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Fix failure to ensure that a snapshot is available to datatype input functions

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when they are invoked by the parser.  We had been setting up a snapshot at
plan time but really it needs to be done earlier, before parse analysis.
Per report from Dmitry Koterov.

Also fix two related problems discovered while poking at this one:
exec_bind_message called datatype input functions without establishing a
snapshot, and SET CONSTRAINTS IMMEDIATE could call trigger functions without
establishing a snapshot.

Backpatch to 8.2.  The underlying problem goes much further back, but it is
masked in 8.1 and before because we didn't attempt to invoke domain check
constraints within datatype input.  It would only be exposed if a C-language
datatype input function used the snapshot; which evidently none do, or we'd
have heard complaints sooner.  Since this code has changed a lot over time,
a back-patch is hardly risk-free, and so I'm disinclined to patch further
than absolutely necessary.
This commit is contained in:
Tom Lane
2008-12-13 02:00:20 +00:00
parent 0f864a63ea
commit c98a923786
5 changed files with 145 additions and 14 deletions
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57
src/backend/tcop/postgres.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.560 2008/12/09 15:59:39 heikki Exp $
* $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.561 2008/12/13 02:00:19 tgl Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
@@ -685,6 +685,9 @@ pg_plan_query(Query *querytree, int cursorOptions, ParamListInfo boundParams)
if (querytree->commandType == CMD_UTILITY)
return NULL;
/* Planner must have a snapshot in case it calls user-defined functions. */
Assert(ActiveSnapshotSet());
TRACE_POSTGRESQL_QUERY_PLAN_START();
if (log_planner_stats)
@@ -872,6 +875,7 @@ exec_simple_query(const char *query_string)
foreach(parsetree_item, parsetree_list)
{
Node *parsetree = (Node *) lfirst(parsetree_item);
bool snapshot_set = false;
const char *commandTag;
char completionTag[COMPLETION_TAG_BUFSIZE];
List *querytree_list,
@@ -913,6 +917,15 @@ exec_simple_query(const char *query_string)
/* If we got a cancel signal in parsing or prior command, quit */
CHECK_FOR_INTERRUPTS();
/*
* Set up a snapshot if parse analysis/planning will need one.
*/
if (analyze_requires_snapshot(parsetree))
{
PushActiveSnapshot(GetTransactionSnapshot());
snapshot_set = true;
}
/*
* OK to analyze, rewrite, and plan this query.
*
@@ -924,7 +937,11 @@ exec_simple_query(const char *query_string)
querytree_list = pg_analyze_and_rewrite(parsetree, query_string,
NULL, 0);
plantree_list = pg_plan_queries(querytree_list, 0, NULL, true);
plantree_list = pg_plan_queries(querytree_list, 0, NULL, false);
/* Done with the snapshot used for parsing/planning */
if (snapshot_set)
PopActiveSnapshot();
/* If we got a cancel signal in analysis or planning, quit */
CHECK_FOR_INTERRUPTS();
@@ -939,7 +956,7 @@ exec_simple_query(const char *query_string)
/*
* We don't have to copy anything into the portal, because everything
* we are passsing here is in MessageContext, which will outlive the
* we are passing here is in MessageContext, which will outlive the
* portal anyway.
*/
PortalDefineQuery(portal,
@@ -1178,6 +1195,7 @@ exec_parse_message(const char *query_string, /* string to execute */
if (parsetree_list != NIL)
{
Query *query;
bool snapshot_set = false;
int i;
raw_parse_tree = (Node *) linitial(parsetree_list);
@@ -1202,6 +1220,15 @@ exec_parse_message(const char *query_string, /* string to execute */
errmsg("current transaction is aborted, "
"commands ignored until end of transaction block")));
/*
* Set up a snapshot if parse analysis/planning will need one.
*/
if (analyze_requires_snapshot(raw_parse_tree))
{
PushActiveSnapshot(GetTransactionSnapshot());
snapshot_set = true;
}
/*
* OK to analyze, rewrite, and plan this query. Note that the
* originally specified parameter set is not required to be complete,
@@ -1249,9 +1276,13 @@ exec_parse_message(const char *query_string, /* string to execute */
}
else
{
stmt_list = pg_plan_queries(querytree_list, 0, NULL, true);
stmt_list = pg_plan_queries(querytree_list, 0, NULL, false);
fully_planned = true;
}
/* Done with the snapshot used for parsing/planning */
if (snapshot_set)
PopActiveSnapshot();
}
else
{
@@ -1375,6 +1406,7 @@ exec_bind_message(StringInfo input_message)
List *plan_list;
MemoryContext oldContext;
bool save_log_statement_stats = log_statement_stats;
bool snapshot_set = false;
char msec_str[32];
/* Get the fixed part of the message */
@@ -1494,6 +1526,17 @@ exec_bind_message(StringInfo input_message)
else
saved_stmt_name = NULL;
/*
* Set a snapshot if we have parameters to fetch (since the input
* functions might need it) or the query isn't a utility command (and
* hence could require redoing parse analysis and planning).
*/
if (numParams > 0 || analyze_requires_snapshot(psrc->raw_parse_tree))
{
PushActiveSnapshot(GetTransactionSnapshot());
snapshot_set = true;
}
/*
* Fetch parameters, if any, and store in the portal's memory context.
*/
@@ -1682,7 +1725,7 @@ exec_bind_message(StringInfo input_message)
*/
oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
query_list = copyObject(cplan->stmt_list);
plan_list = pg_plan_queries(query_list, 0, params, true);
plan_list = pg_plan_queries(query_list, 0, params, false);
MemoryContextSwitchTo(oldContext);
/* We no longer need the cached plan refcount ... */
@@ -1691,6 +1734,10 @@ exec_bind_message(StringInfo input_message)
cplan = NULL;
}
/* Done with the snapshot used for parameter I/O and parsing/planning */
if (snapshot_set)
PopActiveSnapshot();
/*
* Define portal and start execution.
*/