diff options
| author | Robert Haas <rhaas@postgresql.org> | 2017-08-29 13:12:23 -0400 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2017-08-29 13:16:55 -0400 |
| commit | 3452dc5240da43e833118484e1e9b4894d04431c (patch) | |
| tree | d158d5d9630d80bc8a5ca838ba76eede60c77ba9 /src/include/nodes/execnodes.h | |
| parent | ce5dcf54b942a469194ae390730f803b3f3fb928 (diff) | |
Push tuple limits through Gather and Gather Merge.
If we only need, say, 10 tuples in total, then we certainly don't need
more than 10 tuples from any single process. Pushing down the limit
lets workers exit early when possible. For Gather Merge, there is
an additional benefit: a Sort immediately below the Gather Merge can
be done as a bounded sort if there is an applicable limit.
Robert Haas and Tom Lane
Discussion: http://postgr.es/m/CA+TgmoYa3QKKrLj5rX7UvGqhH73G1Li4B-EKxrmASaca2tFu9Q@mail.gmail.com
Diffstat (limited to 'src/include/nodes/execnodes.h')
| -rw-r--r-- | src/include/nodes/execnodes.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index 3272c4b3155..15a84269ec9 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -1919,6 +1919,7 @@ typedef struct GatherState struct TupleQueueReader **reader; TupleTableSlot *funnel_slot; bool need_to_scan_locally; + int64 tuples_needed; /* tuple bound, see ExecSetTupleBound */ } GatherState; /* ---------------- @@ -1944,6 +1945,7 @@ typedef struct GatherMergeState struct binaryheap *gm_heap; /* binary heap of slot indices */ bool gm_initialized; /* gather merge initilized ? */ bool need_to_scan_locally; + int64 tuples_needed; /* tuple bound, see ExecSetTupleBound */ int gm_nkeys; SortSupport gm_sortkeys; /* array of length ms_nkeys */ struct GMReaderTupleBuffer *gm_tuple_buffers; /* tuple buffer per reader */ |