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Allow parallel aggregate on string_agg and array_agg

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This adds combine, serial and deserial functions for the array_agg() and
string_agg() aggregate functions, thus allowing these aggregates to
partake in partial aggregations.  This allows both parallel aggregation to
take place when these aggregates are present and also allows additional
partition-wise aggregation plan shapes to include plans that require
additional aggregation once the partially aggregated results from the
partitions have been combined.

Author: David Rowley
Reviewed-by: Andres Freund, Tomas Vondra, Stephen Frost, Tom Lane
Discussion: https://postgr.es/m/CAKJS1f9sx_6GTcvd6TMuZnNtCh0VhBzhX6FZqw17TgVFH-ga_A@mail.gmail.com
This commit is contained in:
David Rowley
2023-01-23 17:35:01 +13:00
parent 5a3a95385b
commit 16fd03e956
13 changed files with 1103 additions and 30 deletions
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28
src/backend/optimizer/prep/prepagg.c
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@ -305,10 +305,30 @@ preprocess_aggref(Aggref *aggref, PlannerInfo *root)
* functions; if not, we can't serialize partial-aggregation
* results.
*/
else if (transinfo->aggtranstype == INTERNALOID &&
(!OidIsValid(transinfo->serialfn_oid) ||
!OidIsValid(transinfo->deserialfn_oid)))
root->hasNonSerialAggs = true;
else if (transinfo->aggtranstype == INTERNALOID)
{
if (!OidIsValid(transinfo->serialfn_oid) ||
!OidIsValid(transinfo->deserialfn_oid))
root->hasNonSerialAggs = true;
/*
* array_agg_serialize and array_agg_deserialize make use
* of the aggregate non-byval input type's send and
* receive functions. There's a chance that the type
* being aggregated has one or both of these functions
* missing. In this case we must not allow the
* aggregate's serial and deserial functions to be used.
* It would be nice not to have special case this and
* instead provide some sort of supporting function within
* the aggregate to do this, but for now, that seems like
* overkill for this one case.
*/
if ((transinfo->serialfn_oid == F_ARRAY_AGG_SERIALIZE ||
transinfo->deserialfn_oid == F_ARRAY_AGG_DESERIALIZE) &&
!agg_args_support_sendreceive(aggref))
root->hasNonSerialAggs = true;
}
}
}
agginfo->transno = transno;