Horton

Re: WIP: Avoid creation of the free space map for small tables

Amit Kapila <amit.kapila16@gmail.com>

View thread View on postgr.es
From: Amit Kapila <amit.kapila16@gmail.com>
To: John Naylor <john.naylor@2ndquadrant.com>
Cc: Mithun Cy <mithun.cy@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-01-25T02:50:03Z
Lists: pgsql-hackers 
On Fri, Jan 25, 2019 at 1:03 AM John Naylor <john.naylor@2ndquadrant.com> wrote:
>
> On Wed, Jan 23, 2019 at 11:17 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > I think what doc means to say is
> > that it copies any unlinked files present in primary's new cluster
> > (which in your case will be data2).
>
> In that case, I'm still confused why that doc says, "Unfortunately,
> rsync needlessly copies files associated with temporary and unlogged
> tables because these files don't normally exist on standby servers."
> I fail to see why the primary's new cluster would have these if they
> weren't linked.
>

Why unlogged files won't be in primary's new cluster?  After the
upgrade, they should be present in a new cluster if they were present
in the old cluster.

> And in the case we're discussing here, the skipped
> FSMs won't be on data2, so won't end up in standby/data2.
>

Right.  I think we are safe with respect to rsync because I have seen
that we do rewrite the vm files in link mode and rsync will copy them
from primary's new cluster.

I think you can try to address my other comments on your pg_upgrade
patch.   Once we agree on the code, we need to test below scenarios:
(a) upgrade from all supported versions to the latest version
(b) upgrade standby with and without using rsync.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Commits

  1. Improve code comments in b0eaa4c51b.

  2. During pg_upgrade, conditionally skip transfer of FSMs.

  3. Add more tests for FSM.

  4. Doc: Update the documentation for FSM behavior for small tables.

  5. Make FSM test portable.

  6. Avoid creation of the free space map for small heap relations, take 2.

  7. Move page initialization from RelationAddExtraBlocks() to use, take 2.

  8. Avoid creation of the free space map for small heap relations.

  9. In bootstrap mode, don't allow the creation of files if they don't already