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-rw-r--r--src/backend/tcop/fastpath.c7
-rw-r--r--src/backend/tcop/postgres.c11
-rw-r--r--src/backend/tcop/pquery.c93
-rw-r--r--src/backend/tcop/utility.c93
4 files changed, 170 insertions, 34 deletions
diff --git a/src/backend/tcop/fastpath.c b/src/backend/tcop/fastpath.c
index 165b46475cf..66edf545d9c 100644
--- a/src/backend/tcop/fastpath.c
+++ b/src/backend/tcop/fastpath.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/fastpath.c,v 1.75 2004/08/29 05:06:49 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/fastpath.c,v 1.76 2004/09/13 20:07:05 tgl Exp $
*
* NOTES
* This cruft is the server side of PQfn.
@@ -334,11 +334,6 @@ HandleFunctionRequest(StringInfo msgBuf)
get_func_name(fid));
/*
- * Set up a query snapshot in case function needs one.
- */
- SetQuerySnapshot();
-
- /*
* Prepare function call info block and insert arguments.
*/
MemSet(&fcinfo, 0, sizeof(fcinfo));
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 50364bd79d3..85fcc49c839 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.431 2004/09/10 18:39:59 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.432 2004/09/13 20:07:05 tgl Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
@@ -700,7 +700,7 @@ pg_plan_queries(List *querytrees, ParamListInfo boundParams,
{
if (needSnapshot)
{
- SetQuerySnapshot();
+ ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
needSnapshot = false;
}
plan = pg_plan_query(query, boundParams);
@@ -883,7 +883,7 @@ exec_simple_query(const char *query_string)
/*
* Start the portal. No parameters here.
*/
- PortalStart(portal, NULL);
+ PortalStart(portal, NULL, InvalidSnapshot);
/*
* Select the appropriate output format: text unless we are doing
@@ -1539,7 +1539,7 @@ exec_bind_message(StringInfo input_message)
pstmt->plan_list,
pstmt->context);
- PortalStart(portal, params);
+ PortalStart(portal, params, InvalidSnapshot);
/*
* Apply the result format requests to the portal.
@@ -3027,6 +3027,9 @@ PostgresMain(int argc, char *argv[], const char *username)
/* switch back to message context */
MemoryContextSwitchTo(MessageContext);
+ /* set snapshot in case function needs one */
+ ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
+
if (HandleFunctionRequest(&input_message) == EOF)
{
/* lost frontend connection during F message input */
diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
index fca98fc0fa5..5a1c8b4867b 100644
--- a/src/backend/tcop/pquery.c
+++ b/src/backend/tcop/pquery.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.86 2004/09/10 18:40:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.87 2004/09/13 20:07:05 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -32,6 +32,11 @@
Portal ActivePortal = NULL;
+static void ProcessQuery(Query *parsetree,
+ Plan *plan,
+ ParamListInfo params,
+ DestReceiver *dest,
+ char *completionTag);
static uint32 RunFromStore(Portal portal, ScanDirection direction, long count,
DestReceiver *dest);
static long PortalRunSelect(Portal portal, bool forward, long count,
@@ -54,6 +59,8 @@ static void DoPortalRewind(Portal portal);
QueryDesc *
CreateQueryDesc(Query *parsetree,
Plan *plantree,
+ Snapshot snapshot,
+ Snapshot crosscheck_snapshot,
DestReceiver *dest,
ParamListInfo params,
bool doInstrument)
@@ -63,6 +70,8 @@ CreateQueryDesc(Query *parsetree,
qd->operation = parsetree->commandType; /* operation */
qd->parsetree = parsetree; /* parse tree */
qd->plantree = plantree; /* plan */
+ qd->snapshot = snapshot; /* snapshot */
+ qd->crosscheck_snapshot = crosscheck_snapshot; /* RI check snapshot */
qd->dest = dest; /* output dest */
qd->params = params; /* parameter values passed into query */
qd->doInstrument = doInstrument; /* instrumentation wanted? */
@@ -90,7 +99,7 @@ FreeQueryDesc(QueryDesc *qdesc)
/*
* ProcessQuery
- * Execute a single query
+ * Execute a single plannable query within a PORTAL_MULTI_QUERY portal
*
* parsetree: the query tree
* plan: the plan tree for the query
@@ -104,7 +113,7 @@ FreeQueryDesc(QueryDesc *qdesc)
* Must be called in a memory context that will be reset or deleted on
* error; otherwise the executor's memory usage will be leaked.
*/
-void
+static void
ProcessQuery(Query *parsetree,
Plan *plan,
ParamListInfo params,
@@ -114,6 +123,9 @@ ProcessQuery(Query *parsetree,
int operation = parsetree->commandType;
QueryDesc *queryDesc;
+ ereport(DEBUG3,
+ (errmsg_internal("ProcessQuery")));
+
/*
* Check for special-case destinations
*/
@@ -133,9 +145,17 @@ ProcessQuery(Query *parsetree,
}
/*
+ * Must always set snapshot for plannable queries. Note we assume
+ * that caller will take care of restoring ActiveSnapshot on exit/error.
+ */
+ ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
+
+ /*
* Create the QueryDesc object
*/
- queryDesc = CreateQueryDesc(parsetree, plan, dest, params, false);
+ queryDesc = CreateQueryDesc(parsetree, plan,
+ ActiveSnapshot, InvalidSnapshot,
+ dest, params, false);
/*
* Set up to collect AFTER triggers
@@ -145,7 +165,7 @@ ProcessQuery(Query *parsetree,
/*
* Call ExecStart to prepare the plan for execution
*/
- ExecutorStart(queryDesc, false, false);
+ ExecutorStart(queryDesc, false);
/*
* Run the plan to completion.
@@ -195,6 +215,9 @@ ProcessQuery(Query *parsetree,
AfterTriggerEndQuery();
FreeQueryDesc(queryDesc);
+
+ FreeSnapshot(ActiveSnapshot);
+ ActiveSnapshot = NULL;
}
/*
@@ -238,13 +261,19 @@ ChoosePortalStrategy(List *parseTrees)
* the query, they must be passed in here (caller is responsible for
* giving them appropriate lifetime).
*
+ * The caller can optionally pass a snapshot to be used; pass InvalidSnapshot
+ * for the normal behavior of setting a new snapshot. This parameter is
+ * presently ignored for non-PORTAL_ONE_SELECT portals (it's only intended
+ * to be used for cursors).
+ *
* On return, portal is ready to accept PortalRun() calls, and the result
* tupdesc (if any) is known.
*/
void
-PortalStart(Portal portal, ParamListInfo params)
+PortalStart(Portal portal, ParamListInfo params, Snapshot snapshot)
{
Portal saveActivePortal;
+ Snapshot saveActiveSnapshot;
ResourceOwner saveResourceOwner;
MemoryContext savePortalContext;
MemoryContext oldContext;
@@ -259,11 +288,13 @@ PortalStart(Portal portal, ParamListInfo params)
* QueryContext?)
*/
saveActivePortal = ActivePortal;
+ saveActiveSnapshot = ActiveSnapshot;
saveResourceOwner = CurrentResourceOwner;
savePortalContext = PortalContext;
PG_TRY();
{
ActivePortal = portal;
+ ActiveSnapshot = NULL; /* will be set later */
CurrentResourceOwner = portal->resowner;
PortalContext = PortalGetHeapMemory(portal);
@@ -285,9 +316,13 @@ PortalStart(Portal portal, ParamListInfo params)
case PORTAL_ONE_SELECT:
/*
- * Must set query snapshot before starting executor.
+ * Must set snapshot before starting executor. Be sure to
+ * copy it into the portal's context.
*/
- SetQuerySnapshot();
+ if (snapshot)
+ ActiveSnapshot = CopySnapshot(snapshot);
+ else
+ ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
/*
* Create QueryDesc in portal's context; for the moment,
@@ -295,6 +330,8 @@ PortalStart(Portal portal, ParamListInfo params)
*/
queryDesc = CreateQueryDesc((Query *) linitial(portal->parseTrees),
(Plan *) linitial(portal->planTrees),
+ ActiveSnapshot,
+ InvalidSnapshot,
None_Receiver,
params,
false);
@@ -309,7 +346,7 @@ PortalStart(Portal portal, ParamListInfo params)
/*
* Call ExecStart to prepare the plan for execution
*/
- ExecutorStart(queryDesc, false, false);
+ ExecutorStart(queryDesc, false);
/*
* This tells PortalCleanup to shut down the executor
@@ -333,8 +370,8 @@ PortalStart(Portal portal, ParamListInfo params)
case PORTAL_UTIL_SELECT:
/*
- * We don't set query snapshot here, because
- * PortalRunUtility will take care of it.
+ * We don't set snapshot here, because
+ * PortalRunUtility will take care of it if needed.
*/
portal->tupDesc =
UtilityTupleDescriptor(((Query *) linitial(portal->parseTrees))->utilityStmt);
@@ -361,6 +398,7 @@ PortalStart(Portal portal, ParamListInfo params)
/* Restore global vars and propagate error */
ActivePortal = saveActivePortal;
+ ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
@@ -371,6 +409,7 @@ PortalStart(Portal portal, ParamListInfo params)
MemoryContextSwitchTo(oldContext);
ActivePortal = saveActivePortal;
+ ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
@@ -453,6 +492,7 @@ PortalRun(Portal portal, long count,
{
bool result;
Portal saveActivePortal;
+ Snapshot saveActiveSnapshot;
ResourceOwner saveResourceOwner;
MemoryContext savePortalContext;
MemoryContext saveQueryContext;
@@ -485,12 +525,14 @@ PortalRun(Portal portal, long count,
* Set up global portal context pointers.
*/
saveActivePortal = ActivePortal;
+ saveActiveSnapshot = ActiveSnapshot;
saveResourceOwner = CurrentResourceOwner;
savePortalContext = PortalContext;
saveQueryContext = QueryContext;
PG_TRY();
{
ActivePortal = portal;
+ ActiveSnapshot = NULL; /* will be set later */
CurrentResourceOwner = portal->resowner;
PortalContext = PortalGetHeapMemory(portal);
QueryContext = portal->queryContext;
@@ -579,6 +621,7 @@ PortalRun(Portal portal, long count,
/* Restore global vars and propagate error */
ActivePortal = saveActivePortal;
+ ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
QueryContext = saveQueryContext;
@@ -590,6 +633,7 @@ PortalRun(Portal portal, long count,
MemoryContextSwitchTo(oldContext);
ActivePortal = saveActivePortal;
+ ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
QueryContext = saveQueryContext;
@@ -670,6 +714,7 @@ PortalRunSelect(Portal portal,
nprocessed = RunFromStore(portal, direction, count, dest);
else
{
+ ActiveSnapshot = queryDesc->snapshot;
ExecutorRun(queryDesc, direction, count);
nprocessed = queryDesc->estate->es_processed;
}
@@ -711,6 +756,7 @@ PortalRunSelect(Portal portal,
nprocessed = RunFromStore(portal, direction, count, dest);
else
{
+ ActiveSnapshot = queryDesc->snapshot;
ExecutorRun(queryDesc, direction, count);
nprocessed = queryDesc->estate->es_processed;
}
@@ -834,6 +880,9 @@ PortalRunUtility(Portal portal, Query *query,
* the database --- if, say, it has to update an index with
* expressions that invoke user-defined functions, then it had better
* have a snapshot.
+ *
+ * Note we assume that caller will take care of restoring ActiveSnapshot
+ * on exit/error.
*/
if (!(IsA(utilityStmt, TransactionStmt) ||
IsA(utilityStmt, LockStmt) ||
@@ -847,7 +896,9 @@ PortalRunUtility(Portal portal, Query *query,
IsA(utilityStmt, NotifyStmt) ||
IsA(utilityStmt, UnlistenStmt) ||
IsA(utilityStmt, CheckPointStmt)))
- SetQuerySnapshot();
+ ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
+ else
+ ActiveSnapshot = NULL;
if (query->canSetTag)
{
@@ -864,6 +915,10 @@ PortalRunUtility(Portal portal, Query *query,
/* Some utility statements may change context on us */
MemoryContextSwitchTo(PortalGetHeapMemory(portal));
+
+ if (ActiveSnapshot)
+ FreeSnapshot(ActiveSnapshot);
+ ActiveSnapshot = NULL;
}
/*
@@ -924,15 +979,6 @@ PortalRunMulti(Portal portal,
/*
* process a plannable query.
*/
- ereport(DEBUG3,
- (errmsg_internal("ProcessQuery")));
-
- /* Must always set snapshot for plannable queries */
- SetQuerySnapshot();
-
- /*
- * execute the plan
- */
if (log_executor_stats)
ResetUsage();
@@ -1005,6 +1051,7 @@ PortalRunFetch(Portal portal,
{
long result;
Portal saveActivePortal;
+ Snapshot saveActiveSnapshot;
ResourceOwner saveResourceOwner;
MemoryContext savePortalContext;
MemoryContext saveQueryContext;
@@ -1025,12 +1072,14 @@ PortalRunFetch(Portal portal,
* Set up global portal context pointers.
*/
saveActivePortal = ActivePortal;
+ saveActiveSnapshot = ActiveSnapshot;
saveResourceOwner = CurrentResourceOwner;
savePortalContext = PortalContext;
saveQueryContext = QueryContext;
PG_TRY();
{
ActivePortal = portal;
+ ActiveSnapshot = NULL; /* will be set later */
CurrentResourceOwner = portal->resowner;
PortalContext = PortalGetHeapMemory(portal);
QueryContext = portal->queryContext;
@@ -1056,6 +1105,7 @@ PortalRunFetch(Portal portal,
/* Restore global vars and propagate error */
ActivePortal = saveActivePortal;
+ ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
QueryContext = saveQueryContext;
@@ -1070,6 +1120,7 @@ PortalRunFetch(Portal portal,
portal->status = PORTAL_READY;
ActivePortal = saveActivePortal;
+ ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
QueryContext = saveQueryContext;
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 6aec17bf9a5..d44e986e3c1 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.229 2004/09/10 18:40:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.230 2004/09/13 20:07:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -222,6 +222,46 @@ CheckRelationOwnership(RangeVar *rel, bool noCatalogs)
}
+/*
+ * QueryIsReadOnly: is an analyzed/rewritten query read-only?
+ *
+ * This is a much stricter test than we apply for XactReadOnly mode;
+ * the query must be *in truth* read-only, because the caller wishes
+ * not to do CommandCounterIncrement for it.
+ */
+bool
+QueryIsReadOnly(Query *parsetree)
+{
+ switch (parsetree->commandType)
+ {
+ case CMD_SELECT:
+ if (parsetree->into != NULL)
+ return false; /* SELECT INTO */
+ else if (parsetree->rowMarks != NIL)
+ return false; /* SELECT FOR UPDATE */
+ else
+ return true;
+ case CMD_UPDATE:
+ case CMD_INSERT:
+ case CMD_DELETE:
+ return false;
+ case CMD_UTILITY:
+ /* For now, treat all utility commands as read/write */
+ return false;
+ default:
+ elog(WARNING, "unrecognized commandType: %d",
+ (int) parsetree->commandType);
+ break;
+ }
+ return false;
+}
+
+/*
+ * check_xact_readonly: is a utility command read-only?
+ *
+ * Here we use the loose rules of XactReadOnly mode: no permanent effects
+ * on the database are allowed.
+ */
static void
check_xact_readonly(Node *parsetree)
{
@@ -299,8 +339,7 @@ check_xact_readonly(Node *parsetree)
* completionTag: points to a buffer of size COMPLETION_TAG_BUFSIZE
* in which to store a command completion status string.
*
- * completionTag is only set nonempty if we want to return a nondefault
- * status (currently, only used for MOVE/FETCH).
+ * completionTag is only set nonempty if we want to return a nondefault status.
*
* completionTag may be NULL if caller doesn't want a status string.
*/
@@ -1586,3 +1625,51 @@ CreateCommandTag(Node *parsetree)
return tag;
}
+
+/*
+ * CreateQueryTag
+ * utility to get a string representation of a Query operation.
+ *
+ * This is exactly like CreateCommandTag, except it works on a Query
+ * that has already been through parse analysis (and possibly further).
+ */
+const char *
+CreateQueryTag(Query *parsetree)
+{
+ const char *tag;
+
+ switch (parsetree->commandType)
+ {
+ case CMD_SELECT:
+ /*
+ * We take a little extra care here so that the result will
+ * be useful for complaints about read-only statements
+ */
+ if (parsetree->into != NULL)
+ tag = "SELECT INTO";
+ else if (parsetree->rowMarks != NIL)
+ tag = "SELECT FOR UPDATE";
+ else
+ tag = "SELECT";
+ break;
+ case CMD_UPDATE:
+ tag = "UPDATE";
+ break;
+ case CMD_INSERT:
+ tag = "INSERT";
+ break;
+ case CMD_DELETE:
+ tag = "DELETE";
+ break;
+ case CMD_UTILITY:
+ tag = CreateCommandTag(parsetree->utilityStmt);
+ break;
+ default:
+ elog(WARNING, "unrecognized commandType: %d",
+ (int) parsetree->commandType);
+ tag = "???";
+ break;
+ }
+
+ return tag;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-08-07 13:00:20 +0000