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Re: postgresql is slow with larger table even it is in RAM

From: "sathiya psql" <sathiya(dot)psql(at)gmail(dot)com>
To: "Bill Moran" <wmoran(at)collaborativefusion(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: postgresql is slow with larger table even it is in RAM
Date: 2008-03-25 13:27:12
Message-ID: f966c2ee0803250627gdd5f1eai61b0bbb199320fd3@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
>
> Yes.  It takes your hardware about 3 seconds to read through 700M of ram.
>



>
> Keep in mind that you're not just reading RAM.  You're pushing system
> requests through the VFS layer of your operating system, which is treating
> the RAM like a disk (with cylinder groups and inodes and blocks, etc) so
> you have all that processing overhead as well.  What filesystem did you
> format the RAM disk with?
>
tmpfs

>
> Why are you doing this?  If you have enough RAM to store the table, why
> not just allocate it to shared buffers?


just allocating will  make read from hdd to RAM at first time, to eliminate
that

>
>
are you saying it will take 3 seconds surely if i have 50 lakh record

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