Search Postgresql Archives

Re: Bitmap Heap scan 8.1/8.2

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Pavel Stehule wrote:
2007/10/22, Martin Marques <martin@xxxxxxxxxxxxxxx>:
Pavel Stehule wrote:
2007/10/22, Martin Marques <martin@xxxxxxxxxxxxxxx>:
Pavel Stehule wrote:
Hello

I am unsure, did you check config values?
Don't know which ones you are talking about, but all enable_* are set to on.

Anything else?

shared_buffers
8.1:

  16000
~ 128M

8.2:

  400MB


work_mem
8.1:

  8192
8M !!!! 8>4
8.2:

  4MB


effective_cache_size
8.1:

  1000
8M
8.2:

  128MB



try

set work_mem to '8MB';
and
explain analyze select ..

These things didn't help. What changed the plan completely was this:

seq_page_cost = 5.0                     # measured on an arbitrary scale
cpu_tuple_cost = 0.05                   # same scale as above

Specially the first one. Now I get this:

explain analyze SELECT usuarios,nticket,objeto,vencimiento FROM prestamos WHERE biblioteca = 19 AND vencimiento < now() AND NOT devuelto ORDER BY vencimiento DESC;

QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sort (cost=7058.86..7060.86 rows=800 width=20) (actual time=22.850..22.888 rows=95 loops=1)
   Sort Key: vencimiento
-> Index Scan using prestamos_objetos_devuelto_idx on prestamos (cost=0.00..7020.28 rows=800 width=20) (actual time=0.346..22.590 rows=95 loops=1)
         Index Cond: (devuelto = false)
Filter: ((biblioteca = 19) AND (vencimiento < now()) AND (NOT devuelto))
 Total runtime: 22.973 ms


--
 21:50:04 up 2 days,  9:07,  0 users,  load average: 0.92, 0.37, 0.18
---------------------------------------------------------
Lic. Martín Marqués         |   SELECT 'mmarques' ||
Centro de Telemática        |       '@' || 'unl.edu.ar';
Universidad Nacional        |   DBA, Programador,
    del Litoral             |   Administrador
---------------------------------------------------------

---------------------------(end of broadcast)---------------------------
TIP 2: Don't 'kill -9' the postmaster

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux