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docs: PG 12 relnotes, update btree items

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Reported-by: Peter Geoghegan

Discussion: https://postgr.es/m/CAH2-Wzn-aH4ToZEWR05ELSSp7bO_JMn=sMPfUhNruwVmCXKh-w@mail.gmail.com
This commit is contained in:
Bruce Momjian 2019-06-12 22:48:04 -04:00
parent 3d99a81397
commit 4bfb79ff6b
1 changed files with 50 additions and 27 deletions
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doc/src/sgml/release-12.sgml
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@ -606,22 +606,64 @@ Author: Tom Lane <tgl@sss.pgh.pa.us>
<listitem>
<!--
Author: Alexander Korotkov <akorotkov@postgresql.org>
2018-07-28 [d2086b08b] Reduce path length for locking leaf B-tree pages during
Author: Peter Geoghegan <pg@bowt.ie>
2019-03-20 [dd299df81] Make heap TID a tiebreaker nbtree index column.
Author: Peter Geoghegan <pg@bowt.ie>
2019-03-20 [fab250243] Consider secondary factors during nbtree splits.
Author: Peter Geoghegan <pg@bowt.ie>
2019-03-25 [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>
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.
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>
Indexes <application>pg_upgraded</application> from previous
releases will not have these benefits.
</para>
</listitem>
<listitem>
<!--
Author: Alexander Korotkov <akorotkov@postgresql.org>
2018-07-28 [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>
@ -680,25 +722,6 @@ Author: Tom Lane <tgl@sss.pgh.pa.us>
<listitem>
<!--
Author: Peter Geoghegan <pg@bowt.ie>
2019-03-20 [dd299df81] Make heap TID a tiebreaker nbtree index column.
Author: Peter Geoghegan <pg@bowt.ie>
2019-03-20 [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>
2019-03-05 [fe280694d] Scan GiST indexes in physical order during VACUUM.
-->