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

After examining the benchmark design - I see we are probably not being 
helped by the repeated insertion of keys all of form 'userxxxxxxx' 
leading to some page splitting.

However your index rebuild gets you from 5 to 3 GB - does that really 
help performance significantly?

regards

Mark

On 11/08/16 16:08, Kisung Kim wrote:
> 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.
>
>
>