Re: Proposal for CSN based snapshots - Mailing list pgsql-hackers

From Jeff Davis
Subject Re: Proposal for CSN based snapshots
Date
Msg-id 1409083927.2335.401.camel@jeff-desktop
Whole thread Raw
In response to Re: Proposal for CSN based snapshots  (Greg Stark <stark@mit.edu>)
List pgsql-hackers
On Tue, 2014-08-26 at 21:00 +0100, Greg Stark wrote:
> Well fundamentally the reason the visibility information is with the
> user data is so that we don't need to do two i/os to access the data.
> The whole point of hint bits is to guarantee that after some amount of
> time you can read data directly out of the heap page and use it
> without doing any additional I/O.

If the data is that static, then the visibility information would be
highly compressible, and surely in shared_buffers already.

(Yes, it would need to be pinned, which has a cost.)

Regards,Jeff Davis





pgsql-hackers by date:

Previous
From: Robert Haas
Date:
Subject: Re: [v9.5] Custom Plan API
Next
From: Robert Haas
Date:
Subject: Re: proposal: rounding up time value less than its unit.