git.postgresql.org Git - postgresql.git/commitdiff

git projects / postgresql.git / commitdiff

summary | shortlog | log | commit | commitdiff | tree
raw | patch | inline | side by side (parent: 3e0d80f)

Include chunk overhead in hash table entry size estimate.

author Jeff Davis <jdavis@postgresql.org>

Sat, 4 Apr 2020 02:52:16 +0000 (19:52 -0700)

committer Jeff Davis <jdavis@postgresql.org>

Sat, 4 Apr 2020 03:07:58 +0000 (20:07 -0700)

Don't try to be precise about it, just use a constant 16 bytes of
chunk overhead. Being smarter would require knowing the memory context
where the chunk will be allocated, which is not known by all callers.

Discussion: https://postgr.es/m/20200325220936.il3ni2fj2j2b45y5@alap3.anarazel.de

src/backend/executor/nodeAgg.c patch | blob | blame | history

src/include/executor/nodeAgg.h patch | blob | blame | history

diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c

index 4c8c5cfc07af05c0497b2726e663fe420620af94..4e100e5755f1c562b2f90c3aa399794da5a9788e 100644 (file)

--- a/src/backend/executor/nodeAgg.c

+++ b/src/backend/executor/nodeAgg.c

@@ -297,6 +297,12 @@

/* minimum number of initial hash table buckets */

#define HASHAGG_MIN_BUCKETS 256

+/*

+ * Estimate chunk overhead as a constant 16 bytes. XXX: should this be

+ * improved?

+ */

+#define CHUNKHDRSZ 16

+

/*

* Track all tapes needed for a HashAgg that spills. We don't know the maximum

* number of tapes needed at the start of the algorithm (because it can

@@ -1639,14 +1645,32 @@ find_hash_columns(AggState *aggstate)

* Estimate per-hash-table-entry overhead.

*/

Size

-hash_agg_entry_size(int numAggs, Size tupleWidth, Size transitionSpace)

+hash_agg_entry_size(int numTrans, Size tupleWidth, Size transitionSpace)

{

+ Size tupleChunkSize;

+ Size pergroupChunkSize;

+ Size transitionChunkSize;

+ Size tupleSize = (MAXALIGN(SizeofMinimalTupleHeader) +

+ tupleWidth);

+ Size pergroupSize = numTrans * sizeof(AggStatePerGroupData);

+

+ tupleChunkSize = CHUNKHDRSZ + tupleSize;

+

+ if (pergroupSize > 0)

+ pergroupChunkSize = CHUNKHDRSZ + pergroupSize;

+ else

+ pergroupChunkSize = 0;

+

+ if (transitionSpace > 0)

+ transitionChunkSize = CHUNKHDRSZ + transitionSpace;

+ else

+ transitionChunkSize = 0;

+

return

- MAXALIGN(SizeofMinimalTupleHeader) +

- MAXALIGN(tupleWidth) +

- MAXALIGN(sizeof(TupleHashEntryData) +

- numAggs * sizeof(AggStatePerGroupData)) +

- transitionSpace;

+ sizeof(TupleHashEntryData) +

+ tupleChunkSize +

+ pergroupChunkSize +

+ transitionChunkSize;

}

/*

diff --git a/src/include/executor/nodeAgg.h b/src/include/executor/nodeAgg.h

index a5b8a004d1e55cae279b2bd185e5d160eba0568d..c2b55728bfa2c6fd242d13413f76f8f5f8b1d4d9 100644 (file)

--- a/src/include/executor/nodeAgg.h

+++ b/src/include/executor/nodeAgg.h

@@ -314,7 +314,7 @@ extern AggState *ExecInitAgg(Agg *node, EState *estate, int eflags);

extern void ExecEndAgg(AggState *node);

extern void ExecReScanAgg(AggState *node);

-extern Size hash_agg_entry_size(int numAggs, Size tupleWidth,

+extern Size hash_agg_entry_size(int numTrans, Size tupleWidth,

Size transitionSpace);

extern void hash_agg_set_limits(double hashentrysize, uint64 input_groups,

int used_bits, Size *mem_limit,

This is the main PostgreSQL git repository.