Horton

Re: making relfilenodes 56 bits

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Heikki Linnakangas <hlinnaka@iki.fi>, Thomas Munro <thomas.munro@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-07-20T11:26:47Z
Lists: pgsql-hackers

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On Mon, Jul 18, 2022 at 4:51 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> I was doing some more testing by setting the FirstNormalRelFileNumber
> to a high value(more than 32 bits) I have noticed a couple of problems
> there e.g. relpath is still using OIDCHARS macro which says max
> relfilenumber file name can be only 10 character long which is no
> longer true.  So there we need to change this value to 20 and also
> need to carefully rename the macros and other variable names used for
> this purpose.
>
> Similarly there was some issue in macro in buf_internal.h while
> fetching the relfilenumber.  So I will relook into all those issues
> and repost the patch soon.

I have fixed these existing issues and there was also some issue in
pg_dump.c which was creating problems in upgrading to the same version
while using a higher range of the relfilenumber.

There was also an issue where the user table from the old cluster's
relfilenode could conflict with the system table of the new cluster.
As a solution currently for system table object (while creating
storage first time) we are keeping the low range of relfilenumber,
basically we are using the same relfilenumber as OID so that during
upgrade the normal user table from the old cluster will not conflict
with the system tables in the new cluster.  But with this solution
Robert told me (in off list chat) a problem that in future if we want
to make relfilenumber completely unique within a cluster by
implementing the CREATEDB differently then we can not do that as we
have created fixed relfilenodes for the system tables.

I am not sure what exactly we can do to avoid that because even if we
do something  to avoid that in the new cluster the old cluster might
be already using the non-unique relfilenode so after upgrading the new
cluster will also get those non-unique relfilenode.

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

Commits

  1. Fix typos in comments, code and documentation

  2. Increase width of RelFileNumbers from 32 bits to 56 bits.

  3. Move RelFileNumber declarations to common/relpath.h.

  4. Include RelFileLocator fields individually in BufferTag.

  5. Convert macros to static inline functions (buf_internals.h)

  6. Remove the restriction that the relmap must be 512 bytes.

  7. Change internal RelFileNode references to RelFileNumber or RelFileLocator.

  8. Reorder subskiplsn in pg_subscription to avoid alignment issues.

  9. Fix DROP {DATABASE,TABLESPACE} on Windows.

  10. Restructure smgr API as per recent proposal. smgr no longer depends on