E.12.1. Migration to Version 8.4.2

A dump/restore is not required for those running 8.4.X. However, if you have any hash indexes, you should REINDEX them after updating to 8.4.2, to repair possible damage.

E.12.2. Changes

• Protect against indirect security threats caused by index functions changing session-local state (Gurjeet Singh, Tom)

  This change prevents allegedly-immutable index functions from possibly subverting a superuser's session (CVE-2009-4136).

• Reject SSL certificates containing an embedded null byte in the common name (CN) field (Magnus)

  This prevents unintended matching of a certificate to a server or client name during SSL validation (CVE-2009-4034).

• Fix hash index corruption (Tom)

  The 8.4 change that made hash indexes keep entries sorted by hash value failed to update the bucket splitting and compaction routines to preserve the ordering. So application of either of those operations could lead to permanent corruption of an index, in the sense that searches might fail to find entries that are present. To deal with this, it is recommended to REINDEX any hash indexes you may have after installing this update.

• Fix possible crash during backend-startup-time cache initialization (Tom)

• Avoid crash on empty thesaurus dictionary (Tom)

• Prevent signals from interrupting VACUUM at unsafe times (Alvaro)

  This fix prevents a PANIC if a VACUUM FULL is cancelled after it's already committed its tuple movements, as well as transient errors if a plain VACUUM is interrupted after having truncated the table.

• Fix possible crash due to integer overflow in hash table size calculation (Tom)

  This could occur with extremely large planner estimates for the size of a hashjoin's result.

• Fix crash if a DROP is attempted on an internally-dependent object (Tom)

• Fix very rare crash in inet/cidr comparisons (Chris Mikkelson)

• Ensure that shared tuple-level locks held by prepared transactions are not ignored (Heikki)

• Fix premature drop of temporary files used for a cursor that is accessed within a subtransaction (Heikki)

• Fix memory leak in syslogger process when rotating to a new CSV logfile (Tom)

• Fix memory leak in postmaster when re-parsing pg_hba.conf (Tom)

• Fix Windows permission-downgrade logic (Jesse Morris)

  This fixes some cases where the database failed to start on Windows, often with misleading error messages such as "could not locate matching postgres executable".

• Make FOR UPDATE/SHARE in the primary query not propagate into WITH queries (Tom)

  For example, in

  WITH w AS (SELECT * FROM foo) SELECT * FROM w, bar ... FOR UPDATE

  the FOR UPDATE will now affect bar but not foo. This is more useful and consistent than the original 8.4 behavior, which tried to propagate FOR UPDATE into the WITH query but always failed due to assorted implementation restrictions. It also follows the design rule that WITH queries are executed as if independent of the main query.

• Fix bug with a WITH RECURSIVE query immediately inside another one (Tom)

• Fix concurrency bug in hash indexes (Tom)

  Concurrent insertions could cause index scans to transiently report wrong results.

• Fix incorrect logic for GiST index page splits, when the split depends on a non-first column of the index (Paul Ramsey)

• Fix wrong search results for a multi-column GIN index with fastupdate enabled (Teodor)

• Fix bugs in WAL entry creation for GIN indexes (Tom)

  These bugs were masked when full_page_writes was on, but with it off a WAL replay failure was certain if a crash occurred before the next checkpoint.

• Don't error out if recycling or removing an old WAL file fails at the end of checkpoint (Heikki)

  It's better to treat the problem as non-fatal and allow the checkpoint to complete. Future checkpoints will retry the removal. Such problems are not expected in normal operation, but have been seen to be caused by misdesigned Windows anti-virus and backup software.

• Ensure WAL files aren't repeatedly archived on Windows (Heikki)

  This is another symptom that could happen if some other process interfered with deletion of a no-longer-needed file.

• Fix PAM password processing to be more robust (Tom)

  The previous code is known to fail with the combination of the Linux pam_krb5 PAM module with Microsoft Active Directory as the domain controller. It might have problems elsewhere too, since it was making unjustified assumptions about what arguments the PAM stack would pass to it.

• Raise the maximum authentication token (Kerberos ticket) size in GSSAPI and SSPI authentication methods (Ian Turner)

  While the old 2000-byte limit was more than enough for Unix Kerberos implementations, tickets issued by Windows Domain Controllers can be much larger.

• Ensure that domain constraints are enforced in constructs like ARRAY[...]::domain, where the domain is over an array type (Heikki)

• Fix foreign-key logic for some cases involving composite-type columns as foreign keys (Tom)

• Ensure that a cursor's snapshot is not modified after it is created (Alvaro)

  This could lead to a cursor delivering wrong results if later operations in the same transaction modify the data the cursor is supposed to return.

• Fix CREATE TABLE to properly merge default expressions coming from different inheritance parent tables (Tom)

  This used to work but was broken in 8.4.

• Re-enable collection of access statistics for sequences (Akira Kurosawa)

  This used to work but was broken in 8.3.

• Fix processing of ownership dependencies during CREATE OR REPLACE FUNCTION (Tom)

• Fix incorrect handling of WHERE x=x conditions (Tom)

  In some cases these could get ignored as redundant, but they aren't — they're equivalent to x IS NOT NULL.

• Fix incorrect plan construction when using hash aggregation to implement DISTINCT for textually identical volatile expressions (Tom)

• Fix Assert failure for a volatile SELECT DISTINCT ON expression (Tom)

• Fix ts_stat() to not fail on an empty tsvector value (Tom)

• Make text search parser accept underscores in XML attributes (Peter)

• Fix encoding handling in xml binary input (Heikki)

  If the XML header doesn't specify an encoding, we now assume UTF-8 by default; the previous handling was inconsistent.

• Fix bug with calling plperl from plperlu or vice versa (Tom)

  An error exit from the inner function could result in crashes due to failure to re-select the correct Perl interpreter for the outer function.

• Fix session-lifespan memory leak when a PL/Perl function is redefined (Tom)

• Ensure that Perl arrays are properly converted to PostgreSQL arrays when returned by a set-returning PL/Perl function (Andrew Dunstan, Abhijit Menon-Sen)

  This worked correctly already for non-set-returning functions.

• Fix rare crash in exception processing in PL/Python (Peter)

• Fix ecpg problem with comments in DECLARE CURSOR statements (Michael)

• Fix ecpg to not treat recently-added keywords as reserved words (Tom)

  This affected the keywords CALLED, CATALOG, DEFINER, ENUM, FOLLOWING, INVOKER, OPTIONS, PARTITION, PRECEDING, RANGE, SECURITY, SERVER, UNBOUNDED, and WRAPPER.

• Re-allow regular expression special characters in psql's \df function name parameter (Tom)

• In contrib/fuzzystrmatch, correct the calculation of levenshtein distances with non-default costs (Marcin Mank)

• In contrib/pg_standby, disable triggering failover with a signal on Windows (Fujii Masao)

  This never did anything useful, because Windows doesn't have Unix-style signals, but recent changes made it actually crash.

• Put FREEZE and VERBOSE options in the right order in the VACUUM command that contrib/vacuumdb produces (Heikki)

• Fix possible leak of connections when contrib/dblink encounters an error (Tatsuhito Kasahara)

• Ensure psql's flex module is compiled with the correct system header definitions (Tom)

  This fixes build failures on platforms where --enable-largefile causes incompatible changes in the generated code.

• Make the postmaster ignore any application_name parameter in connection request packets, to improve compatibility with future libpq versions (Tom)

• Update the timezone abbreviation files to match current reality (Joachim Wieland)

  This includes adding IDT to the default timezone abbreviation set.

• Update time zone data files to tzdata release 2009s for DST law changes in Antarctica, Argentina, Bangladesh, Fiji, Novokuznetsk, Pakistan, Palestine, Samoa, Syria; also historical corrections for Hong Kong.