PostgreSQL 9.1.24 Documentation
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# E.5. Release 9.1.20

> Release Date: 2016-02-11

This release contains a variety of fixes from 9.1.19. For information about new features in the 9.1 major release, see Section E.25.

## E.5.1. Migration to Version 9.1.20

A dump/restore is not required for those running 9.1.X.

However, if you are upgrading from a version earlier than 9.1.16, see Section E.9.

## E.5.2. Changes

- Fix infinite loops and buffer-overrun problems in regular expressions (Tom Lane)

  Very large character ranges in bracket expressions could cause infinite loops in some cases, and memory overwrites in other cases. (CVE-2016-0773)

- Perform an immediate shutdown if the `postmaster.pid` file is removed (Tom Lane)

  The postmaster now checks every minute or so that `postmaster.pid` is still there and still contains its own PID. If not, it performs an immediate shutdown, as though it had received SIGQUIT. The main motivation for this change is to ensure that failed buildfarm runs will get cleaned up without manual intervention; but it also serves to limit the bad effects if a DBA forcibly removes `postmaster.pid` and then starts a new postmaster.

- In `SERIALIZABLE` transaction isolation mode, serialization anomalies could be missed due to race conditions during insertions (Kevin Grittner, Thomas Munro)

- Fix failure to emit appropriate WAL records when doing `ALTER TABLE ... SET TABLESPACE` for unlogged relations (Michael Paquier, Andres Freund)

  Even though the relation's data is unlogged, the move must be logged or the relation will be inaccessible after a standby is promoted to master.

- Fix possible misinitialization of unlogged relations at the end of crash recovery (Andres Freund, Michael Paquier)

- Fix `ALTER COLUMN TYPE` to reconstruct inherited check constraints properly (Tom Lane)

- Fix `REASSIGN OWNED` to change ownership of composite types properly (Álvaro Herrera)

- Fix `REASSIGN OWNED` and `ALTER OWNER` to correctly update granted-permissions lists when changing owners of data types, foreign data wrappers, or foreign servers (Bruce Momjian, Álvaro Herrera)

- Fix `REASSIGN OWNED` to ignore foreign user mappings, rather than fail (Álvaro Herrera)

- Add more defenses against bad planner cost estimates for GIN index scans when the index's internal statistics are very out-of-date (Tom Lane)

- Make planner cope with hypothetical GIN indexes suggested by an index advisor plug-in (Julien Rouhaud)

- Fix dumping of whole-row Vars in `ROW()` and `VALUES()` lists (Tom Lane)

- Fix possible internal overflow in `numeric` division (Dean Rasheed)

- Fix enforcement of restrictions inside parentheses within regular expression lookahead constraints (Tom Lane)

  Lookahead constraints aren't allowed to contain backrefs, and parentheses within them are always considered non-capturing, according to the manual. However, the code failed to handle these cases properly inside a parenthesized subexpression, and would give unexpected results.

- Conversion of regular expressions to indexscan bounds could produce incorrect bounds from regexps containing lookahead constraints (Tom Lane)

- Fix regular-expression compiler to handle loops of constraint arcs (Tom Lane)

  The code added for CVE-2007-4772 was both incomplete, in that it didn't handle loops involving more than one state, and incorrect, in that it could cause assertion failures (though there seem to be no bad consequences of that in a non-assert build). Multi-state loops would cause the compiler to run until the query was canceled or it reached the too-many-states error condition.

- Improve memory-usage accounting in regular-expression compiler (Tom Lane)

  This causes the code to emit "regular expression is too complex" errors in some cases that previously used unreasonable amounts of time and memory.

- Improve performance of regular-expression compiler (Tom Lane)

- Make `%h` and `%r` escapes in `log_line_prefix` work for messages emitted due to `log_connections` (Tom Lane)

  Previously, `%h`/`%r` started to work just after a new session had emitted the "connection received" log message; now they work for that message too.

- On Windows, ensure the shared-memory mapping handle gets closed in child processes that don't need it (Tom Lane, Amit Kapila)

  This oversight resulted in failure to recover from crashes whenever `logging_collector` is turned on.

- Fix possible failure to detect socket EOF in non-blocking mode on Windows (Tom Lane)

  It's not entirely clear whether this problem can happen in pre-9.5 branches, but if it did, the symptom would be that a walsender process would wait indefinitely rather than noticing a loss of connection.

- Avoid leaking a token handle during SSPI authentication (Christian Ullrich)

- In psql, ensure that libreadline's idea of the screen size is updated when the terminal window size changes (Merlin Moncure)

  Previously, libreadline did not notice if the window was resized during query output, leading to strange behavior during later input of multiline queries.

- Fix psql's `\det` command to interpret its pattern argument the same way as other `\d` commands with potentially schema-qualified patterns do (Reece Hart)

- Avoid possible crash in psql's `\c` command when previous connection was via Unix socket and command specifies a new hostname and same username (Tom Lane)

- In `pg_ctl start -w`, test child process status directly rather than relying on heuristics (Tom Lane, Michael Paquier)

  Previously, pg_ctl relied on an assumption that the new postmaster would always create `postmaster.pid` within five seconds. But that can fail on heavily-loaded systems, causing pg_ctl to report incorrectly that the postmaster failed to start.

  Except on Windows, this change also means that a `pg_ctl start -w` done immediately after another such command will now reliably fail, whereas previously it would report success if done within two seconds of the first command.

- In `pg_ctl start -w`, don't attempt to use a wildcard listen address to connect to the postmaster (Kondo Yuta)

  On Windows, pg_ctl would fail to detect postmaster startup if `listen_addresses` is set to `0.0.0.0` or `::`, because it would try to use that value verbatim as the address to connect to, which doesn't work. Instead assume that `127.0.0.1` or `::1`, respectively, is the right thing to use.

- In pg_ctl on Windows, check service status to decide where to send output, rather than checking if standard output is a terminal (Michael Paquier)

- In pg_dump and pg_basebackup, adopt the GNU convention for handling tar-archive members exceeding 8GB (Tom Lane)

  The POSIX standard for `tar` file format does not allow archive member files to exceed 8GB, but most modern implementations of tar support an extension that fixes that. Adopt this extension so that pg_dump with `-Ft` no longer fails on tables with more than 8GB of data, and so that pg_basebackup can handle files larger than 8GB. In addition, fix some portability issues that could cause failures for members between 4GB and 8GB on some platforms. Potentially these problems could cause unrecoverable data loss due to unreadable backup files.

- Fix assorted corner-case bugs in pg_dump's processing of extension member objects (Tom Lane)

- Make pg_dump mark a view's triggers as needing to be processed after its rule, to prevent possible failure during parallel pg_restore (Tom Lane)

- Ensure that relation option values are properly quoted in pg_dump (Kouhei Sutou, Tom Lane)

  A reloption value that isn't a simple identifier or number could lead to dump/reload failures due to syntax errors in CREATE statements issued by pg_dump. This is not an issue with any reloption currently supported by core PostgreSQL, but extensions could allow reloptions that cause the problem.

- Fix pg_upgrade's file-copying code to handle errors properly on Windows (Bruce Momjian)

- Install guards in pgbench against corner-case overflow conditions during evaluation of script-specified division or modulo operators (Fabien Coelho, Michael Paquier)

- Prevent certain PL/Java parameters from being set by non-superusers (Noah Misch)

  This change mitigates a PL/Java security bug (CVE-2016-0766), which was fixed in PL/Java by marking these parameters as superuser-only. To fix the security hazard for sites that update PostgreSQL more frequently than PL/Java, make the core code aware of them also.

- Improve libpq's handling of out-of-memory situations (Michael Paquier, Amit Kapila, Heikki Linnakangas)

- Fix order of arguments in ecpg-generated `typedef` statements (Michael Meskes)

- Use `%g` not `%f` format in ecpg's `PGTYPESnumeric_from_double()` (Tom Lane)

- Fix ecpg-supplied header files to not contain comments continued from a preprocessor directive line onto the next line (Michael Meskes)

  Such a comment is rejected by ecpg. It's not yet clear whether ecpg itself should be changed.

- Ensure that `contrib/pgcrypto`'s `crypt()` function can be interrupted by query cancel (Andreas Karlsson)

- Accept flex versions later than 2.5.x (Tom Lane, Michael Paquier)

  Now that flex 2.6.0 has been released, the version checks in our build scripts needed to be adjusted.

- Install our `missing` script where PGXS builds can find it (Jim Nasby)

  This allows sane behavior in a PGXS build done on a machine where build tools such as bison are missing.

- Ensure that `dynloader.h` is included in the installed header files in MSVC builds (Bruce Momjian, Michael Paquier)

- Add variant regression test expected-output file to match behavior of current libxml2 (Tom Lane)

  The fix for libxml2's CVE-2015-7499 causes it not to output error context reports in some cases where it used to do so. This seems to be a bug, but we'll probably have to live with it for some time, so work around it.

- Update time zone data files to tzdata release 2016a for DST law changes in Cayman Islands, Metlakatla, and Trans-Baikal Territory (Zabaykalsky Krai), plus historical corrections for Pakistan.

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