Re: [PATCH] Pageinspect - add functions on GIN and GiST indexes from gevel

Hi, Alexey!

On Fri, Jul 21, 2017 at 3:05 PM, Alexey Chernyshov <
a(dot)chernyshov(at)postgrespro(dot)ru> wrote:

> the following patch transfers functionality from gevel module
> (http://www.sai.msu.su/~megera/wiki/Gevel) which provides functions for
> analyzing GIN and GiST indexes to pageinspect. Gevel was originally
> designed by Oleg Bartunov, and Teodor Sigaev for developers of GiST and
> GIN indexes.
>

It's very good that you've picked up this work! pageinspect is lacking of
this functionality.

Functions added:
> - gist_stat(text) - shows statistics on GiST Tree
> - gist_tree(text) - shows GiST tree
> - gist_tree(text, int4) - shows GiST tree up to MAXLEVEL
> - gist_print(text) - prints objects stored in GiST tree
> - spgist_stat(text) - shows statistics on SP-GiST
> - spgist_print(text) - prints objects stored in index
> - gin_value_count() - originally gin_stat(text) - prints estimated counts
> for index values
> - gin_stats() - originally gin_statpage(text) - shows statistics
> - gin_count_estimate(text, tsquery) - shows number of indexed rows matched
> query
>
> Tests also transferred, docs for new functions are added. I run pgindent
> over the code, but the result is different from those I expected, so I
> leave
> pgindented one.
> The patch is applicable to the commit 866f4a7c210857aa342bf901558d17
> 0325094dde.
>

As we can see, gevel contains functions which analyze the whole index.
pageinspect is written in another manner: it gives you functionality to
analyze individual pages, tuples and so on.
Thus, we probably shouldn't try to move gevel functions to pageinspect "as
is". They should be rewritten in more granular manner as well as other
pageinspact functions are. Any other opinions?

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company