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>Appendix E. Release Notes</TD
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><H1
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><A
NAME="RELEASE-9-2-6"
>E.56. Release 9.2.6</A
></H1
><DIV
CLASS="FORMALPARA"
><P
><B
>Release date: </B
>2013-12-05</P
></DIV
><P
> This release contains a variety of fixes from 9.2.5.
For information about new features in the 9.2 major release, see
<A
HREF="release-9-2.html"
>Section E.62</A
>.
</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN129867"
>E.56.1. Migration to Version 9.2.6</A
></H2
><P
> A dump/restore is not required for those running 9.2.X.
</P
><P
> However, this release corrects a number of potential data corruption
issues. See the first two changelog entries below to find out whether
your installation has been affected and what steps you can take if so.
</P
><P
> Also, if you are upgrading from a version earlier than 9.2.4,
see <A
HREF="release-9-2-4.html"
>Section E.58</A
>.
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN129873"
>E.56.2. Changes</A
></H2
><P
></P
><UL
><LI
><P
> Fix <TT
CLASS="COMMAND"
>VACUUM</TT
>'s tests to see whether it can
update <TT
CLASS="STRUCTFIELD"
>relfrozenxid</TT
> (Andres Freund)
</P
><P
> In some cases <TT
CLASS="COMMAND"
>VACUUM</TT
> (either manual or autovacuum) could
incorrectly advance a table's <TT
CLASS="STRUCTFIELD"
>relfrozenxid</TT
> value,
allowing tuples to escape freezing, causing those rows to become
invisible once 2^31 transactions have elapsed. The probability of
data loss is fairly low since multiple incorrect advancements would
need to happen before actual loss occurs, but it's not zero. In 9.2.0
and later, the probability of loss is higher, and it's also possible
to get <SPAN
CLASS="QUOTE"
>"could not access status of transaction"</SPAN
> errors as a
consequence of this bug. Users upgrading from releases 9.0.4 or 8.4.8
or earlier are not affected, but all later versions contain the bug.
</P
><P
> The issue can be ameliorated by, after upgrading, vacuuming all tables
in all databases while having <A
HREF="runtime-config-client.html#GUC-VACUUM-FREEZE-TABLE-AGE"
><TT
CLASS="VARNAME"
>vacuum_freeze_table_age</TT
></A
>
set to zero. This will fix any latent corruption but will not be able
to fix all pre-existing data errors. However, an installation can be
presumed safe after performing this vacuuming if it has executed fewer
than 2^31 update transactions in its lifetime (check this with
<TT
CLASS="LITERAL"
>SELECT txid_current() < 2^31</TT
>).
</P
></LI
><LI
><P
> Fix initialization of <TT
CLASS="FILENAME"
>pg_clog</TT
> and <TT
CLASS="FILENAME"
>pg_subtrans</TT
>
during hot standby startup (Andres Freund, Heikki Linnakangas)
</P
><P
> This bug can cause data loss on standby servers at the moment they
start to accept hot-standby queries, by marking committed transactions
as uncommitted. The likelihood of such corruption is small unless, at
the time of standby startup, the primary server has executed many
updating transactions since its last checkpoint. Symptoms include
missing rows, rows that should have been deleted being still visible,
and obsolete versions of updated rows being still visible alongside
their newer versions.
</P
><P
> This bug was introduced in versions 9.3.0, 9.2.5, 9.1.10, and 9.0.14.
Standby servers that have only been running earlier releases are not
at risk. It's recommended that standby servers that have ever run any
of the buggy releases be re-cloned from the primary (e.g., with a new
base backup) after upgrading.
</P
></LI
><LI
><P
> Fix dangling-pointer problem in fast-path locking (Tom Lane)
</P
><P
> This could lead to corruption of the lock data structures in shared
memory, causing <SPAN
CLASS="QUOTE"
>"lock already held"</SPAN
> and other odd errors.
</P
></LI
><LI
><P
> Truncate <TT
CLASS="FILENAME"
>pg_multixact</TT
> contents during WAL replay
(Andres Freund)
</P
><P
> This avoids ever-increasing disk space consumption in standby servers.
</P
></LI
><LI
><P
> Ensure an anti-wraparound <TT
CLASS="COMMAND"
>VACUUM</TT
> counts a page as scanned
when it's only verified that no tuples need freezing (Sergey
Burladyan, Jeff Janes)
</P
><P
> This bug could result in failing to
advance <TT
CLASS="STRUCTFIELD"
>relfrozenxid</TT
>, so that the table would still be
thought to need another anti-wraparound vacuum. In the worst case the
database might even shut down to prevent wraparound.
</P
></LI
><LI
><P
> Fix race condition in GIN index posting tree page deletion (Heikki
Linnakangas)
</P
><P
> This could lead to transient wrong answers or query failures.
</P
></LI
><LI
><P
> Fix <SPAN
CLASS="QUOTE"
>"unexpected spgdoinsert() failure"</SPAN
> error during SP-GiST
index creation (Teodor Sigaev)
</P
></LI
><LI
><P
> Avoid flattening a subquery whose <TT
CLASS="LITERAL"
>SELECT</TT
> list contains a
volatile function wrapped inside a sub-<TT
CLASS="LITERAL"
>SELECT</TT
> (Tom Lane)
</P
><P
> This avoids unexpected results due to extra evaluations of the
volatile function.
</P
></LI
><LI
><P
> Fix planner's processing of non-simple-variable subquery outputs
nested within outer joins (Tom Lane)
</P
><P
> This error could lead to incorrect plans for queries involving
multiple levels of subqueries within <TT
CLASS="LITERAL"
>JOIN</TT
> syntax.
</P
></LI
><LI
><P
> Fix incorrect planning in cases where the same non-strict expression
appears in multiple <TT
CLASS="LITERAL"
>WHERE</TT
> and outer <TT
CLASS="LITERAL"
>JOIN</TT
>
equality clauses (Tom Lane)
</P
></LI
><LI
><P
> Fix planner crash with whole-row reference to a subquery (Tom Lane)
</P
></LI
><LI
><P
> Fix incorrect generation of optimized MIN()/MAX() plans for
inheritance trees (Tom Lane)
</P
><P
> The planner could fail in cases where the MIN()/MAX() argument was an
expression rather than a simple variable.
</P
></LI
><LI
><P
> Fix premature deletion of temporary files (Andres Freund)
</P
></LI
><LI
><P
> Prevent intra-transaction memory leak when printing range values
(Tom Lane)
</P
><P
> This fix actually cures transient memory leaks in any datatype output
function, but range types are the only ones known to have had a
significant problem.
</P
></LI
><LI
><P
> Prevent incorrect display of dropped columns in NOT NULL and CHECK
constraint violation messages (Michael Paquier and Tom Lane)
</P
></LI
><LI
><P
> Allow default arguments and named-argument notation for window
functions (Tom Lane)
</P
><P
> Previously, these cases were likely to crash.
</P
></LI
><LI
><P
> Fix possible read past end of memory in rule printing (Peter Eisentraut)
</P
></LI
><LI
><P
> Fix array slicing of <TT
CLASS="TYPE"
>int2vector</TT
> and <TT
CLASS="TYPE"
>oidvector</TT
> values
(Tom Lane)
</P
><P
> Expressions of this kind are now implicitly promoted to
regular <TT
CLASS="TYPE"
>int2</TT
> or <TT
CLASS="TYPE"
>oid</TT
> arrays.
</P
></LI
><LI
><P
> Fix incorrect behaviors when using a SQL-standard, simple GMT offset
timezone (Tom Lane)
</P
><P
> In some cases, the system would use the simple GMT offset value when
it should have used the regular timezone setting that had prevailed
before the simple offset was selected. This change also causes
the <CODE
CLASS="FUNCTION"
>timeofday</CODE
> function to honor the simple GMT offset
zone.
</P
></LI
><LI
><P
> Prevent possible misbehavior when logging translations of Windows
error codes (Tom Lane)
</P
></LI
><LI
><P
> Properly quote generated command lines in <SPAN
CLASS="APPLICATION"
>pg_ctl</SPAN
>
(Naoya Anzai and Tom Lane)
</P
><P
> This fix applies only to Windows.
</P
></LI
><LI
><P
> Fix <SPAN
CLASS="APPLICATION"
>pg_dumpall</SPAN
> to work when a source database
sets <A
HREF="runtime-config-client.html#GUC-DEFAULT-TRANSACTION-READ-ONLY"
><TT
CLASS="VARNAME"
>default_transaction_read_only</TT
></A
>
via <TT
CLASS="COMMAND"
>ALTER DATABASE SET</TT
> (Kevin Grittner)
</P
><P
> Previously, the generated script would fail during restore.
</P
></LI
><LI
><P
> Make <SPAN
CLASS="APPLICATION"
>ecpg</SPAN
> search for quoted cursor names
case-sensitively (Zoltán Böszörményi)
</P
></LI
><LI
><P
> Fix <SPAN
CLASS="APPLICATION"
>ecpg</SPAN
>'s processing of lists of variables
declared <TT
CLASS="TYPE"
>varchar</TT
> (Zoltán Böszörményi)
</P
></LI
><LI
><P
> Make <TT
CLASS="FILENAME"
>contrib/lo</TT
> defend against incorrect trigger definitions
(Marc Cousin)
</P
></LI
><LI
><P
> Update time zone data files to <SPAN
CLASS="APPLICATION"
>tzdata</SPAN
> release 2013h
for DST law changes in Argentina, Brazil, Jordan, Libya,
Liechtenstein, Morocco, and Palestine. Also, new timezone
abbreviations WIB, WIT, WITA for Indonesia.
</P
></LI
></UL
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