Querying an index's btree version
Hello,
We've read that PG 12 has improved btree index support, and that the latest
internal btree version was bumped from 3 to 4. Is it possible to query the
btree version that a particular index is using? We'd like to automatically
start a concurrent re-index if we detect any btree indexes are still on
version 3.
Thank you,
Darren Lafreniere
On Wed, Mar 11, 2020 at 1:26 PM Darren Lafreniere
<dlafreniere@onezero.com> wrote:
We've read that PG 12 has improved btree index support, and that the latest internal btree version was bumped from 3 to 4. Is it possible to query the btree version that a particular index is using? We'd like to automatically start a concurrent re-index if we detect any btree indexes are still on version 3.
It's possible, but you have to install the superuser-only pageinspect
extension. Here is how you'd determine that an index called
'pg_aggregate_fnoid_index' is on version 4:
regression=# create extension pageinspect;
CREATE EXTENSION
regression=# select version from bt_metap('pg_aggregate_fnoid_index');
version
---------
4
(1 row)
--
Peter Geoghegan
Thank you for the info, Peter.
Separate but related follow-up question: when you restore a DB from a
backup, does the restored index use the old format or the latest one?
Thank you,
Darren Lafreniere
On Wed, Mar 11, 2020 at 4:30 PM Peter Geoghegan <pg@bowt.ie> wrote:
On Wed, Mar 11, 2020 at 1:26 PM Darren Lafreniere
<dlafreniere@onezero.com> wrote:We've read that PG 12 has improved btree index support, and that the
latest internal btree version was bumped from 3 to 4. Is it possible to
query the btree version that a particular index is using? We'd like to
automatically start a concurrent re-index if we detect any btree indexes
are still on version 3.It's possible, but you have to install the superuser-only pageinspect
extension. Here is how you'd determine that an index called
'pg_aggregate_fnoid_index' is on version 4:regression=# create extension pageinspect;
CREATE EXTENSION
regression=# select version from bt_metap('pg_aggregate_fnoid_index');
version
---------
4
(1 row)--
Peter Geoghegan
--
*Darren Lafreniere*
Senior Software Engineer | oneZero Financial Systems
site: www.onezero.com
email: dlafreniere@onezero.com
On Wed, Mar 11, 2020 at 2:13 PM Darren Lafreniere
<dlafreniere@onezero.com> wrote:
when you restore a DB from a backup, does the restored index use the old format or the latest one?
If you use pg_restore, it uses the latest index format.
If you're using pg_upgrade, the version won't change unless and until
you REINDEX. This includes cases where you're running pg_upgrade
against a restored physical backup.
--
Peter Geoghegan
On Wed, 2020-03-11 at 17:12 -0400, Darren Lafreniere wrote:
Separate but related follow-up question: when you restore a DB from a backup, does the restored index use the old format or the latest one?
If you restore a pg_dump, you will have the latest version.
If you restore a file system backup, you will have what you had before.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com