X-Git-Url: https://granicus.if.org/sourcecode?a=blobdiff_plain;f=doc%2FTODO;h=4b7b3da476193eb994b8aa8c02bf8c8b0cfc81d9;hb=abfd0095c1e1a2e3fad2696516b64871895334ec;hp=4803f12cceb92cf928d08d0895eb608cdd04745e;hpb=8008988be30f69f2c4534a8a8bad47d08cff7a21;p=postgresql diff --git a/doc/TODO b/doc/TODO index 4803f12cce..4b7b3da476 100644 --- a/doc/TODO +++ b/doc/TODO @@ -1,2071 +1,3 @@ -PostgreSQL TODO List -==================== -Current maintainer: Bruce Momjian (bruce@momjian.us) -Last updated: Wed May 7 00:45:53 EDT 2008 +The TODO list is now maintained at: -The most recent version of this document can be viewed at -http://www.postgresql.org/docs/faqs.TODO.html. - -#A hyphen, "-", marks changes that will appear in the upcoming 8.4 release.# -#A percent sign, "%", marks items that are easier to implement.# - -This list contains all known PostgreSQL bugs and feature requests. If -you would like to work on an item, please read the Developer's FAQ -first. There is also a developer's wiki at -http://developer.postgresql.org. - - -Administration -============== - -* -Allow administrators to safely terminate individual sessions either - via an SQL function or SIGTERM -* Check for unreferenced table files created by transactions that were - in-progress when the server terminated abruptly - - http://archives.postgresql.org/pgsql-patches/2006-06/msg00096.php - -* Set proper permissions on non-system schemas during db creation - - Currently all schemas are owned by the super-user because they are copied - from the template1 database. However, since all objects are inherited - from the template database, it is not clear that setting schemas to the db - owner is correct. - -* -Add function to report the time of the most recent server reload -* Allow statistics collector information to be pulled from the collector - process directly, rather than requiring the collector to write a - filesystem file twice a second? -* Reduce file system activity overhead of statistics file pgstat.stat - - http://archives.postgresql.org/pgsql-general/2007-12/msg00106.php - -* Allow statistics last vacuum/analyze execution times to be displayed - without requiring stats_row_level to be enabled - - http://archives.postgresql.org/pgsql-docs/2007-04/msg00028.php - -* Allow log_min_messages to be specified on a per-module basis - - This would allow administrators to see more detailed information from - specific sections of the backend, e.g. checkpoints, autovacuum, etc. - Another idea is to allow separate configuration files for each module, - or allow arbitrary SET commands to be passed to them. - -* Simplify ability to create partitioned tables - - This would allow creation of partitioned tables without requiring - creation of triggers or rules for INSERT/UPDATE/DELETE, and constraints - for rapid partition selection. Options could include range and hash - partition selection. - - http://archives.postgresql.org/pgsql-hackers/2007-03/msg00375.php - http://archives.postgresql.org/pgsql-hackers/2007-04/msg00151.php - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00028.php - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00248.php - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00387.php - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00413.php - -* Allow auto-selection of partitioned tables for min/max() operations -* Allow more complex user/database default GUC settings - - Currently ALTER USER and ALTER DATABASE support per-user and - per-database defaults. Consider adding per-user-and-database - defaults so things like search_path can be defaulted for a - specific user connecting to a specific database. - -* Allow custom variable classes that can restrict who can set the values - - http://archives.postgresql.org/pgsql-hackers/2006-11/msg00911.php - -* Implement the SQL standard mechanism whereby REVOKE ROLE revokes only - the privilege granted by the invoking role, and not those granted - by other roles - - http://archives.postgresql.org/pgsql-bugs/2007-05/msg00010.php - -* Allow SSL authentication/encryption over unix domain sockets - - http://archives.postgresql.org/pgsql-hackers/2007-12/msg00924.php - -* Allow SSL key file permission checks to be optionally disabled when - sharing SSL keys with other applications - - http://archives.postgresql.org/pgsql-bugs/2007-12/msg00069.php - -* Allow client certificate names to be checked against the client - hostname - - This is already implemented in - libpq/fe-secure.c::verify_peer_name_matches_certificate() but the code - is commented out. - -* Configuration files - - o Allow pg_hba.conf to specify host names along with IP addresses - - Host name lookup could occur when the postmaster reads the - pg_hba.conf file, or when the backend starts. Another - solution would be to reverse lookup the connection IP and - check that hostname against the host names in pg_hba.conf. - We could also then check that the host name maps to the IP - address. - - o %Allow postgresql.conf file values to be changed via an SQL - API, perhaps using SET GLOBAL - o Allow the server to be stopped/restarted via an SQL API - o Issue a warning if a change-on-restart-only postgresql.conf value - is modified and the server config files are reloaded - o Consider normalizing fractions in postgresql.conf, perhaps - using '%' - - http://archives.postgresql.org/pgsql-hackers/2007-06/msg00550.php - - o Allow Kerberos to disable stripping of realms so we can - check the username@realm against multiple realms - - http://archives.postgresql.org/pgsql-hackers/2007-11/msg00009.php - - -* Tablespaces - - o Allow a database in tablespace t1 with tables created in - tablespace t2 to be used as a template for a new database created - with default tablespace t2 - - Currently all objects in the default database tablespace must - have default tablespace specifications. This is because new - databases are created by copying directories. If you mix default - tablespace tables and tablespace-specified tables in the same - directory, creating a new database from such a mixed directory - would create a new database with tables that had incorrect - explicit tablespaces. To fix this would require modifying - pg_class in the newly copied database, which we don't currently - do. - - o Allow reporting of which objects are in which tablespaces - - This item is difficult because a tablespace can contain objects - from multiple databases. There is a server-side function that - returns the databases which use a specific tablespace, so this - requires a tool that will call that function and connect to each - database to find the objects in each database for that tablespace. - - o Allow WAL replay of CREATE TABLESPACE to work when the directory - structure on the recovery computer is different from the original - - o Allow per-tablespace quotas - - -* Point-In-Time Recovery (PITR) - - o Allow a warm standby system to also allow read-only statements - - http://archives.postgresql.org/pgsql-hackers/2007-03/msg00050.php - - o %Create dump tool for write-ahead logs for use in determining - transaction id for point-in-time recovery - - This is useful for checking PITR recovery. - - o Allow recovery.conf to support the same syntax as - postgresql.conf, including quoting - - http://archives.postgresql.org/pgsql-hackers/2006-12/msg00497.php - - o Fix server restart problem when the server was shutdown during - a PITR backup - - http://archives.postgresql.org/pgsql-hackers/2007-11/msg00800.php - - o Recreate pg_xlog/archive_status/ if it doesn't exist after - restoring from a PITR backup - - http://archives.postgresql.org/pgsql-hackers/2007-12/msg00487.php - - -Data Types -========== - -* Change NUMERIC to enforce the maximum precision -* Reduce storage space for small NUMERICs - - http://archives.postgresql.org/pgsql-hackers/2007-02/msg01331.php - http://archives.postgresql.org/pgsql-patches/2007-02/msg00505.php - http://archives.postgresql.org/pgsql-hackers/2007-06/msg00715.php - -* Fix data types where equality comparison isn't intuitive, e.g. box -* Add support for public SYNONYMs - - http://archives.postgresql.org/pgsql-hackers/2006-03/msg00519.php - -* Fix CREATE CAST on DOMAINs - - http://archives.postgresql.org/pgsql-hackers/2006-05/msg00072.php - http://archives.postgresql.org/pgsql-hackers/2006-09/msg01681.php - -* Allow domains to be cast - - http://archives.postgresql.org/pgsql-hackers/2003-06/msg01206.php - http://archives.postgresql.org/pgsql-hackers/2007-08/msg00289.php - -* Add support for SQL-standard GENERATED/IDENTITY columns - - http://archives.postgresql.org/pgsql-hackers/2006-07/msg00543.php - http://archives.postgresql.org/pgsql-hackers/2006-08/msg00038.php - http://archives.postgresql.org/pgsql-hackers/2007-05/msg00344.php - http://archives.postgresql.org/pgsql-patches/2007-05/msg00076.php - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00604.php - -* Improve XML support - - http://developer.postgresql.org/index.php/XML_Support - -* Consider placing all sequences in a single table, or create a system - view - - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php - -* Allow the UUID type to accept non-standard formats - - http://archives.postgresql.org/pgsql-hackers/2008-02/msg01214.php - -* Consider a special data type for regular expressions - - http://archives.postgresql.org/pgsql-hackers/2007-08/msg01067.php - -* Reduce BIT data type overhead using short varlena headers - - http://archives.postgresql.org/pgsql-general/2007-12/msg00273.php - -* Allow xml arrays to be cast to other data types - - http://archives.postgresql.org/pgsql-hackers/2007-09/msg00981.php - http://archives.postgresql.org/pgsql-hackers/2007-10/msg00231.php - http://archives.postgresql.org/pgsql-hackers/2007-11/msg00471.php - -* Simplify integer cross-data-type operators - - http://archives.postgresql.org/pgsql-bugs/2008-01/msg00189.php - -* Allow XML to accept more liberal DOCTYPE specifications - - http://archives.postgresql.org/pgsql-general/2008-02/msg00347.php - -* Allow adding/renaming/removing enumerated values to an existing - enumerated data type - - http://archives.postgresql.org/pgsql-hackers/2008-04/msg01718.php - -* Dates and Times - - o Allow infinite dates and intervals just like infinite timestamps - o Merge hardwired timezone names with the TZ database; allow either - kind everywhere a TZ name is currently taken - o Allow TIMESTAMP WITH TIME ZONE to store the original timezone - information, either zone name or offset from UTC - - If the TIMESTAMP value is stored with a time zone name, interval - computations should adjust based on the time zone rules. - http://archives.postgresql.org/pgsql-hackers/2004-10/msg00705.php - - o Fix SELECT '0.01 years'::interval, '0.01 months'::interval - o Add a GUC variable to allow output of interval values in ISO8601 - format - o Have timestamp subtraction not call justify_hours()? - - http://archives.postgresql.org/pgsql-sql/2006-10/msg00059.php - - o Improve timestamptz subtraction to be DST-aware - - Currently subtracting one date from another that crosses a - daylight savings time adjustment can return '1 day 1 hour', but - adding that back to the first date returns a time one hour in - the future. This is caused by the adjustment of '25 hours' to - '1 day 1 hour', and '1 day' is the same time the next day, even - if daylight savings adjustments are involved. - - o Fix interval display to support values exceeding 2^31 hours - o Add overflow checking to timestamp and interval arithmetic - o Extend timezone code to allow 64-bit values so we can - represent years beyond 2038 - - http://archives.postgresql.org/pgsql-hackers/2006-09/msg01363.php - - o Use LC_TIME for localized weekday/month names, rather than - LC_MESSAGES - - http://archives.postgresql.org/pgsql-hackers/2006-11/msg00390.php - - o Add ISO INTERVAL handling - - http://archives.postgresql.org/pgsql-hackers/2006-01/msg00250.php - http://archives.postgresql.org/pgsql-bugs/2006-04/msg00248.php - - o Support ISO INTERVAL syntax if units cannot be determined from - the string, and are supplied after the string - - The SQL standard states that the units after the string - specify the units of the string, e.g. INTERVAL '2' MINUTE - should return '00:02:00'. The current behavior has the units - restrict the interval value to the specified unit or unit - range, INTERVAL '70' SECOND returns '00:00:10'. - - For syntax that isn't uniquely ISO or PG syntax, like '1' or - '1:30', treat as ISO if there is a range specification clause, - and as PG if there no clause is present, e.g. interpret '1:30' - MINUTE TO SECOND as '1 minute 30 seconds', and interpret - '1:30' as '1 hour, 30 minutes'. - - This makes common cases like SELECT INTERVAL '1' MONTH - SQL-standard results. The SQL standard supports a limited - number of unit combinations and doesn't support unit names in - the string. The PostgreSQL syntax is more flexible in the - range of units supported, e.g. PostgreSQL supports '1 year 1 - hour', while the SQL standard does not. - - o Add support for year-month syntax, INTERVAL '50-6' YEAR - TO MONTH - o Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1 - year' AS INTERVAL MONTH), and this should return '12 months' - o Round or truncate values to the requested precision, e.g. - INTERVAL '11 months' AS YEAR should return one or zero - o Support precision, CREATE TABLE foo (a INTERVAL MONTH(3)) - - -* Arrays - - o Delay resolution of array expression's data type so assignment - coercion can be performed on empty array expressions - o Add support for arrays of domains - - http://archives.postgresql.org/pgsql-patches/2007-05/msg00114.php - - o Allow single-byte header storage for array elements - - -* Binary Data - - o Improve vacuum of large objects, like contrib/vacuumlo? - o Add security checking for large objects - o Auto-delete large objects when referencing row is deleted - - contrib/lo offers this functionality. - - o Allow read/write into TOAST values like large objects - - This requires the TOAST column to be stored EXTERNAL. - - o Add API for 64-bit large object access - - http://archives.postgresql.org/pgsql-hackers/2005-09/msg00781.php - -* MONEY data type - - * Add locale-aware MONEY type, and support multiple currencies - - http://archives.postgresql.org/pgsql-general/2005-08/msg01432.php - http://archives.postgresql.org/pgsql-hackers/2007-03/msg01181.php - - * MONEY dumps in a locale-specific format making it difficult to - restore to a system with a different locale - * Allow MONEY to be easily cast to/from other numeric data types - -* Text Search - - o Allow dictionaries to change the token that is passed on to - later dictionaries - - http://archives.postgresql.org/pgsql-patches/2007-11/msg00081.php - - o Consider a function-based API for '@@' searches - - http://archives.postgresql.org/pgsql-hackers/2007-11/msg00511.php - - o Improve text search error messages - - http://archives.postgresql.org/pgsql-hackers/2007-10/msg00966.php - http://archives.postgresql.org/pgsql-hackers/2007-11/msg01146.php - - o Consider changing error to warning for strings larger than one - megabyte - - http://archives.postgresql.org/pgsql-bugs/2008-02/msg00190.php - http://archives.postgresql.org/pgsql-patches/2008-03/msg00062.php - - - -Functions -========= - -* Allow INET subnet tests using non-constants to be indexed -* Allow to_date() and to_timestamp() accept localized month names -* Fix to_date()-related functions to consistently issue errors - - http://archives.postgresql.org/pgsql-hackers/2007-02/msg00915.php - -* Add missing parameter handling in to_char() - - http://archives.postgresql.org/pgsql-hackers/2005-12/msg00948.php - -* Allow substring/replace() to get/set bit values -* Allow to_char() on interval values to accumulate the highest unit - requested - - Some special format flag would be required to request such - accumulation. Such functionality could also be added to EXTRACT. - Prevent accumulation that crosses the month/day boundary because of - the uneven number of days in a month. - - o to_char(INTERVAL '1 hour 5 minutes', 'MI') => 65 - o to_char(INTERVAL '43 hours 20 minutes', 'MI' ) => 2600 - o to_char(INTERVAL '43 hours 20 minutes', 'WK:DD:HR:MI') => 0:1:19:20 - o to_char(INTERVAL '3 years 5 months','MM') => 41 - -* Implement inlining of set-returning functions defined in SQL -* Allow SQL-language functions to return results from RETURNING queries - - http://archives.postgresql.org/pgsql-hackers/2006-10/msg00665.php - -* Allow SQL-language functions to reference parameters by parameter name - - Currently SQL-language functions can only refer to dollar parameters, - e.g. $1 - -* Add SPI_gettypmod() to return the typemod for a TupleDesc -* Enforce typmod for function inputs, function results and parameters for - spi_prepare'd statements called from PLs - - http://archives.postgresql.org/pgsql-hackers/2007-01/msg01403.php - -* Allow holdable cursors in SPI -* Tighten function permission checks - - http://archives.postgresql.org/pgsql-hackers/2006-12/msg00568.php - -* Fix IS OF so it matches the ISO specification, and add documentation - - http://archives.postgresql.org/pgsql-patches/2003-08/msg00060.php - http://archives.postgresql.org/pgsql-hackers/2007-02/msg00060.php - -* Add missing operators for geometric data types - - Some geometric types do not have the full suite of geometric operators, - e.g. box @> point - -* Implement Boyer-Moore searching in strpos() - - http://archives.postgresql.org/pgsql-patches/2007-08/msg00012.php - -* Prevent malicious functions from being executed with the permissions - of unsuspecting users - - Index functions are safe, so VACUUM and ANALYZE are safe too. - Triggers, CHECK and DEFAULT expressions, and rules are still vulnerable. - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00268.php - -* Reduce memory usage of aggregates in set returning functions - - http://archives.postgresql.org/pgsql-performance/2008-01/msg00031.php - -* Add temporal versions of generate_series() - - http://archives.postgresql.org/pgsql-hackers/2007-04/msg01180.php - -* Add array_accum() and array_to_set() functions for arrays - - The standards specify array_agg() and UNNEST. - http://archives.postgresql.org/pgsql-hackers/2007-08/msg00464.php - -* Fix /contrib/ltree operator - - http://archives.postgresql.org/pgsql-bugs/2007-11/msg00044.php - -* Fix inconsistent precedence of =, >, and < compared to <>, >=, and <= - - http://archives.postgresql.org/pgsql-bugs/2007-12/msg00145.php - -* Fix regular expression bug when using complex back-references - - http://archives.postgresql.org/pgsql-bugs/2007-10/msg00000.php - -* Have /contrib/dblink reuse unnamed connections - - http://archives.postgresql.org/pgsql-hackers/2007-10/msg00895.php - -* Add SQL-standard array_agg() and unnest() array functions - - http://archives.postgresql.org/pgsql-hackers/2008-01/msg01017.php - -* Allow calling of a procedure outside a SELECT that can control the - transaction state - - http://archives.postgresql.org/pgsql-hackers/2007-10/msg01375.php - - - -Multi-Language Support -====================== - -* Add NCHAR (as distinguished from ordinary varchar), -* Allow locale to be set at database creation - - Currently locale can only be set during initdb. No global tables have - locale-aware columns. However, the database template used during - database creation might have locale-aware indexes. The indexes would - need to be reindexed to match the new locale. - -* Allow encoding on a per-column basis optionally using the ICU library; - Add CREATE COLLATE - - Right now only one encoding is allowed per database. - - http://archives.postgresql.org/pgsql-hackers/2005-03/msg00932.php - http://archives.postgresql.org/pgsql-patches/2005-08/msg00039.php - http://archives.postgresql.org/pgsql-patches/2005-08/msg00309.php - http://archives.postgresql.org/pgsql-hackers/2005-09/msg00110.php - http://archives.postgresql.org/pgsql-patches/2005-09/msg00020.php - http://archives.postgresql.org/pgsql-hackers/2005-12/msg01121.php - http://archives.postgresql.org/pgsql-hackers/2006-01/msg00767.php - http://archives.postgresql.org/pgsql-patches/2006-03/msg00233.php - http://archives.postgresql.org/pgsql-hackers/2006-09/msg00662.php - http://wiki.postgresql.org/wiki/Todo:Collate - http://wiki.postgresql.org/wiki/Todo:ICU - -* Support multiple simultaneous character sets, per SQL92 -* Improve UTF8 combined character handling? -* Add octet_length_server() and octet_length_client() -* Make octet_length_client() the same as octet_length()? -* Fix problems with wrong runtime encoding conversion for NLS message files -* Add URL to more complete multi-byte regression tests - - http://archives.postgresql.org/pgsql-hackers/2005-07/msg00272.php - -* Fix ILIKE and regular expressions to handle case insensitivity - properly in multibyte encodings - - http://archives.postgresql.org/pgsql-bugs/2005-10/msg00001.php - http://archives.postgresql.org/pgsql-patches/2005-11/msg00173.php - -* Set client encoding based on the client operating system encoding - - Currently client_encoding is set in postgresql.conf, which - defaults to the server encoding. - http://archives.postgresql.org/pgsql-hackers/2006-08/msg01696.php - -* Change memory allocation for multi-byte functions so memory is - allocated inside conversion functions - - Currently we preallocate memory based on worst-case usage. - - - -Views / Rules -============= - -* Automatically create rules on views so they are updateable, per SQL99 - - We can only auto-create rules for simple views. For more complex - cases users will still have to write rules manually. - - http://archives.postgresql.org/pgsql-hackers/2006-03/msg00586.php - http://archives.postgresql.org/pgsql-patches/2006-08/msg00255.php - -* Add the functionality for WITH CHECK OPTION clause of CREATE VIEW -* Allow VIEW/RULE recompilation when the underlying tables change - - Another issue is whether underlying table changes should be reflected - in the view, e.g. should SELECT * show additional columns if they - are added after the view is created. - -* Make it possible to use RETURNING together with conditional DO INSTEAD - rules, such as for partitioning setups - - http://archives.postgresql.org/pgsql-hackers/2007-09/msg00577.php - -* Add the ability to automatically create materialized views - - Right now materialized views require the user to create triggers on the - main table to keep the summary table current. SQL syntax should be able - to manager the triggers and summary table automatically. A more - sophisticated implementation would automatically retrieve from the - summary table when the main table is referenced, if possible. - - - -SQL Commands -============ - -* 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 transactions recovered during startup - - http://archives.postgresql.org/pgsql-hackers/2006-11/msg00092.php - -* Improve failure message when DROP DATABASE is used on a database that - has prepared transactions -* Allow prepared transactions with temporary tables created and dropped - in the same transaction, and when an ON COMMIT DELETE ROWS temporary - table is accessed - - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00047.php - -* Add a GUC variable to warn about non-standard SQL usage in queries -* Add SQL-standard MERGE/REPLACE/UPSERT command - - MERGE is typically used to merge two tables. REPLACE or UPSERT - command does UPDATE, or on failure, INSERT. This is similar to UPDATE, - then for unmatched rows, INSERT. Whether concurrent access allows - modifications which could cause row loss is implementation independent. - 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 - http://archives.postgresql.org/pgsql-hackers/2008-04/msg01475.php - -* Add NOVICE output level for helpful messages like automatic sequence/index - creation -* 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 8.5? - - 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 represented 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 - - http://archives.postgresql.org/pgsql-hackers/2007-01/msg01375.php - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00642.php - http://archives.postgresql.org/pgsql-patches/2007-03/msg00139.php - http://archives.postgresql.org/pgsql-hackers/2007-11/msg01334.php - http://archives.postgresql.org/pgsql-patches/2008-01/msg00105.php - http://archives.postgresql.org/pgsql-patches/2008-03/msg00327.php - -* 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 -* 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 - -* -Allow AS in "SELECT col AS label" to be optional in certain cases - -* Allow INSERT ... DELETE ... RETURNING, namely allow the DELETE ... - RETURNING to supply values to the INSERT - http://archives.postgresql.org/pgsql-hackers/2008-02/thrd2.php#00979 - -* Add comments on system tables/columns using the information in - catalogs.sgml - - Ideally the information would be pulled from the SGML file - automatically. - -* Improve reporting of UNION type mismatches - - http://archives.postgresql.org/pgsql-hackers/2007-04/msg00944.php - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00597.php - - -* CREATE - - o Allow CREATE TABLE AS to determine column lengths for complex - expressions like SELECT col1 || col2 - - o Have WITH CONSTRAINTS also create constraint indexes - - http://archives.postgresql.org/pgsql-patches/2007-04/msg00149.php - - o Have CONSTRAINT cname NOT NULL record the contraint name - - Right now pg_attribute.attnotnull records the NOT NULL status - of the column, but does not record the contraint name - - o Prevent concurrent CREATE TABLE table1 from sometimes returning - a cryptic error message - - http://archives.postgresql.org/pgsql-bugs/2007-10/msg00169.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 - http://archives.postgresql.org/pgsql-patches/2007-04/msg00315.php - http://archives.postgresql.org/pgsql-patches/2008-03/msg00237.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 - - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php - - o Have ALTER SEQUENCE RENAME rename the sequence name stored - in the sequence table - - http://archives.postgresql.org/pgsql-bugs/2007-09/msg00092.php - http://archives.postgresql.org/pgsql-bugs/2007-10/msg00007.php - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php - - 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 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 - - -* 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. - http://archives.postgresql.org/pgsql-hackers/2007-12/msg00572.php - - 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. This currently is done if the table is - created inside the same transaction block as the COPY because - no other backends can see the table. - - o Consider using a ring buffer for COPY FROM - - http://archives.postgresql.org/pgsql-patches/2008-02/msg00140.php - http://archives.postgresql.org/pgsql-hackers/2008-02/msg01080.php - - o Allow COPY FROM to create index entries in bulk - - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00811.php - - o Allow COPY in CSV mode to control whether a quoted zero-length - string is treated as NULL - - Currently this is always treated as a zero-length string, - which generates an error when loading into an integer column - http://archives.postgresql.org/pgsql-hackers/2007-07/msg00905.php - - o Impove COPY performance - - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00954.php - - - -* 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 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 - - -* LISTEN/NOTIFY - - o 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. - - o 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. - - o Allow multiple identical NOTIFY events to always be communicated - to the client, rather than sent as a single notification to the - listener - - http://archives.postgresql.org/pgsql-general/2008-01/msg00057.php - - o Allow NOTIFY in rules involving conditionals - o Improve LISTEN concurrency - - http://archives.postgresql.org/pgsql-hackers/2008-02/msg01106.php - - - -Referential Integrity -===================== - -* Add MATCH PARTIAL referential integrity -* Change foreign key constraint for array -> element to mean element - in array? -* 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 - -* 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 - -* Optimize referential integrity checks - - http://archives.postgresql.org/pgsql-performance/2005-10/msg00458.php - http://archives.postgresql.org/pgsql-hackers/2007-04/msg00744.php - - -Server-Side Languages -===================== - -* 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 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 support for SCROLL cursors - o Add support for WITH HOLD cursors - 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 Review handling of MOVE and FETCH - - http://archives.postgresql.org/pgsql-patches/2007-04/msg00527.php - - o Improve logic of determining if an identifier is a a - variable or column name - - http://archives.postgresql.org/pgsql-hackers/2007-07/msg00436.php - - o Consider keeping seperate cached copies when search_path changes - - http://archives.postgresql.org/pgsql-hackers/2008-01/msg01009.php - - o Add CASE capability to language (already in SQL) - - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00696.php - - - - -* 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 data to be passed in native language formats, rather - than only text - - http://archives.postgresql.org/pgsql-hackers/2007-05/msg00289.php - - o Add ability to obfuscate function bodies - - http://archives.postgresql.org/pgsql-patches/2008-01/msg00125.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. - -* Add a function like pg_get_indexdef() that report more detailed index - information - - http://archives.postgresql.org/pgsql-bugs/2007-12/msg00166.php - -* psql - o Have psql show current values for a sequence - o Move psql backslash database information into the backend, use - mnemonic commands? - - This would allow non-psql clients to pull the same information out - of the database as psql. - http://archives.postgresql.org/pgsql-hackers/2004-01/msg00191.php - - o Make 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 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 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 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 - - o Prevent escape string warnings when object names have - backslashes - - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00227.php - - o Have \d show foreign keys that reference a table's primary key - - http://archives.postgresql.org/pgsql-hackers/2007-04/msg00424.php - - o Have \d show child tables that inherit from the specified parent - o Have \l+ show database size, if permissions allow - - Ideally it will not generate an error for invalid permissions - - o Include the symbolic SQLSTATE name in verbose error reports - - http://archives.postgresql.org/pgsql-general/2007-09/msg00438.php - - o -Improve display of enums to show valid enum values - o Add prompt escape to display the client and server versions - - -* pg_dump / pg_restore - 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 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 Change pg_dump so that a comment on the dumped database is - applied to the loaded database, even if the database has a - different name. This will require new backend syntax, perhaps - COMMENT ON CURRENT DATABASE. - o Remove unnecessary function pointer abstractions in pg_dump source - code - o Allow pg_dump to utilize multiple CPUs and I/O channels by dumping - multiple objects simultaneously - - The difficulty with this is getting multiple dump processes to - produce a single dump output file. It also would require - several sessions to share the same snapshot. - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php - - o Allow pg_restore to utilize multiple CPUs and I/O channels by - restoring multiple objects simultaneously - - This might require a pg_restore flag to indicate how many - simultaneous operations should be performed. Only pg_dump's - -Fc format has the necessary dependency information. - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00963.php - - o To better utilize resources, allow pg_restore to check foreign - keys simultaneously, where possible - o Allow pg_restore to create all indexes of a table - concurrently, via a single heap scan - - This requires a pg_dump -Fc file because that format contains - the required dependency information. - http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php - - o Allow pg_restore to load different parts of the COPY data - simultaneously - o Prevent pg_dump/pg_restore from being affected by - statement_timeout - - Using psql to restore a pg_dump dump is also affected. - - o Remove pre-7.3 pg_dump code that assumes pg_depend does not exit - o Allow pre/data/post files when schema and data are dumped - separately, for performance reasons - - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php - - - -* 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 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 - - o Add SQLSTATE severity to PGconn return status - - http://archives.postgresql.org/pgsql-interfaces/2007-11/msg00015.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 - -* -Add ability to trigger on TRUNCATE - - - -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 - http://archives.postgresql.org/pgsql-hackers/2007-03/msg00265.php - http://archives.postgresql.org/pgsql-hackers/2007-03/msg01214.php - http://archives.postgresql.org/pgsql-patches/2007-05/msg00013.php - http://archives.postgresql.org/pgsql-hackers/2007-07/msg00741.php - -* 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 - -* Consider increasing the default and maximum number of statistics targets, - and reduce statistics target overhead - - Also consider having a larger statistics target for indexed columns - and expression indexes. - http://archives.postgresql.org/pgsql-general/2007-05/msg01228.php - http://archives.postgresql.org/pgsql-general/2007-06/msg00542.php - http://archives.postgresql.org/pgsql-hackers/2008-01/msg01066.php - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00188.php - -* Consider smaller indexes that record a range of values per heap page, - rather than having one index entry for every heap row - - This is useful if the heap is clustered by the indexed values. - http://archives.postgresql.org/pgsql-hackers/2006-12/msg00341.php - http://archives.postgresql.org/pgsql-hackers/2007-02/msg01264.php - http://archives.postgresql.org/pgsql-hackers/2007-03/msg00465.php - http://archives.postgresql.org/pgsql-patches/2007-03/msg00163.php - http://archives.postgresql.org/pgsql-hackers/2007-08/msg00014.php - http://archives.postgresql.org/pgsql-hackers/2007-08/msg00487.php - http://archives.postgresql.org/pgsql-hackers/2008-04/msg01589.php - -* 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. - http://archives.postgresql.org/pgsql-performance/2007-08/msg00289.php - -* Allow multiple indexes to be created concurrently, ideally via a - single heap scan, and have pg_restore use it - -* Consider sorting entries before inserting into btree index - - http://archives.postgresql.org/pgsql-general/2008-01/msg01010.php - -* Allow index scans to return matching index keys, not just the matching - heap locations - - http://archives.postgresql.org/pgsql-hackers/2008-04/msg01657.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 - o Require all CHECK constraints to be inherited - - http://archives.postgresql.org/pgsql-bugs/2007-04/msg00026.php - - o Add checks to prevent a CREATE RULE views on inherited tables - - http://archives.postgresql.org/pgsql-general/2008-02/msg01420.php - http://archives.postgresql.org/pgsql-general/2008-03/msg00077.php - - -* 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 - - - -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 program to test if fsync has a delay compared to non-fsync -* Consider sorting writes during checkpoint - - http://archives.postgresql.org/pgsql-hackers/2007-06/msg00541.php - - - -Cache Usage -=========== - -* 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. - - http://archives.postgresql.org/pgsql-patches/2007-10/msg00166.php - http://archives.postgresql.org/pgsql-patches/2008-01/msg00049.php - -* Consider automatic caching of statements at various levels: - - o Parsed query tree - o Query execute plan - o Query results - http://archives.postgresql.org/pgsql-hackers/2008-04/msg00823.php - -* 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 - -* Consider allowing higher priority queries to have referenced buffer - cache pages stay in memory longer - - http://archives.postgresql.org/pgsql-hackers/2007-11/msg00562.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 - http://archives.postgresql.org/pgsql-hackers/2007-08/msg00307.php - -* 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 - http://archives.postgresql.org/pgsql-patches/2007-03/msg00508.php - http://archives.postgresql.org/pgsql-patches/2007-04/msg00347.php - http://archives.postgresql.org/pgsql-hackers/2007-11/msg00156.php - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00546.php - http://archives.postgresql.org/pgsql-hackers/2008-04/msg00416.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? -* Improve dead row detection during multi-statement transactions usage - - http://archives.postgresql.org/pgsql-patches/2007-03/msg00358.php - -* Consider a more compact data representation for dead tuples - - http://archives.postgresql.org/pgsql-patches/2007-05/msg00143.php - - -* Auto-vacuum - - o %Issue log message to suggest VACUUM FULL if a table is nearly - empty? - 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 - - The problem is that autovacuum cannot vacuum them to set frozen xids; - only the session that created them can do that. - http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php - - o Store per-table autovacuum settings in pg_class.reloptions. - - http://archives.postgresql.org/pgsql-hackers/2007-02/msg01440.php - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00724.php - - o Prevent autovacuum from running if an old transaction is still - running from the last vacuum - - http://archives.postgresql.org/pgsql-hackers/2007-11/msg00899.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 - http://archives.postgresql.org/pgsql-hackers/2007-05/msg00773.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 - -* Improve deadlock detection when a page cleaning lock conflicts - with a shared buffer that is pinned - - http://archives.postgresql.org/pgsql-bugs/2008-01/msg00138.php - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php - http://archives.postgresql.org/pgsql-committers/2008-01/msg00365.php - -* Detect deadlocks involving LockBufferForCleanup() - - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php - - - -Startup Time Improvements -========================= - -* Experiment with multi-threaded backend for backend creation - - 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. - - - -Write-Ahead Log -=============== - -* Eliminate need to write full pages to WAL before page modification - - 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. - http://archives.postgresql.org/pgsql-hackers/2002-06/msg00655.php - - 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 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. - http://archives.postgresql.org/pgsql-hackers/2002-11/msg00483.php - -* Allow WAL logging to be turned off for a table, but the table - might be dropped or truncated during crash recovery - - 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. - http://archives.postgresql.org/pgsql-hackers/2005-12/msg01016.php - -* Allow WAL logging to be turned off for a table, but the table would - avoid being truncated/dropped - - 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. - http://archives.postgresql.org/pgsql-hackers/2005-12/msg01016.php - -* Speed WAL recovery by allowing more than one page to be prefetched - - This should be done utilizing the same infrastructure used for - prefetching in general to avoid introducing complex error-prone code - in WAL replay. - http://archives.postgresql.org/pgsql-general/2007-12/msg00683.php - http://archives.postgresql.org/pgsql-hackers/2007-12/msg00497.php - http://archives.postgresql.org/pgsql-hackers/2008-02/msg01279.php - -* Improve WAL concurrency by increasing lock granularity - - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00556.php - -* Be more aggressive about creating WAL files - - http://archives.postgresql.org/pgsql-hackers/2007-10/msg01325.php - http://archives.postgresql.org/pgsql-hackers/2004-07/msg01075.php - http://archives.postgresql.org/pgsql-hackers/2005-04/msg00556.php - -* Have resource managers report the duration of their status changes - - http://archives.postgresql.org/pgsql-hackers/2007-10/msg01468.php - -* Move pgfoundry's xlogdump to /contrib and have it rely more closely - on the WAL backend code - - http://archives.postgresql.org/pgsql-hackers/2007-11/msg00035.php - - - - -Optimizer / Executor -==================== - -* Improve selectivity functions for geometric operators -* 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 -* Improve how ANALYZE computes in-doubt tuples - - http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php - -* 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 - -* Consider using a hash for joining to a large IN (VALUES ...) list - - http://archives.postgresql.org/pgsql-hackers/2007-05/msg00450.php - - - -Background Writer -================= - -* Consider having the background writer update the transaction status - hint bits before writing out the page - - Implementing this requires the background writer to have access to system - catalogs and the transaction status log. - -* Consider adding buffers the background writer finds reusable to the - free list - - http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php - -* Automatically tune bgwriter_delay based on activity rather then using a - fixed interval - - http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php - -* Consider wither increasing BM_MAX_USAGE_COUNT improves performance - - http://archives.postgresql.org/pgsql-hackers/2007-06/msg01007.php - -* Test to see if calling PreallocXlogFiles() from the background writer - will help with WAL segment creation latency - - http://archives.postgresql.org/pgsql-patches/2007-06/msg00340.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 - http://archives.postgresql.org/pgsql-performance/2007-09/msg00255.php - http://archives.postgresql.org/pgsql-hackers/2007-12/msg00027.php - http://archives.postgresql.org/pgsql-patches/2008-01/msg00170.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 -* Consider ways of storing rows more compactly on disk - - 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 - - http://archives.postgresql.org/pgsql-hackers/2007-08/msg00030.php - http://archives.postgresql.org/pgsql-performance/2007-08/msg00024.php - -* Consider transaction start/end performance improvements - - http://archives.postgresql.org/pgsql-hackers/2007-07/msg00948.php - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php - -* Allow user configuration of TOAST thresholds - - http://archives.postgresql.org/pgsql-hackers/2007-02/msg00213.php - http://archives.postgresql.org/pgsql-hackers/2007-08/msg00082.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 - -* Experiment with multi-threaded backend better I/O utilization - - This would allow a single query to make use of 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. - -* Experiment with multi-threaded backend better CPU utilization - - This would allow several CPUs to be used for a single query, such as - for sorting or query execution. - -* Consider increasing the minimum allowed number of shared buffers - - http://archives.postgresql.org/pgsql-bugs/2008-02/msg00157.php - -* Expire published xmin for read-only and idle transactions - - http://archives.postgresql.org/pgsql-hackers/2007-09/msg00343.php - -* Consider if CommandCounterIncrement() can avoid its - AcceptInvalidationMessages() call - - http://archives.postgresql.org/pgsql-committers/2007-11/msg00585.php - -* Improve performance of shared invalidation queue for multiple CPUs - - http://archives.postgresql.org/pgsql-performance/2008-01/msg00023.php - -* Consider Cartesian joins when both relations are needed to form an - indexscan qualification for a third relation - - http://archives.postgresql.org/pgsql-performance/2007-12/msg00090.php - -* Consider not storing a NULL bitmap on disk if all the NULLs are - trailing - - http://archives.postgresql.org/pgsql-hackers/2007-12/msg00624.php - http://archives.postgresql.org/pgsql-patches/2007-12/msg00109.php - -* Sort large UPDATE/DELETEs so it is done in heap order - - http://archives.postgresql.org/pgsql-hackers/2008-01/msg01119.php - -* -Avoid tuple some tuple copying in sort routines -* SMP scalability improvements - - http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php - http://archives.postgresql.org/pgsql-hackers/2007-09/msg00206.php - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php - -* Research reducing deTOASTing in more places - - http://archives.postgresql.org/pgsql-hackers/2007-09/msg00895.php - -* Consider being smarter about memory and external files used during - sorts - - http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php - http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php - -* Allow one transaction to see tuples using the snapshot of another - transaction - - This would assist multiple backends in working together. - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00400.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 -* Acquire lock on a relation before building a relcache entry for it -* Allow cross-compiling by generating the zic database on the target system -* Improve NLS maintenance of libpgport messages linked onto applications -* Clean up casting in contrib/isn - - http://archives.postgresql.org/pgsql-hackers/2006-11/msg00245.php - -* 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 - -* 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 - -* Consider changing documentation format from SGML to XML - - http://archives.postgresql.org/pgsql-docs/2006-12/msg00152.php - -* 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 - -* 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. - -* Research use of signals and sleep wake ups - - http://archives.postgresql.org/pgsql-hackers/2007-07/msg00003.php - -* Add automated check for invalid C++ source code constructs - - http://archives.postgresql.org/pgsql-patches/2007-07/msg00056.php - -* Consider simplifying how memory context resets handle child contexts - - http://archives.postgresql.org/pgsql-patches/2007-08/msg00067.php - -* Remove use of MAKE_PTR and MAKE_OFFSET macros - - http://archives.postgresql.org/pgsql-general/2007-08/msg01510.php - -* Convert single quotes to apostrophes in the PDF documentation - - http://archives.postgresql.org/pgsql-docs/2007-12/msg00059.php - -* Create three versions of libpgport to simplify client code - - http://archives.postgresql.org/pgsql-hackers/2007-10/msg00154.php - -* Remove old-style routines for manipulating tuples - - http://archives.postgresql.org/pgsql-hackers/2007-10/msg00851.php - -* Improve detection of shared memory segments being used by other - FreeBSD jails - - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00656.php - -* Implement the non-threaded Avahi service discovery protocol - - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00939.php - http://archives.postgresql.org/pgsql-patches/2008-02/msg00097.php - http://archives.postgresql.org/pgsql-hackers/2008-03/msg01211.php - http://archives.postgresql.org/pgsql-patches/2008-04/msg00001.php - -* 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 Fix problem with shared memory on the Win32 Terminal Server - o Diagnose problem where shared memory can sometimes not be - attached by postmaster children - - http://archives.postgresql.org/pgsql-general/2007-08/msg01377.php - - o Improve signal handling - - http://archives.postgresql.org/pgsql-patches/2005-06/msg00027.php - - o Convert MSVC build system to remove most batch files - - http://archives.postgresql.org/pgsql-hackers/2007-08/msg00961.php - - o Prevent SSL from sending network packets to avoid interference - with Win32 signal emulation - - http://archives.postgresql.org/pgsql-hackers/2007-12/msg00455.php - - o Support pgxs when using MSVC - - o Fix MSVC NLS support, like for to_char() - - http://archives.postgresql.org/pgsql-hackers/2008-02/msg00485.php - http://archives.postgresql.org/pgsql-patches/2008-02/msg00038.php - - o Find a correct rint() substitute on Windows - - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00808.php - - - -* 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 -* Add features of 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 any schema and not use a separate "packages" - syntax at all. - - http://archives.postgresql.org/pgsql-hackers/2006-08/msg00384.php - -* 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 - http://archives.postgresql.org/pgsql-hackers/2008-03/msg00849.php - -* Add autonomous transactions - - http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.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 - - - Because we support postfix operators, it isn't possible to make AS - optional and continue to use bison. - http://archives.postgresql.org/pgsql-hackers/2003-04/msg00436.php - - 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. + http://wiki.postgresql.org/wiki/Todo