Re: [HACKERS] Custom compression methods - Mailing list pgsql-hackers

From Dilip Kumar
Subject Re: [HACKERS] Custom compression methods
Date
Msg-id CAFiTN-tj+8CVvjmKBs2FX_nZS16d_7STUrx69+snWEVRVY7eXg@mail.gmail.com
Whole thread Raw
In response to Re: [HACKERS] Custom compression methods  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: [HACKERS] Custom compression methods
List pgsql-hackers
On Wed, Mar 24, 2021 at 10:57 PM Robert Haas <robertmhaas@gmail.com> wrote:
>
> On Wed, Mar 24, 2021 at 12:14 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > Actually, we are already doing this, I mean ALTER TABLE .. ALTER
> > COLUMN .. SET COMPRESSION is already updating the compression method
> > of the index attribute.  So 0003 doesn't make sense, sorry for the
> > noise.  However, 0001 and 0002 are still valid, or do you think that
> > we don't want 0001 also?  If we don't need 0001 also then we need to
> > update the test output for 0002 slightly.
>
> It seems to me that 0002 is still not right. We can't fix the
> attcompression to whatever the default is at the time the index is
> created, because the default can be changed later, and there's no way
> to fix index afterward. I mean, it would be fine to do it that way if
> we were going to go with the other model, where the index state is
> separate from the table state, either can be changed independently,
> and it all gets dumped and restored. But, as it is, I think we should
> be deciding how to compress new values for an expression column based
> on the default_toast_compression setting at the time of compression,
> not the time of index creation.
>

Okay got it.  Fixed as suggested.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

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