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Allow HOT updates for some expression indexes

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If the value of an index expression is unchanged after UPDATE,
allow HOT updates where previously we disallowed them, giving
a significant performance boost in those cases.

Particularly useful for indexes such as JSON->>field where the
JSON value changes but the indexed value does not.

Submitted as "surjective indexes" patch, now enabled by use
of new "recheck_on_update" parameter.

Author: Konstantin Knizhnik
Reviewer: Simon Riggs, with much wordsmithing and some cleanup
This commit is contained in:
Simon Riggs
2018-03-27 19:57:02 +01:00
parent 1944cdc982
commit c203d6cf81
13 changed files with 395 additions and 22 deletions
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3
src/include/utils/relcache.h
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@@ -53,7 +53,8 @@ extern List *RelationGetIndexPredicate(Relation relation);
typedef enum IndexAttrBitmapKind
{
INDEX_ATTR_BITMAP_ALL,
INDEX_ATTR_BITMAP_HOT,
INDEX_ATTR_BITMAP_PROJ,
INDEX_ATTR_BITMAP_KEY,
INDEX_ATTR_BITMAP_PRIMARY_KEY,
INDEX_ATTR_BITMAP_IDENTITY_KEY