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Fix PARAM_EXEC assignment mechanism to be safe in the presence of WITH.

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The planner previously assumed that parameter Vars having the same absolute
query level, varno, and varattno could safely be assigned the same runtime
PARAM_EXEC slot, even though they might be different Vars appearing in
different subqueries.  This was (probably) safe before the introduction of
CTEs, but the lazy-evalution mechanism used for CTEs means that a CTE can
be executed during execution of some other subquery, causing the lifespan
of Params at the same syntactic nesting level as the CTE to overlap with
use of the same slots inside the CTE.  In 9.1 we created additional hazards
by using the same parameter-assignment technology for nestloop inner scan
parameters, but it was broken before that, as illustrated by the added
regression test.

To fix, restructure the planner's management of PlannerParamItems so that
items having different semantic lifespans are kept rigorously separated.
This will probably result in complex queries using more runtime PARAM_EXEC
slots than before, but the slots are cheap enough that this hardly matters.
Also, stop generating PlannerParamItems containing Params for subquery
outputs: all we really need to do is reserve the PARAM_EXEC slot number,
and that now only takes incrementing a counter.  The planning code is
simpler and probably faster than before, as well as being more correct.

Per report from Vik Reykja.

Back-patch of commit 46c508fbcf into all
branches that support WITH.
This commit is contained in:
Tom Lane
2012-09-07 20:38:42 -04:00
parent 83f2584f15
commit 25b6df1e35
9 changed files with 220 additions and 152 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
src/backend/optimizer/path/allpaths.c
View File

@ -626,6 +626,9 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
else
tuple_fraction = root->tuple_fraction;
/* plan_params should not be in use in current query level */
Assert(root->plan_params == NIL);
/* Generate the plan for the subquery */
rel->subplan = subquery_planner(root->glob, subquery,
root,
@ -634,6 +637,13 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
rel->subrtable = subroot->parse->rtable;
rel->subrowmark = subroot->rowMarks;
/*
* Since we don't yet support LATERAL, it should not be possible for the
* sub-query to have requested parameters of this level.
*/
if (root->plan_params)
elog(ERROR, "unexpected outer reference in subquery in FROM");
/* Copy number of output rows from subplan */
rel->tuples = rel->subplan->plan_rows;

7
src/backend/optimizer/plan/planner.c
View File

@ -155,7 +155,6 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
glob = makeNode(PlannerGlobal);
glob->boundParams = boundParams;
glob->paramlist = NIL;
glob->subplans = NIL;
glob->subrtables = NIL;
glob->subrowmarks = NIL;
@ -164,6 +163,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
glob->finalrowmarks = NIL;
glob->relationOids = NIL;
glob->invalItems = NIL;
glob->nParamExec = 0;
glob->lastPHId = 0;
glob->lastRowMarkId = 0;
glob->transientPlan = false;
@ -250,7 +250,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
result->rowMarks = glob->finalrowmarks;
result->relationOids = glob->relationOids;
result->invalItems = glob->invalItems;
result->nParamExec = list_length(glob->paramlist);
result->nParamExec = glob->nParamExec;
return result;
}
@ -302,6 +302,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
root->glob = glob;
root->query_level = parent_root ? parent_root->query_level + 1 : 1;
root->parent_root = parent_root;
root->plan_params = NIL;
root->planner_cxt = CurrentMemoryContext;
root->init_plans = NIL;
root->cte_plan_ids = NIL;
@ -575,7 +576,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
* and attach the initPlans to the top plan node.
*/
if (list_length(glob->subplans) != num_old_subplans ||
root->glob->paramlist != NIL)
root->glob->nParamExec > 0)
SS_finalize_plan(root, plan, true);
/* Return internal info if caller wants it */

253
src/backend/optimizer/plan/subselect.c
View File

@ -55,6 +55,7 @@ typedef struct finalize_primnode_context
static Node *build_subplan(PlannerInfo *root, Plan *plan,
List *rtable, List *rowmarks,
List *plan_params,
SubLinkType subLinkType, Node *testexpr,
bool adjust_testexpr, bool unknownEqFalse);
static List *generate_subquery_params(PlannerInfo *root, List *tlist,
@ -92,36 +93,34 @@ replace_outer_var(PlannerInfo *root, Var *var)
Param *retval;
ListCell *ppl;
PlannerParamItem *pitem;
Index abslevel;
int i;
Index levelsup;
Assert(var->varlevelsup > 0 && var->varlevelsup < root->query_level);
abslevel = root->query_level - var->varlevelsup;
/*
* If there's already a paramlist entry for this same Var, just use it.
* NOTE: in sufficiently complex querytrees, it is possible for the same
* varno/abslevel to refer to different RTEs in different parts of the
* parsetree, so that different fields might end up sharing the same Param
* number. As long as we check the vartype/typmod as well, I believe that
* this sort of aliasing will cause no trouble. The correct field should
* get stored into the Param slot at execution in each part of the tree.
*/
i = 0;
foreach(ppl, root->glob->paramlist)
/* Find the query level the Var belongs to */
for (levelsup = var->varlevelsup; levelsup > 0; levelsup--)
root = root->parent_root;
/* If there's already a matching PlannerParamItem there, just use it */
foreach(ppl, root->plan_params)
{
pitem = (PlannerParamItem *) lfirst(ppl);
if (pitem->abslevel == abslevel && IsA(pitem->item, Var))
if (IsA(pitem->item, Var))
{
Var *pvar = (Var *) pitem->item;
/*
* This comparison must match _equalVar(), except for ignoring
* varlevelsup. Note that _equalVar() ignores the location.
*/
if (pvar->varno == var->varno &&
pvar->varattno == var->varattno &&
pvar->vartype == var->vartype &&
pvar->vartypmod == var->vartypmod)
pvar->vartypmod == var->vartypmod &&
pvar->varnoold == var->varnoold &&
pvar->varoattno == var->varoattno)
break;
}
i++;
}
if (!ppl)
@ -132,18 +131,17 @@ replace_outer_var(PlannerInfo *root, Var *var)
pitem = makeNode(PlannerParamItem);
pitem->item = (Node *) var;
pitem->abslevel = abslevel;
pitem->paramId = root->glob->nParamExec++;
root->glob->paramlist = lappend(root->glob->paramlist, pitem);
/* i is already the correct index for the new item */
root->plan_params = lappend(root->plan_params, pitem);
}
retval = makeNode(Param);
retval->paramkind = PARAM_EXEC;
retval->paramid = i;
retval->paramid = pitem->paramId;
retval->paramtype = var->vartype;
retval->paramtypmod = var->vartypmod;
retval->location = -1;
retval->location = var->location;
return retval;
}
@ -160,18 +158,19 @@ replace_outer_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv)
Param *retval;
ListCell *ppl;
PlannerParamItem *pitem;
Index abslevel;
int i;
Index levelsup;
Assert(phv->phlevelsup > 0 && phv->phlevelsup < root->query_level);
abslevel = root->query_level - phv->phlevelsup;
/* If there's already a paramlist entry for this same PHV, just use it */
i = 0;
foreach(ppl, root->glob->paramlist)
/* Find the query level the PHV belongs to */
for (levelsup = phv->phlevelsup; levelsup > 0; levelsup--)
root = root->parent_root;
/* If there's already a matching PlannerParamItem there, just use it */
foreach(ppl, root->plan_params)
{
pitem = (PlannerParamItem *) lfirst(ppl);
if (pitem->abslevel == abslevel && IsA(pitem->item, PlaceHolderVar))
if (IsA(pitem->item, PlaceHolderVar))
{
PlaceHolderVar *pphv = (PlaceHolderVar *) pitem->item;
@ -179,7 +178,6 @@ replace_outer_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv)
if (pphv->phid == phv->phid)
break;
}
i++;
}
if (!ppl)
@ -191,15 +189,14 @@ replace_outer_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv)
pitem = makeNode(PlannerParamItem);
pitem->item = (Node *) phv;
pitem->abslevel = abslevel;
pitem->paramId = root->glob->nParamExec++;
root->glob->paramlist = lappend(root->glob->paramlist, pitem);
/* i is already the correct index for the new item */
root->plan_params = lappend(root->plan_params, pitem);
}
retval = makeNode(Param);
retval->paramkind = PARAM_EXEC;
retval->paramid = i;
retval->paramid = pitem->paramId;
retval->paramtype = exprType((Node *) phv->phexpr);
retval->paramtypmod = exprTypmod((Node *) phv->phexpr);
retval->location = -1;
@ -216,11 +213,13 @@ replace_outer_agg(PlannerInfo *root, Aggref *agg)
{
Param *retval;
PlannerParamItem *pitem;
Index abslevel;
int i;
Index levelsup;
Assert(agg->agglevelsup > 0 && agg->agglevelsup < root->query_level);
abslevel = root->query_level - agg->agglevelsup;
/* Find the query level the Aggref belongs to */
for (levelsup = agg->agglevelsup; levelsup > 0; levelsup--)
root = root->parent_root;
/*
* It does not seem worthwhile to try to match duplicate outer aggs. Just
@ -232,17 +231,16 @@ replace_outer_agg(PlannerInfo *root, Aggref *agg)
pitem = makeNode(PlannerParamItem);
pitem->item = (Node *) agg;
pitem->abslevel = abslevel;
pitem->paramId = root->glob->nParamExec++;
root->glob->paramlist = lappend(root->glob->paramlist, pitem);
i = list_length(root->glob->paramlist) - 1;
root->plan_params = lappend(root->plan_params, pitem);
retval = makeNode(Param);
retval->paramkind = PARAM_EXEC;
retval->paramid = i;
retval->paramid = pitem->paramId;
retval->paramtype = agg->aggtype;
retval->paramtypmod = -1;
retval->location = -1;
retval->location = agg->location;
return retval;
}
@ -250,27 +248,22 @@ replace_outer_agg(PlannerInfo *root, Aggref *agg)
/*
* Generate a new Param node that will not conflict with any other.
*
* This is used to allocate PARAM_EXEC slots for subplan outputs.
* This is used to create Params representing subplan outputs.
* We don't need to build a PlannerParamItem for such a Param, but we do
* need to record the PARAM_EXEC slot number as being allocated.
*/
static Param *
generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod)
{
Param *retval;
PlannerParamItem *pitem;
retval = makeNode(Param);
retval->paramkind = PARAM_EXEC;
retval->paramid = list_length(root->glob->paramlist);
retval->paramid = root->glob->nParamExec++;
retval->paramtype = paramtype;
retval->paramtypmod = paramtypmod;
retval->location = -1;
pitem = makeNode(PlannerParamItem);
pitem->item = (Node *) retval;
pitem->abslevel = root->query_level;
root->glob->paramlist = lappend(root->glob->paramlist, pitem);
return retval;
}
@ -279,17 +272,13 @@ generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod)
* is not actually used to carry a value at runtime). Such parameters are
* used for special runtime signaling purposes, such as connecting a
* recursive union node to its worktable scan node or forcing plan
* re-evaluation within the EvalPlanQual mechanism.
* re-evaluation within the EvalPlanQual mechanism. No actual Param node
* exists with this ID, however.
*/
int
SS_assign_special_param(PlannerInfo *root)
{
Param *param;
/* We generate a Param of datatype INTERNAL */
param = generate_new_param(root, INTERNALOID, -1);
/* ... but the caller only cares about its ID */
return param->paramid;
return root->glob->nParamExec++;
}
/*
@ -346,6 +335,7 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
double tuple_fraction;
Plan *plan;
PlannerInfo *subroot;
List *plan_params;
Node *result;
/*
@ -389,6 +379,9 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
else
tuple_fraction = 0.0; /* default behavior */
/* plan_params should not be in use in current query level */
Assert(root->plan_params == NIL);
/*
* Generate the plan for the subquery.
*/
@ -397,9 +390,14 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
false, tuple_fraction,
&subroot);
/* Isolate the params needed by this specific subplan */
plan_params = root->plan_params;
root->plan_params = NIL;
/* And convert to SubPlan or InitPlan format. */
result = build_subplan(root, plan,
subroot->parse->rtable, subroot->rowMarks,
plan_params,
subLinkType, testexpr, true, isTopQual);
/*
@ -432,6 +430,10 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
false, 0.0,
&subroot);
/* Isolate the params needed by this specific subplan */
plan_params = root->plan_params;
root->plan_params = NIL;
/* Now we can check if it'll fit in work_mem */
if (subplan_is_hashable(plan))
{
@ -442,6 +444,7 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
hashplan = (SubPlan *) build_subplan(root, plan,
subroot->parse->rtable,
subroot->rowMarks,
plan_params,
ANY_SUBLINK, newtestexpr,
false, true);
/* Check we got what we expected */
@ -470,14 +473,14 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
*/
static Node *
build_subplan(PlannerInfo *root, Plan *plan, List *rtable, List *rowmarks,
List *plan_params,
SubLinkType subLinkType, Node *testexpr,
bool adjust_testexpr, bool unknownEqFalse)
{
Node *result;
SubPlan *splan;
bool isInitPlan;
Bitmapset *tmpset;
int paramid;
ListCell *lc;
/*
* Initialize the SubPlan node. Note plan_id, plan_name, and cost fields
@ -498,36 +501,26 @@ build_subplan(PlannerInfo *root, Plan *plan, List *rtable, List *rowmarks,
* Make parParam and args lists of param IDs and expressions that current
* query level will pass to this child plan.
*/
tmpset = bms_copy(plan->extParam);
while ((paramid = bms_first_member(tmpset)) >= 0)
foreach(lc, plan_params)
{
PlannerParamItem *pitem = list_nth(root->glob->paramlist, paramid);
PlannerParamItem *pitem = (PlannerParamItem *) lfirst(lc);
Node *arg = pitem->item;
if (pitem->abslevel == root->query_level)
{
Node *arg;
/*
* The Var, PlaceHolderVar, or Aggref has already been adjusted to
* have the correct varlevelsup, phlevelsup, or agglevelsup.
*
* If it's a PlaceHolderVar or Aggref, its arguments might contain
* SubLinks, which have not yet been processed (see the comments for
* SS_replace_correlation_vars). Do that now.
*/
if (IsA(arg, PlaceHolderVar) ||
IsA(arg, Aggref))
arg = SS_process_sublinks(root, arg, false);
/*
* The Var, PlaceHolderVar, or Aggref has already been adjusted to
* have the correct varlevelsup, phlevelsup, or agglevelsup. We
* probably don't even need to copy it again, but be safe.
*/
arg = copyObject(pitem->item);
/*
* If it's a PlaceHolderVar or Aggref, its arguments might contain
* SubLinks, which have not yet been processed (see the comments
* for SS_replace_correlation_vars). Do that now.
*/
if (IsA(arg, PlaceHolderVar) ||
IsA(arg, Aggref))
arg = SS_process_sublinks(root, arg, false);
splan->parParam = lappend_int(splan->parParam, paramid);
splan->args = lappend(splan->args, arg);
}
splan->parParam = lappend_int(splan->parParam, pitem->paramId);
splan->args = lappend(splan->args, arg);
}
bms_free(tmpset);
/*
* Un-correlated or undirect correlated plans of EXISTS, EXPR, ARRAY, or
@ -931,9 +924,7 @@ SS_process_ctes(PlannerInfo *root)
Plan *plan;
PlannerInfo *subroot;
SubPlan *splan;
Bitmapset *tmpset;
int paramid;
Param *prm;
/*
* Ignore CTEs that are not actually referenced anywhere.
@ -951,6 +942,9 @@ SS_process_ctes(PlannerInfo *root)
*/
subquery = (Query *) copyObject(cte->ctequery);
/* plan_params should not be in use in current query level */
Assert(root->plan_params == NIL);
/*
* Generate the plan for the CTE query. Always plan for full
* retrieval --- we don't have enough info to predict otherwise.
@ -960,6 +954,14 @@ SS_process_ctes(PlannerInfo *root)
cte->cterecursive, 0.0,
&subroot);
/*
* Since the current query level doesn't yet contain any RTEs, it
* should not be possible for the CTE to have requested parameters of
* this level.
*/
if (root->plan_params)
elog(ERROR, "unexpected outer reference in CTE query");
/*
* Make a SubPlan node for it. This is just enough unlike
* build_subplan that we can't share code.
@ -978,35 +980,22 @@ SS_process_ctes(PlannerInfo *root)
splan->args = NIL;
/*
* Make parParam and args lists of param IDs and expressions that
* current query level will pass to this child plan. Even though this
* is an initplan, there could be side-references to earlier
* initplan's outputs, specifically their CTE output parameters.
* The node can't have any inputs (since it's an initplan), so the
* parParam and args lists remain empty. (It could contain references
* to earlier CTEs' output param IDs, but CTE outputs are not
* propagated via the args list.)
*/
tmpset = bms_copy(plan->extParam);
while ((paramid = bms_first_member(tmpset)) >= 0)
{
PlannerParamItem *pitem = list_nth(root->glob->paramlist, paramid);
if (pitem->abslevel == root->query_level)
{
prm = (Param *) pitem->item;
if (!IsA(prm, Param) ||
prm->paramtype != INTERNALOID)
elog(ERROR, "bogus local parameter passed to WITH query");
splan->parParam = lappend_int(splan->parParam, paramid);
splan->args = lappend(splan->args, copyObject(prm));
}
}
bms_free(tmpset);
/*
* Assign a param to represent the query output. We only really care
* about reserving a parameter ID number.
* Assign a param ID to represent the CTE's output. No ordinary
* "evaluation" of this param slot ever happens, but we use the param
* ID for setParam/chgParam signaling just as if the CTE plan were
* returning a simple scalar output. (Also, the executor abuses the
* ParamExecData slot for this param ID for communication among
* multiple CteScan nodes that might be scanning this CTE.)
*/
prm = generate_new_param(root, INTERNALOID, -1);
splan->setParam = list_make1_int(prm->paramid);
paramid = SS_assign_special_param(root);
splan->setParam = list_make1_int(paramid);
/*
* Add the subplan and its rtable to the global lists.
@ -1811,7 +1800,7 @@ SS_finalize_plan(PlannerInfo *root, Plan *plan, bool attach_initplans)
*initExtParam,
*initSetParam;
Cost initplan_cost;
int paramid;
PlannerInfo *proot;
ListCell *l;
/*
@ -1843,30 +1832,36 @@ SS_finalize_plan(PlannerInfo *root, Plan *plan, bool attach_initplans)
/*
* Now determine the set of params that are validly referenceable in this
* query level; to wit, those available from outer query levels plus the
* output parameters of any initPlans. (We do not include output
* output parameters of any local initPlans. (We do not include output
* parameters of regular subplans. Those should only appear within the
* testexpr of SubPlan nodes, and are taken care of locally within
* finalize_primnode. Likewise, special parameters that are generated by
* nodes such as ModifyTable are handled within finalize_plan.)
*
* Note: this is a bit overly generous since some parameters of upper
* query levels might belong to query subtrees that don't include this
* query. However, valid_params is only a debugging crosscheck, so it
* doesn't seem worth expending lots of cycles to try to be exact.
*/
valid_params = bms_copy(initSetParam);
paramid = 0;
foreach(l, root->glob->paramlist)
for (proot = root->parent_root; proot != NULL; proot = proot->parent_root)
{
PlannerParamItem *pitem = (PlannerParamItem *) lfirst(l);
if (pitem->abslevel < root->query_level)
/* Include ordinary Var/PHV/Aggref params */
foreach(l, proot->plan_params)
{
/* valid outer-level parameter */
valid_params = bms_add_member(valid_params, paramid);
}
PlannerParamItem *pitem = (PlannerParamItem *) lfirst(l);
paramid++;
valid_params = bms_add_member(valid_params, pitem->paramId);
}
/* Include any outputs of outer-level initPlans */
foreach(l, proot->init_plans)
{
SubPlan *initsubplan = (SubPlan *) lfirst(l);
ListCell *l2;
foreach(l2, initsubplan->setParam)
{
valid_params = bms_add_member(valid_params, lfirst_int(l2));
}
}
/* Include worktable ID, if a recursive query is being planned */
if (proot->wt_param_id >= 0)
valid_params = bms_add_member(valid_params, proot->wt_param_id);
}
/*

1
src/backend/optimizer/prep/prepjointree.c
View File

@ -664,6 +664,7 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
subroot->glob = root->glob;
subroot->query_level = root->query_level;
subroot->parent_root = root->parent_root;
subroot->plan_params = NIL;
subroot->planner_cxt = CurrentMemoryContext;
subroot->init_plans = NIL;
subroot->cte_plan_ids = NIL;

10
src/backend/optimizer/prep/prepunion.c
View File

@ -211,6 +211,9 @@ recurse_set_operations(Node *setOp, PlannerInfo *root,
Assert(subquery != NULL);
/* plan_params should not be in use in current query level */
Assert(root->plan_params == NIL);
/*
* Generate plan for primitive subquery
*/
@ -219,6 +222,13 @@ recurse_set_operations(Node *setOp, PlannerInfo *root,
false, tuple_fraction,
&subroot);
/*
* It should not be possible for the primitive query to contain any
* cross-references to other primitive queries in the setop tree.
*/
if (root->plan_params)
elog(ERROR, "unexpected outer reference in set operation subquery");
/*
* Estimate number of groups if caller wants it. If the subquery used
* grouping or aggregation, its output is probably mostly unique