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Reduce btree scan overhead for < and > strategies

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For <, <=, > and >= strategies, mark the first scan key
as already matched if scanning in an appropriate direction.
If index tuple contains no nulls we can skip the first
re-check for each tuple.

Author: Rajeev Rastogi
Reviewer: Haribabu Kommi
Rework of the code and comments by Simon Riggs
This commit is contained in:
Simon Riggs
2014-11-18 10:24:55 +00:00
parent dedae6c211
commit 606c0123d6
3 changed files with 35 additions and 0 deletions
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src/include/access/nbtree.h
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@@ -618,6 +618,7 @@ typedef BTScanOpaqueData *BTScanOpaque;
*/
#define SK_BT_REQFWD 0x00010000 /* required to continue forward scan */
#define SK_BT_REQBKWD 0x00020000 /* required to continue backward scan */
#define SK_BT_MATCHED 0x00040000 /* required to skip further key match */
#define SK_BT_INDOPTION_SHIFT 24 /* must clear the above bits */
#define SK_BT_DESC (INDOPTION_DESC << SK_BT_INDOPTION_SHIFT)
#define SK_BT_NULLS_FIRST (INDOPTION_NULLS_FIRST << SK_BT_INDOPTION_SHIFT)