Since pgstattuple v1.5 hasn't been released yet, no need for a new
extension version. The new function exposes statistics about hash
indexes similar to what other pgstatindex functions return for other
index types.
Ashutosh Sharma, reviewed by Kuntal Ghosh. Substantial further
revisions by me.
Dead or half-dead index leaf pages were incorrectly reported as live, as a
consequence of a code rearrangement I made (during a moment of severe brain
fade, evidently) in commit d287818eb5.
The index metapage was not counted in index_size, causing that result to
not agree with the actual index size on-disk.
Index root pages were not counted in internal_pages, which is inconsistent
compared to the case of a root that's also a leaf (one-page index), where
the root would be counted in leaf_pages. Aside from that inconsistency,
this could lead to additional transient discrepancies between the reported
page counts and index_size, since it's possible for pgstatindex's scan to
see zero or multiple pages marked as BTP_ROOT, if the root moves due to
a split during the scan. With these fixes, index_size will always be
exactly one page more than the sum of the displayed page counts.
Also, the index_size result was incorrectly documented as being measured in
pages; it's always been measured in bytes. (While fixing that, I couldn't
resist doing some small additional wordsmithing on the pgstattuple docs.)
Including the metapage causes the reported index_size to not be zero for
an empty index. To preserve the desired property that the pgstattuple
regression test results are platform-independent (ie, BLCKSZ configuration
independent), scale the index_size result in the regression tests.
The documentation issue was reported by Otsuka Kenji, and the inconsistent
root page counting by Peter Geoghegan; the other problems noted by me.
Back-patch to all supported branches, because this has been broken for
a long time.
This allows us to specify the target relation with several expressions,
'relname', 'schemaname.relname' and OID in all pgstattuple functions.
pgstatindex() and pg_relpages() could not accept OID as the argument
so far.
Per discussion on -hackers, we decided to keep two types of interfaces,
with regclass-type and TEXT-type argument, for each pgstattuple
function because of the backward-compatibility issue. The functions
which have TEXT-type argument will be deprecated in the future release.
Patch by Satoshi Nagayasu, reviewed by Rushabh Lathia and Fujii Masao.