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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2009-03-21 00:04:40 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2009-03-21 00:04:40 +0000 |
| commit | 596efd27edce20bba706f50de99a0f15bcc2a567 (patch) | |
| tree | 63c07c3c310e1b072f0a29a79220c81254dba3d8 /src/include/nodes/execnodes.h | |
| parent | 249d936bed069877923f0369bd2ce51a6f8f925e (diff) | |
| download | postgresql-596efd27edce20bba706f50de99a0f15bcc2a567.tar.gz postgresql-596efd27edce20bba706f50de99a0f15bcc2a567.zip | |
Optimize multi-batch hash joins when the outer relation has a nonuniform
distribution, by creating a special fast path for the (first few) most common
values of the outer relation. Tuples having hashvalues matching the MCVs
are effectively forced to be in the first batch, so that we never write
them out to the batch temp files.
Bryce Cutt and Ramon Lawrence, with some editorialization by me.
Diffstat (limited to 'src/include/nodes/execnodes.h')
| -rw-r--r-- | src/include/nodes/execnodes.h | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index 8d87ec19e1d..996efa8f87d 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.201 2009/01/12 05:10:45 tgl Exp $ + * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.202 2009/03/21 00:04:40 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1374,11 +1374,12 @@ typedef struct MergeJoinState * hj_HashTable hash table for the hashjoin * (NULL if table not built yet) * hj_CurHashValue hash value for current outer tuple - * hj_CurBucketNo bucket# for current outer tuple + * hj_CurBucketNo regular bucket# for current outer tuple + * hj_CurSkewBucketNo skew bucket# for current outer tuple * hj_CurTuple last inner tuple matched to current outer * tuple, or NULL if starting search - * (CurHashValue, CurBucketNo and CurTuple are - * undefined if OuterTupleSlot is empty!) + * (hj_CurXXX variables are undefined if + * OuterTupleSlot is empty!) * hj_OuterHashKeys the outer hash keys in the hashjoin condition * hj_InnerHashKeys the inner hash keys in the hashjoin condition * hj_HashOperators the join operators in the hashjoin condition @@ -1403,6 +1404,7 @@ typedef struct HashJoinState HashJoinTable hj_HashTable; uint32 hj_CurHashValue; int hj_CurBucketNo; + int hj_CurSkewBucketNo; HashJoinTuple hj_CurTuple; List *hj_OuterHashKeys; /* list of ExprState nodes */ List *hj_InnerHashKeys; /* list of ExprState nodes */ |