Re: pgstattuple extension for indexes

Patch applied.  Thanks.

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ITAGAKI Takahiro wrote:
> 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.
> 
> Suggestions welcome.
> 
> ----
> $ pgbench -i
> $ pgbench -n -t 100 -c 10
> # select * from pgstattuple('accounts_pkey');
> NOTICE:  0.36% fragmented
> HINT:  continuous=273, forward=1, backward=0
> -[ RECORD 1 ]------+--------
> table_len          | 2260992
> tuple_count        | 100996     -- 996 tuples are dead practically,
> tuple_len          | 1615936       but no LP_DELETE yet.
> tuple_percent      | 71.47
> dead_tuple_count   | 4
> dead_tuple_len     | 64         -- 64 tuples are marked as LP_DELETE.
> dead_tuple_percent | 0
> free_space         | 208188
> free_percent       | 9.21
> ----
> 
> 
> Regards,
> ---
> ITAGAKI Takahiro
> NTT Open Source Software Center

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