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

On 2016-08-20 11:42, Pavel Stehule wrote:

2016-08-20 13:31 GMT+02:00 <debasis.moharana@ipathsolutions.co.in>:

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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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]
[3]
 https://explain.depesz.com/ [4] [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
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 [4] https://explain.depesz.com/ [4]

 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"

It is same query? It needs only 14ms

Regards

Pavel

Regards,
Debasis Moharana

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[3] https://www.postgresql.org/docs/current/static/sql-explain.html
[4] https://explain.depesz.com/

Hi,

Yes you right.But it will take more time(10.3 sec.) Plase check the snap.

Can you please tell me what we need to setup so that it will take the actual time.

Regards,
Debasis Moharana