Re: Microvacuum for gist. Question about GISTPageOpaqueData flag

On 07/27/2015 06:46 PM, Teodor Sigaev wrote:

I need an advice, what would be better:
- to add new flag like F_HAS_GARBAGE,
- or to delete all mentions of F_TUPLES_DELETED and use it in gist microvacuum.

According to commit message:
commit 2effb72e682a7dbdc9a8a60a80c22ec1fa9d8079
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date:   Fri Nov 7 15:03:46 2014 +0200
..
      The code that generated a record to clear the F_TUPLES_DELETED flag hasn't
      existed since we got rid of old-style VACUUM FULL. I kept the code that sets
      the flag, although it's not used for anything anymore, because it might
      still be interesting information for debugging purposes that some tuples
      have been deleted from a page.
..

If Heikki doesn't change his opinion then introduce new flag. Although I don't
think that we need to keep F_TUPLES_DELETED.

It's certainly not needed for anything at the moment, although conceivably we might reintroduce code that needs it in the future. There are plenty of flag bits available, so let's use a new flag. If there was a shortage, I wouldn't blink reusing F_TUPLES_DELETED.

- Heikki