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Tweak indexscan machinery to avoid taking an AccessShareLock on an index

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if we already have a stronger lock due to the index's table being the
update target table of the query.  Same optimization I applied earlier
at the table level.  There doesn't seem to be much interest in the more
radical idea of not locking indexes at all, so do what we can ...
This commit is contained in:
Tom Lane
2005-12-03 05:51:03 +00:00
parent 1cf65140d0
commit a98871b7ac
12 changed files with 95 additions and 35 deletions
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4
src/include/access/genam.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/genam.h,v 1.53 2005/10/15 02:49:42 momjian Exp $
* $PostgreSQL: pgsql/src/include/access/genam.h,v 1.54 2005/12/03 05:51:03 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -79,9 +79,11 @@ extern bool index_insert(Relation indexRelation,
extern IndexScanDesc index_beginscan(Relation heapRelation,
Relation indexRelation,
bool need_index_lock,
Snapshot snapshot,
int nkeys, ScanKey key);
extern IndexScanDesc index_beginscan_multi(Relation indexRelation,
bool need_index_lock,
Snapshot snapshot,
int nkeys, ScanKey key);
extern void index_rescan(IndexScanDesc scan, ScanKey key);

3
src/include/access/relscan.h
View File

@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.42 2005/11/26 03:03:07 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.43 2005/12/03 05:51:03 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -61,6 +61,7 @@ typedef struct IndexScanDescData
int numberOfKeys; /* number of scan keys */
ScanKey keyData; /* array of scan key descriptors */
bool is_multiscan; /* TRUE = using amgetmulti */
bool have_lock; /* TRUE = holding AccessShareLock for scan */
/* signaling to index AM about killing index tuples */
bool kill_prior_tuple; /* last-returned tuple is dead */