	StringInfo	buf = context->buf;
	RangeTblEntry *rte;

	/*
	 * Start the query with DELETE FROM relname
	 */
	rte = rt_fetch(query->resultRelation, query->rtable);
	Assert(rte->rtekind == RTE_RELATION);
	if (PRETTY_INDENT(context))
	{
		context->indentLevel += PRETTYINDENT_STD;
		a