This release contains a variety of fixes from 9.0.2. For information about new features in the 9.0 major release, see Section E.14, « Release 9.0 ».
A dump/restore is not required for those running 9.0.X.
Before exiting walreceiver, ensure all the received WAL is fsync'd to disk (Heikki Linnakangas)
Otherwise the standby server could replay some un-synced WAL, conceivably leading to data corruption if the system crashes just at that point.
Avoid excess fsync activity in walreceiver (Heikki Linnakangas)
Make ALTER TABLE revalidate uniqueness and exclusion constraints when needed (Noah Misch)
This was broken in 9.0 by a change that was intended to suppress revalidation during VACUUM FULL and CLUSTER, but unintentionally affected ALTER TABLE as well.
Fix EvalPlanQual for UPDATE of an inheritance tree in which the tables are not all alike (Tom Lane)
Any variation in the table row types (including dropped columns present in only some child tables) would confuse the EvalPlanQual code, leading to misbehavior or even crashes. Since EvalPlanQual is only executed during concurrent updates to the same row, the problem was only seen intermittently.
Avoid failures when EXPLAIN tries to display a simple-form CASE expression (Tom Lane)
If the CASE's test expression was a constant, the planner could simplify the CASE into a form that confused the expression-display code, resulting in « unexpected CASE WHEN clause » errors.
Fix assignment to an array slice that is before the existing range of subscripts (Tom Lane)
If there was a gap between the newly added subscripts and the first pre-existing subscript, the code miscalculated how many entries needed to be copied from the old array's null bitmap, potentially leading to data corruption or crash.
Avoid unexpected conversion overflow in planner for very distant date values (Tom Lane)
The date type supports a wider range of dates than can be represented by the timestamp types, but the planner assumed it could always convert a date to timestamp with impunity.
Fix PL/Python crash when an array contains null entries (Alex Hunsaker)
Remove ecpg's fixed length limit for constants defining an array dimension (Michael Meskes)
Fix erroneous parsing of tsquery values containing ... & !(subexpression) | ... (Tom Lane)
Queries containing this combination of operators were not executed correctly. The same error existed in contrib/intarray's query_int type and contrib/ltree's ltxtquery type.
Fix buffer overrun in contrib/intarray's input function for the query_int type (Apple)
This bug is a security risk since the function's return address could be overwritten. Thanks to Apple Inc's security team for reporting this issue and supplying the fix. (CVE-2010-4015)
Fix bug in contrib/seg's GiST picksplit algorithm (Alexander Korotkov)
This could result in considerable inefficiency, though not actually incorrect answers, in a GiST index on a seg column. If you have such an index, consider REINDEXing it after installing this update. (This is identical to the bug that was fixed in contrib/cube in the previous update.)