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><A
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>E.1. Release 9.3.9</A
></H1
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Release Date: </B
>2015-06-12</P
></BLOCKQUOTE
></DIV
><P
> This release contains a small number of fixes from 9.3.8.
For information about new features in the 9.3 major release, see
<A
HREF="release-9-3.html"
>Section E.10</A
>.
</P
><DIV
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><H2
CLASS="SECT2"
><A
NAME="AEN114477"
>E.1.1. Migration to Version 9.3.9</A
></H2
><P
> A dump/restore is not required for those running 9.3.X.
</P
><P
> However, if you are upgrading an installation that was previously
upgraded using a <SPAN
CLASS="APPLICATION"
>pg_upgrade</SPAN
> version between 9.3.0 and
9.3.4 inclusive, see the first changelog entry below.
</P
><P
> Also, if you are upgrading from a version earlier than 9.3.7,
see <A
HREF="release-9-3-7.html"
>Section E.3</A
>.
</P
></DIV
><DIV
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><H2
CLASS="SECT2"
><A
NAME="AEN114484"
>E.1.2. Changes</A
></H2
><P
></P
><UL
><LI
><P
> Fix possible failure to recover from an inconsistent database state
(Robert Haas)
</P
><P
> Recent <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> releases introduced mechanisms to
protect against multixact wraparound, but some of that code did not
account for the possibility that it would need to run during crash
recovery, when the database may not be in a consistent state. This
could result in failure to restart after a crash, or failure to start
up a secondary server. The lingering effects of a previously-fixed
bug in <SPAN
CLASS="APPLICATION"
>pg_upgrade</SPAN
> could also cause such a failure, in
installations that had used <SPAN
CLASS="APPLICATION"
>pg_upgrade</SPAN
> versions
between 9.3.0 and 9.3.4.
</P
><P
> The <SPAN
CLASS="APPLICATION"
>pg_upgrade</SPAN
> bug in question was that it would
set <TT
CLASS="LITERAL"
>oldestMultiXid</TT
> to 1 in <TT
CLASS="FILENAME"
>pg_control</TT
> even
if the true value should be higher. With the fixes introduced in
this release, such a situation will result in immediate emergency
autovacuuming until a correct <TT
CLASS="LITERAL"
>oldestMultiXid</TT
> value can be
determined. If that would pose a hardship, users can avoid it by
doing manual vacuuming <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>before</I
></SPAN
> upgrading to this release.
In detail:
<P
></P
></P><OL
TYPE="1"
><LI
><P
> Check whether <SPAN
CLASS="APPLICATION"
>pg_controldata</SPAN
> reports <SPAN
CLASS="QUOTE"
>"Latest
checkpoint's oldestMultiXid"</SPAN
> to be 1. If not, there's nothing
to do.
</P
></LI
><LI
><P
> Look in <TT
CLASS="FILENAME"
>PGDATA/pg_multixact/offsets</TT
> to see if there's a
file named <TT
CLASS="FILENAME"
>0000</TT
>. If there is, there's nothing to do.
</P
></LI
><LI
><P
> Otherwise, for each table that has
<TT
CLASS="STRUCTNAME"
>pg_class</TT
>.<TT
CLASS="STRUCTFIELD"
>relminmxid</TT
> equal to 1,
<TT
CLASS="COMMAND"
>VACUUM</TT
> that table with
both <A
HREF="runtime-config-client.html#GUC-VACUUM-MULTIXACT-FREEZE-MIN-AGE"
>vacuum_multixact_freeze_min_age</A
>
and <A
HREF="runtime-config-client.html#GUC-VACUUM-MULTIXACT-FREEZE-TABLE-AGE"
>vacuum_multixact_freeze_table_age</A
> set to
zero. (You can use the vacuum cost delay parameters described
in <A
HREF="runtime-config-resource.html#RUNTIME-CONFIG-RESOURCE-VACUUM-COST"
>Section 18.4.4</A
> to reduce
the performance consequences for concurrent sessions.) You must
use <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> 9.3.5 or later to perform this step.
</P
></LI
></OL
><P>
</P
></LI
><LI
><P
> Fix rare failure to invalidate relation cache init file (Tom Lane)
</P
><P
> With just the wrong timing of concurrent activity, a <TT
CLASS="COMMAND"
>VACUUM
FULL</TT
> on a system catalog might fail to update the <SPAN
CLASS="QUOTE"
>"init file"</SPAN
>
that's used to avoid cache-loading work for new sessions. This would
result in later sessions being unable to access that catalog at all.
This is a very ancient bug, but it's so hard to trigger that no
reproducible case had been seen until recently.
</P
></LI
><LI
><P
> Avoid deadlock between incoming sessions and <TT
CLASS="LITERAL"
>CREATE/DROP
DATABASE</TT
> (Tom Lane)
</P
><P
> A new session starting in a database that is the target of
a <TT
CLASS="COMMAND"
>DROP DATABASE</TT
> command, or is the template for
a <TT
CLASS="COMMAND"
>CREATE DATABASE</TT
> command, could cause the command to wait
for five seconds and then fail, even if the new session would have
exited before that.
</P
></LI
><LI
><P
> Improve planner's cost estimates for semi-joins and anti-joins with
inner indexscans (Tom Lane, Tomas Vondra)
</P
><P
> This type of plan is quite cheap when all the join clauses are used
as index scan conditions, even if the inner scan would nominally
fetch many rows, because the executor will stop after obtaining one
row. The planner only partially accounted for that effect, and would
therefore overestimate the cost, leading it to possibly choose some
other much less efficient plan type.
</P
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