3 Current maintainer: Bruce Momjian (bruce@momjian.us)
4 Last updated: Fri Apr 11 15:16:40 EDT 2008
6 The most recent version of this document can be viewed at
7 http://www.postgresql.org/docs/faqs.TODO.html.
9 #A hyphen, "-", marks changes that will appear in the upcoming 8.3 release.#
10 #A percent sign, "%", marks items that are easier to implement.#
12 Bracketed items, "[]", have more detail.
14 This list contains all known PostgreSQL bugs and feature requests. If
15 you would like to work on an item, please read the Developer's FAQ
16 first. There is also a developer's wiki at
17 http://developer.postgresql.org.
23 * Allow administrators to safely terminate individual sessions either
24 via an SQL function or SIGTERM
26 Lock table corruption following SIGTERM of an individual backend
27 has been reported in 8.0. A possible cause was fixed in 8.1, but
28 it is unknown whether other problems exist. This item mostly
29 requires additional testing rather than of writing any new code.
31 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00174.php
32 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00218.php
34 * Check for unreferenced table files created by transactions that were
35 in-progress when the server terminated abruptly
37 http://archives.postgresql.org/pgsql-patches/2006-06/msg00096.php
39 * Set proper permissions on non-system schemas during db creation
41 Currently all schemas are owned by the super-user because they are copied
42 from the template1 database. However, since all objects are inherited
43 from the template database, it is not clear that setting schemas to the db
46 * Add function to report the time of the most recent server reload
47 * Allow statistics collector information to be pulled from the collector
48 process directly, rather than requiring the collector to write a
49 filesystem file twice a second?
50 * Reduce file system activity overhead of statistics file pgstat.stat
52 http://archives.postgresql.org/pgsql-general/2007-12/msg00106.php
54 * Allow statistics last vacuum/analyze execution times to be displayed
55 without requiring stats_row_level to be enabled
57 http://archives.postgresql.org/pgsql-docs/2007-04/msg00028.php
59 * Allow log_min_messages to be specified on a per-module basis
61 This would allow administrators to see more detailed information from
62 specific sections of the backend, e.g. checkpoints, autovacuum, etc.
63 Another idea is to allow separate configuration files for each module,
64 or allow arbitrary SET commands to be passed to them.
66 * Simplify ability to create partitioned tables
68 This would allow creation of partitioned tables without requiring
69 creation of triggers or rules for INSERT/UPDATE/DELETE, and constraints
70 for rapid partition selection. Options could include range and hash
73 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00375.php
74 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00151.php
75 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00028.php
76 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00248.php
77 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00387.php
78 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00413.php
80 * Allow auto-selection of partitioned tables for min/max() operations
81 * Allow more complex user/database default GUC settings
83 Currently ALTER USER and ALTER DATABASE support per-user and
84 per-database defaults. Consider adding per-user-and-database
85 defaults so things like search_path can be defaulted for a
86 specific user connecting to a specific database.
88 * Allow custom variable classes that can restrict who can set the values
90 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00911.php
92 * Implement the SQL standard mechanism whereby REVOKE ROLE revokes only
93 the privilege granted by the invoking role, and not those granted
96 http://archives.postgresql.org/pgsql-bugs/2007-05/msg00010.php
98 * Allow SSL authentication/encryption over unix domain sockets
100 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00924.php
102 * Allow SSL key file permission checks to be optionally disabled when
103 sharing SSL keys with other applications
105 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00069.php
107 * Allow client certificate names to be checked against the client
110 This is already implemented in
111 libpq/fe-secure.c::verify_peer_name_matches_certificate() but the code
114 * Configuration files
116 o Allow pg_hba.conf to specify host names along with IP addresses
118 Host name lookup could occur when the postmaster reads the
119 pg_hba.conf file, or when the backend starts. Another
120 solution would be to reverse lookup the connection IP and
121 check that hostname against the host names in pg_hba.conf.
122 We could also then check that the host name maps to the IP
125 o %Allow postgresql.conf file values to be changed via an SQL
126 API, perhaps using SET GLOBAL
127 o Allow the server to be stopped/restarted via an SQL API
128 o Issue a warning if a change-on-restart-only postgresql.conf value
129 is modified and the server config files are reloaded
130 o Consider normalizing fractions in postgresql.conf, perhaps
133 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00550.php
135 o Allow Kerberos to disable stripping of realms so we can
136 check the username@realm against multiple realms
138 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00009.php
143 o Allow a database in tablespace t1 with tables created in
144 tablespace t2 to be used as a template for a new database created
145 with default tablespace t2
147 Currently all objects in the default database tablespace must
148 have default tablespace specifications. This is because new
149 databases are created by copying directories. If you mix default
150 tablespace tables and tablespace-specified tables in the same
151 directory, creating a new database from such a mixed directory
152 would create a new database with tables that had incorrect
153 explicit tablespaces. To fix this would require modifying
154 pg_class in the newly copied database, which we don't currently
157 o Allow reporting of which objects are in which tablespaces
159 This item is difficult because a tablespace can contain objects
160 from multiple databases. There is a server-side function that
161 returns the databases which use a specific tablespace, so this
162 requires a tool that will call that function and connect to each
163 database to find the objects in each database for that tablespace.
165 o Allow WAL replay of CREATE TABLESPACE to work when the directory
166 structure on the recovery computer is different from the original
168 o Allow per-tablespace quotas
171 * Point-In-Time Recovery (PITR)
173 o Allow a warm standby system to also allow read-only statements
176 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00050.php
178 o %Create dump tool for write-ahead logs for use in determining
179 transaction id for point-in-time recovery
181 This is useful for checking PITR recovery.
183 o Allow recovery.conf to support the same syntax as
184 postgresql.conf, including quoting
186 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00497.php
188 o Fix server restart problem when the server was shutdown during
191 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00800.php
193 o Recreate pg_xlog/archive_status/ if it doesn't exist after
194 restoring from a PITR backup
196 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00487.php
202 * Change NUMERIC to enforce the maximum precision
203 * Reduce storage space for small NUMERICs
205 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01331.php
206 http://archives.postgresql.org/pgsql-patches/2007-02/msg00505.php
207 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00715.php
209 * Fix data types where equality comparison isn't intuitive, e.g. box
210 * Add support for public SYNONYMs
212 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00519.php
214 * Fix CREATE CAST on DOMAINs
216 http://archives.postgresql.org/pgsql-hackers/2006-05/msg00072.php
217 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01681.php
219 * Allow domains to be cast
221 http://archives.postgresql.org/pgsql-hackers/2003-06/msg01206.php
222 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00289.php
224 * Add support for SQL-standard GENERATED/IDENTITY columns
226 http://archives.postgresql.org/pgsql-hackers/2006-07/msg00543.php
227 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00038.php
228 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00344.php
229 http://archives.postgresql.org/pgsql-patches/2007-05/msg00076.php
230 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00604.php
232 * Improve XML support
234 http://developer.postgresql.org/index.php/XML_Support
236 * Consider placing all sequences in a single table, or create a system
239 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
241 * Allow the UUID type to accept non-standard formats
243 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01214.php
245 * Allow text search dictionary to filter out only stop words
247 http://archives.postgresql.org/pgsql-patches/2007-11/msg00081.php
249 * Consider a function-based API for '@@' full text searches
251 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00511.php
253 * Improve text search error messages
255 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00966.php
256 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01146.php
258 * Consider a special data type for regular expressions
260 http://archives.postgresql.org/pgsql-hackers/2007-08/msg01067.php
262 * Reduce BIT data type overhead using short varlena headers
264 http://archives.postgresql.org/pgsql-general/2007-12/msg00273.php
266 * Allow xml arrays to be cast to other data types
268 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00981.php
269 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00231.php
270 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00471.php
272 * Simplify integer cross-data-type operators
274 http://archives.postgresql.org/pgsql-bugs/2008-01/msg00189.php
280 o Allow infinite dates and intervals just like infinite timestamps
281 o Merge hardwired timezone names with the TZ database; allow either
282 kind everywhere a TZ name is currently taken
283 o Allow TIMESTAMP WITH TIME ZONE to store the original timezone
284 information, either zone name or offset from UTC [timezone]
286 If the TIMESTAMP value is stored with a time zone name, interval
287 computations should adjust based on the time zone rules.
289 o Fix SELECT '0.01 years'::interval, '0.01 months'::interval
290 o Add a GUC variable to allow output of interval values in ISO8601
292 o Have timestamp subtraction not call justify_hours()?
294 http://archives.postgresql.org/pgsql-sql/2006-10/msg00059.php
296 o Improve timestamptz subtraction to be DST-aware
298 Currently subtracting one date from another that crosses a
299 daylight savings time adjustment can return '1 day 1 hour', but
300 adding that back to the first date returns a time one hour in
301 the future. This is caused by the adjustment of '25 hours' to
302 '1 day 1 hour', and '1 day' is the same time the next day, even
303 if daylight savings adjustments are involved.
305 o Fix interval display to support values exceeding 2^31 hours
306 o Add overflow checking to timestamp and interval arithmetic
307 o Extend timezone code to allow 64-bit values so we can
308 represent years beyond 2038
310 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01363.php
312 o Use LC_TIME for localized weekday/month names, rather than
315 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00390.php
317 o Add ISO INTERVAL handling
319 http://archives.postgresql.org/pgsql-hackers/2006-01/msg00250.php
320 http://archives.postgresql.org/pgsql-bugs/2006-04/msg00248.php
322 o Support ISO INTERVAL syntax if units cannot be determined from
323 the string, and are supplied after the string
325 The SQL standard states that the units after the string
326 specify the units of the string, e.g. INTERVAL '2' MINUTE
327 should return '00:02:00'. The current behavior has the units
328 restrict the interval value to the specified unit or unit
329 range, INTERVAL '70' SECOND returns '00:00:10'.
331 For syntax that isn't uniquely ISO or PG syntax, like '1' or
332 '1:30', treat as ISO if there is a range specification clause,
333 and as PG if there no clause is present, e.g. interpret '1:30'
334 MINUTE TO SECOND as '1 minute 30 seconds', and interpret
335 '1:30' as '1 hour, 30 minutes'.
337 This makes common cases like SELECT INTERVAL '1' MONTH
338 SQL-standard results. The SQL standard supports a limited
339 number of unit combinations and doesn't support unit names in
340 the string. The PostgreSQL syntax is more flexible in the
341 range of units supported, e.g. PostgreSQL supports '1 year 1
342 hour', while the SQL standard does not.
344 o Add support for year-month syntax, INTERVAL '50-6' YEAR
346 o Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1
347 year' AS INTERVAL MONTH), and this should return '12 months'
348 o Round or truncate values to the requested precision, e.g.
349 INTERVAL '11 months' AS YEAR should return one or zero
350 o Support precision, CREATE TABLE foo (a INTERVAL MONTH(3))
355 o Delay resolution of array expression's data type so assignment
356 coercion can be performed on empty array expressions
357 o Add support for arrays of domains
359 http://archives.postgresql.org/pgsql-patches/2007-05/msg00114.php
361 o Allow single-byte header storage for array elements
366 o Improve vacuum of large objects, like contrib/vacuumlo?
367 o Add security checking for large objects
368 o Auto-delete large objects when referencing row is deleted
370 contrib/lo offers this functionality.
372 o Allow read/write into TOAST values like large objects
374 This requires the TOAST column to be stored EXTERNAL.
376 o Add API for 64-bit large object access
378 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00781.php
382 * Add locale-aware MONEY type, and support multiple currencies
384 http://archives.postgresql.org/pgsql-general/2005-08/msg01432.php
385 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01181.php
387 * MONEY dumps in a locale-specific format making it difficult to
388 restore to a system with a different locale
389 * Allow MONEY to be easily cast to/from other numeric data types
395 * Allow INET subnet tests using non-constants to be indexed
396 * Allow to_date() and to_timestamp() accept localized month names
397 * Fix to_date()-related functions to consistently issue errors
399 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00915.php
401 * Add missing parameter handling in to_char()
403 http://archives.postgresql.org/pgsql-hackers/2005-12/msg00948.php
405 * Allow substring/replace() to get/set bit values
406 * Allow to_char() on interval values to accumulate the highest unit
409 Some special format flag would be required to request such
410 accumulation. Such functionality could also be added to EXTRACT.
411 Prevent accumulation that crosses the month/day boundary because of
412 the uneven number of days in a month.
414 o to_char(INTERVAL '1 hour 5 minutes', 'MI') => 65
415 o to_char(INTERVAL '43 hours 20 minutes', 'MI' ) => 2600
416 o to_char(INTERVAL '43 hours 20 minutes', 'WK:DD:HR:MI') => 0:1:19:20
417 o to_char(INTERVAL '3 years 5 months','MM') => 41
419 * Implement inlining of set-returning functions defined in SQL
420 * Allow SQL-language functions to return results from RETURNING queries
422 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00665.php
424 * Allow SQL-language functions to reference parameters by parameter name
426 Currently SQL-language functions can only refer to dollar parameters,
429 * Add SPI_gettypmod() to return the typemod for a TupleDesc
430 * Enforce typmod for function inputs, function results and parameters for
431 spi_prepare'd statements called from PLs
433 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01403.php
435 * Allow holdable cursors in SPI
436 * Tighten function permission checks
438 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00568.php
440 * Fix IS OF so it matches the ISO specification, and add documentation
442 http://archives.postgresql.org/pgsql-patches/2003-08/msg00060.php
443 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00060.php
445 * Add missing operators for geometric data types
447 Some geometric types do not have the full suite of geometric operators,
450 * Implement Boyer-Moore searching in strpos()
452 http://archives.postgresql.org/pgsql-patches/2007-08/msg00012.php
454 * Prevent malicious functions from being executed with the permissions
455 of unsuspecting users
457 Index functions are safe, so VACUUM and ANALYZE are safe too.
458 Triggers, CHECK and DEFAULT expressions, and rules are still vulnerable.
459 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00268.php
461 * Reduce memory usage of aggregates in set returning functions
463 http://archives.postgresql.org/pgsql-performance/2008-01/msg00031.php
465 * Add temporal versions of generate_series()
467 http://archives.postgresql.org/pgsql-hackers/2007-04/msg01180.php
469 * Add array_accum() and array_to_set() functions for arrays
471 The standards specify array_agg() and UNNEST.
472 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00464.php
474 * Fix /contrib/ltree operator
476 http://archives.postgresql.org/pgsql-bugs/2007-11/msg00044.php
478 * Fix inconsistent precedence of =, >, and < compared to <>, >=, and <=
480 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00145.php
482 * Fix regular expression bug when using complex back-references
484 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00000.php
486 * Have /contrib/dblink reuse unnamed connections
488 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00895.php
490 * Add SQL-standard array_agg() and unnest() array functions
492 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01017.php
494 * Support procedures, which return no value
496 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01375.php
500 Multi-Language Support
501 ======================
503 * Add NCHAR (as distinguished from ordinary varchar),
504 * Allow locale to be set at database creation
506 Currently locale can only be set during initdb. No global tables have
507 locale-aware columns. However, the database template used during
508 database creation might have locale-aware indexes. The indexes would
509 need to be reindexed to match the new locale.
511 * Allow encoding on a per-column basis optionally using the ICU library
513 Right now only one encoding is allowed per database. [locale]
515 http://archives.postgresql.org/pgsql-hackers/2005-03/msg00932.php
516 http://archives.postgresql.org/pgsql-patches/2005-08/msg00309.php
517 http://archives.postgresql.org/pgsql-patches/2006-03/msg00233.php
518 http://archives.postgresql.org/pgsql-hackers/2006-09/msg00662.php
519 http://wiki.postgresql.org/wiki/Todo:Collate
520 http://wiki.postgresql.org/wiki/Todo:ICU
522 * Add CREATE COLLATE? [locale]
523 * Support multiple simultaneous character sets, per SQL92
524 * Improve UTF8 combined character handling?
525 * Add octet_length_server() and octet_length_client()
526 * Make octet_length_client() the same as octet_length()?
527 * Fix problems with wrong runtime encoding conversion for NLS message files
528 * Add URL to more complete multi-byte regression tests
530 http://archives.postgresql.org/pgsql-hackers/2005-07/msg00272.php
532 * Fix ILIKE and regular expressions to handle case insensitivity
533 properly in multibyte encodings
535 http://archives.postgresql.org/pgsql-bugs/2005-10/msg00001.php
536 http://archives.postgresql.org/pgsql-patches/2005-11/msg00173.php
538 * Set client encoding based on the client operating system encoding
540 Currently client_encoding is set in postgresql.conf, which
541 defaults to the server encoding.
542 http://archives.postgresql.org/pgsql-hackers/2006-08/msg01696.php
544 * Change memory allocation for multi-byte functions so memory is
545 allocated inside conversion functions
547 Currently we preallocate memory based on worst-case usage.
554 * Automatically create rules on views so they are updateable, per SQL99
556 We can only auto-create rules for simple views. For more complex
557 cases users will still have to write rules manually.
559 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00586.php
560 http://archives.postgresql.org/pgsql-patches/2006-08/msg00255.php
562 * Add the functionality for WITH CHECK OPTION clause of CREATE VIEW
563 * Allow NOTIFY in rules involving conditionals
564 * Allow VIEW/RULE recompilation when the underlying tables change
566 Another issue is whether underlying table changes should be reflected
567 in the view, e.g. should SELECT * show additional columns if they
568 are added after the view is created.
570 * Make it possible to use RETURNING together with conditional DO INSTEAD
571 rules, such as for partitioning setups
573 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00577.php
575 * Add the ability to automatically create materialized views
577 Right now materialized views require the user to create triggers on the
578 main table to keep the summary table current. SQL syntax should be able
579 to manager the triggers and summary table automatically. A more
580 sophisticated implementation would automatically retrieve from the
581 summary table when the main table is referenced, if possible.
588 * Add CORRESPONDING BY to UNION/INTERSECT/EXCEPT
589 * Add ROLLUP, CUBE, GROUPING SETS options to GROUP BY
590 * %Allow SET CONSTRAINTS to be qualified by schema/table name
591 * %Add a separate TRUNCATE permission
593 Currently only the owner can TRUNCATE a table because triggers are not
594 called, and the table is locked in exclusive mode.
596 * Allow PREPARE of cursors
597 * Allow finer control over the caching of prepared query plans
599 Currently queries prepared via the libpq API are planned on first
600 execute using the supplied parameters --- allow SQL PREPARE to do the
601 same. Also, allow control over replanning prepared queries either
602 manually or automatically when statistics for execute parameters
603 differ dramatically from those used during planning.
605 * Improve logging of prepared transactions recovered during startup
607 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00092.php
609 * Allow LISTEN/NOTIFY to store info in memory rather than tables?
611 Currently LISTEN/NOTIFY information is stored in pg_listener. Storing
612 such information in memory would improve performance.
614 * Add optional textual message to NOTIFY
616 This would allow an informational message to be added to the notify
617 message, perhaps indicating the row modified or other custom
620 * Allow multiple identical NOTIFY events to always be communicated to the
621 client, rather than sent as a single notification to the listener
623 http://archives.postgresql.org/pgsql-general/2008-01/msg00057.php
625 * Add a GUC variable to warn about non-standard SQL usage in queries
626 * Add SQL-standard MERGE command, typically used to merge two tables
629 This is similar to UPDATE, then for unmatched rows, INSERT.
630 Whether concurrent access allows modifications which could cause
631 row loss is implementation independent.
633 * Add REPLACE or UPSERT command that does UPDATE, or on failure, INSERT
636 To implement this cleanly requires that the table have a unique index
637 so duplicate checking can be easily performed. It is possible to
638 do it without a unique index if we require the user to LOCK the table
641 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00501.php
642 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00536.php
644 * Add NOVICE output level for helpful messages like automatic sequence/index
646 * Add GUC to issue notice about statements that use unjoined tables
647 * Allow EXPLAIN to identify tables that were skipped because of
649 * Allow EXPLAIN output to be more easily processed by scripts, perhaps XML
650 * Enable standard_conforming_strings
651 * Make standard_conforming_strings the default in 8.5?
653 When this is done, backslash-quote should be prohibited in non-E''
654 strings because of possible confusion over how such strings treat
655 backslashes. Basically, '' is always safe for a literal single
656 quote, while \' might or might not be based on the backslash
659 * Simplify dropping roles that have objects in several databases
660 * Allow COMMENT ON to accept an expression rather than just a string
661 * Allow the count returned by SELECT, etc to be represented as an int64
662 to allow a higher range of values
663 * Add SQL99 WITH clause to SELECT
664 * Add SQL:2003 WITH RECURSIVE (hierarchical) queries to SELECT
666 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01375.php
667 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00642.php
668 http://archives.postgresql.org/pgsql-patches/2007-03/msg00139.php
669 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01334.php
670 http://archives.postgresql.org/pgsql-patches/2008-01/msg00105.php
671 http://archives.postgresql.org/pgsql-patches/2008-03/msg00327.php
673 * Add DEFAULT .. AS OWNER so permission checks are done as the table
676 This would be useful for SERIAL nextval() calls and CHECK constraints.
678 * Allow DISTINCT to work in multiple-argument aggregate calls
679 * Add column to pg_stat_activity that shows the progress of long-running
680 commands like CREATE INDEX and VACUUM
681 * Implement SQL:2003 window functions
682 * Improve failure message when DROP DATABASE is used on a database that
683 has prepared transactions
684 * Allow INSERT/UPDATE ... RETURNING inside a SELECT 'FROM' clause
686 http://archives.postgresql.org/pgsql-general/2006-09/msg00803.php
687 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00693.php
689 * Increase locking when DROPing objects so dependent objects cannot
690 get dropped while the DROP operation is happening
692 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00937.php
694 * -Allow AS in "SELECT col AS label" to be optional in certain cases
696 * Allow INSERT ... DELETE ... RETURNING, namely allow the DELETE ...
697 RETURNING to supply values to the INSERT
698 http://archives.postgresql.org/pgsql-hackers/2008-02/thrd2.php#00979
700 * Add comments on system tables/columns using the information in
703 Ideally the information would be pulled from the SGML file
706 * Improve reporting of UNION type mismatches
708 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00944.php
709 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00597.php
714 o Allow CREATE TABLE AS to determine column lengths for complex
715 expressions like SELECT col1 || col2
717 o Have WITH CONSTRAINTS also create constraint indexes
719 http://archives.postgresql.org/pgsql-patches/2007-04/msg00149.php
721 o Have CONSTRAINT cname NOT NULL record the contraint name
723 Right now pg_attribute.attnotnull records the NOT NULL status
724 of the column, but does not record the contraint name
726 o Prevent concurrent CREATE TABLE table1 from sometimes returning
727 a cryptic error message
729 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00169.php
733 o Allow UPDATE tab SET ROW (col, ...) = (SELECT...)
735 http://archives.postgresql.org/pgsql-hackers/2006-07/msg01306.php
736 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00865.php
737 http://archives.postgresql.org/pgsql-patches/2007-04/msg00315.php
738 http://archives.postgresql.org/pgsql-patches/2008-03/msg00237.php
740 o Research self-referential UPDATEs that see inconsistent row versions
741 in read-committed mode
743 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00507.php
744 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00016.php
746 o Allow GLOBAL temporary tables to exist as empty by default in
749 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00006.php
754 o Have ALTER TABLE RENAME rename SERIAL sequence names
756 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
758 o Have ALTER SEQUENCE RENAME rename the sequence name stored
759 in the sequence table
761 http://archives.postgresql.org/pgsql-bugs/2007-09/msg00092.php
762 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00007.php
763 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
765 o Add ALTER DOMAIN to modify the underlying data type
766 o %Allow ALTER TABLE ... ALTER CONSTRAINT ... RENAME
768 http://archives.postgresql.org/pgsql-patches/2006-02/msg00168.php
770 o %Allow ALTER TABLE to change constraint deferrability and actions
771 o Add missing object types for ALTER ... SET SCHEMA
772 o Allow ALTER TABLESPACE to move to different directories
773 o Allow databases to be moved to different tablespaces
774 o Allow moving system tables to other tablespaces, where possible
776 Currently non-global system tables must be in the default database
777 tablespace. Global system tables can never be moved.
779 o Prevent parent tables from altering or dropping constraints
780 like CHECK that are inherited by child tables unless CASCADE
782 o %Prevent child tables from altering or dropping constraints
783 like CHECK that were inherited from the parent table
784 o Have ALTER INDEX update the name of a constraint using that index
785 o Add ALTER TABLE RENAME CONSTRAINT, update index name also
786 o Allow column display reordering by recording a display,
787 storage, and permanent id for every column?
789 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00782.php
795 o Automatically maintain clustering on a table
797 This might require some background daemon to maintain clustering
798 during periods of low usage. It might also require tables to be only
799 partially filled for easier reorganization. Another idea would
800 be to create a merged heap/index data file so an index lookup would
801 automatically access the heap data too. A third idea would be to
802 store heap rows in hashed groups, perhaps using a user-supplied
804 http://archives.postgresql.org/pgsql-performance/2004-08/msg00349.php
806 o %Add default clustering to system tables
808 To do this, determine the ideal cluster index for each system
809 table and set the cluster setting during initdb.
811 o %Add VERBOSE option to report tables as they are processed,
817 o Allow COPY to report error lines and continue
819 This requires the use of a savepoint before each COPY line is
820 processed, with ROLLBACK on COPY failure.
821 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00572.php
823 o Allow COPY on a newly-created table to skip WAL logging
825 On crash recovery, the table involved in the COPY would
826 be removed or have its heap and index files truncated. One
827 issue is that no other backend should be able to add to
828 the table at the same time, which is something that is
829 currently allowed. This currently is done if the table is
830 created inside the same transaction block as the COPY because
831 no other backends can see the table.
833 o Consider using a ring buffer for COPY FROM
835 http://archives.postgresql.org/pgsql-patches/2008-02/msg00140.php
836 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01080.php
838 o Allow COPY FROM to create index entries in bulk
840 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00811.php
842 o Allow COPY in CSV mode to control whether a quoted zero-length
843 string is treated as NULL
845 Currently this is always treated as a zero-length string,
846 which generates an error when loading into an integer column
847 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00905.php
853 o Allow column-level privileges
854 o %Allow GRANT/REVOKE permissions to be applied to all schema objects
857 The proposed syntax is:
858 GRANT SELECT ON ALL TABLES IN public TO phpuser;
859 GRANT SELECT ON NEW TABLES IN public TO phpuser;
861 o Allow GRANT/REVOKE permissions to be inherited by objects based on
864 o Allow SERIAL sequences to inherit permissions from the base table?
869 o Prevent DROP TABLE from dropping a row referenced by its own open
875 o Allow INSERT/UPDATE of the system-generated oid value for a row
876 o In rules, allow VALUES() to contain a mixture of 'old' and 'new'
882 o Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM
887 Referential Integrity
888 =====================
890 * Add MATCH PARTIAL referential integrity
891 * Change foreign key constraint for array -> element to mean element
893 * Fix problem when cascading referential triggers make changes on
894 cascaded tables, seeing the tables in an intermediate state
896 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
897 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
899 * Allow DEFERRABLE and end-of-statement UNIQUE constraints?
901 This would allow UPDATE tab SET col = col + 1 to work if col has
902 a unique index. Currently, uniqueness checks are done while the
903 command is being executed, rather than at the end of the statement
905 http://people.planetpostgresql.org/greg/index.php?/archives/2006/06/10.html
906 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01458.php
908 * Optimize referential integrity checks
910 http://archives.postgresql.org/pgsql-performance/2005-10/msg00458.php
911 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00744.php
914 Server-Side Languages
915 =====================
918 o Fix RENAME to work on variables other than OLD/NEW
920 http://archives.postgresql.org/pgsql-hackers/2002-03/msg00591.php
921 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01615.php
922 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01587.php
924 o Allow function parameters to be passed by name,
925 get_employee_salary(12345 AS emp_id, 2001 AS tax_year)
926 o Allow handling of %TYPE arrays, e.g. tab.col%TYPE[]
927 o Allow listing of record column names, and access to
928 record columns via variables, e.g. columns := r.(*),
931 http://archives.postgresql.org/pgsql-patches/2005-07/msg00458.php
932 http://archives.postgresql.org/pgsql-patches/2006-05/msg00302.php
933 http://archives.postgresql.org/pgsql-patches/2006-06/msg00031.php
935 o Add support for SCROLL cursors
936 o Add support for WITH HOLD cursors
937 o Allow row and record variables to be set to NULL constants,
938 and allow NULL tests on such variables
940 Because a row is not scalar, do not allow assignment
941 from NULL-valued scalars.
943 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00070.php
945 o Review handling of MOVE and FETCH
947 http://archives.postgresql.org/pgsql-patches/2007-04/msg00527.php
949 o Improve logic of determining if an identifier is a a
950 variable or column name
952 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00436.php
954 o Consider keeping seperate cached copies when search_path changes
956 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01009.php
958 o Add CASE capability to language (already in SQL)
960 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00696.php
966 o Add table function support to pltcl, plpythonu
967 o Add support for polymorphic arguments and return types to
968 languages other than PL/PgSQL
969 o Add capability to create and call PROCEDURES
970 o Add support for OUT and INOUT parameters to languages other
972 o Add PL/PythonU tracebacks
974 http://archives.postgresql.org/pgsql-patches/2006-02/msg00288.php
976 o Allow data to be passed in native language formats, rather
979 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00289.php
981 o Add ability to obfuscate function bodies
983 http://archives.postgresql.org/pgsql-patches/2008-01/msg00125.php
990 * Have pg_ctl look at PGHOST in case it is a socket directory?
991 * Allow pg_ctl to work properly with configuration files located outside
994 pg_ctl can not read the pid file because it isn't located in the
995 config directory but in the PGDATA directory. The solution is to
996 allow pg_ctl to read and understand postgresql.conf to find the
997 data_directory value.
999 * Add a function like pg_get_indexdef() that report more detailed index
1002 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00166.php
1005 o Have psql show current values for a sequence
1006 o Move psql backslash database information into the backend, use
1007 mnemonic commands? [psql]
1009 This would allow non-psql clients to pull the same information out
1010 of the database as psql.
1012 o Fix psql's \d commands more consistent
1014 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1015 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1017 o Consistently display privilege information for all objects in psql
1018 o Add auto-expanded mode so expanded output is used if the row
1019 length is wider than the screen width.
1021 Consider using auto-expanded mode for backslash commands like \df+.
1023 o Prevent tab completion of SET TRANSACTION from querying the
1024 database and therefore preventing the transaction isolation
1025 level from being set.
1027 Currently SET <tab> causes a database lookup to check all
1028 supported session variables. This query causes problems
1029 because setting the transaction isolation level must be the
1030 first statement of a transaction.
1032 o Add a \set variable to control whether \s displays line numbers
1034 Another option is to add \# which lists line numbers, and
1035 allows command execution.
1037 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00255.php
1039 o Prevent escape string warnings when object names have
1042 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00227.php
1044 o Have \d show foreign keys that reference a table's primary key
1046 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00424.php
1048 o Have \d show child tables that inherit from the specified parent
1049 o Have \l+ show database size, if permissions allow
1051 Ideally it will not generate an error for invalid permissions
1053 o Include the symbolic SQLSTATE name in verbose error reports
1055 http://archives.postgresql.org/pgsql-general/2007-09/msg00438.php
1057 o Improve display if enums
1059 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00826.php
1064 * pg_dump / pg_restore
1065 o %Add dumping of comments on index columns and composite type columns
1066 o %Add full object name to the tag field. eg. for operators we need
1067 '=(integer, integer)', instead of just '='.
1068 o Add pg_dumpall custom format dumps?
1069 o Allow selection of individual object(s) of all types, not just
1071 o In a selective dump, allow dumping of an object and all its
1073 o Add options like pg_restore -l and -L to pg_dump
1074 o Stop dumping CASCADE on DROP TYPE commands in clean mode
1075 o Allow pg_dump --clean to drop roles that own objects or have
1077 o Change pg_dump so that a comment on the dumped database is
1078 applied to the loaded database, even if the database has a
1079 different name. This will require new backend syntax, perhaps
1080 COMMENT ON CURRENT DATABASE.
1081 o Remove unnecessary function pointer abstractions in pg_dump source
1083 o Allow pg_dump to utilize multiple CPUs and I/O channels by dumping
1084 multiple objects simultaneously
1086 The difficulty with this is getting multiple dump processes to
1087 produce a single dump output file. It also would require
1088 several sessions to share the same snapshot.
1089 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1091 o Allow pg_restore to utilize multiple CPUs and I/O channels by
1092 restoring multiple objects simultaneously
1094 This might require a pg_restore flag to indicate how many
1095 simultaneous operations should be performed. Only pg_dump's
1096 -Fc format has the necessary dependency information.
1097 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00963.php
1099 o To better utilize resources, allow pg_restore to check foreign
1100 keys simultaneously, where possible
1101 o Allow pg_restore to create all indexes of a table
1102 concurrently, via a single heap scan
1104 This requires a pg_dump -Fc file because that format contains
1105 the required dependency information.
1106 http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php
1108 o Allow pg_restore to load different parts of the COPY data
1110 o Prevent pg_dump/pg_restore from being affected by
1113 Using psql to restore a pg_dump dump is also affected.
1115 o Remove pre-7.3 pg_dump code that assumes pg_depend does not exit
1116 o Allow pre/data/post files when schema and data are dumped
1117 separately, for performance reasons
1119 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1126 Document differences between ecpg and the SQL standard and
1127 information about the Informix-compatibility module.
1129 o Solve cardinality > 1 for input descriptors / variables?
1130 o Add a semantic check level, e.g. check if a table really exists
1131 o fix handling of DB attributes that are arrays
1132 o Use backend PREPARE/EXECUTE facility for ecpg where possible
1134 o Fix nested C comments
1135 o %sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified
1136 o Make SET CONNECTION thread-aware, non-standard?
1137 o Allow multidimensional arrays
1138 o Add internationalized message strings
1139 o Implement COPY FROM STDIN
1143 o Add PQescapeIdentifierConn()
1144 o Prevent PQfnumber() from lowercasing unquoted the column name
1146 PQfnumber() should never have been doing lowercasing, but
1147 historically it has so we need a way to prevent it
1149 o Allow statement results to be automatically batched to the client
1151 Currently all statement results are transferred to the libpq
1152 client before libpq makes the results available to the
1153 application. This feature would allow the application to make
1154 use of the first result rows while the rest are transferred, or
1155 held on the server waiting for them to be requested by libpq.
1156 One complexity is that a statement like SELECT 1/col could error
1157 out mid-way through the result set.
1159 o Consider disallowing multiple queries in PQexec() as an
1160 additional barrier to SQL injection attacks
1162 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00184.php
1164 o Add PQexecf() that allows complex parameter substitution
1166 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01803.php
1168 o Add SQLSTATE severity to PGconn return status
1170 http://archives.postgresql.org/pgsql-interfaces/2007-11/msg00015.php
1176 * Add deferred trigger queue file
1178 Right now all deferred trigger information is stored in backend
1179 memory. This could exhaust memory for very large trigger queues.
1180 This item involves dumping large queues into files.
1182 * Allow triggers to be disabled in only the current session.
1184 This is currently possible by starting a multi-statement transaction,
1185 modifying the system tables, performing the desired SQL, restoring the
1186 system tables, and committing the transaction. ALTER TABLE ...
1187 TRIGGER requires a table lock so it is not ideal for this usage.
1189 * With disabled triggers, allow pg_dump to use ALTER TABLE ADD FOREIGN KEY
1191 If the dump is known to be valid, allow foreign keys to be added
1192 without revalidating the data.
1194 * Allow statement-level triggers to access modified rows
1195 * Support triggers on columns
1197 http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php
1199 * Allow AFTER triggers on system tables
1201 System tables are modified in many places in the backend without going
1202 through the executor and therefore not causing triggers to fire. To
1203 complete this item, the functions that modify system tables will have
1206 * Tighten trigger permission checks
1208 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00564.php
1210 * Allow BEFORE INSERT triggers on views
1212 http://archives.postgresql.org/pgsql-general/2007-02/msg01466.php
1214 * -Add ability to trigger on TRUNCATE
1221 * Add UNIQUE capability to non-btree indexes
1222 * Prevent index uniqueness checks when UPDATE does not modify the column
1224 Uniqueness (index) checks are done when updating a column even if the
1225 column is not modified by the UPDATE.
1227 * Allow the creation of on-disk bitmap indexes which can be quickly
1228 combined with other bitmap indexes
1230 Such indexes could be more compact if there are only a few distinct values.
1231 Such indexes can also be compressed. Keeping such indexes updated can be
1234 http://archives.postgresql.org/pgsql-patches/2005-07/msg00512.php
1235 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01107.php
1236 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00265.php
1237 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01214.php
1238 http://archives.postgresql.org/pgsql-patches/2007-05/msg00013.php
1239 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00741.php
1241 * Allow accurate statistics to be collected on indexes with more than
1242 one column or expression indexes, perhaps using per-index statistics
1244 http://archives.postgresql.org/pgsql-performance/2006-10/msg00222.php
1245 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01131.php
1247 * Consider increasing the number of default statistics target, and
1248 reduce statistics target overhead
1250 Also consider having a larger statistics target for indexed columns
1251 and expression indexes
1252 http://archives.postgresql.org/pgsql-general/2007-05/msg01228.php
1253 http://archives.postgresql.org/pgsql-general/2007-06/msg00542.php
1254 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01066.php
1256 * Consider compressing indexes by storing key values duplicated in
1257 several rows as a single index entry
1259 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00341.php
1260 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01264.php
1261 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00465.php
1262 http://archives.postgresql.org/pgsql-patches/2007-03/msg00163.php
1263 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00014.php
1264 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00487.php
1266 * Add REINDEX CONCURRENTLY, like CREATE INDEX CONCURRENTLY
1268 This is difficult because you must upgrade to an exclusive table lock
1269 to replace the existing index file. CREATE INDEX CONCURRENTLY does not
1270 have this complication. This would allow index compaction without
1272 http://archives.postgresql.org/pgsql-performance/2007-08/msg00289.php
1274 * Allow multiple indexes to be created concurrently, ideally via a
1275 single heap scan, and have pg_restore use it
1277 * Consider sorting entries before inserting into btree index
1279 http://archives.postgresql.org/pgsql-general/2008-01/msg01010.php
1281 * Allow index scans to return matching index keys
1283 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01079.php
1288 o Allow inherited tables to inherit indexes, UNIQUE constraints,
1289 and primary/foreign keys
1290 o Honor UNIQUE INDEX on base column in INSERTs/UPDATEs
1291 on inherited table, e.g. INSERT INTO inherit_table
1292 (unique_index_col) VALUES (dup) should fail
1294 The main difficulty with this item is the problem of
1295 creating an index that can span multiple tables.
1297 o Allow SELECT ... FOR UPDATE on inherited tables
1298 o Require all CHECK constraints to be inherited
1300 http://archives.postgresql.org/pgsql-bugs/2007-04/msg00026.php
1302 o Add checks to prevent a CREATE RULE views on inherited tables
1304 http://archives.postgresql.org/pgsql-general/2008-02/msg01420.php
1305 http://archives.postgresql.org/pgsql-general/2008-03/msg00077.php
1310 o Add more GIST index support for geometric data types
1311 o Allow GIST indexes to create certain complex index types, like
1312 digital trees (see Aoki)
1317 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00051.php
1319 o Pack hash index buckets onto disk pages more efficiently
1321 Currently only one hash bucket can be stored on a page. Ideally
1322 several hash buckets could be stored on a single page and greater
1323 granularity used for the hash algorithm.
1325 http://archives.postgresql.org/pgsql-hackers/2004-06/msg00168.php
1327 o Consider sorting hash buckets so entries can be found using a
1328 binary search, rather than a linear scan
1329 o In hash indexes, consider storing the hash value with or instead
1331 o Add WAL logging for crash recovery
1332 o Allow multi-column hash indexes
1333 o -During index creation, pre-sort the tuples to improve build speed
1340 * Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
1342 Ideally this requires a separate test program that can be run
1343 at initdb time or optionally later. Consider O_SYNC when
1346 * Add program to test if fsync has a delay compared to non-fsync
1347 * Consider sorting writes during checkpoint
1349 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00541.php
1358 We could use a fixed row count and a +/- count to follow MVCC
1359 visibility rules, or a single cached value could be used and
1360 invalidated if anyone modifies the table. Another idea is to
1361 get a count directly from a unique index, but for this to be
1362 faster than a sequential scan it must avoid access to the heap
1363 to obtain tuple visibility information.
1365 * Provide a way to calculate an "estimated COUNT(*)"
1367 Perhaps by using the optimizer's cardinality estimates or random
1370 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00943.php
1372 * Allow data to be pulled directly from indexes
1374 Currently indexes do not have enough tuple visibility information
1375 to allow data to be pulled from the index without also accessing
1376 the heap. One way to allow this is to set a bit on index tuples
1377 to indicate if a tuple is currently visible to all transactions
1378 when the first valid heap lookup happens. This bit would have to
1379 be cleared when a heap tuple is expired.
1381 Another idea is to maintain a bitmap of heap pages where all rows
1382 are visible to all backends, and allow index lookups to reference
1383 that bitmap to avoid heap lookups, perhaps the same bitmap we might
1384 add someday to determine which heap pages need vacuuming. Frequently
1385 accessed bitmaps would have to be stored in shared memory. One 8k
1386 page of bitmaps could track 512MB of heap pages.
1388 A third idea would be for a heap scan to check if all rows are visible
1389 and if so set a per-table flag which can be checked by index scans.
1390 Any change to the table would have to clear the flag. To detect
1391 changes during the heap scan a counter could be set at the start and
1392 checked at the end --- if it is the same, the table has not been
1393 modified --- any table change would increment the counter.
1395 http://archives.postgresql.org/pgsql-patches/2007-10/msg00166.php
1396 http://archives.postgresql.org/pgsql-patches/2008-01/msg00049.php
1398 * Consider automatic caching of statements at various levels:
1401 o Query execute plan
1404 * Consider increasing internal areas when shared buffers is increased
1406 http://archives.postgresql.org/pgsql-hackers/2005-10/msg01419.php
1408 * Consider decreasing the amount of memory used by PrivateRefCount
1410 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00797.php
1411 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php
1413 * Consider allowing higher priority queries to have referenced buffer
1414 cache pages stay in memory longer
1416 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00562.php
1423 * Improve speed with indexes
1425 For large table adjustments during VACUUM FULL, it is faster to cluster
1426 or reindex rather than update the index. Also, index updates can bloat
1429 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00024.php
1430 http://archives.postgresql.org/pgsql-performance/2007-05/msg00296.php
1431 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00307.php
1433 * Auto-fill the free space map by scanning the buffer cache or by
1434 checking pages written by the background writer
1436 http://archives.postgresql.org/pgsql-hackers/2006-02/msg01125.php
1437 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00011.php
1439 * Create a bitmap of pages that need vacuuming
1441 Instead of sequentially scanning the entire table, have the background
1442 writer or some other process record pages that have expired rows, then
1443 VACUUM can look at just those pages rather than the entire table. In
1444 the event of a system crash, the bitmap would probably be invalidated.
1445 One complexity is that index entries still have to be vacuumed, and
1446 doing this without an index scan (by using the heap values to find the
1447 index entry) might be slow and unreliable, especially for user-defined
1450 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01188.php
1451 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00121.php
1452 http://archives.postgresql.org/pgsql-patches/2007-03/msg00508.php
1453 http://archives.postgresql.org/pgsql-patches/2007-04/msg00347.php
1454 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00156.php
1455 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00546.php
1456 http://archives.postgresql.org/pgsql-hackers/2008-04/msg00416.php
1458 * Allow FSM to return free space toward the beginning of the heap file,
1459 in hopes that empty pages at the end can be truncated by VACUUM
1460 * Allow FSM page return free space based on table clustering, to assist
1461 in maintaining clustering?
1462 * Improve dead row detection during multi-statement transactions usage
1464 http://archives.postgresql.org/pgsql-patches/2007-03/msg00358.php
1466 * Consider a more compact data representation for dead tuples
1468 http://archives.postgresql.org/pgsql-patches/2007-05/msg00143.php
1473 o %Issue log message to suggest VACUUM FULL if a table is nearly
1475 o Improve control of auto-vacuum
1477 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00876.php
1479 o Prevent long-lived temporary tables from causing frozen-xid
1480 advancement starvation
1482 The problem is that autovacuum cannot vacuum them to set frozen xids;
1483 only the session that created them can do that.
1484 http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php
1486 o Store per-table autovacuum settings in pg_class.reloptions.
1488 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01440.php
1489 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00724.php
1491 o Prevent autovacuum from running if an old transaction is still
1492 running from the last vacuum
1494 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00899.php
1501 * Fix priority ordering of read and write light-weight locks (Neil)
1503 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00893.php
1504 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00905.php
1506 * Fix problem when multiple subtransactions of the same outer transaction
1507 hold different types of locks, and one subtransaction aborts
1509 http://archives.postgresql.org/pgsql-hackers/2006-11/msg01011.php
1510 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00001.php
1511 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00435.php
1512 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00773.php
1514 * Allow UPDATEs on only non-referential integrity columns not to conflict
1515 with referential integrity locks
1517 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00073.php
1519 * Add idle_in_transaction_timeout GUC so locks are not held for long
1522 * Improve deadlock detection when a page cleaning lock conflicts
1523 with a shared buffer that is pinned
1525 http://archives.postgresql.org/pgsql-bugs/2008-01/msg00138.php
1526 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1527 http://archives.postgresql.org/pgsql-committers/2008-01/msg00365.php
1529 * Detect deadlocks involving LockBufferForCleanup()
1531 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1535 Startup Time Improvements
1536 =========================
1538 * Experiment with multi-threaded backend for backend creation [thread]
1540 This would prevent the overhead associated with process creation. Most
1541 operating systems have trivial process creation time compared to
1542 database startup overhead, but a few operating systems (Win32,
1543 Solaris) might benefit from threading. Also explore the idea of
1544 a single session using multiple threads to execute a statement faster.
1551 * Eliminate need to write full pages to WAL before page modification [wal]
1553 Currently, to protect against partial disk page writes, we write
1554 full page images to WAL before they are modified so we can correct any
1555 partial page writes during recovery. These pages can also be
1556 eliminated from point-in-time archive files.
1558 o When off, write CRC to WAL and check file system blocks
1561 If CRC check fails during recovery, remember the page in case
1562 a later CRC for that page properly matches.
1564 o Write full pages during file system write and not when
1565 the page is modified in the buffer cache
1567 This allows most full page writes to happen in the background
1568 writer. It might cause problems for applying WAL on recovery
1569 into a partially-written page, but later the full page will be
1572 * Allow WAL traffic to be streamed to another server for stand-by
1574 * Reduce WAL traffic so only modified values are written rather than
1577 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01589.php
1579 * Allow WAL information to recover corrupted pg_controldata
1581 http://archives.postgresql.org/pgsql-patches/2006-06/msg00025.php
1583 * Find a way to reduce rotational delay when repeatedly writing
1586 Currently fsync of WAL requires the disk platter to perform a full
1587 rotation to fsync again. One idea is to write the WAL to different
1588 offsets that might reduce the rotational delay.
1590 * Allow WAL logging to be turned off for a table, but the table
1591 might be dropped or truncated during crash recovery [walcontrol]
1593 Allow tables to bypass WAL writes and just fsync() dirty pages on
1594 commit. This should be implemented using ALTER TABLE, e.g. ALTER
1595 TABLE PERSISTENCE [ DROP | TRUNCATE | DEFAULT ]. Tables using
1596 non-default logging should not use referential integrity with
1597 default-logging tables. A table without dirty buffers during a
1598 crash could perhaps avoid the drop/truncate.
1600 * Allow WAL logging to be turned off for a table, but the table would
1601 avoid being truncated/dropped [walcontrol]
1603 To do this, only a single writer can modify the table, and writes
1604 must happen only on new pages so the new pages can be removed during
1605 crash recovery. Readers can continue accessing the table. Such
1606 tables probably cannot have indexes. One complexity is the handling
1607 of indexes on TOAST tables.
1609 * Speed WAL recovery by allowing more than one page to be prefetched
1611 This should be done utilizing the same infrastructure used for
1612 prefetching in general to avoid introducing complex error-prone code
1614 http://archives.postgresql.org/pgsql-general/2007-12/msg00683.php
1615 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00497.php
1616 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01279.php
1618 * Improve WAL concurrency by increasing lock granularity
1620 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00556.php
1622 * Be more aggressive about creating WAL files
1624 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01325.php
1625 http://archives.postgresql.org/pgsql-hackers/2004-07/msg01075.php
1626 http://archives.postgresql.org/pgsql-hackers/2005-04/msg00556.php
1628 * Have resource managers report the duration of their status changes
1630 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01468.php
1632 * Move pgfoundry's xlogdump to /contrib and have it rely more closely
1633 on the WAL backend code
1635 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00035.php
1640 Optimizer / Executor
1641 ====================
1643 * Improve selectivity functions for geometric operators
1644 * Precompile SQL functions to avoid overhead
1645 * Create utility to compute accurate random_page_cost value
1646 * Improve ability to display optimizer analysis using OPTIMIZER_DEBUG
1647 * Have EXPLAIN ANALYZE issue NOTICE messages when the estimated and
1648 actual row counts differ by a specified percentage
1649 * Improve how ANALYZE computes in-doubt tuples
1651 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php
1653 * Consider using hash buckets to do DISTINCT, rather than sorting
1655 This would be beneficial when there are few distinct values. This is
1656 already used by GROUP BY.
1658 * Log statements where the optimizer row estimates were dramatically
1659 different from the number of rows actually found?
1660 * Consider compressed annealing to search for query plans
1662 This might replace GEQO, http://sixdemonbag.org/Djinni.
1664 * Improve merge join performance by allowing mark/restore of
1667 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00096.php
1669 * Consider using a hash for joining to a large IN (VALUES ...) list
1671 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00450.php
1678 * Consider having the background writer update the transaction status
1679 hint bits before writing out the page
1681 Implementing this requires the background writer to have access to system
1682 catalogs and the transaction status log.
1684 * Consider adding buffers the background writer finds reusable to the
1687 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1689 * Automatically tune bgwriter_delay based on activity rather then using a
1692 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1694 * Consider wither increasing BM_MAX_USAGE_COUNT improves performance
1696 http://archives.postgresql.org/pgsql-hackers/2007-06/msg01007.php
1698 * Test to see if calling PreallocXlogFiles() from the background writer
1699 will help with WAL segment creation latency
1701 http://archives.postgresql.org/pgsql-patches/2007-06/msg00340.php
1705 Miscellaneous Performance
1706 =========================
1708 * Do async I/O for faster random read-ahead of data
1710 Async I/O allows multiple I/O requests to be sent to the disk with
1711 results coming back asynchronously.
1713 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00820.php
1714 http://archives.postgresql.org/pgsql-performance/2007-09/msg00255.php
1715 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00027.php
1716 http://archives.postgresql.org/pgsql-patches/2008-01/msg00170.php
1718 * Use mmap() rather than SYSV shared memory or to write WAL files?
1720 This would remove the requirement for SYSV SHM but would introduce
1721 portability issues. Anonymous mmap (or mmap to /dev/zero) is required
1722 to prevent I/O overhead.
1724 * Consider mmap()'ing files into a backend?
1726 Doing I/O to large tables would consume a lot of address space or
1727 require frequent mapping/unmapping. Extending the file also causes
1728 mapping problems that might require mapping only individual pages,
1729 leading to thousands of mappings. Another problem is that there is no
1730 way to _prevent_ I/O to disk from the dirty shared buffers so changes
1731 could hit disk before WAL is written.
1733 * Add a script to ask system configuration questions and tune postgresql.conf
1734 * Consider ways of storing rows more compactly on disk
1736 o Reduce the row header size?
1737 o Consider reducing on-disk varlena length from four bytes to
1738 two because a heap row cannot be more than 64k in length
1740 * Consider increasing NUM_CLOG_BUFFERS
1742 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00030.php
1743 http://archives.postgresql.org/pgsql-performance/2007-08/msg00024.php
1745 * Consider transaction start/end performance improvements
1747 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00948.php
1748 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1750 * Allow user configuration of TOAST thresholds
1752 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00213.php
1753 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00082.php
1755 * Allow configuration of backend priorities via the operating system
1757 Though backend priorities make priority inversion during lock
1758 waits possible, research shows that this is not a huge problem.
1760 http://archives.postgresql.org/pgsql-general/2007-02/msg00493.php
1762 * Experiment with multi-threaded backend better I/O utilization
1764 This would allow a single query to make use of multiple I/O channels
1765 simultaneously. One idea is to create a background reader that can
1766 pre-fetch sequential and index scan pages needed by other backends.
1767 This could be expanded to allow concurrent reads from multiple devices
1768 in a partitioned table.
1770 * Experiment with multi-threaded backend better CPU utilization
1772 This would allow several CPUs to be used for a single query, such as
1773 for sorting or query execution.
1775 * Consider increasing the minimum allowed number of shared buffers
1777 http://archives.postgresql.org/pgsql-bugs/2008-02/msg00157.php
1779 * Expire published xmin for read-only and idle transactions
1781 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00343.php
1783 * Consider if CommandCounterIncrement() can avoid its
1784 AcceptInvalidationMessages() call
1786 http://archives.postgresql.org/pgsql-committers/2007-11/msg00585.php
1788 * Improve performance of shared invalidation queue for multiple CPUs
1790 http://archives.postgresql.org/pgsql-performance/2008-01/msg00023.php
1792 * Consider Cartesian joins when both relations are needed to form an
1793 indexscan qualification for a third relation
1795 http://archives.postgresql.org/pgsql-performance/2007-12/msg00090.php
1797 * Consider not storing a NULL bitmap on disk if all the NULLs are
1800 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00624.php
1801 http://archives.postgresql.org/pgsql-patches/2007-12/msg00109.php
1803 * Sort large UPDATE/DELETEs so it is done in heap order
1805 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01119.php
1807 * -Avoid tuple some tuple copying in sort routines
1808 * SMP scalability improvements
1810 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php
1811 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00206.php
1812 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1814 * Research reducing deTOASTing in more places
1816 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00895.php
1818 * Consider being smarter about memory and external files used during
1821 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php
1822 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php
1824 * Allow one transaction to see tuples using the snapshot of another
1827 This would assist multiple backends in working together.
1828 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00400.php
1834 * Add use of 'const' for variables in source tree
1835 * Move some things from contrib into main tree
1836 * %Remove warnings created by -Wcast-align
1837 * Move platform-specific ps status display info from ps_status.c to ports
1838 * Add optional CRC checksum to heap and index pages
1839 * Improve documentation to build only interfaces (Marc)
1840 * Remove or relicense modules that are not under the BSD license, if possible
1841 * Acquire lock on a relation before building a relcache entry for it
1842 * Allow cross-compiling by generating the zic database on the target system
1843 * Improve NLS maintenance of libpgport messages linked onto applications
1844 * Clean up casting in contrib/isn
1846 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00245.php
1848 * Use UTF8 encoding for NLS messages so all server encodings can
1850 * Update Bonjour to work with newer cross-platform SDK
1852 http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php
1853 http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php
1855 * Consider detoasting keys before sorting
1856 * Consider GnuTLS if OpenSSL license becomes a problem
1858 http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php
1859 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php
1861 * Consider changing documentation format from SGML to XML
1863 http://archives.postgresql.org/pgsql-docs/2006-12/msg00152.php
1865 * Consider making NAMEDATALEN more configurable in future releases
1866 * Update our code to handle 64-bit timezone files to match the zic
1867 source code, which now uses them
1868 * Have configure choose integer datetimes by default
1870 http://archives.postgresql.org/pgsql-patches/2007-05/msg00046.php
1872 * Support scoped IPv6 addresses
1874 http://archives.postgresql.org/pgsql-bugs/2007-05/msg00111.php
1876 * Consider allowing 64-bit integers and floats to be passed by value on
1879 Also change 32-bit floats (float4) to be passed by value at the same
1882 * Research use of signals and sleep wake ups
1884 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00003.php
1886 * Add automated check for invalid C++ source code constructs
1888 http://archives.postgresql.org/pgsql-patches/2007-07/msg00056.php
1890 * Consider simplifying how memory context resets handle child contexts
1892 http://archives.postgresql.org/pgsql-patches/2007-08/msg00067.php
1894 * Remove use of MAKE_PTR and MAKE_OFFSET macros
1896 http://archives.postgresql.org/pgsql-general/2007-08/msg01510.php
1898 * Convert single quotes to apostrophes in the PDF documentation
1900 http://archives.postgresql.org/pgsql-docs/2007-12/msg00059.php
1902 * Create three versions of libpgport to simplify client code
1904 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00154.php
1906 * Remove old-style routines for manipulating tuples
1908 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00851.php
1910 * Improve detection of shared memory segments being used by other
1913 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00656.php
1919 o Remove configure.in check for link failure when cause is found
1920 o Remove readdir() errno patch when runtime/mingwex/dirent.c rev
1922 o Remove psql newline patch when we find out why mingw outputs an
1924 o Allow psql to use readline once non-US code pages work with
1926 o Fix problem with shared memory on the Win32 Terminal Server
1927 o Diagnose problem where shared memory can sometimes not be
1928 attached by postmaster children
1930 http://archives.postgresql.org/pgsql-general/2007-08/msg01377.php
1932 o Improve signal handling
1934 http://archives.postgresql.org/pgsql-patches/2005-06/msg00027.php
1936 o Convert MSVC build system to remove most batch files
1938 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00961.php
1940 o Prevent SSL from sending network packets to avoid interference
1941 with Win32 signal emulation
1943 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00455.php
1945 o Support pgxs when using MSVC
1947 o Fix MSVC NLS support, like for to_char()
1949 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00485.php
1950 http://archives.postgresql.org/pgsql-patches/2008-02/msg00038.php
1952 o Find a correct rint() substitute on Windows
1954 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00808.php
1958 * Wire Protocol Changes
1960 o Allow dynamic character set handling
1961 o Add decoded type, length, precision
1963 o Update clients to use data types, typmod, schema.table.column names
1964 of result sets using new statement protocol
1970 * Add pre-parsing phase that converts non-ISO syntax to supported
1973 This could allow SQL written for other databases to run without
1976 * Allow plug-in modules to emulate features from other databases
1977 * Add features of Oracle-style packages (Pavel)
1979 A package would be a schema with session-local variables,
1980 public/private functions, and initialization functions. It
1981 is also possible to implement these capabilities
1982 in any schema and not use a separate "packages"
1985 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00384.php
1987 * Consider allowing control of upper/lower case folding of unquoted
1990 http://archives.postgresql.org/pgsql-hackers/2004-04/msg00818.php
1991 http://archives.postgresql.org/pgsql-hackers/2006-10/msg01527.php
1992 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00849.php
1994 * Add autonomous transactions
1996 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.php
2000 Features We Do _Not_ Want
2001 =========================
2003 * All backends running as threads in a single process (not wanted)
2005 This eliminates the process protection we get from the current setup.
2006 Thread creation is usually the same overhead as process creation on
2007 modern systems, so it seems unwise to use a pure threaded model.
2009 * Optimizer hints (not wanted)
2011 Optimizer hints are used to work around problems in the optimizer. We
2012 would rather have the problems reported and fixed.
2014 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00506.php
2015 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00517.php
2016 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00663.php
2019 Because we support postfix operators, it isn't possible to make AS
2020 optional and continue to use bison.
2021 http://archives.postgresql.org/pgsql-hackers/2003-04/msg00436.php
2023 http://archives.postgresql.org/pgsql-sql/2006-08/msg00164.php
2025 * Embedded server (not wanted)
2027 While PostgreSQL clients runs fine in limited-resource environments, the
2028 server requires multiple processes and a stable pool of resources to
2029 run reliabily and efficiently. Stripping down the PostgreSQL server
2030 to run in the same process address space as the client application
2031 would add too much complexity and failure cases.