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(dot)linnakangas(at)iki(dot)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