Re: Btree Index on PostgreSQL and Wiredtiger (MongoDB3.2)

Thank you for your information.
Here is the result:

After insertions:

ycsb=# select * from pgstatindex('usertable_pkey');
version | tree_level | index_size | root_block_no | internal_pages |
leaf_pages | empty_pages | deleted_pages | avg_leaf_density |
leaf_fragmentation
---------+------------+------------+---------------+----------------+------------+-------------+---------------+------------------+--------------------
2 | 3 | 5488721920 | 44337 | 4464 |
665545 | 0 | 0 | 52 | 11
(1 row)

After rebuild:

ycsb=# select * from pgstatindex('usertable_pkey');
version | tree_level | index_size | root_block_no | internal_pages |
leaf_pages | empty_pages | deleted_pages | avg_leaf_density |
leaf_fragmentation
---------+------------+------------+---------------+--------
--------+------------+-------------+---------------+--------
----------+--------------------
2 | 3 | 3154296832 | 41827 | 1899 |
383146 | 0 | 0 | 90.08 | 0

It seems like that rebuild has an effect to reduce the number of internal
and leaf_pages and make more dense leaf pages.

On Wed, Aug 10, 2016 at 6:47 PM, Lukas Fittl <lukas(at)fittl(dot)com> wrote:

> On Wed, Aug 10, 2016 at 4:24 PM, Kisung Kim <kskim(at)bitnine(dot)net> wrote:
>>
>> When I used the index bloating estimation script in
>> https://github.com/ioguix/pgsql-bloat-estimation,
>> the result is as follows:
>>
>
> Regardless of the issue at hand, it might make sense to verify these
> statistics using pgstattuple - those bloat estimation queries can be wildly
> off at times.
>
> See also https://www.postgresql.org/docs/9.5/static/pgstattuple.html as
> well as https://www.keithf4.com/checking-for-postgresql-bloat/
>
> Best,
> Lukas
>
> --
> Lukas Fittl
>
> Skype: lfittl
> Phone: +1 415 321 0630
>

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