Release Date: 2012-08-17
This release contains a variety of fixes from 9.0.8. For information about new features in the 9.0 major release, see Section E.47.
A dump/restore is not required for those running 9.0.X.
However, if you are upgrading from a version earlier than 9.0.6, see Section E.41.
Prevent access to external files/URLs via XML entity references (Noah Misch, Tom Lane)
xml_parse() would attempt
to fetch external files or URLs as needed to resolve DTD
and entity references in an XML value, thus allowing
unprivileged database users to attempt to fetch data with
the privileges of the database server. While the external
data wouldn't get returned directly to the user, portions
of it could be exposed in error messages if the data didn't
parse as valid XML; and in any case the mere ability to
check existence of a file might be useful to an attacker.
Prevent access to external files/URLs via contrib/xml2's
xslt_process() (Peter Eisentraut)
libxslt offers the ability to read and write both files and URLs through stylesheet commands, thus allowing unprivileged database users to both read and write data with the privileges of the database server. Disable that through proper use of libxslt's security options. (CVE-2012-3488)
xslt_process()'s ability to fetch
documents and stylesheets from external files/URLs. While
this was a documented "feature",
it was long regarded as a bad idea. The fix for
CVE-2012-3489 broke that capability, and rather than expend
effort on trying to fix it, we're just going to summarily
Prevent too-early recycling of btree index pages (Noah Misch)
When we allowed read-only transactions to skip assigning XIDs, we introduced the possibility that a deleted btree page could be recycled while a read-only transaction was still in flight to it. This would result in incorrect index search results. The probability of such an error occurring in the field seems very low because of the timing requirements, but nonetheless it should be fixed.
Fix crash-safety bug with newly-created-or-reset sequences (Tom Lane)
If ALTER SEQUENCE was executed
on a freshly created or reset sequence, and then precisely
nextval() call was made
on it, and then the server crashed, WAL replay would
restore the sequence to a state in which it appeared that
nextval() had been done,
thus allowing the first sequence value to be returned again
by the next
In particular this could manifest for serial columns, since creation of a serial
column's sequence includes an ALTER
SEQUENCE OWNED BY step.
report the correct epoch when not in hot standby (Heikki
This fixes a regression introduced in the previous minor release.
Fix bug in startup of Hot Standby when a master transaction has many subtransactions (Andres Freund)
This mistake led to failures reported as "out-of-order XID insertion in KnownAssignedXids".
Ensure the backup_label file
is fsync'd after
pg_start_backup() (Dave Kerr)
Fix timeout handling in walsender processes (Tom Lane)
WAL sender background processes neglected to establish a SIGALRM handler, meaning they would wait forever in some corner cases where a timeout ought to happen.
Back-patch 9.1 improvement to compress the fsync request queue (Robert Haas)
This improves performance during checkpoints. The 9.1 change has now seen enough field testing to seem safe to back-patch.
Fix LISTEN/NOTIFY to cope better with I/O problems, such as out of disk space (Tom Lane)
After a write failure, all subsequent attempts to send more NOTIFY messages would fail with messages like "Could not read from file "pg_notify/nnnn" at offset nnnnn: Success".
Only allow autovacuum to be auto-canceled by a directly blocked process (Tom Lane)
The original coding could allow inconsistent behavior in some cases; in particular, an autovacuum could get canceled after less than deadlock_timeout grace period.
Improve logging of autovacuum cancels (Robert Haas)
Fix log collector so that log_truncate_on_rotation works during the very first log rotation after server start (Tom Lane)
Fix WITH attached to a nested set operation (UNION/INTERSECT/EXCEPT) (Tom Lane)
Ensure that a whole-row reference to a subquery doesn't include any extra GROUP BY or ORDER BY columns (Tom Lane)
Disallow copying whole-row references in CHECK constraints and index definitions during CREATE TABLE (Tom Lane)
This situation can arise in CREATE TABLE with LIKE or INHERITS. The copied whole-row variable was incorrectly labeled with the row type of the original table not the new one. Rejecting the case seems reasonable for LIKE, since the row types might well diverge later. For INHERITS we should ideally allow it, with an implicit coercion to the parent table's row type; but that will require more work than seems safe to back-patch.
Fix memory leak in ARRAY(SELECT ...) subqueries (Heikki Linnakangas, Tom Lane)
Fix extraction of common prefixes from regular expressions (Tom Lane)
The code could get confused by quantified parenthesized subexpressions, such as ^(foo)?bar. This would lead to incorrect index optimization of searches for such patterns.
Fix bugs with parsing signed hh:mm and hh:mm:ss fields in interval constants (Amit Kapila, Tom Lane)
Use Postgres' encoding conversion functions, not Python's, when converting a Python Unicode string to the server encoding in PL/Python (Jan Urbanski)
This avoids some corner-case problems, notably that Python doesn't support all the encodings Postgres does. A notable functional change is that if the server encoding is SQL_ASCII, you will get the UTF-8 representation of the string; formerly, any non-ASCII characters in the string would result in an error.
Fix mapping of PostgreSQL encodings to Python encodings in PL/Python (Jan Urbanski)
Report errors properly in contrib/xml2's
xslt_process() (Tom Lane)
Update time zone data files to tzdata release 2012e for DST law changes in Morocco and Tokelau
If you see anything in the documentation that is not correct, does not match your experience with the particular feature or requires further clarification, please use this form to report a documentation issue.