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| author | Andres Freund <andres@anarazel.de> | 2016-11-30 17:30:09 -0800 |
|---|---|---|
| committer | Andres Freund <andres@anarazel.de> | 2016-11-30 17:30:09 -0800 |
| commit | fc4b3dea2950e4f6081f1ed2380f82c9efd672e0 (patch) | |
| tree | 9ab6f63fcd0a5752d1db2d1f2180831915cbf318 /src/include/nodes/execnodes.h | |
| parent | 8ed3f11bb045ad7a3607690be668dbd5b3cc31d7 (diff) | |
User narrower representative tuples in the hash-agg hashtable.
So far the hashtable stored representative tuples in the form of its
input slot, with all columns in the hashtable that are not
needed (i.e. not grouped upon or functionally dependent) set to NULL.
Thats good for saving memory, but it turns out that having tuples full
of NULL isn't free. slot_deform_tuple is faster if there's no NULL
bitmap even if no NULLs are encountered, and skipping over leading NULLs
isn't free.
So compute a separate tuple descriptor that only contains the needed
columns. As columns have already been moved in/out the slot for the
hashtable that does not imply additional per-row overhead.
Author: Andres Freund
Reviewed-By: Heikki Linnakangas
Discussion: https://postgr.es/m/20161103110721.h5i5t5saxfk5eeik@alap3.anarazel.de
Diffstat (limited to 'src/include/nodes/execnodes.h')
| -rw-r--r-- | src/include/nodes/execnodes.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index f85b7ea5a7c..8004d856cc7 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -1860,7 +1860,10 @@ typedef struct AggState /* these fields are used in AGG_HASHED mode: */ TupleHashTable hashtable; /* hash table with one entry per group */ TupleTableSlot *hashslot; /* slot for loading hash table */ - List *hash_needed; /* list of columns needed in hash table */ + int numhashGrpCols; /* number of columns in hash table */ + int largestGrpColIdx; /* largest column required for hashing */ + AttrNumber *hashGrpColIdxInput; /* and their indices in input slot */ + AttrNumber *hashGrpColIdxHash; /* indices for execGrouping in hashtbl */ bool table_filled; /* hash table filled yet? */ TupleHashIterator hashiter; /* for iterating through hash table */ /* support for evaluation of agg inputs */ |