Refactor hash_agg_entry_size().

Consolidate the calculations for hash table size estimation. This will
help with upcoming Hash Aggregation work that will add additional call
sites.
This commit is contained in:
Jeff Davis 2020-02-06 11:49:56 -08:00
parent c02fdc9223
commit 7d4395d0a1
4 changed files with 14 additions and 33 deletions

View File

@ -1422,24 +1422,17 @@ find_hash_columns(AggState *aggstate)
}
/*
* Estimate per-hash-table-entry overhead for the planner.
*
* Note that the estimate does not include space for pass-by-reference
* transition data values, nor for the representative tuple of each group.
* Nor does this account of the target fill-factor and growth policy of the
* hash table.
* Estimate per-hash-table-entry overhead.
*/
Size
hash_agg_entry_size(int numAggs)
hash_agg_entry_size(int numAggs, Size tupleWidth, Size transitionSpace)
{
Size entrysize;
/* This must match build_hash_table */
entrysize = sizeof(TupleHashEntryData) +
numAggs * sizeof(AggStatePerGroupData);
entrysize = MAXALIGN(entrysize);
return entrysize;
return
MAXALIGN(SizeofMinimalTupleHeader) +
MAXALIGN(tupleWidth) +
MAXALIGN(sizeof(TupleHashEntryData) +
numAggs * sizeof(AggStatePerGroupData)) +
transitionSpace;
}
/*

View File

@ -4867,13 +4867,8 @@ create_distinct_paths(PlannerInfo *root,
allow_hash = false; /* policy-based decision not to hash */
else
{
Size hashentrysize;
/* Estimate per-hash-entry space at tuple width... */
hashentrysize = MAXALIGN(cheapest_input_path->pathtarget->width) +
MAXALIGN(SizeofMinimalTupleHeader);
/* plus the per-hash-entry overhead */
hashentrysize += hash_agg_entry_size(0);
Size hashentrysize = hash_agg_entry_size(
0, cheapest_input_path->pathtarget->width, 0);
/* Allow hashing only if hashtable is predicted to fit in work_mem */
allow_hash = (hashentrysize * numDistinctRows <= work_mem * 1024L);

View File

@ -3526,16 +3526,8 @@ double
estimate_hashagg_tablesize(Path *path, const AggClauseCosts *agg_costs,
double dNumGroups)
{
Size hashentrysize;
/* Estimate per-hash-entry space at tuple width... */
hashentrysize = MAXALIGN(path->pathtarget->width) +
MAXALIGN(SizeofMinimalTupleHeader);
/* plus space for pass-by-ref transition values... */
hashentrysize += agg_costs->transitionSpace;
/* plus the per-hash-entry overhead */
hashentrysize += hash_agg_entry_size(agg_costs->numAggs);
Size hashentrysize = hash_agg_entry_size(
agg_costs->numAggs, path->pathtarget->width, agg_costs->transitionSpace);
/*
* Note that this disregards the effect of fill-factor and growth policy

View File

@ -309,6 +309,7 @@ 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);
extern Size hash_agg_entry_size(int numAggs, Size tupleWidth,
Size transitionSpace);
#endif /* NODEAGG_H */