E.1.1. Migration to Version 9.0.23

A dump/restore is not required for those running 9.0.X.

However, if you are upgrading from a version earlier than 9.0.18, see Section E.6.

E.1.2. Changes

• Fix contrib/pgcrypto to detect and report too-short crypt() salts (Josh Kupershmidt)

  Certain invalid salt arguments crashed the server or disclosed a few bytes of server memory. We have not ruled out the viability of attacks that arrange for presence of confidential information in the disclosed bytes, but they seem unlikely. (CVE-2015-5288)

• Fix subtransaction cleanup after a portal (cursor) belonging to an outer subtransaction fails (Tom Lane, Michael Paquier)

  A function executed in an outer-subtransaction cursor could cause an assertion failure or crash by referencing a relation created within an inner subtransaction.

• Fix insertion of relations into the relation cache "init file" (Tom Lane)

  An oversight in a patch in the most recent minor releases caused pg_trigger_tgrelid_tgname_index to be omitted from the init file. Subsequent sessions detected this, then deemed the init file to be broken and silently ignored it, resulting in a significant degradation in session startup time. In addition to fixing the bug, install some guards so that any similar future mistake will be more obvious.

• Avoid O(N^2) behavior when inserting many tuples into a SPI query result (Neil Conway)

• Improve LISTEN startup time when there are many unread notifications (Matt Newell)

• Disable SSL renegotiation by default (Michael Paquier, Andres Freund)

  While use of SSL renegotiation is a good idea in theory, we have seen too many bugs in practice, both in the underlying OpenSSL library and in our usage of it. Renegotiation will be removed entirely in 9.5 and later. In the older branches, just change the default value of ssl_renegotiation_limit to zero (disabled).

• Lower the minimum values of the *_freeze_max_age parameters (Andres Freund)

  This is mainly to make tests of related behavior less time-consuming, but it may also be of value for installations with limited disk space.

• Limit the maximum value of wal_buffers to 2GB to avoid server crashes (Josh Berkus)

• Fix rare internal overflow in multiplication of numeric values (Dean Rasheed)

• Guard against hard-to-reach stack overflows involving record types, range types, json, jsonb, tsquery, ltxtquery and query_int (Noah Misch)

• Fix handling of DOW and DOY in datetime input (Greg Stark)

  These tokens aren't meant to be used in datetime values, but previously they resulted in opaque internal error messages rather than "invalid input syntax".

• Add more query-cancel checks to regular expression matching (Tom Lane)

• Add recursion depth protections to regular expression, SIMILAR TO, and LIKE matching (Tom Lane)

  Suitable search patterns and a low stack depth limit could lead to stack-overrun crashes.

• Fix potential infinite loop in regular expression execution (Tom Lane)

  A search pattern that can apparently match a zero-length string, but actually doesn't match because of a back reference, could lead to an infinite loop.

• Fix low-memory failures in regular expression compilation (Andreas Seltenreich)

• Fix low-probability memory leak during regular expression execution (Tom Lane)

• Fix rare low-memory failure in lock cleanup during transaction abort (Tom Lane)

• Fix "unexpected out-of-memory situation during sort" errors when using tuplestores with small work_mem settings (Tom Lane)

• Fix very-low-probability stack overrun in qsort (Tom Lane)

• Fix "invalid memory alloc request size" failure in hash joins with large work_mem settings (Tomas Vondra, Tom Lane)

• Fix assorted planner bugs (Tom Lane)

  These mistakes could lead to incorrect query plans that would give wrong answers, or to assertion failures in assert-enabled builds, or to odd planner errors such as "could not devise a query plan for the given query", "could not find pathkey item to sort", "plan should not reference subplan's variable", or "failed to assign all NestLoopParams to plan nodes". Thanks are due to Andreas Seltenreich and Piotr Stefaniak for fuzz testing that exposed these problems.

• Use fuzzy path cost tiebreaking rule in all supported branches (Tom Lane)

  This change is meant to avoid platform-specific behavior when alternative plan choices have effectively-identical estimated costs.

• During postmaster shutdown, ensure that per-socket lock files are removed and listen sockets are closed before we remove the postmaster.pid file (Tom Lane)

  This avoids race-condition failures if an external script attempts to start a new postmaster as soon as pg_ctl stop returns.

• Fix postmaster's handling of a startup-process crash during crash recovery (Tom Lane)

  If, during a crash recovery cycle, the startup process crashes without having restored database consistency, we'd try to launch a new startup process, which typically would just crash again, leading to an infinite loop.

• Do not print a WARNING when an autovacuum worker is already gone when we attempt to signal it, and reduce log verbosity for such signals (Tom Lane)

• Prevent autovacuum launcher from sleeping unduly long if the server clock is moved backwards a large amount (Álvaro Herrera)

• Ensure that cleanup of a GIN index's pending-insertions list is interruptable by cancel requests (Jeff Janes)

• Allow all-zeroes pages in GIN indexes to be reused (Heikki Linnakangas)

  Such a page might be left behind after a crash.

• Fix off-by-one error that led to otherwise-harmless warnings about "apparent wraparound" in subtrans/multixact truncation (Thomas Munro)

• Fix misreporting of CONTINUE and MOVE statement types in PL/pgSQL's error context messages (Pavel Stehule, Tom Lane)

• Fix some places in PL/Tcl that neglected to check for failure of malloc() calls (Michael Paquier, Álvaro Herrera)

• Improve libpq's handling of out-of-memory conditions (Michael Paquier, Heikki Linnakangas)

• Fix memory leaks and missing out-of-memory checks in ecpg (Michael Paquier)

• Fix psql's code for locale-aware formatting of numeric output (Tom Lane)

  The formatting code invoked by \pset numericlocale on did the wrong thing for some uncommon cases such as numbers with an exponent but no decimal point. It could also mangle already-localized output from the money data type.

• Prevent crash in psql's \c command when there is no current connection (Noah Misch)

• Ensure that temporary files created during a pg_dump run with tar-format output are not world-readable (Michael Paquier)

• Fix pg_dump and pg_upgrade to support cases where the postgres or template1 database is in a non-default tablespace (Marti Raudsepp, Bruce Momjian)

• Fix pg_dump to handle object privileges sanely when dumping from a server too old to have a particular privilege type (Tom Lane)

  When dumping functions or procedural languages from pre-7.3 servers, pg_dump would produce GRANT/REVOKE commands that revoked the owner's grantable privileges and instead granted all privileges to PUBLIC. Since the privileges involved are just USAGE and EXECUTE, this isn't a security problem, but it's certainly a surprising representation of the older systems' behavior. Fix it to leave the default privilege state alone in these cases.

• Fix pg_dump to dump shell types (Tom Lane)

  Shell types (that is, not-yet-fully-defined types) aren't useful for much, but nonetheless pg_dump should dump them.

• Fix spinlock assembly code for PPC hardware to be compatible with AIX's native assembler (Tom Lane)

  Building with gcc didn't work if gcc had been configured to use the native assembler, which is becoming more common.

• On AIX, test the -qlonglong compiler option rather than just assuming it's safe to use (Noah Misch)

• On AIX, use -Wl,-brtllib link option to allow symbols to be resolved at runtime (Noah Misch)

  Perl relies on this ability in 5.8.0 and later.

• Avoid use of inline functions when compiling with 32-bit xlc, due to compiler bugs (Noah Misch)

• Use librt for sched_yield() when necessary, which it is on some Solaris versions (Oskari Saarenmaa)

• Fix Windows install.bat script to handle target directory names that contain spaces (Heikki Linnakangas)

• Make the numeric form of the PostgreSQL version number (e.g., 90405) readily available to extension Makefiles, as a variable named VERSION_NUM (Michael Paquier)

• Update time zone data files to tzdata release 2015g for DST law changes in Cayman Islands, Fiji, Moldova, Morocco, Norfolk Island, North Korea, Turkey, and Uruguay. There is a new zone name America/Fort_Nelson for the Canadian Northern Rockies.