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Allow aggregate transition states to be serialized and deserialized.

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This is necessary infrastructure for supporting parallel aggregation
for aggregates whose transition type is "internal".  Such values
can't be passed between cooperating processes, because they are
just pointers.

David Rowley, reviewed by Tomas Vondra and by me.
This commit is contained in:
Robert Haas
2016-03-29 15:04:05 -04:00
parent 7f0a2c85fb
commit 5fe5a2cee9
25 changed files with 794 additions and 193 deletions
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12
src/backend/optimizer/util/clauses.c
View File

@ -464,11 +464,15 @@ aggregates_allow_partial_walker(Node *node, partial_agg_context *context)
}
/*
* If we find any aggs with an internal transtype then we must ensure
* that pointers to aggregate states are not passed to other processes;
* therefore, we set the maximum allowed type to PAT_INTERNAL_ONLY.
* If we find any aggs with an internal transtype then we must check
* that these have a serialization type, serialization func and
* deserialization func; otherwise, we set the maximum allowed type to
* PAT_INTERNAL_ONLY.
*/
if (aggform->aggtranstype == INTERNALOID)
if (aggform->aggtranstype == INTERNALOID &&
(!OidIsValid(aggform->aggserialtype) ||
!OidIsValid(aggform->aggserialfn) ||
!OidIsValid(aggform->aggdeserialfn)))
context->allowedtype = PAT_INTERNAL_ONLY;
ReleaseSysCache(aggTuple);

4
src/backend/optimizer/util/pathnode.c
View File

@ -2433,7 +2433,8 @@ create_agg_path(PlannerInfo *root,
const AggClauseCosts *aggcosts,
double numGroups,
bool combineStates,
bool finalizeAggs)
bool finalizeAggs,
bool serialStates)
{
AggPath *pathnode = makeNode(AggPath);
@ -2458,6 +2459,7 @@ create_agg_path(PlannerInfo *root,
pathnode->qual = qual;
pathnode->finalizeAggs = finalizeAggs;
pathnode->combineStates = combineStates;
pathnode->serialStates = serialStates;
cost_agg(&pathnode->path, root,
aggstrategy, aggcosts,

11
src/backend/optimizer/util/tlist.c
View File

@ -756,8 +756,8 @@ apply_pathtarget_labeling_to_tlist(List *tlist, PathTarget *target)
* apply_partialaggref_adjustment
* Convert PathTarget to be suitable for a partial aggregate node. We simply
* adjust any Aggref nodes found in the target and set the aggoutputtype to
* the aggtranstype. This allows exprType() to return the actual type that
* will be produced.
* the aggtranstype or aggserialtype. This allows exprType() to return the
* actual type that will be produced.
*
* Note: We expect 'target' to be a flat target list and not have Aggrefs burried
* within other expressions.
@ -785,7 +785,12 @@ apply_partialaggref_adjustment(PathTarget *target)
aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
newaggref = (Aggref *) copyObject(aggref);
newaggref->aggoutputtype = aggform->aggtranstype;
/* use the serialization type, if one exists */
if (OidIsValid(aggform->aggserialtype))
newaggref->aggoutputtype = aggform->aggserialtype;
else
newaggref->aggoutputtype = aggform->aggtranstype;
lfirst(lc) = newaggref;