Re: No write stats in pg_statio system views

From: ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>
To: "Nikhil Sontakke" <nikhil(dot)sontakke(at)enterprisedb(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: No write stats in pg_statio system views
Date: 2008-11-07 00:41:43
Message-ID: 20081107093707.9DD8.52131E4D@oss.ntt.co.jp
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"Nikhil Sontakke" <nikhil(dot)sontakke(at)enterprisedb(dot)com> wrote:

> What is the reason for not having heap_blks_write kind of stats in the
> pg_statio system views? Is it because bgwriter does the writing (we do have
> bg stats there) most of the times? Wouldn't the write stats help to get the
> complete IO picture for the relation?

That's because we don't have relfilenode-based statistics.
We have only relation oid based statistics and the oid information
is not available on writing (including bgwriter).

If we can change statistics to be relfilenode-based,
heap_blks_write would be available. It might be worth trying,
but some works are needed.

Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center

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