index 4a6c989f3f064cd2c1855bb46f04963f71217f4a..fcc49ffcf9ada0d7075f6394896ab51807d009f4 100644 (file)
<listitem>
<!--
-Author: Alexander Korotkov <akorotkov@postgresql.org>
-2018年07月28日 [d2086b08b] Reduce path length for locking leaf B-tree pages during
+Author: Peter Geoghegan <pg@bowt.ie>
+2019年03月20日 [dd299df81] Make heap TID a tiebreaker nbtree index column.
+Author: Peter Geoghegan <pg@bowt.ie>
+2019年03月20日 [fab250243] Consider secondary factors during nbtree splits.
Author: Peter Geoghegan <pg@bowt.ie>
2019年03月25日 [f21668f32] Add "split after new tuple" nbtree optimization.
-->
<para>
- Improve speed of btree index insertions (Peter Geoghegan,
- Alexander Korotkov)
+ Improve performance and space utilization of btree indexes with
+ many duplicates (Peter Geoghegan, Heikki Linnakangas)
+ </para>
+
+ <para>
+ Previously, duplicate index entries were stored unordered within
+ their duplicate groups. This caused overhead during index
+ inserts, wasted space due to excessive page splits, and reduced
+ <command>VACUUM</command>'s ability to recycle entire pages.
+ Duplicate index entries are now sorted in heap-storage order.
+ </para>
+
+ <para>
+ Indexes <application>pg_upgraded</application> from previous
+ releases will not have these benefits.
+ </para>
+ </listitem>
+
+ <listitem>
+<!--
+see commits above
+-->
+
+ <para>
+ Allow multi-column btree indexes to be smaller (Peter Geoghegan,
+ Heikki Linnakangas)
+ </para>
+
+ <para>
+ Internal pages and min/max leaf page indicators now only store
+ index keys until the change key, rather than all indexed keys.
+ This also improves the locality of index access.
</para>
<para>
- The new code improves the space-efficiency of page splits,
- reduces locking overhead, and gives better performance for
- <command>UPDATE</command>s and <command>DELETE</command>s on
- indexes with many duplicates.
+ Indexes <application>pg_upgraded</application> from previous
+ releases will not have these benefits.
+ </para>
+ </listitem>
+
+ <listitem>
+<!--
+Author: Alexander Korotkov <akorotkov@postgresql.org>
+2018年07月28日 [d2086b08b] Reduce path length for locking leaf B-tree pages during
+-->
+
+ <para>
+ Improve speed of btree index insertions by reducing locking
+ overhead (Alexander Korotkov)
</para>
</listitem>
<listitem>
<!--
-Author: Peter Geoghegan <pg@bowt.ie>
-2019年03月20日 [dd299df81] Make heap TID a tiebreaker nbtree index column.
-Author: Peter Geoghegan <pg@bowt.ie>
-2019年03月20日 [fab250243] Consider secondary factors during nbtree splits.
--->
-
- <para>
- Have new btree indexes sort duplicate index entries in heap-storage
- order (Peter Geoghegan, Heikki Linnakangas)
- </para>
-
- <para>
- Indexes <application>pg_upgraded</application> from previous
- releases will not have this ordering.
- </para>
- </listitem>
-
- <listitem>
-<!--
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
2019年03月05日 [fe280694d] Scan GiST indexes in physical order during VACUUM.
-->