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First phase of plan-invalidation project: create a plan cache management

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module and teach PREPARE and protocol-level prepared statements to use it.
In service of this, rearrange utility-statement processing so that parse
analysis does not assume table schemas can't change before execution for
utility statements (necessary because we don't attempt to re-acquire locks
for utility statements when reusing a stored plan).  This requires some
refactoring of the ProcessUtility API, but it ends up cleaner anyway,
for instance we can get rid of the QueryContext global.

Still to do: fix up SPI and related code to use the plan cache; I'm tempted to
try to make SQL functions use it too.  Also, there are at least some aspects
of system state that we want to ensure remain the same during a replan as in
the original processing; search_path certainly ought to behave that way for
instance, and perhaps there are others.
This commit is contained in:
Tom Lane
2007-03-13 00:33:44 +00:00
parent f84308f195
commit b9527e9840
61 changed files with 2478 additions and 1354 deletions
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70
src/backend/commands/portalcmds.c
View File

@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.61 2007/02/20 17:32:14 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.62 2007/03/13 00:33:39 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -38,8 +38,11 @@
* Execute SQL DECLARE CURSOR command.
*/
void
PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params)
PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params,
const char *queryString, bool isTopLevel)
{
Oid *param_types;
int num_params;
List *rewritten;
Query *query;
PlannedStmt *plan;
@ -61,40 +64,53 @@ PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params)
* user-visible effect).
*/
if (!(stmt->options & CURSOR_OPT_HOLD))
RequireTransactionChain((void *) stmt, "DECLARE CURSOR");
RequireTransactionChain(isTopLevel, "DECLARE CURSOR");
/*
* Because the planner is not cool about not scribbling on its input, we
* 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 and is
* executed repeatedly. XXX the planner really shouldn't modify its input
* ... FIXME someday.
* 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.
*/
query = copyObject(stmt->query);
rewritten = pg_analyze_and_rewrite((Node *) copyObject(stmt->query),
queryString, param_types, num_params);
/*
* The query has been through parse analysis, but not rewriting or
* planning as yet. Note that the grammar ensured we have a SELECT query,
* so we are not expecting rule rewriting to do anything strange.
*/
AcquireRewriteLocks(query);
rewritten = QueryRewrite(query);
/* 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, true, stmt->options, params);
/*
@ -106,23 +122,22 @@ PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params)
plan = copyObject(plan);
/*
* XXX: debug_query_string is wrong here: the user might have submitted
* multiple semicolon delimited queries.
*/
PortalDefineQuery(portal,
NULL,
debug_query_string ? pstrdup(debug_query_string) : NULL,
queryString,
"SELECT", /* cursor's query is always a SELECT */
list_make1(plan),
PortalGetHeapMemory(portal));
NULL);
/*
/*----------
* Also copy the outer portal's parameter list into the inner portal's
* memory context. We want to pass down the parameter values in case we
* had a command like DECLARE c CURSOR FOR SELECT ... WHERE foo = $1 This
* will have been parsed using the outer parameter set and the parameter
* value needs to be preserved for use when the cursor is executed.
* had a command like
* DECLARE c CURSOR FOR SELECT ... WHERE foo = $1
* This will have been parsed using the outer parameter set and the
* parameter value needs to be preserved for use when the cursor is
* executed.
*----------
*/
params = copyParamList(params);
@ -314,7 +329,6 @@ PersistHoldablePortal(Portal portal)
Snapshot saveActiveSnapshot;
ResourceOwner saveResourceOwner;
MemoryContext savePortalContext;
MemoryContext saveQueryContext;
MemoryContext oldcxt;
/*
@ -356,14 +370,12 @@ PersistHoldablePortal(Portal portal)
saveActiveSnapshot = ActiveSnapshot;
saveResourceOwner = CurrentResourceOwner;
savePortalContext = PortalContext;
saveQueryContext = QueryContext;
PG_TRY();
{
ActivePortal = portal;
ActiveSnapshot = queryDesc->snapshot;
CurrentResourceOwner = portal->resowner;
PortalContext = PortalGetHeapMemory(portal);
QueryContext = portal->queryContext;
MemoryContextSwitchTo(PortalContext);
@ -434,7 +446,6 @@ PersistHoldablePortal(Portal portal)
ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
QueryContext = saveQueryContext;
PG_RE_THROW();
}
@ -449,7 +460,6 @@ PersistHoldablePortal(Portal portal)
ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
QueryContext = saveQueryContext;
/*
* We can now release any subsidiary memory of the portal's heap context;