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> * -Consider shrinking expired tuples to just their headers > * -Allow heap reuse of UPDATEd rows if no indexed columns are changed, > and old and new versions are on the same heap page Not needed anymore: < * Reuse index tuples that point to heap tuples that are not visible to < anyone?
1603 lines
58 KiB
Plaintext
1603 lines
58 KiB
Plaintext
PostgreSQL TODO List
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====================
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Current maintainer: Bruce Momjian (bruce@momjian.us)
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Last updated: Thu Sep 20 14:53:32 EDT 2007
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The most recent version of this document can be viewed at
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http://www.postgresql.org/docs/faqs.TODO.html.
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#A hyphen, "-", marks changes that will appear in the upcoming 8.3 release.#
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#A percent sign, "%", marks items that are easier to implement.#
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Bracketed items, "[]", have more detail.
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This list contains all known PostgreSQL bugs and feature requests. If
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you would like to work on an item, please read the Developer's FAQ
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first. There is also a developer's wiki at
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http://developer.postgresql.org.
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Administration
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==============
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* Allow major upgrades without dump/reload, perhaps using pg_upgrade
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[pg_upgrade]
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* Check for unreferenced table files created by transactions that were
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in-progress when the server terminated abruptly
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http://archives.postgresql.org/pgsql-patches/2006-06/msg00096.php
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* Allow administrators to safely terminate individual sessions either
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via an SQL function or SIGTERM
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Lock table corruption following SIGTERM of an individual backend
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has been reported in 8.0. A possible cause was fixed in 8.1, but
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it is unknown whether other problems exist. This item mostly
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requires additional testing rather than of writing any new code.
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http://archives.postgresql.org/pgsql-hackers/2006-08/msg00174.php
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* Set proper permissions on non-system schemas during db creation
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Currently all schemas are owned by the super-user because they are copied
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from the template1 database. However, since all objects are inherited
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from the template database, it is not clear that setting schemas to the db
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owner is correct.
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* Support table partitioning that allows a single table to be stored
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in subtables that are partitioned based on the primary key or a WHERE
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clause
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* Add function to report the time of the most recent server reload
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* Allow statistics collector information to be pulled from the collector
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process directly, rather than requiring the collector to write a
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filesystem file twice a second?
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* Allow log_min_messages to be specified on a per-module basis
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This would allow administrators to see more detailed information from
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specific sections of the backend, e.g. checkpoints, autovacuum, etc.
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Another idea is to allow separate configuration files for each module,
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or allow arbitrary SET commands to be passed to them.
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* Simplify ability to create partitioned tables
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This would allow creation of partitioned tables without requiring
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creation of rules for INSERT/UPDATE/DELETE, and constraints for
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rapid partition selection. Options could include range and hash
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partition selection.
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http://archives.postgresql.org/pgsql-hackers/2007-03/msg00375.php
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http://archives.postgresql.org/pgsql-hackers/2007-04/msg00151.php
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* Allow auto-selection of partitioned tables for min/max() operations
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* Allow more complex user/database default GUC settings
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Currently ALTER USER and ALTER DATABASE support per-user and
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per-database defaults. Consider adding per-user-and-database
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defaults so things like search_path can be defaulted for a
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specific user connecting to a specific database.
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* Allow custom variable classes that can restrict who can set the values
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http://archives.postgresql.org/pgsql-hackers/2006-11/msg00911.php
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* Implement the SQL standard mechanism whereby REVOKE ROLE revokes only
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the privilege granted by the invoking role, and not those granted
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by other roles
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http://archives.postgresql.org/pgsql-bugs/2007-05/msg00010.php
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* Improve replication solutions
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o Load balancing
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You can use any of the master/slave replication servers to use a
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standby server for data warehousing. To allow read/write queries to
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multiple servers, you need multi-master replication like pgcluster.
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o Allow replication over unreliable or non-persistent links
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* Configuration files
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o -Allow commenting of variables in postgresql.conf to restore them
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to defaults
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o Allow pg_hba.conf to specify host names along with IP addresses
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Host name lookup could occur when the postmaster reads the
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pg_hba.conf file, or when the backend starts. Another
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solution would be to reverse lookup the connection IP and
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check that hostname against the host names in pg_hba.conf.
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We could also then check that the host name maps to the IP
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address.
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o %Allow postgresql.conf file values to be changed via an SQL
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API, perhaps using SET GLOBAL
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o Allow the server to be stopped/restarted via an SQL API
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o Issue a warning if a change-on-restart-only postgresql.conf value
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is modified and the server config files are reloaded
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o Mark change-on-restart-only values in postgresql.conf
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* Tablespaces
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o Allow a database in tablespace t1 with tables created in
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tablespace t2 to be used as a template for a new database created
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with default tablespace t2
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All objects in the default database tablespace must have default
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tablespace specifications. This is because new databases are
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created by copying directories. If you mix default tablespace
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tables and tablespace-specified tables in the same directory,
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creating a new database from such a mixed directory would create a
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new database with tables that had incorrect explicit tablespaces.
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To fix this would require modifying pg_class in the newly copied
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database, which we don't currently do.
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o Allow reporting of which objects are in which tablespaces
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This item is difficult because a tablespace can contain objects
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from multiple databases. There is a server-side function that
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returns the databases which use a specific tablespace, so this
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requires a tool that will call that function and connect to each
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database to find the objects in each database for that tablespace.
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o -Add a GUC variable to control the tablespace for temporary objects
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and sort files
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o Allow WAL replay of CREATE TABLESPACE to work when the directory
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structure on the recovery computer is different from the original
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o Allow per-tablespace quotas
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* Point-In-Time Recovery (PITR)
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o Allow a warm standby system to also allow read-only statements
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[pitr]
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This is useful for checking PITR recovery.
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http://archives.postgresql.org/pgsql-hackers/2007-03/msg00050.php
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o %Create dump tool for write-ahead logs for use in determining
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transaction id for point-in-time recovery
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o Allow the PITR process to be debugged and data examined
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o Allow recovery.conf to allow the same syntax as
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postgresql.conf, including quoting
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http://archives.postgresql.org/pgsql-hackers/2006-12/msg00497.php
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Monitoring
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==========
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* -Allow server log information to be output as CSV format
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* -Add ability to monitor the use of temporary sort files
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Data Types
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==========
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* -Make 64-bit version of the MONEY data type
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* Add locale-aware MONEY type, and support multiple currencies
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http://archives.postgresql.org/pgsql-general/2005-08/msg01432.php
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http://archives.postgresql.org/pgsql-hackers/2007-03/msg01181.php
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* Change NUMERIC to enforce the maximum precision
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* Reduce storage space for small NUMERICs
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http://archives.postgresql.org/pgsql-hackers/2007-02/msg01331.php
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http://archives.postgresql.org/pgsql-patches/2007-02/msg00505.php
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* Fix data types where equality comparison isn't intuitive, e.g. box
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* Allow user-defined types to specify a type modifier at table creation
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time
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* -Allow user-defined types to accept 'typmod' parameters
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http://archives.postgresql.org/pgsql-hackers/2005-08/msg01142.php
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http://archives.postgresql.org/pgsql-hackers/2005-09/msg00012.php
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http://archives.postgresql.org/pgsql-hackers/2006-08/msg00149.php
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* Add support for public SYNONYMs
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http://archives.postgresql.org/pgsql-hackers/2006-03/msg00519.php
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* Fix CREATE CAST on DOMAINs
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http://archives.postgresql.org/pgsql-hackers/2006-05/msg00072.php
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http://archives.postgresql.org/pgsql-hackers/2006-09/msg01681.php
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* -Add Globally/Universally Unique Identifier (GUID/UUID)
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http://archives.postgresql.org/pgsql-patches/2006-09/msg00209.php
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http://archives.postgresql.org/pgsql-general/2007-01/msg00853.php
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* Add support for SQL-standard GENERATED/IDENTITY columns
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http://archives.postgresql.org/pgsql-hackers/2006-07/msg00543.php
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http://archives.postgresql.org/pgsql-hackers/2006-08/msg00038.php
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http://archives.postgresql.org/pgsql-hackers/2007-05/msg00344.php
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http://archives.postgresql.org/pgsql-patches/2007-05/msg00076.php
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* -Support a data type with specific enumerated values (ENUM)
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* Improve XML support
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http://developer.postgresql.org/index.php/XML_Support
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* Consider placing all sequences in a single table, or create a system
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view
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* Allow all data types to cast to and from TEXT
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http://archives.postgresql.org/pgsql-hackers/2007-04/msg00017.php
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* Dates and Times
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o Allow infinite dates and intervals just like infinite timestamps
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o Merge hardwired timezone names with the TZ database; allow either
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kind everywhere a TZ name is currently taken
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o Allow TIMESTAMP WITH TIME ZONE to store the original timezone
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information, either zone name or offset from UTC [timezone]
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If the TIMESTAMP value is stored with a time zone name, interval
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computations should adjust based on the time zone rules.
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o Fix SELECT '0.01 years'::interval, '0.01 months'::interval
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o Add a GUC variable to allow output of interval values in ISO8601
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format
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o Have timestamp subtraction not call justify_hours()?
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http://archives.postgresql.org/pgsql-sql/2006-10/msg00059.php
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o Improve timestamptz subtraction to be DST-aware
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Currently subtracting one date from another that crosses a
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daylight savings time adjustment can return '1 day 1 hour', but
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adding that back to the first date returns a time one hour in
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the future. This is caused by the adjustment of '25 hours' to
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'1 day 1 hour', and '1 day' is the same time the next day, even
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if daylight savings adjustments are involved.
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o Fix interval display to support values exceeding 2^31 hours
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o Add overflow checking to timestamp and interval arithmetic
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o Extend timezone code to allow 64-bit values so we can
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represent years beyond 2038
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http://archives.postgresql.org/pgsql-hackers/2006-09/msg01363.php
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o Use LC_TIME for localized weekday/month names, rather than
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LC_MESSAGES
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http://archives.postgresql.org/pgsql-hackers/2006-11/msg00390.php
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o Add ISO INTERVAL handling
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http://archives.postgresql.org/pgsql-hackers/2006-01/msg00250.php
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http://archives.postgresql.org/pgsql-bugs/2006-04/msg00248.php
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o Support ISO INTERVAL syntax if units cannot be determined from
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the string, and are supplied after the string
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The SQL standard states that the units after the string
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specify the units of the string, e.g. INTERVAL '2' MINUTE
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should return '00:02:00'. The current behavior has the units
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restrict the interval value to the specified unit or unit
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range, INTERVAL '70' SECOND returns '00:00:10'.
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For syntax that isn't uniquely ISO or PG syntax, like '1' or
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'1:30', treat as ISO if there is a range specification clause,
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and as PG if there no clause is present, e.g. interpret '1:30'
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MINUTE TO SECOND as '1 minute 30 seconds', and interpret
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'1:30' as '1 hour, 30 minutes'.
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This makes common cases like SELECT INTERVAL '1' MONTH
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SQL-standard results. The SQL standard supports a limited
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number of unit combinations and doesn't support unit names in
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the string. The PostgreSQL syntax is more flexible in the
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range of units supported, e.g. PostgreSQL supports '1 year 1
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hour', while the SQL standard does not.
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o Add support for year-month syntax, INTERVAL '50-6' YEAR TO MONTH
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o Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1 year' AS
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INTERVAL MONTH), and this should return '12 months'
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o Round or truncate values to the requested precision, e.g.
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INTERVAL '11 months' AS YEAR should return one or zero
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o Support precision, CREATE TABLE foo (a INTERVAL MONTH(3))
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* Arrays
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o Delay resolution of array expression's data type so assignment
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coercion can be performed on empty array expressions
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o Add support for arrays of domains
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http://archives.postgresql.org/pgsql-patches/2007-05/msg00114.php
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o -Add support for arrays of complex types
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o Allow single-byte header storage for array elements
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* Binary Data
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o Improve vacuum of large objects, like /contrib/vacuumlo?
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o Add security checking for large objects
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o Auto-delete large objects when referencing row is deleted
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/contrib/lo offers this functionality.
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o Allow read/write into TOAST values like large objects
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This requires the TOAST column to be stored EXTERNAL.
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o Add API for 64-bit large object access
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http://archives.postgresql.org/pgsql-hackers/2005-09/msg00781.php
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Functions
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=========
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* Allow INET subnet tests using non-constants to be indexed
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* Allow to_date() and to_timestamp() accept localized month names
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* Fix to_date()-related functions to consistently issue errors
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http://archives.postgresql.org/pgsql-hackers/2007-02/msg00915.php
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* Add missing parameter handling in to_char()
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http://archives.postgresql.org/pgsql-hackers/2005-12/msg00948.php
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* Allow functions to have a schema search path specified at creation time
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* Allow substring/replace() to get/set bit values
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* Allow to_char() on interval values to accumulate the highest unit
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requested
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Some special format flag would be required to request such
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accumulation. Such functionality could also be added to EXTRACT.
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Prevent accumulation that crosses the month/day boundary because of
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the uneven number of days in a month.
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o to_char(INTERVAL '1 hour 5 minutes', 'MI') => 65
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o to_char(INTERVAL '43 hours 20 minutes', 'MI' ) => 2600
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o to_char(INTERVAL '43 hours 20 minutes', 'WK:DD:HR:MI') => 0:1:19:20
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o to_char(INTERVAL '3 years 5 months','MM') => 41
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* -Add ISO day of week format 'ID' to to_char() where Monday = 1
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* -Add a field 'isoyear' to extract(), based on the ISO week
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* Implement inlining of set-returning functions defined in SQL
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* Allow SQL-language functions to return results from RETURNING queries
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http://archives.postgresql.org/pgsql-hackers/2006-10/msg00665.php
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* Allow SQL-language functions to reference parameters by parameter name
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Currently SQL-language functions can only refer to dollar parameters,
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e.g. $1
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* Add SPI_gettypmod() to return the typemod for a TupleDesc
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* Enforce typmod for function inputs, function results and parameters for
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spi_prepare'd statements called from PLs
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http://archives.postgresql.org/pgsql-hackers/2007-01/msg01403.php
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* Allow holdable cursors in SPI
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* Tighten function permission checks
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http://archives.postgresql.org/pgsql-hackers/2006-12/msg00568.php
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* Fix IS OF so it matches the ISO specification, and add documentation
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http://archives.postgresql.org/pgsql-patches/2003-08/msg00060.php
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http://archives.postgresql.org/pgsql-hackers/2007-02/msg00060.php
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* Add missing operators for geometric data types
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Some geometric types do not have the full suite of geometric operators,
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e.g. box @> point
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Multi-Language Support
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======================
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* Add NCHAR (as distinguished from ordinary varchar),
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* Allow locale to be set at database creation
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Currently locale can only be set during initdb. No global tables have
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locale-aware columns. However, the database template used during
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database creation might have locale-aware indexes. The indexes would
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need to be reindexed to match the new locale.
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* Allow encoding on a per-column basis optionally using the ICU library:
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Right now only one encoding is allowed per database. [locale]
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http://archives.postgresql.org/pgsql-hackers/2005-03/msg00932.php
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http://archives.postgresql.org/pgsql-patches/2005-08/msg00309.php
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http://archives.postgresql.org/pgsql-patches/2006-03/msg00233.php
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http://archives.postgresql.org/pgsql-hackers/2006-09/msg00662.php
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* Add CREATE COLLATE? [locale]
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* Support multiple simultaneous character sets, per SQL92
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* Improve UTF8 combined character handling?
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* Add octet_length_server() and octet_length_client()
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* Make octet_length_client() the same as octet_length()?
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* Fix problems with wrong runtime encoding conversion for NLS message files
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* Add URL to more complete multi-byte regression tests
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http://archives.postgresql.org/pgsql-hackers/2005-07/msg00272.php
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* Fix ILIKE and regular expressions to handle case insensitivity
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properly in multibyte encodings
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http://archives.postgresql.org/pgsql-bugs/2005-10/msg00001.php
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http://archives.postgresql.org/pgsql-patches/2005-11/msg00173.php
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* Set client encoding based on the client operating system encoding
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Currently client_encoding is set in postgresql.conf, which
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defaults to the server encoding.
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|
http://archives.postgresql.org/pgsql-hackers/2006-08/msg01696.php
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* Fix cases where invalid byte encodings are accepted by the database,
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but throw an error on SELECT
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http://archives.postgresql.org/pgsql-hackers/2007-03/msg00767.php
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Views / Rules
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=============
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* Automatically create rules on views so they are updateable, per SQL99
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We can only auto-create rules for simple views. For more complex
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cases users will still have to write rules manually.
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|
http://archives.postgresql.org/pgsql-hackers/2006-03/msg00586.php
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http://archives.postgresql.org/pgsql-patches/2006-08/msg00255.php
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* Add the functionality for WITH CHECK OPTION clause of CREATE VIEW
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* Allow NOTIFY in rules involving conditionals
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* Allow VIEW/RULE recompilation when the underlying tables change
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Another issue is whether underlying table changes should be reflected
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in the view, e.g. should SELECT * show additional columns if they
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are added after the view is created.
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* Make it possible to use RETURNING together with conditional DO INSTEAD
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rules, such as for partitioning setups
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|
http://archives.postgresql.org/pgsql-hackers/2007-09/msg00577.php
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SQL Commands
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============
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* Add CORRESPONDING BY to UNION/INTERSECT/EXCEPT
|
|
* Add ROLLUP, CUBE, GROUPING SETS options to GROUP BY
|
|
* %Allow SET CONSTRAINTS to be qualified by schema/table name
|
|
* %Add a separate TRUNCATE permission
|
|
|
|
Currently only the owner can TRUNCATE a table because triggers are not
|
|
called, and the table is locked in exclusive mode.
|
|
|
|
* Allow PREPARE of cursors
|
|
* Allow finer control over the caching of prepared query plans
|
|
|
|
Currently queries prepared via the libpq API are planned on first
|
|
execute using the supplied parameters --- allow SQL PREPARE to do the
|
|
same. Also, allow control over replanning prepared queries either
|
|
manually or automatically when statistics for execute parameters
|
|
differ dramatically from those used during planning.
|
|
|
|
* Improve logging of prepared statements recovered during startup
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-11/msg00092.php
|
|
|
|
* Allow LISTEN/NOTIFY to store info in memory rather than tables?
|
|
|
|
Currently LISTEN/NOTIFY information is stored in pg_listener. Storing
|
|
such information in memory would improve performance.
|
|
|
|
* Add optional textual message to NOTIFY
|
|
|
|
This would allow an informational message to be added to the notify
|
|
message, perhaps indicating the row modified or other custom
|
|
information.
|
|
|
|
* Add a GUC variable to warn about non-standard SQL usage in queries
|
|
* Add SQL-standard MERGE command, typically used to merge two tables
|
|
[merge]
|
|
|
|
This is similar to UPDATE, then for unmatched rows, INSERT.
|
|
Whether concurrent access allows modifications which could cause
|
|
row loss is implementation independent.
|
|
|
|
* Add REPLACE or UPSERT command that does UPDATE, or on failure, INSERT
|
|
[merge]
|
|
|
|
To implement this cleanly requires that the table have a unique index
|
|
so duplicate checking can be easily performed. It is possible to
|
|
do it without a unique index if we require the user to LOCK the table
|
|
before the MERGE.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2005-11/msg00501.php
|
|
http://archives.postgresql.org/pgsql-hackers/2005-11/msg00536.php
|
|
|
|
|
|
* Add NOVICE output level for helpful messages like automatic sequence/index
|
|
creation
|
|
* -Add RESET SESSION command to reset all session state
|
|
* Add GUC to issue notice about statements that use unjoined tables
|
|
* Allow EXPLAIN to identify tables that were skipped because of
|
|
constraint_exclusion
|
|
* Allow EXPLAIN output to be more easily processed by scripts, perhaps XML
|
|
* Enable standard_conforming_strings
|
|
* Make standard_conforming_strings the default in 8.4?
|
|
|
|
When this is done, backslash-quote should be prohibited in non-E''
|
|
strings because of possible confusion over how such strings treat
|
|
backslashes. Basically, '' is always safe for a literal single
|
|
quote, while \' might or might not be based on the backslash
|
|
handling rules.
|
|
|
|
* Simplify dropping roles that have objects in several databases
|
|
* Allow COMMENT ON to accept an expression rather than just a string
|
|
* Allow the count returned by SELECT, etc to be to represent as an int64
|
|
to allow a higher range of values
|
|
* Add SQL99 WITH clause to SELECT
|
|
* Add SQL:2003 WITH RECURSIVE (hierarchical) queries to SELECT
|
|
* Add DEFAULT .. AS OWNER so permission checks are done as the table
|
|
owner
|
|
|
|
This would be useful for SERIAL nextval() calls and CHECK constraints.
|
|
|
|
* Allow DISTINCT to work in multiple-argument aggregate calls
|
|
* Add column to pg_stat_activity that shows the progress of long-running
|
|
commands like CREATE INDEX and VACUUM
|
|
* Implement SQL:2003 window functions
|
|
* Improve failure message when DROP DATABASE is used on a database that
|
|
has prepared transactions
|
|
* Allow INSERT/UPDATE ... RETURNING inside a SELECT 'FROM' clause
|
|
|
|
http://archives.postgresql.org/pgsql-general/2006-09/msg00803.php
|
|
http://archives.postgresql.org/pgsql-hackers/2006-10/msg00693.php
|
|
|
|
* Increase locking when DROPing objects so dependent objects cannot
|
|
get dropped while the DROP operation is happening
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg00937.php
|
|
|
|
* CREATE
|
|
|
|
o Allow CREATE TABLE AS to determine column lengths for complex
|
|
expressions like SELECT col1 || col2
|
|
o Use more reliable method for CREATE DATABASE to get a consistent
|
|
copy of db?
|
|
o Fix transaction restriction checks for CREATE DATABASE and
|
|
other commands
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg00133.php
|
|
|
|
o Have WITH CONSTRAINTS also create constraint indexes
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2007-04/msg00149.php
|
|
|
|
* UPDATE
|
|
o Allow UPDATE tab SET ROW (col, ...) = (SELECT...)
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-07/msg01306.php
|
|
http://archives.postgresql.org/pgsql-hackers/2007-03/msg00865.php
|
|
|
|
o Research self-referential UPDATEs that see inconsistent row versions
|
|
in read-committed mode
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-05/msg00507.php
|
|
http://archives.postgresql.org/pgsql-hackers/2007-06/msg00016.php
|
|
|
|
o Allow GLOBAL temporary tables to exist as empty by default in
|
|
all sessions
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-07/msg00006.php
|
|
|
|
|
|
* ALTER
|
|
|
|
o %Have ALTER TABLE RENAME rename SERIAL sequence names
|
|
o Add ALTER DOMAIN to modify the underlying data type
|
|
o %Allow ALTER TABLE ... ALTER CONSTRAINT ... RENAME
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2006-02/msg00168.php
|
|
|
|
o %Allow ALTER TABLE to change constraint deferrability and actions
|
|
o Add missing object types for ALTER ... SET SCHEMA
|
|
o Allow ALTER TABLESPACE to move to different directories
|
|
o Allow databases to be moved to different tablespaces
|
|
o Allow moving system tables to other tablespaces, where possible
|
|
|
|
Currently non-global system tables must be in the default database
|
|
tablespace. Global system tables can never be moved.
|
|
|
|
o Prevent parent tables from altering or dropping constraints
|
|
like CHECK that are inherited by child tables unless CASCADE
|
|
is used
|
|
o %Prevent child tables from altering or dropping constraints
|
|
like CHECK that were inherited from the parent table
|
|
o Have ALTER INDEX update the name of a constraint using that index
|
|
o Add ALTER TABLE RENAME CONSTRAINT, update index name also
|
|
o Allow column display reordering by recording a display,
|
|
storage, and permanent id for every column?
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-12/msg00782.php
|
|
|
|
|
|
|
|
* CLUSTER
|
|
|
|
o -Make CLUSTER preserve recently-dead tuples per MVCC requirements
|
|
o Automatically maintain clustering on a table
|
|
|
|
This might require some background daemon to maintain clustering
|
|
during periods of low usage. It might also require tables to be only
|
|
partially filled for easier reorganization. Another idea would
|
|
be to create a merged heap/index data file so an index lookup would
|
|
automatically access the heap data too. A third idea would be to
|
|
store heap rows in hashed groups, perhaps using a user-supplied
|
|
hash function.
|
|
http://archives.postgresql.org/pgsql-performance/2004-08/msg00349.php
|
|
|
|
o %Add default clustering to system tables
|
|
|
|
To do this, determine the ideal cluster index for each system
|
|
table and set the cluster setting during initdb.
|
|
|
|
o %Add VERBOSE option to report tables as they are processed,
|
|
like VACUUM VERBOSE
|
|
o -Add more logical syntax CLUSTER table USING index;
|
|
support current syntax for backward compatibility
|
|
|
|
|
|
* COPY
|
|
|
|
o Allow COPY to report error lines and continue
|
|
|
|
This requires the use of a savepoint before each COPY line is
|
|
processed, with ROLLBACK on COPY failure.
|
|
|
|
o Allow COPY on a newly-created table to skip WAL logging
|
|
|
|
On crash recovery, the table involved in the COPY would
|
|
be removed or have its heap and index files truncated. One
|
|
issue is that no other backend should be able to add to
|
|
the table at the same time, which is something that is
|
|
currently allowed.
|
|
|
|
|
|
* GRANT/REVOKE
|
|
|
|
o Allow column-level privileges
|
|
o %Allow GRANT/REVOKE permissions to be applied to all schema objects
|
|
with one command
|
|
|
|
The proposed syntax is:
|
|
GRANT SELECT ON ALL TABLES IN public TO phpuser;
|
|
GRANT SELECT ON NEW TABLES IN public TO phpuser;
|
|
|
|
o Allow GRANT/REVOKE permissions to be inherited by objects based on
|
|
schema permissions
|
|
|
|
o Allow SERIAL sequences to inherit permissions from the base table?
|
|
|
|
|
|
* CURSOR
|
|
|
|
o -Allow UPDATE/DELETE WHERE CURRENT OF cursor
|
|
o Prevent DROP TABLE from dropping a row referenced by its own open
|
|
cursor?
|
|
|
|
|
|
* INSERT
|
|
|
|
o Allow INSERT/UPDATE of the system-generated oid value for a row
|
|
o In rules, allow VALUES() to contain a mixture of 'old' and 'new'
|
|
references
|
|
|
|
|
|
* SHOW/SET
|
|
|
|
o Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM
|
|
ANALYZE, and CLUSTER
|
|
o Add SET PATH for schemas?
|
|
|
|
This is basically the same as SET search_path.
|
|
|
|
|
|
* Referential Integrity
|
|
|
|
o Add MATCH PARTIAL referential integrity
|
|
o Change foreign key constraint for array -> element to mean element
|
|
in array?
|
|
o Enforce referential integrity for system tables
|
|
o Fix problem when cascading referential triggers make changes on
|
|
cascaded tables, seeing the tables in an intermediate state
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
|
|
http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
|
|
|
|
o Allow DEFERRABLE and end-of-statement UNIQUE constraints?
|
|
|
|
This would allow UPDATE tab SET col = col + 1 to work if col has
|
|
a unique index. Currently, uniqueness checks are done while the
|
|
command is being executed, rather than at the end of the statement
|
|
or transaction.
|
|
|
|
http://people.planetpostgresql.org/greg/index.php?/archives/2006/06/10.html
|
|
http://archives.postgresql.org/pgsql-hackers/2006-09/msg01458.php
|
|
|
|
|
|
* Server-Side Languages
|
|
|
|
o PL/pgSQL
|
|
o Fix RENAME to work on variables other than OLD/NEW
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2002-03/msg00591.php
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg01615.php
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg01587.php
|
|
|
|
o Allow function parameters to be passed by name,
|
|
get_employee_salary(12345 AS emp_id, 2001 AS tax_year)
|
|
o Add Oracle-style packages (Pavel)
|
|
|
|
A package would be a schema with session-local variables,
|
|
public/private functions, and initialization functions. It
|
|
is also possible to implement these capabilities
|
|
in all schemas and not use a separate "packages"
|
|
syntax at all.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-08/msg00384.php
|
|
|
|
o Allow handling of %TYPE arrays, e.g. tab.col%TYPE[]
|
|
o Allow listing of record column names, and access to
|
|
record columns via variables, e.g. columns := r.(*),
|
|
tval2 := r.(colname)
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2005-07/msg00458.php
|
|
http://archives.postgresql.org/pgsql-patches/2006-05/msg00302.php
|
|
http://archives.postgresql.org/pgsql-patches/2006-06/msg00031.php
|
|
|
|
o Add single-step debugging of functions
|
|
o -Add support for MOVE cursors
|
|
o Add support for SCROLL cursors
|
|
o Add support for WITH HOLD cursors
|
|
o Allow RETURN to return row or record functions
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2005-11/msg00045.php
|
|
http://archives.postgresql.org/pgsql-patches/2006-08/msg00397.php
|
|
http://archives.postgresql.org/pgsql-hackers/2006-09/msg00388.php
|
|
|
|
o Fix problems with RETURN NEXT on tables with
|
|
dropped/added columns after function creation
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2006-02/msg00165.php
|
|
|
|
o Allow row and record variables to be set to NULL constants,
|
|
and allow NULL tests on such variables
|
|
|
|
Because a row is not scalar, do not allow assignment
|
|
from NULL-valued scalars.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-10/msg00070.php
|
|
|
|
o Other
|
|
o Add table function support to pltcl, plpythonu
|
|
o Add support for polymorphic arguments and return types to
|
|
languages other than PL/PgSQL
|
|
o Add capability to create and call PROCEDURES
|
|
o Add support for OUT and INOUT parameters to languages other
|
|
than PL/PgSQL
|
|
o Add PL/PythonU tracebacks
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2006-02/msg00288.php
|
|
|
|
o -Allow PL/PythonU to return boolean rather than 1/0
|
|
o Allow data to be passed in native language formats, rather
|
|
than only text
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-05/msg00289.php
|
|
|
|
|
|
Clients
|
|
=======
|
|
|
|
* Have pg_ctl look at PGHOST in case it is a socket directory?
|
|
* Allow pg_ctl to work properly with configuration files located outside
|
|
the PGDATA directory
|
|
|
|
pg_ctl can not read the pid file because it isn't located in the
|
|
config directory but in the PGDATA directory. The solution is to
|
|
allow pg_ctl to read and understand postgresql.conf to find the
|
|
data_directory value.
|
|
|
|
* Make consistent use of long/short command options --- pg_ctl needs
|
|
long ones, pg_config doesn't have short ones, postgres doesn't have
|
|
enough long ones, etc.
|
|
|
|
|
|
* psql
|
|
|
|
o Have psql show current values for a sequence
|
|
o Move psql backslash database information into the backend, use
|
|
mnemonic commands? [psql]
|
|
|
|
This would allow non-psql clients to pull the same information out
|
|
of the database as psql.
|
|
|
|
o Fix psql's \d commands more consistent
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
|
|
http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
|
|
|
|
o -Allow psql \pset boolean variables to set to fixed values, rather
|
|
than toggle
|
|
o Consistently display privilege information for all objects in psql
|
|
o Add auto-expanded mode so expanded output is used if the row
|
|
length is wider than the screen width.
|
|
|
|
Consider using auto-expanded mode for backslash commands like \df+.
|
|
|
|
o Prevent tab completion of SET TRANSACTION from querying the
|
|
database and therefore preventing the transaction isolation
|
|
level from being set.
|
|
|
|
Currently SET <tab> causes a database lookup to check all
|
|
supported session variables. This query causes problems
|
|
because setting the transaction isolation level must be the
|
|
first statement of a transaction.
|
|
|
|
o Consider parsing the -c string into individual queries so each
|
|
is run in its own transaction
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg00291.php
|
|
|
|
o Add a \set variable to control whether \s displays line numbers
|
|
|
|
Another option is to add \# which lists line numbers, and
|
|
allows command execution.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-12/msg00255.php
|
|
|
|
|
|
* pg_dump
|
|
|
|
o %Add dumping of comments on index columns and composite type columns
|
|
o %Add full object name to the tag field. eg. for operators we need
|
|
'=(integer, integer)', instead of just '='.
|
|
o Add pg_dumpall custom format dumps?
|
|
o Remove unnecessary function pointer abstractions in pg_dump source
|
|
code
|
|
o Allow selection of individual object(s) of all types, not just
|
|
tables
|
|
o In a selective dump, allow dumping of an object and all its
|
|
dependencies
|
|
o Add options like pg_restore -l and -L to pg_dump
|
|
o Stop dumping CASCADE on DROP TYPE commands in clean mode
|
|
o Allow pg_dump --clean to drop roles that own objects or have
|
|
privileges
|
|
o -Add -f to pg_dumpall
|
|
|
|
|
|
* ecpg
|
|
|
|
o Docs
|
|
|
|
Document differences between ecpg and the SQL standard and
|
|
information about the Informix-compatibility module.
|
|
|
|
o Solve cardinality > 1 for input descriptors / variables?
|
|
o Add a semantic check level, e.g. check if a table really exists
|
|
o fix handling of DB attributes that are arrays
|
|
o Use backend PREPARE/EXECUTE facility for ecpg where possible
|
|
o Implement SQLDA
|
|
o Fix nested C comments
|
|
o %sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified
|
|
o Make SET CONNECTION thread-aware, non-standard?
|
|
o Allow multidimensional arrays
|
|
o Add internationalized message strings
|
|
o Implement COPY FROM STDIN
|
|
|
|
|
|
* libpq
|
|
|
|
o Add PQescapeIdentifierConn()
|
|
o Prevent PQfnumber() from lowercasing unquoted the column name
|
|
|
|
PQfnumber() should never have been doing lowercasing, but
|
|
historically it has so we need a way to prevent it
|
|
|
|
o Allow statement results to be automatically batched to the client
|
|
|
|
Currently all statement results are transferred to the libpq
|
|
client before libpq makes the results available to the
|
|
application. This feature would allow the application to make
|
|
use of the first result rows while the rest are transferred, or
|
|
held on the server waiting for them to be requested by libpq.
|
|
One complexity is that a statement like SELECT 1/col could error
|
|
out mid-way through the result set.
|
|
o Fix SSL retry to avoid useless repeated connection attempts and
|
|
ensuing misleading error messages
|
|
o Consider disallowing multiple queries in PQexec() as an
|
|
additional barrier to SQL injection attacks
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg00184.php
|
|
|
|
o Add PQexecf() that allows complex parameter substitution
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-03/msg01803.php
|
|
|
|
Triggers
|
|
========
|
|
|
|
* Add deferred trigger queue file
|
|
|
|
Right now all deferred trigger information is stored in backend
|
|
memory. This could exhaust memory for very large trigger queues.
|
|
This item involves dumping large queues into files.
|
|
|
|
* Allow triggers to be disabled in only the current session.
|
|
|
|
This is currently possible by starting a multi-statement transaction,
|
|
modifying the system tables, performing the desired SQL, restoring the
|
|
system tables, and committing the transaction. ALTER TABLE ...
|
|
TRIGGER requires a table lock so it is not ideal for this usage.
|
|
|
|
* With disabled triggers, allow pg_dump to use ALTER TABLE ADD FOREIGN KEY
|
|
|
|
If the dump is known to be valid, allow foreign keys to be added
|
|
without revalidating the data.
|
|
|
|
* Allow statement-level triggers to access modified rows
|
|
* Support triggers on columns
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php
|
|
|
|
* Allow AFTER triggers on system tables
|
|
|
|
System tables are modified in many places in the backend without going
|
|
through the executor and therefore not causing triggers to fire. To
|
|
complete this item, the functions that modify system tables will have
|
|
to fire triggers.
|
|
|
|
* Tighten trigger permission checks
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-12/msg00564.php
|
|
|
|
* Allow BEFORE INSERT triggers on views
|
|
|
|
http://archives.postgresql.org/pgsql-general/2007-02/msg01466.php
|
|
|
|
|
|
|
|
Dependency Checking
|
|
===================
|
|
|
|
* -Flush cached query plans when the dependent objects change or
|
|
when new ANALYZE statistics are available
|
|
* -Track dependencies in function bodies and recompile/invalidate
|
|
* -Invalidate prepared queries, like INSERT, when the table definition
|
|
is altered
|
|
|
|
|
|
Indexes
|
|
=======
|
|
|
|
* Add UNIQUE capability to non-btree indexes
|
|
* Prevent index uniqueness checks when UPDATE does not modify the column
|
|
|
|
Uniqueness (index) checks are done when updating a column even if the
|
|
column is not modified by the UPDATE.
|
|
|
|
* Allow the creation of on-disk bitmap indexes which can be quickly
|
|
combined with other bitmap indexes
|
|
|
|
Such indexes could be more compact if there are only a few distinct values.
|
|
Such indexes can also be compressed. Keeping such indexes updated can be
|
|
costly.
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2005-07/msg00512.php
|
|
http://archives.postgresql.org/pgsql-hackers/2006-12/msg01107.php
|
|
|
|
* -Allow use of indexes to search for NULLs
|
|
* Allow accurate statistics to be collected on indexes with more than
|
|
one column or expression indexes, perhaps using per-index statistics
|
|
|
|
http://archives.postgresql.org/pgsql-performance/2006-10/msg00222.php
|
|
http://archives.postgresql.org/pgsql-hackers/2007-03/msg01131.php
|
|
|
|
* -Allow the creation of indexes with mixed ascending/descending
|
|
specifiers
|
|
* Consider compressing indexes by storing key values duplicated in
|
|
several rows as a single index entry
|
|
|
|
This is difficult because it requires datatype-specific knowledge.
|
|
|
|
* Add REINDEX CONCURRENTLY, like CREATE INDEX CONCURRENTLY
|
|
|
|
This is difficult because you must upgrade to an exclusive table lock
|
|
to replace the existing index file. CREATE INDEX CONCURRENTLY does not
|
|
have this complication. This would allow index compaction without
|
|
downtime.
|
|
|
|
* Allow multiple indexes to be created concurrently, ideally via a
|
|
single heap scan, and have a restore of a pg_dump somehow use it
|
|
|
|
http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php
|
|
|
|
|
|
* Inheritance
|
|
|
|
o Allow inherited tables to inherit indexes, UNIQUE constraints,
|
|
and primary/foreign keys
|
|
o Honor UNIQUE INDEX on base column in INSERTs/UPDATEs
|
|
on inherited table, e.g. INSERT INTO inherit_table
|
|
(unique_index_col) VALUES (dup) should fail
|
|
|
|
The main difficulty with this item is the problem of
|
|
creating an index that can span multiple tables.
|
|
|
|
o Allow SELECT ... FOR UPDATE on inherited tables
|
|
|
|
|
|
* GIST
|
|
|
|
o Add more GIST index support for geometric data types
|
|
o Allow GIST indexes to create certain complex index types, like
|
|
digital trees (see Aoki)
|
|
|
|
|
|
* Hash
|
|
http://archives.postgresql.org/pgsql-hackers/2007-09/msg00051.php
|
|
|
|
o Pack hash index buckets onto disk pages more efficiently
|
|
|
|
Currently only one hash bucket can be stored on a page. Ideally
|
|
several hash buckets could be stored on a single page and greater
|
|
granularity used for the hash algorithm.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2004-06/msg00168.php
|
|
|
|
o Consider sorting hash buckets so entries can be found using a
|
|
binary search, rather than a linear scan
|
|
o In hash indexes, consider storing the hash value with or instead
|
|
of the key itself
|
|
o Add WAL logging for crash recovery
|
|
o Allow multi-column hash indexes
|
|
o During index creation, pre-sort the tuples to improve build speed
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-03/msg01199.php
|
|
|
|
|
|
|
|
Fsync
|
|
=====
|
|
|
|
* Improve commit_delay handling to reduce fsync()
|
|
* Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
|
|
|
|
Ideally this requires a separate test program that can be run
|
|
at initdb time or optionally later. Consider O_SYNC when
|
|
O_DIRECT exists.
|
|
|
|
* %Add an option to sync() before fsync()'ing checkpoint files
|
|
* Add program to test if fsync has a delay compared to non-fsync
|
|
* -Reduce checkpoint performance degredation by forcing data to disk
|
|
more evenly
|
|
|
|
|
|
Cache Usage
|
|
===========
|
|
|
|
* Allow free-behind capability for large sequential scans to avoid
|
|
kernel cache spoiling
|
|
|
|
Posix_fadvise() can control both sequential/random file caching and
|
|
free-behind behavior, but it is unclear how the setting affects other
|
|
backends that also have the file open, and the feature is not supported
|
|
on all operating systems.
|
|
|
|
* Speed up COUNT(*)
|
|
|
|
We could use a fixed row count and a +/- count to follow MVCC
|
|
visibility rules, or a single cached value could be used and
|
|
invalidated if anyone modifies the table. Another idea is to
|
|
get a count directly from a unique index, but for this to be
|
|
faster than a sequential scan it must avoid access to the heap
|
|
to obtain tuple visibility information.
|
|
|
|
* Provide a way to calculate an "estimated COUNT(*)"
|
|
|
|
Perhaps by using the optimizer's cardinality estimates or random
|
|
sampling.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2005-11/msg00943.php
|
|
|
|
* Allow data to be pulled directly from indexes
|
|
|
|
Currently indexes do not have enough tuple visibility information
|
|
to allow data to be pulled from the index without also accessing
|
|
the heap. One way to allow this is to set a bit on index tuples
|
|
to indicate if a tuple is currently visible to all transactions
|
|
when the first valid heap lookup happens. This bit would have to
|
|
be cleared when a heap tuple is expired.
|
|
|
|
Another idea is to maintain a bitmap of heap pages where all rows
|
|
are visible to all backends, and allow index lookups to reference
|
|
that bitmap to avoid heap lookups, perhaps the same bitmap we might
|
|
add someday to determine which heap pages need vacuuming. Frequently
|
|
accessed bitmaps would have to be stored in shared memory. One 8k
|
|
page of bitmaps could track 512MB of heap pages.
|
|
|
|
A third idea would be for a heap scan to check if all rows are visible
|
|
and if so set a per-table flag which can be checked by index scans.
|
|
Any change to the table would have to clear the flag. To detect
|
|
changes during the heap scan a counter could be set at the start and
|
|
checked at the end --- if it is the same, the table has not been
|
|
modified --- any table change would increment the counter.
|
|
|
|
* Consider automatic caching of statements at various levels:
|
|
|
|
o Parsed query tree
|
|
o Query execute plan
|
|
o Query results
|
|
|
|
* -Allow sequential scans to take advantage of other concurrent
|
|
sequential scans, also called "Synchronised Scanning"
|
|
* Consider increasing internal areas when shared buffers is increased
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2005-10/msg01419.php
|
|
|
|
* Consider decreasing the amount of memory used by PrivateRefCount
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-11/msg00797.php
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php
|
|
|
|
|
|
|
|
Vacuum
|
|
======
|
|
|
|
* Improve speed with indexes
|
|
|
|
For large table adjustments during VACUUM FULL, it is faster to cluster
|
|
or reindex rather than update the index. Also, index updates can bloat
|
|
the index.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-03/msg00024.php
|
|
http://archives.postgresql.org/pgsql-performance/2007-05/msg00296.php
|
|
|
|
* Reduce lock time during VACUUM FULL by moving tuples with read lock,
|
|
then write lock and truncate table
|
|
|
|
Moved tuples are invisible to other backends so they don't require a
|
|
write lock. However, the read lock promotion to write lock could lead
|
|
to deadlock situations.
|
|
|
|
* Auto-fill the free space map by scanning the buffer cache or by
|
|
checking pages written by the background writer
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-02/msg01125.php
|
|
http://archives.postgresql.org/pgsql-hackers/2006-03/msg00011.php
|
|
|
|
* Create a bitmap of pages that need vacuuming
|
|
|
|
Instead of sequentially scanning the entire table, have the background
|
|
writer or some other process record pages that have expired rows, then
|
|
VACUUM can look at just those pages rather than the entire table. In
|
|
the event of a system crash, the bitmap would probably be invalidated.
|
|
One complexity is that index entries still have to be vacuumed, and
|
|
doing this without an index scan (by using the heap values to find the
|
|
index entry) might be slow and unreliable, especially for user-defined
|
|
index functions.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-12/msg01188.php
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg00121.php
|
|
|
|
* Allow FSM to return free space toward the beginning of the heap file,
|
|
in hopes that empty pages at the end can be truncated by VACUUM
|
|
* Allow FSM page return free space based on table clustering, to assist
|
|
in maintaining clustering?
|
|
* -Consider shrinking expired tuples to just their headers
|
|
* -Allow heap reuse of UPDATEd rows if no indexed columns are changed,
|
|
and old and new versions are on the same heap page
|
|
* Improve dead row detection during multi-statement transactions usage
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2007-03/msg00358.php
|
|
|
|
* -Reduce XID consumption of read-only queries
|
|
* Auto-vacuum
|
|
|
|
o Use free-space map information to guide refilling
|
|
o %Issue log message to suggest VACUUM FULL if a table is nearly
|
|
empty?
|
|
o Consider logging activity either to the logs or a system view
|
|
o -Turn on by default
|
|
o -Allow multiple vacuums so large tables do not starve small
|
|
tables
|
|
o Improve control of auto-vacuum
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-12/msg00876.php
|
|
|
|
o Prevent long-lived temporary tables from causing frozen-xid
|
|
advancement starvation
|
|
|
|
http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php
|
|
|
|
|
|
Locking
|
|
=======
|
|
|
|
* Fix priority ordering of read and write light-weight locks (Neil)
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2004-11/msg00893.php
|
|
http://archives.postgresql.org/pgsql-hackers/2004-11/msg00905.php
|
|
|
|
* Fix problem when multiple subtransactions of the same outer transaction
|
|
hold different types of locks, and one subtransaction aborts
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-11/msg01011.php
|
|
http://archives.postgresql.org/pgsql-hackers/2006-12/msg00001.php
|
|
http://archives.postgresql.org/pgsql-hackers/2007-02/msg00435.php
|
|
|
|
* Allow UPDATEs on only non-referential integrity columns not to conflict
|
|
with referential integrity locks
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-02/msg00073.php
|
|
|
|
* Add idle_in_transaction_timeout GUC so locks are not held for long
|
|
periods of time
|
|
|
|
|
|
|
|
Startup Time Improvements
|
|
=========================
|
|
|
|
* Experiment with multi-threaded backend for backend creation [thread]
|
|
|
|
This would prevent the overhead associated with process creation. Most
|
|
operating systems have trivial process creation time compared to
|
|
database startup overhead, but a few operating systems (Win32,
|
|
Solaris) might benefit from threading. Also explore the idea of
|
|
a single session using multiple threads to execute a statement faster.
|
|
|
|
* Experiment with multi-threaded backend better resource utilization
|
|
|
|
This would allow a single query to make use of multiple CPU's or
|
|
multiple I/O channels simultaneously. One idea is to create a
|
|
background reader that can pre-fetch sequential and index scan
|
|
pages needed by other backends. This could be expanded to allow
|
|
concurrent reads from multiple devices in a partitioned table.
|
|
|
|
* Add connection pooling
|
|
|
|
It is unclear if this should be done inside the backend code or done
|
|
by something external like pgpool. The passing of file descriptors to
|
|
existing backends is one of the difficulties with a backend approach.
|
|
|
|
|
|
Write-Ahead Log
|
|
===============
|
|
|
|
* Eliminate need to write full pages to WAL before page modification [wal]
|
|
|
|
Currently, to protect against partial disk page writes, we write
|
|
full page images to WAL before they are modified so we can correct any
|
|
partial page writes during recovery. These pages can also be
|
|
eliminated from point-in-time archive files.
|
|
|
|
o When off, write CRC to WAL and check file system blocks
|
|
on recovery
|
|
|
|
If CRC check fails during recovery, remember the page in case
|
|
a later CRC for that page properly matches.
|
|
|
|
o Write full pages during file system write and not when
|
|
the page is modified in the buffer cache
|
|
|
|
This allows most full page writes to happen in the background
|
|
writer. It might cause problems for applying WAL on recovery
|
|
into a partially-written page, but later the full page will be
|
|
replaced from WAL.
|
|
|
|
* Allow WAL traffic to be streamed to another server for stand-by
|
|
replication
|
|
* Reduce WAL traffic so only modified values are written rather than
|
|
entire rows
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-03/msg01589.php
|
|
|
|
* -Allow the pg_xlog directory location to be specified during initdb
|
|
with a symlink back to the /data location
|
|
* Allow WAL information to recover corrupted pg_controldata
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2006-06/msg00025.php
|
|
|
|
* Find a way to reduce rotational delay when repeatedly writing
|
|
last WAL page
|
|
|
|
Currently fsync of WAL requires the disk platter to perform a full
|
|
rotation to fsync again. One idea is to write the WAL to different
|
|
offsets that might reduce the rotational delay.
|
|
|
|
* -Allow buffered WAL writes and fsync
|
|
* Allow WAL logging to be turned off for a table, but the table
|
|
might be dropped or truncated during crash recovery [walcontrol]
|
|
|
|
Allow tables to bypass WAL writes and just fsync() dirty pages on
|
|
commit. This should be implemented using ALTER TABLE, e.g. ALTER
|
|
TABLE PERSISTENCE [ DROP | TRUNCATE | DEFAULT ]. Tables using
|
|
non-default logging should not use referential integrity with
|
|
default-logging tables. A table without dirty buffers during a
|
|
crash could perhaps avoid the drop/truncate.
|
|
|
|
* Allow WAL logging to be turned off for a table, but the table would
|
|
avoid being truncated/dropped [walcontrol]
|
|
|
|
To do this, only a single writer can modify the table, and writes
|
|
must happen only on new pages so the new pages can be removed during
|
|
crash recovery. Readers can continue accessing the table. Such
|
|
tables probably cannot have indexes. One complexity is the handling
|
|
of indexes on TOAST tables.
|
|
|
|
|
|
Optimizer / Executor
|
|
====================
|
|
|
|
* Improve selectivity functions for geometric operators
|
|
* -Allow ORDER BY ... LIMIT # to select high/low value without sort or
|
|
index using a sequential scan for highest/lowest values
|
|
* Precompile SQL functions to avoid overhead
|
|
* Create utility to compute accurate random_page_cost value
|
|
* Improve ability to display optimizer analysis using OPTIMIZER_DEBUG
|
|
* Have EXPLAIN ANALYZE issue NOTICE messages when the estimated and
|
|
actual row counts differ by a specified percentage
|
|
* Consider using hash buckets to do DISTINCT, rather than sorting
|
|
|
|
This would be beneficial when there are few distinct values. This is
|
|
already used by GROUP BY.
|
|
|
|
* Log statements where the optimizer row estimates were dramatically
|
|
different from the number of rows actually found?
|
|
* Consider compressed annealing to search for query plans
|
|
|
|
This might replace GEQO, http://sixdemonbag.org/Djinni.
|
|
|
|
* Improve merge join performance by allowing mark/restore of
|
|
tuple sources
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg00096.php
|
|
|
|
|
|
|
|
Miscellaneous Performance
|
|
=========================
|
|
|
|
* Do async I/O for faster random read-ahead of data
|
|
|
|
Async I/O allows multiple I/O requests to be sent to the disk with
|
|
results coming back asynchronously.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-10/msg00820.php
|
|
|
|
* Use mmap() rather than SYSV shared memory or to write WAL files?
|
|
|
|
This would remove the requirement for SYSV SHM but would introduce
|
|
portability issues. Anonymous mmap (or mmap to /dev/zero) is required
|
|
to prevent I/O overhead.
|
|
|
|
* Consider mmap()'ing files into a backend?
|
|
|
|
Doing I/O to large tables would consume a lot of address space or
|
|
require frequent mapping/unmapping. Extending the file also causes
|
|
mapping problems that might require mapping only individual pages,
|
|
leading to thousands of mappings. Another problem is that there is no
|
|
way to _prevent_ I/O to disk from the dirty shared buffers so changes
|
|
could hit disk before WAL is written.
|
|
|
|
* Add a script to ask system configuration questions and tune postgresql.conf
|
|
* -Merge xmin/xmax/cmin/cmax back into three header fields
|
|
* Consider ways of storing rows more compactly on disk
|
|
|
|
o -Support a smaller header for short variable-length fields
|
|
o Reduce the row header size?
|
|
o Consider reducing on-disk varlena length from four bytes to
|
|
two because a heap row cannot be more than 64k in length
|
|
|
|
* Consider increasing NUM_CLOG_BUFFERS
|
|
* Consider having the background writer update the transaction status
|
|
hint bits before writing out the page
|
|
* Allow user configuration of TOAST thresholds
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-02/msg00213.php
|
|
|
|
* Allow configuration of backend priorities via the operating system
|
|
|
|
Though backend priorities make priority inversion during lock
|
|
waits possible, research shows that this is not a huge problem.
|
|
|
|
http://archives.postgresql.org/pgsql-general/2007-02/msg00493.php
|
|
|
|
* Consider reducing memory used for shared buffer reference count
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php
|
|
|
|
|
|
|
|
Source Code
|
|
===========
|
|
|
|
* Add use of 'const' for variables in source tree
|
|
* Move some things from /contrib into main tree
|
|
* %Remove warnings created by -Wcast-align
|
|
* Move platform-specific ps status display info from ps_status.c to ports
|
|
* Add optional CRC checksum to heap and index pages
|
|
* Improve documentation to build only interfaces (Marc)
|
|
* Remove or relicense modules that are not under the BSD license, if possible
|
|
* %Remove memory/file descriptor freeing before ereport(ERROR)
|
|
* Acquire lock on a relation before building a relcache entry for it
|
|
* %Promote debug_query_string into a server-side function current_query()
|
|
* Allow cross-compiling by generating the zic database on the target system
|
|
* Improve NLS maintenance of libpgport messages linked onto applications
|
|
* Allow ecpg to work with MSVC and BCC
|
|
* Add xpath_array() to /contrib/xml2 to return results as an array
|
|
* Clean up casting in /contrib/isn
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-11/msg00245.php
|
|
|
|
* Allow building in directories containing spaces
|
|
|
|
This is probably not possible because 'gmake' and other compiler tools
|
|
do not fully support quoting of paths with spaces.
|
|
|
|
* Fix sgmltools so PDFs can be generated with bookmarks
|
|
* Use UTF8 encoding for NLS messages so all server encodings can
|
|
read them properly
|
|
* Update Bonjour to work with newer cross-platform SDK
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php
|
|
http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php
|
|
|
|
* Split out libpq pgpass and environment documentation sections to make
|
|
it easier for non-developers to find
|
|
* Consider detoasting keys before sorting
|
|
* Consider GnuTLS if OpenSSL license becomes a problem
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php
|
|
http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php
|
|
|
|
* Use strlcpy() rather than our StrNCpy() macro
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-09/msg02108.php
|
|
|
|
* Consider changing documentation format from SGML to XML
|
|
|
|
http://archives.postgresql.org/pgsql-docs/2006-12/msg00152.php
|
|
|
|
* -Move NAMEDATALEN from postgres_ext.h to pg_config_manual.h
|
|
* Consider making NAMEDATALEN more configurable in future releases
|
|
* Update our code to handle 64-bit timezone files to match the zic
|
|
source code, which now uses them
|
|
* Have configure choose integer datetimes by default
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2007-05/msg00046.php
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|
|
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* -Fix problem with excessive logging during SSL disconnection
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|
|
|
http://archives.postgresql.org/pgsql-bugs/2006-12/msg00122.php
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|
http://archives.postgresql.org/pgsql-bugs/2007-05/msg00065.php
|
|
|
|
* Support scoped IPv6 addresses
|
|
|
|
http://archives.postgresql.org/pgsql-bugs/2007-05/msg00111.php
|
|
|
|
* Consider allowing 64-bit integers and floats to be passed by value on
|
|
64-bit platforms
|
|
|
|
Also change 32-bit floats (float4) to be passed by value at the same
|
|
time.
|
|
|
|
|
|
|
|
* Win32
|
|
|
|
o Remove configure.in check for link failure when cause is found
|
|
o Remove readdir() errno patch when runtime/mingwex/dirent.c rev
|
|
1.4 is released
|
|
o Remove psql newline patch when we find out why mingw outputs an
|
|
extra newline
|
|
o Allow psql to use readline once non-US code pages work with
|
|
backslashes
|
|
o Re-enable timezone output on log_line_prefix '%t' when a
|
|
shorter timezone string is available
|
|
o Fix problem with shared memory on the Win32 Terminal Server
|
|
o Improve signal handling
|
|
|
|
http://archives.postgresql.org/pgsql-patches/2005-06/msg00027.php
|
|
|
|
o -Add long file support for binary pg_dump output
|
|
|
|
|
|
* Wire Protocol Changes
|
|
|
|
o Allow dynamic character set handling
|
|
o Add decoded type, length, precision
|
|
o Use compression?
|
|
o Update clients to use data types, typmod, schema.table.column names
|
|
of result sets using new statement protocol
|
|
|
|
|
|
Exotic Features
|
|
===============
|
|
|
|
* Add pre-parsing phase that converts non-ISO syntax to supported
|
|
syntax
|
|
|
|
This could allow SQL written for other databases to run without
|
|
modification.
|
|
|
|
* Allow plug-in modules to emulate features from other databases
|
|
* SQL*Net listener that makes PostgreSQL appear as an Oracle database
|
|
to clients
|
|
* Allow statements across databases or servers with transaction
|
|
semantics
|
|
|
|
This can be done using dblink and two-phase commit.
|
|
|
|
* Add the features of packages
|
|
|
|
o Make private objects accessible only to objects in the same schema
|
|
o Allow current_schema.objname to access current schema objects
|
|
o Add session variables
|
|
o Allow nested schemas
|
|
|
|
* Consider allowing control of upper/lower case folding of unquoted
|
|
identifiers
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2004-04/msg00818.php
|
|
http://archives.postgresql.org/pgsql-hackers/2006-10/msg01527.php
|
|
|
|
|
|
Features We Do _Not_ Want
|
|
=========================
|
|
|
|
* All backends running as threads in a single process (not wanted)
|
|
|
|
This eliminates the process protection we get from the current setup.
|
|
Thread creation is usually the same overhead as process creation on
|
|
modern systems, so it seems unwise to use a pure threaded model.
|
|
|
|
* Optimizer hints (not wanted)
|
|
|
|
Optimizer hints are used to work around problems in the optimizer. We
|
|
would rather have the problems reported and fixed.
|
|
|
|
http://archives.postgresql.org/pgsql-hackers/2006-08/msg00506.php
|
|
http://archives.postgresql.org/pgsql-hackers/2006-10/msg00517.php
|
|
http://archives.postgresql.org/pgsql-hackers/2006-10/msg00663.php
|
|
|
|
* Allow AS in "SELECT col AS label" to be optional (not wanted)
|
|
|
|
Because we support postfix operators, it isn't possible to make AS
|
|
optional and continue to use bison.
|
|
|
|
http://archives.postgresql.org/pgsql-sql/2006-08/msg00164.php
|
|
|
|
* Embedded server (not wanted)
|
|
|
|
While PostgreSQL clients runs fine in limited-resource environments, the
|
|
server requires multiple processes and a stable pool of resources to
|
|
run reliabily and efficiently. Stripping down the PostgreSQL server
|
|
to run in the same process address space as the client application
|
|
would add too much complexity and failure cases.
|