This is an extension of pgstattuple to query information from indexes.
It supports btree, hash and gist. Gin is not supported. It scans only
index pages and does not read corresponding heap tuples. Therefore,
'dead_tuple' means the number of tuples with LP_DELETE flag.
Also, I added an experimental feature for btree indexes. It checks
fragmentation factor of indexes. If an leaf has the right link on the
next adjacent page in the file, it is assumed to be continuous (not
fragmented). It will help us to decide when to REINDEX.
ITAGAKI Takahiro
to the table function, thus preventing memory leakage accumulation across
calls. This means that SRFs need to be careful to distinguish permanent
and local storage; adjust code and documentation accordingly. Patch by
Joe Conway, very minor tweaks by Tom Lane.
sequence functions how to cope with qualified names. Same code is
also used for int4notin, currtid_byrelname, pgstattuple. Also,
move TOAST tables into special pg_toast namespace.
prevents embarassments such as having the table dropped or truncated
partway through the scan. Also, fix free space calculation to include
pages that currently contain no tuples.
