Robert Haas <robertmh...@gmail.com> writes:
> On Wed, Jan 23, 2013 at 11:40 AM, Tom Lane <t...@sss.pgh.pa.us> wrote:
>> Your point that the locking code doesn't quite cope with newly-masked
>> objects makes me feel that we could get away with not solving the case
>> for plan caching either. Or at least that we could put off the problem
>> till another day. If we are willing to just change plancache's handling
>> of search_path, that's a small patch that I think is easily doable for
>> 9.3. If we insist on installing schema-level invalidation logic, it's
>> not happening before 9.4.
> I agree with that analysis. FWIW, I am pretty confident that the
> narrower fix will make quite a few people significantly happier than
> they are today, so if you're willing to take that on, +1 from me. I
> believe the search-path-interpolation problem is a sufficiently
> uncommon case that, in practice, it rarely comes up. That's not to
> say that we shouldn't ever fix it, but I think the simpler fix will be
> a 90% solution and people will be happy to have made that much
> progress this cycle.
Here's a draft patch for that. I've not looked yet to see if there's
any documentation that ought to be touched.
With this patch, PushOverrideSearchPath/PopOverrideSearchPath are used
in only one place: CreateSchemaCommand. And that's a very simple,
stylized usage: temporarily push the new schema onto the front of the
path. It's tempting to think about replacing that klugy code with some
simpler mechanism. But that sort of cleanup should probably be a
separate patch.
regards, tom lane
diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index b256498d4511add3f55c35f07fecf6a92f19e763..ca4635dc51f41b050521d65cd601bccab90b6726 100644
*** a/src/backend/catalog/namespace.c
--- b/src/backend/catalog/namespace.c
*************** CopyOverrideSearchPath(OverrideSearchPat
*** 3097,3102 ****
--- 3097,3124 ----
}
/*
+ * OverrideSearchPathMatchesCurrent - does path match current setting?
+ */
+ bool
+ OverrideSearchPathMatchesCurrent(OverrideSearchPath *path)
+ {
+ /* Easiest way to do this is GetOverrideSearchPath() and compare */
+ bool result;
+ OverrideSearchPath *cur;
+
+ cur = GetOverrideSearchPath(CurrentMemoryContext);
+ if (path->addCatalog == cur->addCatalog &&
+ path->addTemp == cur->addTemp &&
+ equal(path->schemas, cur->schemas))
+ result = true;
+ else
+ result = false;
+ list_free(cur->schemas);
+ pfree(cur);
+ return result;
+ }
+
+ /*
* PushOverrideSearchPath - temporarily override the search path
*
* We allow nested overrides, hence the push/pop terminology. The GUC
diff --git a/src/backend/utils/cache/plancache.c b/src/backend/utils/cache/plancache.c
index cbc7c498d0d533b149fe4395992d9910a2d6b5cd..4630c44e7407c98a2de2df7bafc2753e78bfcfc6 100644
*** a/src/backend/utils/cache/plancache.c
--- b/src/backend/utils/cache/plancache.c
***************
*** 15,27 ****
* that matches the event is marked invalid, as is its generic CachedPlan
* if it has one. When (and if) the next demand for a cached plan occurs,
* parse analysis and rewrite is repeated to build a new valid query tree,
! * and then planning is performed as normal.
*
* Note that if the sinval was a result of user DDL actions, parse analysis
* could throw an error, for example if a column referenced by the query is
! * no longer present. The creator of a cached plan can specify whether it
! * is allowable for the query to change output tupdesc on replan (this
! * could happen with "SELECT *" for example) --- if so, it's up to the
* caller to notice changes and cope with them.
*
* Currently, we track exactly the dependencies of plans on relations and
--- 15,29 ----
* that matches the event is marked invalid, as is its generic CachedPlan
* if it has one. When (and if) the next demand for a cached plan occurs,
* parse analysis and rewrite is repeated to build a new valid query tree,
! * and then planning is performed as normal. We also force re-analysis and
! * re-planning if the active search_path is different from the previous time.
*
* Note that if the sinval was a result of user DDL actions, parse analysis
* could throw an error, for example if a column referenced by the query is
! * no longer present. Another possibility is for the query's output tupdesc
! * to change (for instance "SELECT *" might expand differently than before).
! * The creator of a cached plan can specify whether it is allowable for the
! * query to change output tupdesc on replan --- if so, it's up to the
* caller to notice changes and cope with them.
*
* Currently, we track exactly the dependencies of plans on relations and
*************** CreateCachedPlan(Node *raw_parse_tree,
*** 174,184 ****
plansource->cursor_options = 0;
plansource->fixed_result = false;
plansource->resultDesc = NULL;
- plansource->search_path = NULL;
plansource->context = source_context;
plansource->query_list = NIL;
plansource->relationOids = NIL;
plansource->invalItems = NIL;
plansource->query_context = NULL;
plansource->gplan = NULL;
plansource->is_oneshot = false;
--- 176,186 ----
plansource->cursor_options = 0;
plansource->fixed_result = false;
plansource->resultDesc = NULL;
plansource->context = source_context;
plansource->query_list = NIL;
plansource->relationOids = NIL;
plansource->invalItems = NIL;
+ plansource->search_path = NULL;
plansource->query_context = NULL;
plansource->gplan = NULL;
plansource->is_oneshot = false;
*************** CreateOneShotCachedPlan(Node *raw_parse_
*** 239,249 ****
plansource->cursor_options = 0;
plansource->fixed_result = false;
plansource->resultDesc = NULL;
- plansource->search_path = NULL;
plansource->context = CurrentMemoryContext;
plansource->query_list = NIL;
plansource->relationOids = NIL;
plansource->invalItems = NIL;
plansource->query_context = NULL;
plansource->gplan = NULL;
plansource->is_oneshot = true;
--- 241,251 ----
plansource->cursor_options = 0;
plansource->fixed_result = false;
plansource->resultDesc = NULL;
plansource->context = CurrentMemoryContext;
plansource->query_list = NIL;
plansource->relationOids = NIL;
plansource->invalItems = NIL;
+ plansource->search_path = NULL;
plansource->query_context = NULL;
plansource->gplan = NULL;
plansource->is_oneshot = true;
*************** CompleteCachedPlan(CachedPlanSource *pla
*** 361,366 ****
--- 363,376 ----
&plansource->invalItems);
/*
+ * Also save the current search_path in the query_context. (This should
+ * not generate much extra cruft either, since almost certainly the path
+ * is already valid.) Again, don't really need it for one-shot plans.
+ */
+ if (!plansource->is_oneshot)
+ plansource->search_path = GetOverrideSearchPath(querytree_context);
+
+ /*
* Save the final parameter types (or other parameter specification data)
* into the source_context, as well as our other parameters. Also save
* the result tuple descriptor.
*************** CompleteCachedPlan(CachedPlanSource *pla
*** 383,394 ****
MemoryContextSwitchTo(oldcxt);
- /*
- * Fetch current search_path into dedicated context, but do any
- * recalculation work required in caller's context.
- */
- plansource->search_path = GetOverrideSearchPath(source_context);
-
plansource->is_complete = true;
plansource->is_valid = true;
}
--- 393,398 ----
*************** RevalidateCachedQuery(CachedPlanSource *
*** 547,552 ****
--- 551,573 ----
}
/*
+ * If the query is currently valid, we should have a saved search_path ---
+ * check to see if that matches the current environment. If not, we want
+ * to force replan.
+ */
+ if (plansource->is_valid)
+ {
+ Assert(plansource->search_path != NULL);
+ if (!OverrideSearchPathMatchesCurrent(plansource->search_path))
+ {
+ /* Invalidate the querytree and generic plan */
+ plansource->is_valid = false;
+ if (plansource->gplan)
+ plansource->gplan->is_valid = false;
+ }
+ }
+
+ /*
* If the query is currently valid, acquire locks on the referenced
* objects; then check again. We need to do it this way to cover the race
* condition that an invalidation message arrives before we get the locks.
*************** RevalidateCachedQuery(CachedPlanSource *
*** 578,583 ****
--- 599,605 ----
plansource->query_list = NIL;
plansource->relationOids = NIL;
plansource->invalItems = NIL;
+ plansource->search_path = NULL;
/*
* Free the query_context. We don't really expect MemoryContextDelete to
*************** RevalidateCachedQuery(CachedPlanSource *
*** 603,616 ****
Assert(plansource->is_complete);
/*
- * Restore the search_path that was in use when the plan was made. See
- * comments for PushOverrideSearchPath about limitations of this.
- *
- * (XXX is there anything else we really need to restore?)
- */
- PushOverrideSearchPath(plansource->search_path);
-
- /*
* If a snapshot is already set (the normal case), we can just use that
* for parsing/planning. But if it isn't, install one. Note: no point in
* checking whether parse analysis requires a snapshot; utility commands
--- 625,630 ----
*************** RevalidateCachedQuery(CachedPlanSource *
*** 645,653 ****
if (snapshot_set)
PopActiveSnapshot();
- /* Now we can restore current search path */
- PopOverrideSearchPath();
-
/*
* Check or update the result tupdesc. XXX should we use a weaker
* condition than equalTupleDescs() here?
--- 659,664 ----
*************** RevalidateCachedQuery(CachedPlanSource *
*** 699,704 ****
--- 710,722 ----
&plansource->relationOids,
&plansource->invalItems);
+ /*
+ * Also save the current search_path in the query_context. (This should
+ * not generate much extra cruft either, since almost certainly the path
+ * is already valid.)
+ */
+ plansource->search_path = GetOverrideSearchPath(querytree_context);
+
MemoryContextSwitchTo(oldcxt);
/* Now reparent the finished query_context and save the links */
*************** BuildCachedPlan(CachedPlanSource *planso
*** 849,868 ****
}
/*
- * Restore the search_path that was in use when the plan was made. See
- * comments for PushOverrideSearchPath about limitations of this.
- *
- * (XXX is there anything else we really need to restore?)
- *
- * Note: it's a bit annoying to do this and snapshot-setting twice in the
- * case where we have to do both re-analysis and re-planning. However,
- * until there's some evidence that the cost is actually meaningful
- * compared to parse analysis + planning, I'm not going to contort the
- * code enough to avoid that.
- */
- PushOverrideSearchPath(plansource->search_path);
-
- /*
* If a snapshot is already set (the normal case), we can just use that
* for planning. But if it isn't, and we need one, install one.
*/
--- 867,872 ----
*************** BuildCachedPlan(CachedPlanSource *planso
*** 894,902 ****
if (snapshot_set)
PopActiveSnapshot();
- /* Now we can restore current search path */
- PopOverrideSearchPath();
-
/*
* Normally we make a dedicated memory context for the CachedPlan and its
* subsidiary data. (It's probably not going to be large, but just in
--- 898,903 ----
*************** CopyCachedPlan(CachedPlanSource *plansou
*** 1268,1274 ****
newsource->resultDesc = CreateTupleDescCopy(plansource->resultDesc);
else
newsource->resultDesc = NULL;
- newsource->search_path = CopyOverrideSearchPath(plansource->search_path);
newsource->context = source_context;
querytree_context = AllocSetContextCreate(source_context,
--- 1269,1274 ----
*************** CopyCachedPlan(CachedPlanSource *plansou
*** 1280,1285 ****
--- 1280,1287 ----
newsource->query_list = (List *) copyObject(plansource->query_list);
newsource->relationOids = (List *) copyObject(plansource->relationOids);
newsource->invalItems = (List *) copyObject(plansource->invalItems);
+ if (plansource->search_path)
+ newsource->search_path = CopyOverrideSearchPath(plansource->search_path);
newsource->query_context = querytree_context;
newsource->gplan = NULL;
diff --git a/src/include/catalog/namespace.h b/src/include/catalog/namespace.h
index af82072edb7e90f243b0976337ae7d68fd2b9ce8..c37df8686ea2e835145d1de4b9ba358014b3a4f2 100644
*** a/src/include/catalog/namespace.h
--- b/src/include/catalog/namespace.h
*************** extern void ResetTempTableNamespace(void
*** 128,133 ****
--- 128,134 ----
extern OverrideSearchPath *GetOverrideSearchPath(MemoryContext context);
extern OverrideSearchPath *CopyOverrideSearchPath(OverrideSearchPath *path);
+ extern bool OverrideSearchPathMatchesCurrent(OverrideSearchPath *path);
extern void PushOverrideSearchPath(OverrideSearchPath *newpath);
extern void PopOverrideSearchPath(void);
diff --git a/src/include/utils/plancache.h b/src/include/utils/plancache.h
index 8185427fc4b28ca3caca33f1d177439d626f708e..abaf9dc59c763b4b39978a49b52d5c85c19ed732 100644
*** a/src/include/utils/plancache.h
--- b/src/include/utils/plancache.h
*************** typedef struct CachedPlanSource
*** 86,97 ****
int cursor_options; /* cursor options used for planning */
bool fixed_result; /* disallow change in result tupdesc? */
TupleDesc resultDesc; /* result type; NULL = doesn't return tuples */
- struct OverrideSearchPath *search_path; /* saved search_path */
MemoryContext context; /* memory context holding all above */
/* These fields describe the current analyzed-and-rewritten query tree: */
List *query_list; /* list of Query nodes, or NIL if not valid */
List *relationOids; /* OIDs of relations the queries depend on */
List *invalItems; /* other dependencies, as PlanInvalItems */
MemoryContext query_context; /* context holding the above, or NULL */
/* If we have a generic plan, this is a reference-counted link to it: */
struct CachedPlan *gplan; /* generic plan, or NULL if not valid */
--- 86,98 ----
int cursor_options; /* cursor options used for planning */
bool fixed_result; /* disallow change in result tupdesc? */
TupleDesc resultDesc; /* result type; NULL = doesn't return tuples */
MemoryContext context; /* memory context holding all above */
/* These fields describe the current analyzed-and-rewritten query tree: */
List *query_list; /* list of Query nodes, or NIL if not valid */
List *relationOids; /* OIDs of relations the queries depend on */
List *invalItems; /* other dependencies, as PlanInvalItems */
+ struct OverrideSearchPath *search_path; /* search_path used for
+ * parsing and planning */
MemoryContext query_context; /* context holding the above, or NULL */
/* If we have a generic plan, this is a reference-counted link to it: */
struct CachedPlan *gplan; /* generic plan, or NULL if not valid */
diff --git a/src/test/regress/expected/plancache.out b/src/test/regress/expected/plancache.out
index f0aa102334be6dce39c58ecd0135792e0ea46c90..864f70f7b54e7dbb021296f5213f023d53201dd0 100644
*** a/src/test/regress/expected/plancache.out
--- b/src/test/regress/expected/plancache.out
*************** select cache_test_2();
*** 163,169 ****
10007
(1 row)
! --- Check that change of search_path is ignored by replans
create schema s1
create table abc (f1 int);
create schema s2
--- 163,169 ----
10007
(1 row)
! --- Check that change of search_path is honored when re-using cached plan
create schema s1
create table abc (f1 int);
create schema s2
*************** select f1 from abc;
*** 188,201 ****
execute p1;
f1
-----
! 123
(1 row)
alter table s1.abc add column f2 float8; -- force replan
execute p1;
f1
-----
! 123
(1 row)
drop schema s1 cascade;
--- 188,201 ----
execute p1;
f1
-----
! 456
(1 row)
alter table s1.abc add column f2 float8; -- force replan
execute p1;
f1
-----
! 456
(1 row)
drop schema s1 cascade;
diff --git a/src/test/regress/sql/plancache.sql b/src/test/regress/sql/plancache.sql
index 26848168f0631c1f423d32305e2a7d4d273428b0..bc2086166b985d7a3886d2899862443edee928bd 100644
*** a/src/test/regress/sql/plancache.sql
--- b/src/test/regress/sql/plancache.sql
*************** create or replace temp view v1 as
*** 94,100 ****
select 2+2+4+(select max(unique1) from tenk1) as f1;
select cache_test_2();
! --- Check that change of search_path is ignored by replans
create schema s1
create table abc (f1 int);
--- 94,100 ----
select 2+2+4+(select max(unique1) from tenk1) as f1;
select cache_test_2();
! --- Check that change of search_path is honored when re-using cached plan
create schema s1
create table abc (f1 int);
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