From 8ed3f11bb045ad7a3607690be668dbd5b3cc31d7 Mon Sep 17 00:00:00 2001
From: Andres Freund
Date: Wed, 30 Nov 2016 16:08:11 -0800
Subject: Perform one only projection to compute agg arguments.

Previously we did a ExecProject() for each individual aggregate
argument. That turned out to be a performance bottleneck in queries with
multiple aggregates.

Doing all the argument computations in one ExecProject() is quite a bit
cheaper because ExecProject's fastpath can do the work at once in a
relatively tight loop, and because it can get all the required columns
with a single slot_getsomeattr and save some other redundant setup
costs.

Author: Andres Freund
Reviewed-By: Heikki Linnakangas
Discussion: https://postgr.es/m/20161103110721.h5i5t5saxfk5eeik@alap3.anarazel.de
---
 src/include/nodes/execnodes.h | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'src/include')

diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index f6f73f3c590..f85b7ea5a7c 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1863,6 +1863,10 @@ typedef struct AggState
 	List	   *hash_needed;	/* list of columns needed in hash table */
 	bool		table_filled;	/* hash table filled yet? */
 	TupleHashIterator hashiter; /* for iterating through hash table */
+	/* support for evaluation of agg inputs */
+	TupleTableSlot *evalslot;	/* slot for agg inputs */
+	ProjectionInfo *evalproj;	/* projection machinery */
+	TupleDesc	evaldesc;		/* descriptor of input tuples */
 } AggState;
 
 /* ----------------
-- 
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