Re: TCP network cost

From: Linos
Subject: Re: TCP network cost
Date: ,
Msg-id: 49AACC6F.7080809@linos.es
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In response to: Re: TCP network cost  (Tom Lane)
Responses: Re: TCP network cost  (Tom Lane)
List: pgsql-performance

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TCP network cost  ("Ross J. Reedstrom", )
 Re: TCP network cost  (Rusty Conover, )
  Re: TCP network cost  (, )
  Re: TCP network cost  ("Ross J. Reedstrom", )
   Re: TCP network cost  (Rusty Conover, )
    Re: TCP network cost  ("Ross J. Reedstrom", )
     Re: TCP network cost  ("Ross J. Reedstrom", )
      Re: TCP network cost  (Aaron Turner, )
     Re: TCP network cost  (PFC, )
      Re: TCP network cost  ("Ross J. Reedstrom", )
   Re: TCP network cost  (Gregory Stark, )
    Re: TCP network cost  ("Ross J. Reedstrom", )
     Re: TCP network cost  (Tom Lane, )
      Re: TCP network cost  ("Ross J. Reedstrom", )
       Re: TCP network cost  (Linos, )
        Re: TCP network cost  (Tom Lane, )
         Re: TCP network cost  (Linos, )
          Re: TCP network cost  (Tom Lane, )
           Re: TCP network cost  (Linos, )
            Re: TCP network cost  (Tom Lane, )
             Re: TCP network cost  (Magnus Hagander, )
              Re: TCP network cost  (Linos, )
 Re: TCP network cost  (Aaron Turner, )

Tom Lane escribió:
> Linos <> writes:
>> Hello, i have been having a problem like this in debian machines and i have
>> discovered that (almost in my case), the problem only arises when i am using
>> "ssl = true" in postgresql.conf although i am using clear tcp connections to
>> localhost to perform my query, if i disable ssl in configuration my localhost
>> query times goes from 4200ms to 110ms,
>
> Does that number include connection startup overhead?  (If it doesn't,
> it'd be pretty strange.)  Ross's problem is not about startup overhead,
> unless I've misread him completely.
>
>             regards, tom lane

This difference it is from the runtime of the query, i get this with \timing
parameter in psql, it is from a table that have 300 small png (one for every row
in table) on a bytea column but the problem grows with any large result anyway,
i have attacted pcap files in general list but the differences are like this:

ssl enabled:
`psql -d database`: SELECT * FROM TABLE (110 ms with \timing)
`psql -d database -h localhost`: SELECT * FROM TABLE (4200 ms with \timing)

ssl disabled:
`psql -d database`: SELECT * FROM TABLE (110 ms with \timing)
`psql -d database -h localhost`: SELECT * FROM TABLE (120 ~ 130 ms with \timing)

Anyway i dont know if this apply to Ross problem but reading his post and after
see that he is using debian and have problem with speed on tcp localhost i
suppose that maybe have the same problem.

Regards,
Miguel Angel


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