Re: pgsql-performance issue - Mailing list pgsql-performance

On 2016-08-20 08:58, Pavel Stehule wrote:
> 2016-08-20 10:27 GMT+02:00 <debasis.moharana@ipathsolutions.co.in>:
>
>> On 2016-08-20 08:21, pgsql-performance-owner@postgresql.org wrote:
>>
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>>
> <https://lists.postgresql.org/mj/mj_wwwusr/domain=postgresql.org/debasis.moharana%40ipathsolutions.co.in
>>> [1]>
>> Dear Sir/Mam,
>>
>> I have a PostgreSQL 9.5 instance running on Windows 8 machine with
>> 4GB of RAM.This server is mainly used for inserting/updating large
>> amounts of data via copy/insert/update commands, and seldom for
>> running select queries.
>>
>> Here are the relevant configuration parameters I changed:
>>
>> max_connections = 100
>> shared_buffers = 512MB
>> effective_cache_size = 3GB
>> work_mem = 12233kB
>> maintenance_work_mem = 256MB
>> min_wal_size = 1GB max_wal_size = 2GB
>> checkpoint_completion_target = 0.7
>> wal_buffers = 16MB
>> default_statistics_target = 100
>>
>> After setting in postgresql.conf. I run the select query to fetch
>> large amount of record of 29000 in postgresql but it takes 10.3
>> seconds but the same query takes 2 seconds for execution in MSSQL.
>>
>> So my query is how to improve the perfermance in postgresql.
>
> hi
>
> please, send execution plan of slow query
>
> https://www.postgresql.org/docs/current/static/sql-explain.html [3]
> https://explain.depesz.com/ [4]
>
> p.s. Did you do VACUUM and ANALYZE on database?
>
> Regards
>
> Pavel
>
>> Regards,
>> Debasis Moharana
>> .NET Software Developer
>>
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> [3] https://www.postgresql.org/docs/current/static/sql-explain.html
> [4] https://explain.depesz.com/



Hi,

Please check the execution plan details


Execution Query is = EXPLAIN (ANALYZE, BUFFERS) select * from
tblPurchaseOrderstock cross join tblPurchaseOrderInfo;

"Nested Loop  (cost=0.00..507.51 rows=39593 width=224) (actual
time=0.032..13.026 rows=39593 loops=1)"
"  Buffers: shared read=8"
"  I/O Timings: read=0.058"
"  ->  Seq Scan on tblpurchaseorderstock  (cost=0.00..7.89 rows=289
width=95) (actual time=0.014..0.082 rows=289 loops=1)"
"        Buffers: shared read=5"
"        I/O Timings: read=0.040"
"  ->  Materialize  (cost=0.00..5.05 rows=137 width=129) (actual
time=0.000..0.006 rows=137 loops=289)"
"        Buffers: shared read=3"
"        I/O Timings: read=0.019"
"        ->  Seq Scan on tblpurchaseorderinfo  (cost=0.00..4.37 rows=137
width=129) (actual time=0.011..0.035 rows=137 loops=1)"
"              Buffers: shared read=3"
"              I/O Timings: read=0.019"
"Planning time: 56.052 ms"
"Execution time: 14.038 ms"

Regards,
Debasis Moharana