Re: [PoC] pgstattuple2: block sampling to reduce physical read

On 16/09/13 16:20, Satoshi Nagayasu wrote:
> Thanks for checking. Fixed to eliminate SnapshotNow.

Looking forward to get a new patch, incorporating the comments, that are already given in the following mails:

1. Jaime Casanova: "The name pgstattuple2, doesn't convince me... maybe you can use pgstattuple() if you use a second argument (percentage of the sample) to overload the function".
(http://www.postgresql.org/message-id/5265AD16.3090704@catalyst.net.nz)

The comment related to having an argument, to mention the sampling number, is also given by Greg Smith: "There should be an input parameter to the function for how much sampling to do"
(http://www.postgresql.org/message-id/51EE62D4.7020401@2ndQuadrant.com)

2. Yourself: "I think it could be improved by sorting sample block numbers before physical block reads in order to eliminate random access on the disk."
(http://www.postgresql.org/message-id/525779C5.2020608@uptime.jp) for which, Mark Kirkwood , has given a rough patch.

Regards,
Firoz EV