BUG #13645: pg_basebackup backup hash index & unlogged table

On Mon, Sep 28, 2015 at 06:15:24AM +0000, digoal@126.com wrote:

The following bug has been logged on the website:

Bug reference: 13645
Logged by: digoal
Email address: digoal@126.com
PostgreSQL version: 9.4.4
Operating system: CentOS 6.x x64
Description:

HI,
Hash index and unlogged table don't generate XLOG record, when we use
pg_basebackup's backup datafile & xlog archive recovery database, unlogged
table datafile will purged, and hash index also has unconsistent data page.
Why pg_basebackup not filter the hash index datafile & unlogged table
datafile, these file waste net band and backup file's capcity.

We will issue a warning in 9.5 when hash indexes are created. I am not
sure why we don't filter out hash indexed and unlogged tables.

--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ As you are, so once was I. As I am, so you will be. +
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On Mon, Oct 5, 2015 at 10:37 AM, Bruce Momjian <bruce@momjian.us> wrote:

On Mon, Sep 28, 2015 at 06:15:24AM +0000, digoal@126.com wrote:

Hash index and unlogged table don't generate XLOG record, when we use
pg_basebackup's backup datafile & xlog archive recovery database, unlogged
table datafile will purged, and hash index also has unconsistent data page.
Why pg_basebackup not filter the hash index datafile & unlogged table
datafile, these file waste net band and backup file's capcity.

We will issue a warning in 9.5 when hash indexes are created. I am not
sure why we don't filter out hash indexed and unlogged tables.

basebackup.c does not have much logic yet to see if the file it is
working on is a relation file (this already exists in
filemap.c@isRelDataFile in pg_rewind), and a WAL sender is not
connected to a particular database, which would be needed for pg_class
lookups, so it seems to me that this would be a complicated
infrastructure for a niche use case. Note to mention that perhaps, in
a perhaps-distant day, hash indexes will have WAL support.
--
Michael

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