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Re: [External] Blackhole, Archive and others only as loadable plugins in 10.1 - intentional change?


Thanks Hartmut for having brougth this up.  Comments inline.  Cheers, JFG

On 9 February 2017 at 11:42, Hartmut Holzgraefe <hartmut@xxxxxxxxxxx> wrote:

> In MariaDB 10.1 binary packages several storage engines, e.g BLACKHOLE
> and ARCHIVE, are no longer compiled in by default but only come as
> loadable plugins that need to be loaded into the server explicitly.
> This is mentioned on the knowledge base pages for these engines,
> e.g. https://mariadb.com/kb/en/mariadb/blackhole/
> and https://mariadb.com/kb/en/mariadb/archive/
> but is not mentioned in the release notes and the detailed changelog
> pages for 10.1.x releases at all.
> I also searched my "maria-developers" and "maria-discuss" mail archives
> but could not find any discussion or announcement on this topic either.
> Same for Jira, can't find any ticket that would describe that sort of
> change there either.

My understanding of above boils down to the 3 questions below:

   - was that a conscious change,
   - what were the reasons for that change,
   - do people agree with that change.

If it was not done on purpose and there is no valid reasons to do the
change, it should probably be considered as a bug and fixed.  [1] is opened
to have mysql_upgrade handle the situation, maybe we should also open a but
to add back blackhole enabled by default (I am less sure about ARCHIVE and

[1]: https://jira.mariadb.org/browse/MDEV-11942

Does anyone here have an opinion on this ?  Do you agree (or disagree) that
blackhole should not enabled by default ?  My opinion on that below.

Problems with the current situation:
> * comes as a surprise for installation using these storage engines when
> upgraded to 10.1

I confirm this is a surprise, and I was actually bitten by that.

> * mysql_upgrade should handle this, but doesn't:
> https://jira.mariadb.org/browse/MDEV-11942

I have no strong opinion about keeping blackhole disabled by default or
re-enabling it.  However, if blackhole stays disable by default, I think
mysql_upgrade MUST handle the situation.  More opinion below.

> * it is not even easily possible to identify affected tables after an
> upgrade to 10.1. For BLACKHOLE tables I_S.TABLES only shows these under
> specific conditions, and for ARCHIVE it seems to be impossible to
> identify affected tables at all if the plugin is not loaded
> https://jira.mariadb.org/browse/MDEV-11943

If we cannot, in the next 2 minor version releases, make mysql_upgrade
handle that case, I think blackhole should be re-enabled.  The motivation
for that is that we should maintain an upgrade story, and if a user it
using blackhole in 10.0, it should work after an upgrade.

I have submitted a a fix for MDEV-11942, but without
> having a fix for MDEV-11943 it only works for BLACKHOLE so far, not
> for ARCHIVE (haven't tested FEDERATED or other potentially affected
> engines yet). https://github.com/MariaDB/server/pull/304

Thanks again Hartmut for having brought this up on the mailing list.

Best regards,

Jean-François Gagné
System Engineer

Booking.com B.V.
Vijzelstraat 66-80 Amsterdam 1017HL Netherlands