This release contains a variety of fixes from 9.0.7. For information about new features in the 9.0 major release, see Section E.24, « Release 9.0 ».
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 the release notes for 9.0.6.
Fix incorrect password transformation in contrib/pgcrypto's DES crypt() function (Solar Designer)
If a password string contained the byte value 0x80, the remainder of the password was ignored, causing the password to be much weaker than it appeared. With this fix, the rest of the string is properly included in the DES hash. Any stored password values that are affected by this bug will thus no longer match, so the stored values may need to be updated. (CVE-2012-2143)
Ignore SECURITY DEFINER and SET attributes for a procedural language's call handler (Tom Lane)
Applying such attributes to a call handler could crash the server. (CVE-2012-2655)
Allow numeric timezone offsets in timestamp input to be up to 16 hours away from UTC (Tom Lane)
Some historical time zones have offsets larger than 15 hours, the previous limit. This could result in dumped data values being rejected during reload.
Fix timestamp conversion to cope when the given time is exactly the last DST transition time for the current timezone (Tom Lane)
This oversight has been there a long time, but was not noticed previously because most DST-using zones are presumed to have an indefinite sequence of future DST transitions.
Fix text to name and char to name casts to perform string truncation correctly in multibyte encodings (Karl Schnaitter)
Fix memory copying bug in to_tsquery() (Heikki Linnakangas)
Ensure txid_current() reports the correct epoch when executed in hot standby (Simon Riggs)
Fix planner's handling of outer PlaceHolderVars within subqueries (Tom Lane)
This bug concerns sub-SELECTs that reference variables coming from the nullable side of an outer join of the surrounding query. In 9.1, queries affected by this bug would fail with « ERROR: Upper-level PlaceHolderVar found where not expected ». But in 9.0 and 8.4, you'd silently get possibly-wrong answers, since the value transmitted into the subquery wouldn't go to null when it should.
Fix slow session startup when pg_attribute is very large (Tom Lane)
If pg_attribute exceeds one-fourth of shared_buffers, cache rebuilding code that is sometimes needed during session start would trigger the synchronized-scan logic, causing it to take many times longer than normal. The problem was particularly acute if many new sessions were starting at once.
Ensure sequential scans check for query cancel reasonably often (Merlin Moncure)
A scan encountering many consecutive pages that contain no live tuples would not respond to interrupts meanwhile.
Ensure the Windows implementation of PGSemaphoreLock() clears ImmediateInterruptOK before returning (Tom Lane)
This oversight meant that a query-cancel interrupt received later in the same query could be accepted at an unsafe time, with unpredictable but not good consequences.
Show whole-row variables safely when printing views or rules (Abbas Butt, Tom Lane)
Corner cases involving ambiguous names (that is, the name could be either a table or column name of the query) were printed in an ambiguous way, risking that the view or rule would be interpreted differently after dump and reload. Avoid the ambiguous case by attaching a no-op cast.
Fix COPY FROM to properly handle null marker strings that correspond to invalid encoding (Tom Lane)
A null marker string such as E'\\0' should work, and did work in the past, but the case got broken in 8.4.
Ensure autovacuum worker processes perform stack depth checking properly (Heikki Linnakangas)
Previously, infinite recursion in a function invoked by auto-ANALYZE could crash worker processes.
Fix logging collector to not lose log coherency under high load (Andrew Dunstan)
The collector previously could fail to reassemble large messages if it got too busy.
Fix logging collector to ensure it will restart file rotation after receiving SIGHUP (Tom Lane)
Fix WAL replay logic for GIN indexes to not fail if the index was subsequently dropped (Tom Lane)
Fix memory leak in PL/pgSQL's RETURN NEXT command (Joe Conway)
Fix PL/pgSQL's GET DIAGNOSTICS command when the target is the function's first variable (Tom Lane)
Fix potential access off the end of memory in psql's expanded display (\x) mode (Peter Eisentraut)
Fix several performance problems in pg_dump when the database contains many objects (Jeff Janes, Tom Lane)
pg_dump could get very slow if the database contained many schemas, or if many objects are in dependency loops, or if there are many owned sequences.
Fix pg_upgrade for the case that a database stored in a non-default tablespace contains a table in the cluster's default tablespace (Bruce Momjian)
In ecpg, fix rare memory leaks and possible overwrite of one byte after the sqlca_t structure (Peter Eisentraut)
Fix contrib/dblink's dblink_exec() to not leak temporary database connections upon error (Tom Lane)
Fix contrib/dblink to report the correct connection name in error messages (Kyotaro Horiguchi)
Fix contrib/vacuumlo to use multiple transactions when dropping many large objects (Tim Lewis, Robert Haas, Tom Lane)
This change avoids exceeding max_locks_per_transaction when many objects need to be dropped. The behavior can be adjusted with the new -l (limit) option.
Update time zone data files to tzdata release 2012c for DST law changes in Antarctica, Armenia, Chile, Cuba, Falkland Islands, Gaza, Haiti, Hebron, Morocco, Syria, and Tokelau Islands; also historical corrections for Canada.