E.48. Version 8.1

Amélioration des performances des index GiST et R-tree (Neil)

Amélioration de l'optimiseur, ceci incluant le redimensionnement automatique des jointures hash (Tom)

Révision de l'API interne sur plusieurs domaines

Changement des CRC, passés de 64 à 32 bits, pour l'enregistrement des WAL (Tom)

Nous avons déterminé que le coût supplémentaire du calcul des CRC en 64 bits était important et que le gain en fiabilité était trop marginal pour le justifier.

Empêche la création de gros trous vides dans les pages WAL (Tom)

Amélioration du comportement du spinlock sur les machines SMP, particulièrement pour les Opterons (Tom)

Autorise l'utilisation de colonnes non consécutives d'un index dans un index multicolonnes (Tom)

Par exemple, cela permet l'utilisation d'un index sur les colonnes a, b, c dans une requête dont le filtre est WHERE a = 4 and c = 10.

Passe la journalisation WAL pour CREATE TABLE AS / SELECT INTO (Simon)

Comme l'arrêt brutal durant un CREATE TABLE AS occasionnera la suppression de la table lors de l'opération de récupération, il n'y a aucune raison de conserver le chargement de la table dans les WAL. (Néanmoins, la journalisation se fait quand même si l'archivage des WAL est activé.)

Autorise l'accès en parallèle d'index GiST (Teodor, Oleg)

Ajout d'un paramètre de configuration full_page_writes pour contrôler l'écriture de pages complètes dans les WAL (Bruce)

Pour empêcher que des écritures disques partielles corrompent la base de données, PostgreSQL™ écrit une copie complète de chaque page disque de la base dans les WAL la première fois que la page est modifiée après un point de vérification. Cette option désactive cette fonctionnalité pour gagner en rapidité. Ceci ne doit pas poser de problème avec des caches disques sur batterie où des écritures partielles de page ne peuvent pas arriver.

Utilisation de O_DIRECT si disponible lors de l'utilisation de O_SYNC pour wal_sync_method (Itagaki Takahiro)

O_DIRECT fait que les écritures disques contournent le cache du noyau et cela améliore les performances pour les écritures des WAL.

Amélioration des performances du COPY FROM (Alon Goldshuv)

Ceci se fait en lisant l'entrée de COPY par de plus gros morceaux, plutôt que caractère par caractère.

Amélioration des performances de COUNT(), SUM, AVG(), STDDEV() et VARIANCE() (Neil, Tom)

Empêche les problèmes dûs à la réinitialisation de l'ID de transaction (XID) (Tom)

Maintenant, le serveur avertira quand le compteur de transaction approche du point de réinitialisation. Si le compteur s'en approche trop, le serveur refusera les requêtes. Ceci permet de s'assurer que des données ne seront pas perdues avant que le VACUUM nécessaire ne soit réalisé.

Correction de problèmes avec des conflits entre des identifiants d'objets (OID) et des objets systèmes existants une fois que le compteur d'OID s'est réinitialisé (Tom)

Ajout d'un avertissement sur le besoin d'augmenter max_fsm_relations et max_fsm_pages lors des VACUUM (Ron Mayer)

Ajout du paramètre de configuration temp_buffers autorisant les utilisateurs à déterminer la taille du tampon local pour les accès aux tables temporaires (Tom)

Ajout de l'heure de début de la session et de l'adresse IP du client dans pg_stat_activity (Magnus)

Ajustement des vues pg_stat pour les parcours de bitmap (Tom)

La signification de certains champs a changé légèrement.

Amélioration de la vue pg_locks (Tom)

Trace des requêtes côté client, PREPARE et EXECUTE (Simon)

Autorise l'indication de la sensibilité à la casse pour le nom Kerberos et le nom utilisateur dans postgresql.conf (Magnus)

Ajout du paramètre de configuration krb_server_hostname pour que le nom de l'hôte puisse être indiqué comme faisant parti du service principal (Todd Kover)

S'il n'est pas configuré, aucun service principal correspondant à une entrée dans la table des clés ne peut être utilisé. Ceci est le nouveau comportement de Kerberos pour cette version.

Ajout d'options pour log_line_prefix (datage à la milliseconde avec %m et hôte distant avec %h) (Ed L.)

Ajout des journaux WAL pour les index GiST (Teodor, Oleg)

Les index GiST sont maintenant fiables en ce qui concernent les arrêts brutaux et la récupération à un instant donné.

Suppression des anciens fichiers *.backup lors du pg_stop_backup() (Bruce)

Ceci empêche qu'un grand nombre de fichiers *.backup restent dans pg_xlog/.

Ajout des paramètres de configuration contrôlant certaines constantes keep-alive de TCP/IP (idle, interval et count) (Oliver Jowett)

Ces valeurs sont modifiables pour permettre une détection plus rapide de la perte de connexions clientes.

Ajout de limites de connexion par utilisateur et par base de données (Petr Jelinek)

En utilisant ALTER USER et ALTER DATABASE, des limites peuvent être enregistrées sur le nombre maximum de sessions connectées en même temps pour un utilisateur spécifique ou une base spécifique. Configurer la limite à zéro empêche l'utilisateur de se connecter ou empêche toute connexion sur cette base.

Autorise plus de 2 Go de mémoire partagé et de work_memory par processus serveur sur les machines 64 bits (Koichi Suzuki)

Le nouveau catalogue système pg_pltemplate permet la surcharge des définitions obsolètes de langages de procédures dans les sauvegardes (Tom)

Ajout des vues temporaires (Koju Iijima, Neil)

Correction de HAVING sans fonctions d'agrégat ou GROUP BY pour que la requête ne renvoit qu'un seul groupe (Tom)

Auparavant, la clause HAVING aurait été traitée comme une clause WHERE. Ce n'était pas conforme au standard.

Ajout de la clause USING pour indiquer des tables supplémentaires dans une commande DELETE (Euler Taveira de Oliveira, Neil)

Dans les versions précédentes, il n'existait pas de méthode claire pour utiliser des tables supplémentaires dans des jointures sur une instruction DELETE. UPDATE a déjà une clause FROM pour remplir ce but.

Ajout du support de \x pour les échappements de nombres en hexadécimal dans les chaînes du moteur et dans celles d'ecpg (Bruce)

Cela fonctionne comme la syntaxe d'échappement \x en C. Les échappements de nombres en octal sont déjà supportés.

Ajout de la syntaxe de requête BETWEEN SYMMETRIC (Pavel Stehule)

Cette fonctionnalité autorise l'utilisation de comparaisons BETWEEN sans nécessiter que la première valeur soit inférieure à la seconde. Par exemple, 2 BETWEEN [ASYMMETRIC] 3 AND 1 renvoie faux alors que 2 BETWEEN SYMMETRIC 3 AND 1 renvoie vrai. BETWEEN ASYMMETRIC était déjà supporté.

Ajout de l'option NOWAIT pour SELECT ... FOR UPDATE/SHARE (Hans-Juergen Schoenig)

Bien que le paramètre de configuration statement_timeout autorise l'annulation d'une requête prenant plus d'un certain temps à s'exécuter, l'option NOWAIT permet l'annulation d'une requête à partir du moment où la commande SELECT ... FOR UPDATE/SHARE n'acquiert pas immédiatement un verrou de ligne.

Trace les dépendances des objets partagés (Alvaro)

PostgreSQL™ allows global tables (users, databases, tablespaces) to reference information in multiple databases. This addition adds dependency information for global tables, so, for example, user ownership can be tracked across databases, so a user who owns something in any database can no longer be removed. Dependency tracking already existed for database-local objects.

Allow limited ALTER OWNER commands to be performed by the object owner (Stephen Frost)

Prior releases allowed only superusers to change object owners. Now, ownership can be transferred if the user executing the command owns the object and would be able to create it as the new owner (that is, the user is a member of the new owning role and that role has the CREATE permission that would be needed to create the object afresh).

Add ALTER object SET SCHEMA capability for some object types (tables, functions, types) (Bernd Helmle)

This allows objects to be moved to different schemas.

Ajout de ALTER TABLE ENABLE/DISABLE TRIGGER pour désactiver les déclencheurs (Satoshi Nagayasu)

Allow TRUNCATE to truncate multiple tables in a single command (Alvaro)

Because of referential integrity checks, it is not allowed to truncate a table that is part of a referential integrity constraint. Using this new functionality, TRUNCATE can be used to truncate such tables, if both tables involved in a referential integrity constraint are truncated in a single TRUNCATE command.

Properly process carriage returns and line feeds in COPY CSV mode (Andrew)

In release 8.0, carriage returns and line feeds in CSV COPY TO were processed in an inconsistent manner. (This was documented on the TODO list.)

Add COPY WITH CSV HEADER to allow a header line as the first line in COPY (Andrew)

This allows handling of the common CSV usage of placing the column names on the first line of the data file. For COPY TO, the first line contains the column names, and for COPY FROM, the first line is ignored.

On Windows, display better sub-second precision in EXPLAIN ANALYZE (Magnus)

Add trigger duration display to EXPLAIN ANALYZE (Tom)

Prior releases included trigger execution time as part of the total execution time, but did not show it separately. It is now possible to see how much time is spent in each trigger.

Add support for \x hex escapes in COPY (Sergey Ten)

Previous releases only supported octal escapes.

Make SHOW ALL include variable descriptions (Matthias Schmidt)

SHOW varname still only displays the variable's value and does not include the description.

Make initdb create a new standard database called postgres, and convert utilities to use postgres rather than template1 for standard lookups (Dave)

In prior releases, template1 was used both as a default connection for utilities like createuser, and as a template for new databases. This caused CREATE DATABASE to sometimes fail, because a new database cannot be created if anyone else is in the template database. With this change, the default connection database is now postgres, meaning it is much less likely someone will be using template1 during CREATE DATABASE.

Create new reindexdb command-line utility by moving /contrib/reindexdb into the server (Euler Taveira de Oliveira)

Add MAX() and MIN() aggregates for array types (Koju Iijima)

Fix to_date() and to_timestamp() to behave reasonably when CC and YY fields are both used (Karel Zak)

If the format specification contains CC and a year specification is YYY or longer, ignore the CC. If the year specification is YY or shorter, interpret CC as the previous century.

Add md5(bytea) (Abhijit Menon-Sen)

md5(text) already existed.

Add support for numeric ^ numeric based on power(numeric, numeric)

The function already existed, but there was no operator assigned to it.

Fix NUMERIC modulus by properly truncating the quotient during computation (Bruce)

In previous releases, modulus for large values sometimes returned negative results due to rounding of the quotient.

Add a function lastval()(Dennis Björklund)

lastval() is a simplified version of currval(). It automatically determines the proper sequence name based on the most recent nextval() or setval() call performed by the current session.

Add to_timestamp(DOUBLE PRECISION) (Michael Glaesemann)

Converts Unix seconds since 1970 to a TIMESTAMP WITH TIMEZONE.

Add pg_postmaster_start_time() function (Euler Taveira de Oliveira, Matthias Schmidt)

Allow the full use of time zone names in AT TIME ZONE, not just the short list previously available (Magnus)

Previously, only a predefined list of time zone names were supported by AT TIME ZONE. Now any supported time zone name can be used, e.g.:

         SELECT CURRENT_TIMESTAMP AT TIME ZONE 'Europe/London';
        

In the above query, the time zone used is adjusted based on the daylight saving time rules that were in effect on the supplied date.

Add GREATEST() and LEAST() variadic functions (Pavel Stehule)

These functions take a variable number of arguments and return the greatest or least value among the arguments.

Add pg_column_size() (Mark Kirkwood)

This returns storage size of a column, which might be compressed.

Add regexp_replace() (Atsushi Ogawa)

This allows regular expression replacement, like sed. An optional flag argument allows selection of global (replace all) and case-insensitive modes.

Fix interval division and multiplication (Bruce)

Previous versions sometimes returned unjustified results, like '4 months'::interval / 5 returning '1 mon -6 days'.

Fix roundoff behavior in timestamp, time, and interval output (Tom)

This fixes some cases in which the seconds field would be shown as 60 instead of incrementing the higher-order fields.

Add a separate day field to type interval so a one day interval can be distinguished from a 24 hour interval (Michael Glaesemann)

Days that contain a daylight saving time adjustment are not 24 hours long, but typically 23 or 25 hours. This change creates a conceptual distinction between intervals of « so many days » and intervals of « so many hours ». Adding 1 day to a timestamp now gives the same local time on the next day even if a daylight saving time adjustment occurs between, whereas adding 24 hours will give a different local time when this happens. For example, under US DST rules:

         '2005-04-03 00:00:00-05' + '1 day' = '2005-04-04 00:00:00-04'
         '2005-04-03 00:00:00-05' + '24 hours' = '2005-04-04 01:00:00-04'
        

Add justify_days() and justify_hours() (Michael Glaesemann)

These functions, respectively, adjust days to an appropriate number of full months and days, and adjust hours to an appropriate number of full days and hours.

Move /contrib/dbsize into the backend, and rename some of the functions (Dave Page, Andreas Pflug)

pg_total_relation_size() includes indexes and TOAST tables.

Add functions for read-only file access to the cluster directory (Dave Page, Andreas Pflug)

Add pg_reload_conf() to force reloading of the configuration files (Dave Page, Andreas Pflug)

Add pg_rotate_logfile() to force rotation of the server log file (Dave Page, Andreas Pflug)

Change pg_stat_* views to include TOAST tables (Tom)

Rename some encodings to be more consistent and to follow international standards (Bruce)

The original names still work.

Add support for WIN1252 encoding (Roland Volkmann)

Add support for four-byte UTF8 characters (John Hansen)

Previously only one, two, and three-byte UTF8 characters were supported. This is particularly important for support for some Chinese character sets.

Allow direct conversion between EUC_JP and SJIS to improve performance (Atsushi Ogawa)

Allow the UTF8 encoding to work on Windows (Magnus)

This is done by mapping UTF8 to the Windows-native UTF16 implementation.

Fix ALTER LANGUAGE RENAME (Sergey Yatskevich)

Allow function characteristics, like strictness and volatility, to be modified via ALTER FUNCTION (Neil)

Increase the maximum number of function arguments to 100 (Tom)

Allow SQL and PL/PgSQL functions to use OUT and INOUT parameters (Tom)

OUT is an alternate way for a function to return values. Instead of using RETURN, values can be returned by assigning to parameters declared as OUT or INOUT. This is notationally simpler in some cases, particularly so when multiple values need to be returned. While returning multiple values from a function was possible in previous releases, this greatly simplifies the process. (The feature will be extended to other server-side languages in future releases.)

Move language handler functions into the pg_catalog schema

This makes it easier to drop the public schema if desired.

Add SPI_getnspname() to SPI (Neil)

Overhaul the memory management of PL/PgSQL functions (Neil)

The parsetree of each function is now stored in a separate memory context. This allows this memory to be easily reclaimed when it is no longer needed.

Check function syntax at CREATE FUNCTION time, rather than at runtime (Neil)

Previously, most syntax errors were reported only when the function was executed.

Allow OPEN to open non-SELECT queries like EXPLAIN and SHOW (Tom)

No longer require functions to issue a RETURN statement (Tom)

This is a byproduct of the newly added OUT and INOUT functionality. RETURN can be omitted when it is not needed to provide the function's return value.

Add support for an optional INTO clause to PL/PgSQL's EXECUTE statement (Pavel Stehule, Neil)

Make CREATE TABLE AS set ROW_COUNT (Tom)

Define SQLSTATE and SQLERRM to return the SQLSTATE and error message of the current exception (Pavel Stehule, Neil)

These variables are only defined inside exception blocks.

Allow the parameters to the RAISE statement to be expressions (Pavel Stehule, Neil)

Add a loop CONTINUE statement (Pavel Stehule, Neil)

Allow block and loop labels (Pavel Stehule)

Allow large result sets to be returned efficiently (Abhijit Menon-Sen)

This allows functions to use return_next() to avoid building the entire result set in memory.

Allow one-row-at-a-time retrieval of query results (Abhijit Menon-Sen)

This allows functions to use spi_query() and spi_fetchrow() to avoid accumulating the entire result set in memory.

Force PL/Perl to handle strings as UTF8 if the server encoding is UTF8 (David Kamholz)

Add a validator function for PL/Perl (Andrew)

This allows syntax errors to be reported at definition time, rather than execution time.

Allow PL/Perl to return a Perl array when the function returns an array type (Andrew)

This basically maps PostgreSQL™ arrays to Perl arrays.

Allow Perl nonfatal warnings to generate NOTICE messages (Andrew)

Allow Perl's strict mode to be enabled (Andrew)

Add \set ON_ERROR_ROLLBACK to allow statements in a transaction to error without affecting the rest of the transaction (Greg Sabino Mullane)

This is basically implemented by wrapping every statement in a sub-transaction.

Add support for \x hex strings in psql variables (Bruce)

Octal escapes were already supported.

Add support for troff -ms output format (Roger Leigh)

Allow the history file location to be controlled by HISTFILE (Andreas Seltenreich)

This allows configuration of per-database history storage.

Prevent \x (expanded mode) from affecting the output of \d tablename (Neil)

Add -L option to psql to log sessions (Lorne Sunley)

This option was added because some operating systems do not have simple command-line activity logging functionality.

Make \d show the tablespaces of indexes (Qingqing Zhou)

Allow psql help (\h) to make a best guess on the proper help information (Greg Sabino Mullane)

This allows the user to just add \h to the front of the syntax error query and get help on the supported syntax. Previously any additional query text beyond the command name had to be removed to use \h.

Add \pset numericlocale to allow numbers to be output in a locale-aware format (Eugen Nedelcu)

For example, using C locale 100000 would be output as 100,000.0 while a European locale might output this value as 100.000,0.

Make startup banner show both server version number and psql's version number, when they are different (Bruce)

Also, a warning will be shown if the server and psql are from different major releases.

Add -n / --schema switch to pg_restore (Richard van den Berg)

This allows just the objects in a specified schema to be restored.

Allow pg_dump to dump large objects even in text mode (Tom)

With this change, large objects are now always dumped; the former -b switch is a no-op.

Allow pg_dump to dump a consistent snapshot of large objects (Tom)

Dump comments for large objects (Tom)

Add --encoding to pg_dump (Magnus Hagander)

This allows a database to be dumped in an encoding that is different from the server's encoding. This is valuable when transferring the dump to a machine with a different encoding.

Rely on pg_pltemplate for procedural languages (Tom)

If the call handler for a procedural language is in the pg_catalog schema, pg_dump does not dump the handler. Instead, it dumps the language using just CREATE LANGUAGE name, relying on the pg_pltemplate catalog to provide the language's creation parameters at load time.

Add a PGPASSFILE environment variable to specify the password file's filename (Andrew)

Add lo_create(), that is similar to lo_creat() but allows the OID of the large object to be specified (Tom)

Make libpq consistently return an error to the client application on malloc() failure (Neil)

Fix pgxs to support building against a relocated installation

Add spinlock support for the Itanium processor using Intel compiler (Vikram Kalsi)

Add Kerberos 5 support for Windows (Magnus)

Add Chinese FAQ (laser@pgsqldb.com)

Rename Rendezvous to Bonjour to match OS/X feature renaming (Bruce)

Add support for fsync_writethrough on Darwin (Chris Campbell)

Streamline the passing of information within the server, the optimizer, and the lock system (Tom)

Allow pg_config to be compiled using MSVC (Andrew)

This is required to build DBD::Pg using MSVC.

Remove support for Kerberos V4 (Magnus)

Kerberos 4 had security vulnerabilities and is no longer maintained.

Code cleanups (Coverity static analysis performed by EnterpriseDB)

Modify postgresql.conf to use documentation defaults on/off rather than true/false (Bruce)

Enhance pg_config to be able to report more build-time values (Tom)

Allow libpq to be built thread-safe on Windows (Dave Page)

Allow IPv6 connections to be used on Windows (Andrew)

Add Server Administration documentation about I/O subsystem reliability (Bruce)

Move private declarations from gist.h to gist_private.h (Neil)

In previous releases, gist.h contained both the public GiST API (intended for use by authors of GiST index implementations) as well as some private declarations used by the implementation of GiST itself. The latter have been moved to a separate file, gist_private.h. Most GiST index implementations should be unaffected.

Overhaul GiST memory management (Neil)

GiST methods are now always invoked in a short-lived memory context. Therefore, memory allocated via palloc() will be reclaimed automatically, so GiST index implementations do not need to manually release allocated memory via pfree().

Ajout du module contrib /contrib/pg_buffercache (Mark Kirkwood)

Ceci affiche le contenu du cache tampon pour le débogage et pour des tests de performance.

Suppression de /contrib/array car il est devenu obsolète (Tom)

Nettoyage du module /contrib/lo (Tom)

Déplacement de /contrib/findoidjoins dans /src/tools (Tom)

Renommage des opérateurs <<, >>, &< et &> dans /contrib/cube

Ces opérateurs n'étaient plus utiles.

Amélioration de /contrib/btree_gist (Janko Richter)

Amélioration de /contrib/pgbench (Tomoaki Sato, Tatsuo)

Il existe maintenant une fonctionnalité pour tester avec des scripts SQL fournis par l'utilisateur, plutôt que par des séquences de commandes codées en dur.

Amélioration de /contrib/pgcrypto (Marko Kreen)