database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-14 18:42:34 +03:00
Code Activity

Modify processing of DECLARE CURSOR and EXPLAIN so that they can resolve the

Browse Source 
types of unspecified parameters when submitted via extended query protocol.
This worked in 8.2 but I had broken it during plancache changes.  DECLARE
CURSOR is now treated almost exactly like a plain SELECT through parse
analysis, rewrite, and planning; only just before sending to the executor
do we divert it away to ProcessUtility.  This requires a special-case check
in a number of places, but practically all of them were already special-casing
SELECT INTO, so it's not too ugly.  (Maybe it would be a good idea to merge
the two by treating IntoClause as a form of utility statement?  Not going to
worry about that now, though.)  That approach doesn't work for EXPLAIN,
however, so for that I punted and used a klugy solution of running parse
analysis an extra time if under extended query protocol.
This commit is contained in:
Tom Lane
2007-04-27 22:05:49 +00:00
parent a264671116
commit bbbe825f5f
26 changed files with 333 additions and 246 deletions
Download Patch File Download Diff File Expand all files Collapse all files

82
src/backend/commands/portalcmds.c
View File

@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.64 2007/04/16 01:14:55 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.65 2007/04/27 22:05:47 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -26,34 +26,34 @@
#include "access/xact.h"
#include "commands/portalcmds.h"
#include "executor/executor.h"
#include "optimizer/planner.h"
#include "rewrite/rewriteHandler.h"
#include "tcop/pquery.h"
#include "tcop/tcopprot.h"
#include "utils/memutils.h"
/*
* PerformCursorOpen
* Execute SQL DECLARE CURSOR command.
*
* The query has already been through parse analysis, rewriting, and planning.
* When it gets here, it looks like a SELECT PlannedStmt, except that the
* utilityStmt field is set.
*/
void
PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params,
PerformCursorOpen(PlannedStmt *stmt, ParamListInfo params,
const char *queryString, bool isTopLevel)
{
Oid *param_types;
int num_params;
List *rewritten;
Query *query;
PlannedStmt *plan;
DeclareCursorStmt *cstmt = (DeclareCursorStmt *) stmt->utilityStmt;
Portal portal;
MemoryContext oldContext;
if (cstmt == NULL || !IsA(cstmt, DeclareCursorStmt))
elog(ERROR, "PerformCursorOpen called for non-cursor query");
/*
* Disallow empty-string cursor name (conflicts with protocol-level
* unnamed portal).
*/
if (!stmt->portalname || stmt->portalname[0] == '\0')
if (!cstmt->portalname || cstmt->portalname[0] == '\0')
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_NAME),
errmsg("invalid cursor name: must not be empty")));
@ -63,70 +63,24 @@ PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params,
* been executed inside a transaction block (or else, it would have no
* user-visible effect).
*/
if (!(stmt->options & CURSOR_OPT_HOLD))
if (!(cstmt->options & CURSOR_OPT_HOLD))
RequireTransactionChain(isTopLevel, "DECLARE CURSOR");
/*
* Don't allow both SCROLL and NO SCROLL to be specified
*/
if ((stmt->options & CURSOR_OPT_SCROLL) &&
(stmt->options & CURSOR_OPT_NO_SCROLL))
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
errmsg("cannot specify both SCROLL and NO SCROLL")));
/* Convert parameter type data to the form parser wants */
getParamListTypes(params, &param_types, &num_params);
/*
* Run parse analysis and rewrite. Note this also acquires sufficient
* locks on the source table(s).
*
* Because the parser and planner tend to scribble on their input, we
* make a preliminary copy of the source querytree. This prevents
* problems in the case that the DECLARE CURSOR is in a portal or plpgsql
* function and is executed repeatedly. (See also the same hack in
* COPY and PREPARE.) XXX FIXME someday.
*/
rewritten = pg_analyze_and_rewrite((Node *) copyObject(stmt->query),
queryString, param_types, num_params);
/* We don't expect more or less than one result query */
if (list_length(rewritten) != 1 || !IsA(linitial(rewritten), Query))
elog(ERROR, "unexpected rewrite result");
query = (Query *) linitial(rewritten);
if (query->commandType != CMD_SELECT)
elog(ERROR, "unexpected rewrite result");
/* But we must explicitly disallow DECLARE CURSOR ... SELECT INTO */
if (query->into)
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
errmsg("DECLARE CURSOR cannot specify INTO")));
if (query->rowMarks != NIL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("DECLARE CURSOR ... FOR UPDATE/SHARE is not supported"),
errdetail("Cursors must be READ ONLY.")));
/* plan the query */
plan = planner(query, stmt->options, params);
/*
* Create a portal and copy the plan into its memory context.
*/
portal = CreatePortal(stmt->portalname, false, false);
portal = CreatePortal(cstmt->portalname, false, false);
oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
plan = copyObject(plan);
stmt = copyObject(stmt);
stmt->utilityStmt = NULL; /* make it look like plain SELECT */
PortalDefineQuery(portal,
NULL,
queryString,
"SELECT", /* cursor's query is always a SELECT */
list_make1(plan),
list_make1(stmt),
NULL);
/*----------
@ -150,10 +104,10 @@ PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params,
* based on whether it would require any additional runtime overhead to do
* so.
*/
portal->cursorOptions = stmt->options;
portal->cursorOptions = cstmt->options;
if (!(portal->cursorOptions & (CURSOR_OPT_SCROLL | CURSOR_OPT_NO_SCROLL)))
{
if (ExecSupportsBackwardScan(plan->planTree))
if (ExecSupportsBackwardScan(stmt->planTree))
portal->cursorOptions |= CURSOR_OPT_SCROLL;
else
portal->cursorOptions |= CURSOR_OPT_NO_SCROLL;