3 Current maintainer: Bruce Momjian (bruce@momjian.us)
4 Last updated: Fri Apr 11 15:50:35 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 * Allow calling of a procedure outside a SELECT that can control the
497 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01375.php
501 Multi-Language Support
502 ======================
504 * Add NCHAR (as distinguished from ordinary varchar),
505 * Allow locale to be set at database creation
507 Currently locale can only be set during initdb. No global tables have
508 locale-aware columns. However, the database template used during
509 database creation might have locale-aware indexes. The indexes would
510 need to be reindexed to match the new locale.
512 * Allow encoding on a per-column basis optionally using the ICU library
514 Right now only one encoding is allowed per database. [locale]
516 http://archives.postgresql.org/pgsql-hackers/2005-03/msg00932.php
517 http://archives.postgresql.org/pgsql-patches/2005-08/msg00309.php
518 http://archives.postgresql.org/pgsql-patches/2006-03/msg00233.php
519 http://archives.postgresql.org/pgsql-hackers/2006-09/msg00662.php
520 http://wiki.postgresql.org/wiki/Todo:Collate
521 http://wiki.postgresql.org/wiki/Todo:ICU
523 * Add CREATE COLLATE? [locale]
524 * Support multiple simultaneous character sets, per SQL92
525 * Improve UTF8 combined character handling?
526 * Add octet_length_server() and octet_length_client()
527 * Make octet_length_client() the same as octet_length()?
528 * Fix problems with wrong runtime encoding conversion for NLS message files
529 * Add URL to more complete multi-byte regression tests
531 http://archives.postgresql.org/pgsql-hackers/2005-07/msg00272.php
533 * Fix ILIKE and regular expressions to handle case insensitivity
534 properly in multibyte encodings
536 http://archives.postgresql.org/pgsql-bugs/2005-10/msg00001.php
537 http://archives.postgresql.org/pgsql-patches/2005-11/msg00173.php
539 * Set client encoding based on the client operating system encoding
541 Currently client_encoding is set in postgresql.conf, which
542 defaults to the server encoding.
543 http://archives.postgresql.org/pgsql-hackers/2006-08/msg01696.php
545 * Change memory allocation for multi-byte functions so memory is
546 allocated inside conversion functions
548 Currently we preallocate memory based on worst-case usage.
555 * Automatically create rules on views so they are updateable, per SQL99
557 We can only auto-create rules for simple views. For more complex
558 cases users will still have to write rules manually.
560 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00586.php
561 http://archives.postgresql.org/pgsql-patches/2006-08/msg00255.php
563 * Add the functionality for WITH CHECK OPTION clause of CREATE VIEW
564 * Allow NOTIFY in rules involving conditionals
565 * Allow VIEW/RULE recompilation when the underlying tables change
567 Another issue is whether underlying table changes should be reflected
568 in the view, e.g. should SELECT * show additional columns if they
569 are added after the view is created.
571 * Make it possible to use RETURNING together with conditional DO INSTEAD
572 rules, such as for partitioning setups
574 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00577.php
576 * Add the ability to automatically create materialized views
578 Right now materialized views require the user to create triggers on the
579 main table to keep the summary table current. SQL syntax should be able
580 to manager the triggers and summary table automatically. A more
581 sophisticated implementation would automatically retrieve from the
582 summary table when the main table is referenced, if possible.
589 * Add CORRESPONDING BY to UNION/INTERSECT/EXCEPT
590 * Add ROLLUP, CUBE, GROUPING SETS options to GROUP BY
591 * %Allow SET CONSTRAINTS to be qualified by schema/table name
592 * %Add a separate TRUNCATE permission
594 Currently only the owner can TRUNCATE a table because triggers are not
595 called, and the table is locked in exclusive mode.
597 * Allow PREPARE of cursors
598 * Allow finer control over the caching of prepared query plans
600 Currently queries prepared via the libpq API are planned on first
601 execute using the supplied parameters --- allow SQL PREPARE to do the
602 same. Also, allow control over replanning prepared queries either
603 manually or automatically when statistics for execute parameters
604 differ dramatically from those used during planning.
606 * Improve logging of prepared transactions recovered during startup
608 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00092.php
610 * Allow LISTEN/NOTIFY to store info in memory rather than tables?
612 Currently LISTEN/NOTIFY information is stored in pg_listener. Storing
613 such information in memory would improve performance.
615 * Add optional textual message to NOTIFY
617 This would allow an informational message to be added to the notify
618 message, perhaps indicating the row modified or other custom
621 * Allow multiple identical NOTIFY events to always be communicated to the
622 client, rather than sent as a single notification to the listener
624 http://archives.postgresql.org/pgsql-general/2008-01/msg00057.php
626 * Add a GUC variable to warn about non-standard SQL usage in queries
627 * Add SQL-standard MERGE command, typically used to merge two tables
630 This is similar to UPDATE, then for unmatched rows, INSERT.
631 Whether concurrent access allows modifications which could cause
632 row loss is implementation independent.
634 * Add REPLACE or UPSERT command that does UPDATE, or on failure, INSERT
637 To implement this cleanly requires that the table have a unique index
638 so duplicate checking can be easily performed. It is possible to
639 do it without a unique index if we require the user to LOCK the table
642 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00501.php
643 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00536.php
645 * Add NOVICE output level for helpful messages like automatic sequence/index
647 * Add GUC to issue notice about statements that use unjoined tables
648 * Allow EXPLAIN to identify tables that were skipped because of
650 * Allow EXPLAIN output to be more easily processed by scripts, perhaps XML
651 * Enable standard_conforming_strings
652 * Make standard_conforming_strings the default in 8.5?
654 When this is done, backslash-quote should be prohibited in non-E''
655 strings because of possible confusion over how such strings treat
656 backslashes. Basically, '' is always safe for a literal single
657 quote, while \' might or might not be based on the backslash
660 * Simplify dropping roles that have objects in several databases
661 * Allow COMMENT ON to accept an expression rather than just a string
662 * Allow the count returned by SELECT, etc to be represented as an int64
663 to allow a higher range of values
664 * Add SQL99 WITH clause to SELECT
665 * Add SQL:2003 WITH RECURSIVE (hierarchical) queries to SELECT
667 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01375.php
668 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00642.php
669 http://archives.postgresql.org/pgsql-patches/2007-03/msg00139.php
670 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01334.php
671 http://archives.postgresql.org/pgsql-patches/2008-01/msg00105.php
672 http://archives.postgresql.org/pgsql-patches/2008-03/msg00327.php
674 * Add DEFAULT .. AS OWNER so permission checks are done as the table
677 This would be useful for SERIAL nextval() calls and CHECK constraints.
679 * Allow DISTINCT to work in multiple-argument aggregate calls
680 * Add column to pg_stat_activity that shows the progress of long-running
681 commands like CREATE INDEX and VACUUM
682 * Implement SQL:2003 window functions
683 * Improve failure message when DROP DATABASE is used on a database that
684 has prepared transactions
685 * Allow INSERT/UPDATE ... RETURNING inside a SELECT 'FROM' clause
687 http://archives.postgresql.org/pgsql-general/2006-09/msg00803.php
688 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00693.php
690 * Increase locking when DROPing objects so dependent objects cannot
691 get dropped while the DROP operation is happening
693 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00937.php
695 * -Allow AS in "SELECT col AS label" to be optional in certain cases
697 * Allow INSERT ... DELETE ... RETURNING, namely allow the DELETE ...
698 RETURNING to supply values to the INSERT
699 http://archives.postgresql.org/pgsql-hackers/2008-02/thrd2.php#00979
701 * Add comments on system tables/columns using the information in
704 Ideally the information would be pulled from the SGML file
707 * Improve reporting of UNION type mismatches
709 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00944.php
710 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00597.php
715 o Allow CREATE TABLE AS to determine column lengths for complex
716 expressions like SELECT col1 || col2
718 o Have WITH CONSTRAINTS also create constraint indexes
720 http://archives.postgresql.org/pgsql-patches/2007-04/msg00149.php
722 o Have CONSTRAINT cname NOT NULL record the contraint name
724 Right now pg_attribute.attnotnull records the NOT NULL status
725 of the column, but does not record the contraint name
727 o Prevent concurrent CREATE TABLE table1 from sometimes returning
728 a cryptic error message
730 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00169.php
734 o Allow UPDATE tab SET ROW (col, ...) = (SELECT...)
736 http://archives.postgresql.org/pgsql-hackers/2006-07/msg01306.php
737 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00865.php
738 http://archives.postgresql.org/pgsql-patches/2007-04/msg00315.php
739 http://archives.postgresql.org/pgsql-patches/2008-03/msg00237.php
741 o Research self-referential UPDATEs that see inconsistent row versions
742 in read-committed mode
744 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00507.php
745 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00016.php
747 o Allow GLOBAL temporary tables to exist as empty by default in
750 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00006.php
755 o Have ALTER TABLE RENAME rename SERIAL sequence names
757 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
759 o Have ALTER SEQUENCE RENAME rename the sequence name stored
760 in the sequence table
762 http://archives.postgresql.org/pgsql-bugs/2007-09/msg00092.php
763 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00007.php
764 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
766 o Add ALTER DOMAIN to modify the underlying data type
767 o %Allow ALTER TABLE ... ALTER CONSTRAINT ... RENAME
769 http://archives.postgresql.org/pgsql-patches/2006-02/msg00168.php
771 o %Allow ALTER TABLE to change constraint deferrability and actions
772 o Add missing object types for ALTER ... SET SCHEMA
773 o Allow ALTER TABLESPACE to move to different directories
774 o Allow databases to be moved to different tablespaces
775 o Allow moving system tables to other tablespaces, where possible
777 Currently non-global system tables must be in the default database
778 tablespace. Global system tables can never be moved.
780 o Prevent parent tables from altering or dropping constraints
781 like CHECK that are inherited by child tables unless CASCADE
783 o %Prevent child tables from altering or dropping constraints
784 like CHECK that were inherited from the parent table
785 o Have ALTER INDEX update the name of a constraint using that index
786 o Add ALTER TABLE RENAME CONSTRAINT, update index name also
787 o Allow column display reordering by recording a display,
788 storage, and permanent id for every column?
790 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00782.php
796 o Automatically maintain clustering on a table
798 This might require some background daemon to maintain clustering
799 during periods of low usage. It might also require tables to be only
800 partially filled for easier reorganization. Another idea would
801 be to create a merged heap/index data file so an index lookup would
802 automatically access the heap data too. A third idea would be to
803 store heap rows in hashed groups, perhaps using a user-supplied
805 http://archives.postgresql.org/pgsql-performance/2004-08/msg00349.php
807 o %Add default clustering to system tables
809 To do this, determine the ideal cluster index for each system
810 table and set the cluster setting during initdb.
812 o %Add VERBOSE option to report tables as they are processed,
818 o Allow COPY to report error lines and continue
820 This requires the use of a savepoint before each COPY line is
821 processed, with ROLLBACK on COPY failure.
822 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00572.php
824 o Allow COPY on a newly-created table to skip WAL logging
826 On crash recovery, the table involved in the COPY would
827 be removed or have its heap and index files truncated. One
828 issue is that no other backend should be able to add to
829 the table at the same time, which is something that is
830 currently allowed. This currently is done if the table is
831 created inside the same transaction block as the COPY because
832 no other backends can see the table.
834 o Consider using a ring buffer for COPY FROM
836 http://archives.postgresql.org/pgsql-patches/2008-02/msg00140.php
837 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01080.php
839 o Allow COPY FROM to create index entries in bulk
841 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00811.php
843 o Allow COPY in CSV mode to control whether a quoted zero-length
844 string is treated as NULL
846 Currently this is always treated as a zero-length string,
847 which generates an error when loading into an integer column
848 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00905.php
854 o Allow column-level privileges
855 o %Allow GRANT/REVOKE permissions to be applied to all schema objects
858 The proposed syntax is:
859 GRANT SELECT ON ALL TABLES IN public TO phpuser;
860 GRANT SELECT ON NEW TABLES IN public TO phpuser;
862 o Allow GRANT/REVOKE permissions to be inherited by objects based on
865 o Allow SERIAL sequences to inherit permissions from the base table?
870 o Prevent DROP TABLE from dropping a row referenced by its own open
876 o Allow INSERT/UPDATE of the system-generated oid value for a row
877 o In rules, allow VALUES() to contain a mixture of 'old' and 'new'
883 o Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM
888 Referential Integrity
889 =====================
891 * Add MATCH PARTIAL referential integrity
892 * Change foreign key constraint for array -> element to mean element
894 * Fix problem when cascading referential triggers make changes on
895 cascaded tables, seeing the tables in an intermediate state
897 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
898 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
900 * Allow DEFERRABLE and end-of-statement UNIQUE constraints?
902 This would allow UPDATE tab SET col = col + 1 to work if col has
903 a unique index. Currently, uniqueness checks are done while the
904 command is being executed, rather than at the end of the statement
906 http://people.planetpostgresql.org/greg/index.php?/archives/2006/06/10.html
907 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01458.php
909 * Optimize referential integrity checks
911 http://archives.postgresql.org/pgsql-performance/2005-10/msg00458.php
912 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00744.php
915 Server-Side Languages
916 =====================
919 o Fix RENAME to work on variables other than OLD/NEW
921 http://archives.postgresql.org/pgsql-hackers/2002-03/msg00591.php
922 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01615.php
923 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01587.php
925 o Allow function parameters to be passed by name,
926 get_employee_salary(12345 AS emp_id, 2001 AS tax_year)
927 o Allow handling of %TYPE arrays, e.g. tab.col%TYPE[]
928 o Allow listing of record column names, and access to
929 record columns via variables, e.g. columns := r.(*),
932 http://archives.postgresql.org/pgsql-patches/2005-07/msg00458.php
933 http://archives.postgresql.org/pgsql-patches/2006-05/msg00302.php
934 http://archives.postgresql.org/pgsql-patches/2006-06/msg00031.php
936 o Add support for SCROLL cursors
937 o Add support for WITH HOLD cursors
938 o Allow row and record variables to be set to NULL constants,
939 and allow NULL tests on such variables
941 Because a row is not scalar, do not allow assignment
942 from NULL-valued scalars.
944 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00070.php
946 o Review handling of MOVE and FETCH
948 http://archives.postgresql.org/pgsql-patches/2007-04/msg00527.php
950 o Improve logic of determining if an identifier is a a
951 variable or column name
953 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00436.php
955 o Consider keeping seperate cached copies when search_path changes
957 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01009.php
959 o Add CASE capability to language (already in SQL)
961 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00696.php
967 o Add table function support to pltcl, plpythonu
968 o Add support for polymorphic arguments and return types to
969 languages other than PL/PgSQL
970 o Add capability to create and call PROCEDURES
971 o Add support for OUT and INOUT parameters to languages other
973 o Add PL/PythonU tracebacks
975 http://archives.postgresql.org/pgsql-patches/2006-02/msg00288.php
977 o Allow data to be passed in native language formats, rather
980 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00289.php
982 o Add ability to obfuscate function bodies
984 http://archives.postgresql.org/pgsql-patches/2008-01/msg00125.php
991 * Have pg_ctl look at PGHOST in case it is a socket directory?
992 * Allow pg_ctl to work properly with configuration files located outside
995 pg_ctl can not read the pid file because it isn't located in the
996 config directory but in the PGDATA directory. The solution is to
997 allow pg_ctl to read and understand postgresql.conf to find the
998 data_directory value.
1000 * Add a function like pg_get_indexdef() that report more detailed index
1003 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00166.php
1006 o Have psql show current values for a sequence
1007 o Move psql backslash database information into the backend, use
1008 mnemonic commands? [psql]
1010 This would allow non-psql clients to pull the same information out
1011 of the database as psql.
1013 o Fix psql's \d commands more consistent
1015 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1016 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1018 o Consistently display privilege information for all objects in psql
1019 o Add auto-expanded mode so expanded output is used if the row
1020 length is wider than the screen width.
1022 Consider using auto-expanded mode for backslash commands like \df+.
1024 o Prevent tab completion of SET TRANSACTION from querying the
1025 database and therefore preventing the transaction isolation
1026 level from being set.
1028 Currently SET <tab> causes a database lookup to check all
1029 supported session variables. This query causes problems
1030 because setting the transaction isolation level must be the
1031 first statement of a transaction.
1033 o Add a \set variable to control whether \s displays line numbers
1035 Another option is to add \# which lists line numbers, and
1036 allows command execution.
1038 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00255.php
1040 o Prevent escape string warnings when object names have
1043 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00227.php
1045 o Have \d show foreign keys that reference a table's primary key
1047 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00424.php
1049 o Have \d show child tables that inherit from the specified parent
1050 o Have \l+ show database size, if permissions allow
1052 Ideally it will not generate an error for invalid permissions
1054 o Include the symbolic SQLSTATE name in verbose error reports
1056 http://archives.postgresql.org/pgsql-general/2007-09/msg00438.php
1058 o Improve display if enums
1060 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00826.php
1065 * pg_dump / pg_restore
1066 o %Add dumping of comments on index columns and composite type columns
1067 o %Add full object name to the tag field. eg. for operators we need
1068 '=(integer, integer)', instead of just '='.
1069 o Add pg_dumpall custom format dumps?
1070 o Allow selection of individual object(s) of all types, not just
1072 o In a selective dump, allow dumping of an object and all its
1074 o Add options like pg_restore -l and -L to pg_dump
1075 o Stop dumping CASCADE on DROP TYPE commands in clean mode
1076 o Allow pg_dump --clean to drop roles that own objects or have
1078 o Change pg_dump so that a comment on the dumped database is
1079 applied to the loaded database, even if the database has a
1080 different name. This will require new backend syntax, perhaps
1081 COMMENT ON CURRENT DATABASE.
1082 o Remove unnecessary function pointer abstractions in pg_dump source
1084 o Allow pg_dump to utilize multiple CPUs and I/O channels by dumping
1085 multiple objects simultaneously
1087 The difficulty with this is getting multiple dump processes to
1088 produce a single dump output file. It also would require
1089 several sessions to share the same snapshot.
1090 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1092 o Allow pg_restore to utilize multiple CPUs and I/O channels by
1093 restoring multiple objects simultaneously
1095 This might require a pg_restore flag to indicate how many
1096 simultaneous operations should be performed. Only pg_dump's
1097 -Fc format has the necessary dependency information.
1098 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00963.php
1100 o To better utilize resources, allow pg_restore to check foreign
1101 keys simultaneously, where possible
1102 o Allow pg_restore to create all indexes of a table
1103 concurrently, via a single heap scan
1105 This requires a pg_dump -Fc file because that format contains
1106 the required dependency information.
1107 http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php
1109 o Allow pg_restore to load different parts of the COPY data
1111 o Prevent pg_dump/pg_restore from being affected by
1114 Using psql to restore a pg_dump dump is also affected.
1116 o Remove pre-7.3 pg_dump code that assumes pg_depend does not exit
1117 o Allow pre/data/post files when schema and data are dumped
1118 separately, for performance reasons
1120 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1127 Document differences between ecpg and the SQL standard and
1128 information about the Informix-compatibility module.
1130 o Solve cardinality > 1 for input descriptors / variables?
1131 o Add a semantic check level, e.g. check if a table really exists
1132 o fix handling of DB attributes that are arrays
1133 o Use backend PREPARE/EXECUTE facility for ecpg where possible
1135 o Fix nested C comments
1136 o %sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified
1137 o Make SET CONNECTION thread-aware, non-standard?
1138 o Allow multidimensional arrays
1139 o Add internationalized message strings
1140 o Implement COPY FROM STDIN
1144 o Add PQescapeIdentifierConn()
1145 o Prevent PQfnumber() from lowercasing unquoted the column name
1147 PQfnumber() should never have been doing lowercasing, but
1148 historically it has so we need a way to prevent it
1150 o Allow statement results to be automatically batched to the client
1152 Currently all statement results are transferred to the libpq
1153 client before libpq makes the results available to the
1154 application. This feature would allow the application to make
1155 use of the first result rows while the rest are transferred, or
1156 held on the server waiting for them to be requested by libpq.
1157 One complexity is that a statement like SELECT 1/col could error
1158 out mid-way through the result set.
1160 o Consider disallowing multiple queries in PQexec() as an
1161 additional barrier to SQL injection attacks
1163 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00184.php
1165 o Add PQexecf() that allows complex parameter substitution
1167 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01803.php
1169 o Add SQLSTATE severity to PGconn return status
1171 http://archives.postgresql.org/pgsql-interfaces/2007-11/msg00015.php
1177 * Add deferred trigger queue file
1179 Right now all deferred trigger information is stored in backend
1180 memory. This could exhaust memory for very large trigger queues.
1181 This item involves dumping large queues into files.
1183 * Allow triggers to be disabled in only the current session.
1185 This is currently possible by starting a multi-statement transaction,
1186 modifying the system tables, performing the desired SQL, restoring the
1187 system tables, and committing the transaction. ALTER TABLE ...
1188 TRIGGER requires a table lock so it is not ideal for this usage.
1190 * With disabled triggers, allow pg_dump to use ALTER TABLE ADD FOREIGN KEY
1192 If the dump is known to be valid, allow foreign keys to be added
1193 without revalidating the data.
1195 * Allow statement-level triggers to access modified rows
1196 * Support triggers on columns
1198 http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php
1200 * Allow AFTER triggers on system tables
1202 System tables are modified in many places in the backend without going
1203 through the executor and therefore not causing triggers to fire. To
1204 complete this item, the functions that modify system tables will have
1207 * Tighten trigger permission checks
1209 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00564.php
1211 * Allow BEFORE INSERT triggers on views
1213 http://archives.postgresql.org/pgsql-general/2007-02/msg01466.php
1215 * -Add ability to trigger on TRUNCATE
1222 * Add UNIQUE capability to non-btree indexes
1223 * Prevent index uniqueness checks when UPDATE does not modify the column
1225 Uniqueness (index) checks are done when updating a column even if the
1226 column is not modified by the UPDATE.
1228 * Allow the creation of on-disk bitmap indexes which can be quickly
1229 combined with other bitmap indexes
1231 Such indexes could be more compact if there are only a few distinct values.
1232 Such indexes can also be compressed. Keeping such indexes updated can be
1235 http://archives.postgresql.org/pgsql-patches/2005-07/msg00512.php
1236 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01107.php
1237 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00265.php
1238 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01214.php
1239 http://archives.postgresql.org/pgsql-patches/2007-05/msg00013.php
1240 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00741.php
1242 * Allow accurate statistics to be collected on indexes with more than
1243 one column or expression indexes, perhaps using per-index statistics
1245 http://archives.postgresql.org/pgsql-performance/2006-10/msg00222.php
1246 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01131.php
1248 * Consider increasing the number of default statistics target, and
1249 reduce statistics target overhead
1251 Also consider having a larger statistics target for indexed columns
1252 and expression indexes
1253 http://archives.postgresql.org/pgsql-general/2007-05/msg01228.php
1254 http://archives.postgresql.org/pgsql-general/2007-06/msg00542.php
1255 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01066.php
1257 * Consider compressing indexes by storing key values duplicated in
1258 several rows as a single index entry
1260 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00341.php
1261 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01264.php
1262 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00465.php
1263 http://archives.postgresql.org/pgsql-patches/2007-03/msg00163.php
1264 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00014.php
1265 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00487.php
1267 * Add REINDEX CONCURRENTLY, like CREATE INDEX CONCURRENTLY
1269 This is difficult because you must upgrade to an exclusive table lock
1270 to replace the existing index file. CREATE INDEX CONCURRENTLY does not
1271 have this complication. This would allow index compaction without
1273 http://archives.postgresql.org/pgsql-performance/2007-08/msg00289.php
1275 * Allow multiple indexes to be created concurrently, ideally via a
1276 single heap scan, and have pg_restore use it
1278 * Consider sorting entries before inserting into btree index
1280 http://archives.postgresql.org/pgsql-general/2008-01/msg01010.php
1282 * Allow index scans to return matching index keys
1284 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01079.php
1289 o Allow inherited tables to inherit indexes, UNIQUE constraints,
1290 and primary/foreign keys
1291 o Honor UNIQUE INDEX on base column in INSERTs/UPDATEs
1292 on inherited table, e.g. INSERT INTO inherit_table
1293 (unique_index_col) VALUES (dup) should fail
1295 The main difficulty with this item is the problem of
1296 creating an index that can span multiple tables.
1298 o Allow SELECT ... FOR UPDATE on inherited tables
1299 o Require all CHECK constraints to be inherited
1301 http://archives.postgresql.org/pgsql-bugs/2007-04/msg00026.php
1303 o Add checks to prevent a CREATE RULE views on inherited tables
1305 http://archives.postgresql.org/pgsql-general/2008-02/msg01420.php
1306 http://archives.postgresql.org/pgsql-general/2008-03/msg00077.php
1311 o Add more GIST index support for geometric data types
1312 o Allow GIST indexes to create certain complex index types, like
1313 digital trees (see Aoki)
1318 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00051.php
1320 o Pack hash index buckets onto disk pages more efficiently
1322 Currently only one hash bucket can be stored on a page. Ideally
1323 several hash buckets could be stored on a single page and greater
1324 granularity used for the hash algorithm.
1326 http://archives.postgresql.org/pgsql-hackers/2004-06/msg00168.php
1328 o Consider sorting hash buckets so entries can be found using a
1329 binary search, rather than a linear scan
1330 o In hash indexes, consider storing the hash value with or instead
1332 o Add WAL logging for crash recovery
1333 o Allow multi-column hash indexes
1334 o -During index creation, pre-sort the tuples to improve build speed
1341 * Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
1343 Ideally this requires a separate test program that can be run
1344 at initdb time or optionally later. Consider O_SYNC when
1347 * Add program to test if fsync has a delay compared to non-fsync
1348 * Consider sorting writes during checkpoint
1350 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00541.php
1359 We could use a fixed row count and a +/- count to follow MVCC
1360 visibility rules, or a single cached value could be used and
1361 invalidated if anyone modifies the table. Another idea is to
1362 get a count directly from a unique index, but for this to be
1363 faster than a sequential scan it must avoid access to the heap
1364 to obtain tuple visibility information.
1366 * Provide a way to calculate an "estimated COUNT(*)"
1368 Perhaps by using the optimizer's cardinality estimates or random
1371 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00943.php
1373 * Allow data to be pulled directly from indexes
1375 Currently indexes do not have enough tuple visibility information
1376 to allow data to be pulled from the index without also accessing
1377 the heap. One way to allow this is to set a bit on index tuples
1378 to indicate if a tuple is currently visible to all transactions
1379 when the first valid heap lookup happens. This bit would have to
1380 be cleared when a heap tuple is expired.
1382 Another idea is to maintain a bitmap of heap pages where all rows
1383 are visible to all backends, and allow index lookups to reference
1384 that bitmap to avoid heap lookups, perhaps the same bitmap we might
1385 add someday to determine which heap pages need vacuuming. Frequently
1386 accessed bitmaps would have to be stored in shared memory. One 8k
1387 page of bitmaps could track 512MB of heap pages.
1389 A third idea would be for a heap scan to check if all rows are visible
1390 and if so set a per-table flag which can be checked by index scans.
1391 Any change to the table would have to clear the flag. To detect
1392 changes during the heap scan a counter could be set at the start and
1393 checked at the end --- if it is the same, the table has not been
1394 modified --- any table change would increment the counter.
1396 http://archives.postgresql.org/pgsql-patches/2007-10/msg00166.php
1397 http://archives.postgresql.org/pgsql-patches/2008-01/msg00049.php
1399 * Consider automatic caching of statements at various levels:
1402 o Query execute plan
1405 * Consider increasing internal areas when shared buffers is increased
1407 http://archives.postgresql.org/pgsql-hackers/2005-10/msg01419.php
1409 * Consider decreasing the amount of memory used by PrivateRefCount
1411 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00797.php
1412 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php
1414 * Consider allowing higher priority queries to have referenced buffer
1415 cache pages stay in memory longer
1417 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00562.php
1424 * Improve speed with indexes
1426 For large table adjustments during VACUUM FULL, it is faster to cluster
1427 or reindex rather than update the index. Also, index updates can bloat
1430 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00024.php
1431 http://archives.postgresql.org/pgsql-performance/2007-05/msg00296.php
1432 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00307.php
1434 * Auto-fill the free space map by scanning the buffer cache or by
1435 checking pages written by the background writer
1437 http://archives.postgresql.org/pgsql-hackers/2006-02/msg01125.php
1438 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00011.php
1440 * Create a bitmap of pages that need vacuuming
1442 Instead of sequentially scanning the entire table, have the background
1443 writer or some other process record pages that have expired rows, then
1444 VACUUM can look at just those pages rather than the entire table. In
1445 the event of a system crash, the bitmap would probably be invalidated.
1446 One complexity is that index entries still have to be vacuumed, and
1447 doing this without an index scan (by using the heap values to find the
1448 index entry) might be slow and unreliable, especially for user-defined
1451 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01188.php
1452 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00121.php
1453 http://archives.postgresql.org/pgsql-patches/2007-03/msg00508.php
1454 http://archives.postgresql.org/pgsql-patches/2007-04/msg00347.php
1455 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00156.php
1456 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00546.php
1457 http://archives.postgresql.org/pgsql-hackers/2008-04/msg00416.php
1459 * Allow FSM to return free space toward the beginning of the heap file,
1460 in hopes that empty pages at the end can be truncated by VACUUM
1461 * Allow FSM page return free space based on table clustering, to assist
1462 in maintaining clustering?
1463 * Improve dead row detection during multi-statement transactions usage
1465 http://archives.postgresql.org/pgsql-patches/2007-03/msg00358.php
1467 * Consider a more compact data representation for dead tuples
1469 http://archives.postgresql.org/pgsql-patches/2007-05/msg00143.php
1474 o %Issue log message to suggest VACUUM FULL if a table is nearly
1476 o Improve control of auto-vacuum
1478 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00876.php
1480 o Prevent long-lived temporary tables from causing frozen-xid
1481 advancement starvation
1483 The problem is that autovacuum cannot vacuum them to set frozen xids;
1484 only the session that created them can do that.
1485 http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php
1487 o Store per-table autovacuum settings in pg_class.reloptions.
1489 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01440.php
1490 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00724.php
1492 o Prevent autovacuum from running if an old transaction is still
1493 running from the last vacuum
1495 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00899.php
1502 * Fix priority ordering of read and write light-weight locks (Neil)
1504 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00893.php
1505 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00905.php
1507 * Fix problem when multiple subtransactions of the same outer transaction
1508 hold different types of locks, and one subtransaction aborts
1510 http://archives.postgresql.org/pgsql-hackers/2006-11/msg01011.php
1511 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00001.php
1512 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00435.php
1513 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00773.php
1515 * Allow UPDATEs on only non-referential integrity columns not to conflict
1516 with referential integrity locks
1518 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00073.php
1520 * Add idle_in_transaction_timeout GUC so locks are not held for long
1523 * Improve deadlock detection when a page cleaning lock conflicts
1524 with a shared buffer that is pinned
1526 http://archives.postgresql.org/pgsql-bugs/2008-01/msg00138.php
1527 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1528 http://archives.postgresql.org/pgsql-committers/2008-01/msg00365.php
1530 * Detect deadlocks involving LockBufferForCleanup()
1532 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1536 Startup Time Improvements
1537 =========================
1539 * Experiment with multi-threaded backend for backend creation [thread]
1541 This would prevent the overhead associated with process creation. Most
1542 operating systems have trivial process creation time compared to
1543 database startup overhead, but a few operating systems (Win32,
1544 Solaris) might benefit from threading. Also explore the idea of
1545 a single session using multiple threads to execute a statement faster.
1552 * Eliminate need to write full pages to WAL before page modification [wal]
1554 Currently, to protect against partial disk page writes, we write
1555 full page images to WAL before they are modified so we can correct any
1556 partial page writes during recovery. These pages can also be
1557 eliminated from point-in-time archive files.
1559 o When off, write CRC to WAL and check file system blocks
1562 If CRC check fails during recovery, remember the page in case
1563 a later CRC for that page properly matches.
1565 o Write full pages during file system write and not when
1566 the page is modified in the buffer cache
1568 This allows most full page writes to happen in the background
1569 writer. It might cause problems for applying WAL on recovery
1570 into a partially-written page, but later the full page will be
1573 * Allow WAL traffic to be streamed to another server for stand-by
1575 * Reduce WAL traffic so only modified values are written rather than
1578 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01589.php
1580 * Allow WAL information to recover corrupted pg_controldata
1582 http://archives.postgresql.org/pgsql-patches/2006-06/msg00025.php
1584 * Find a way to reduce rotational delay when repeatedly writing
1587 Currently fsync of WAL requires the disk platter to perform a full
1588 rotation to fsync again. One idea is to write the WAL to different
1589 offsets that might reduce the rotational delay.
1591 * Allow WAL logging to be turned off for a table, but the table
1592 might be dropped or truncated during crash recovery [walcontrol]
1594 Allow tables to bypass WAL writes and just fsync() dirty pages on
1595 commit. This should be implemented using ALTER TABLE, e.g. ALTER
1596 TABLE PERSISTENCE [ DROP | TRUNCATE | DEFAULT ]. Tables using
1597 non-default logging should not use referential integrity with
1598 default-logging tables. A table without dirty buffers during a
1599 crash could perhaps avoid the drop/truncate.
1601 * Allow WAL logging to be turned off for a table, but the table would
1602 avoid being truncated/dropped [walcontrol]
1604 To do this, only a single writer can modify the table, and writes
1605 must happen only on new pages so the new pages can be removed during
1606 crash recovery. Readers can continue accessing the table. Such
1607 tables probably cannot have indexes. One complexity is the handling
1608 of indexes on TOAST tables.
1610 * Speed WAL recovery by allowing more than one page to be prefetched
1612 This should be done utilizing the same infrastructure used for
1613 prefetching in general to avoid introducing complex error-prone code
1615 http://archives.postgresql.org/pgsql-general/2007-12/msg00683.php
1616 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00497.php
1617 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01279.php
1619 * Improve WAL concurrency by increasing lock granularity
1621 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00556.php
1623 * Be more aggressive about creating WAL files
1625 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01325.php
1626 http://archives.postgresql.org/pgsql-hackers/2004-07/msg01075.php
1627 http://archives.postgresql.org/pgsql-hackers/2005-04/msg00556.php
1629 * Have resource managers report the duration of their status changes
1631 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01468.php
1633 * Move pgfoundry's xlogdump to /contrib and have it rely more closely
1634 on the WAL backend code
1636 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00035.php
1641 Optimizer / Executor
1642 ====================
1644 * Improve selectivity functions for geometric operators
1645 * Precompile SQL functions to avoid overhead
1646 * Create utility to compute accurate random_page_cost value
1647 * Improve ability to display optimizer analysis using OPTIMIZER_DEBUG
1648 * Have EXPLAIN ANALYZE issue NOTICE messages when the estimated and
1649 actual row counts differ by a specified percentage
1650 * Improve how ANALYZE computes in-doubt tuples
1652 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php
1654 * Consider using hash buckets to do DISTINCT, rather than sorting
1656 This would be beneficial when there are few distinct values. This is
1657 already used by GROUP BY.
1659 * Log statements where the optimizer row estimates were dramatically
1660 different from the number of rows actually found?
1661 * Consider compressed annealing to search for query plans
1663 This might replace GEQO, http://sixdemonbag.org/Djinni.
1665 * Improve merge join performance by allowing mark/restore of
1668 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00096.php
1670 * Consider using a hash for joining to a large IN (VALUES ...) list
1672 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00450.php
1679 * Consider having the background writer update the transaction status
1680 hint bits before writing out the page
1682 Implementing this requires the background writer to have access to system
1683 catalogs and the transaction status log.
1685 * Consider adding buffers the background writer finds reusable to the
1688 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1690 * Automatically tune bgwriter_delay based on activity rather then using a
1693 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1695 * Consider wither increasing BM_MAX_USAGE_COUNT improves performance
1697 http://archives.postgresql.org/pgsql-hackers/2007-06/msg01007.php
1699 * Test to see if calling PreallocXlogFiles() from the background writer
1700 will help with WAL segment creation latency
1702 http://archives.postgresql.org/pgsql-patches/2007-06/msg00340.php
1706 Miscellaneous Performance
1707 =========================
1709 * Do async I/O for faster random read-ahead of data
1711 Async I/O allows multiple I/O requests to be sent to the disk with
1712 results coming back asynchronously.
1714 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00820.php
1715 http://archives.postgresql.org/pgsql-performance/2007-09/msg00255.php
1716 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00027.php
1717 http://archives.postgresql.org/pgsql-patches/2008-01/msg00170.php
1719 * Use mmap() rather than SYSV shared memory or to write WAL files?
1721 This would remove the requirement for SYSV SHM but would introduce
1722 portability issues. Anonymous mmap (or mmap to /dev/zero) is required
1723 to prevent I/O overhead.
1725 * Consider mmap()'ing files into a backend?
1727 Doing I/O to large tables would consume a lot of address space or
1728 require frequent mapping/unmapping. Extending the file also causes
1729 mapping problems that might require mapping only individual pages,
1730 leading to thousands of mappings. Another problem is that there is no
1731 way to _prevent_ I/O to disk from the dirty shared buffers so changes
1732 could hit disk before WAL is written.
1734 * Add a script to ask system configuration questions and tune postgresql.conf
1735 * Consider ways of storing rows more compactly on disk
1737 o Reduce the row header size?
1738 o Consider reducing on-disk varlena length from four bytes to
1739 two because a heap row cannot be more than 64k in length
1741 * Consider increasing NUM_CLOG_BUFFERS
1743 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00030.php
1744 http://archives.postgresql.org/pgsql-performance/2007-08/msg00024.php
1746 * Consider transaction start/end performance improvements
1748 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00948.php
1749 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1751 * Allow user configuration of TOAST thresholds
1753 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00213.php
1754 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00082.php
1756 * Allow configuration of backend priorities via the operating system
1758 Though backend priorities make priority inversion during lock
1759 waits possible, research shows that this is not a huge problem.
1761 http://archives.postgresql.org/pgsql-general/2007-02/msg00493.php
1763 * Experiment with multi-threaded backend better I/O utilization
1765 This would allow a single query to make use of multiple I/O channels
1766 simultaneously. One idea is to create a background reader that can
1767 pre-fetch sequential and index scan pages needed by other backends.
1768 This could be expanded to allow concurrent reads from multiple devices
1769 in a partitioned table.
1771 * Experiment with multi-threaded backend better CPU utilization
1773 This would allow several CPUs to be used for a single query, such as
1774 for sorting or query execution.
1776 * Consider increasing the minimum allowed number of shared buffers
1778 http://archives.postgresql.org/pgsql-bugs/2008-02/msg00157.php
1780 * Expire published xmin for read-only and idle transactions
1782 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00343.php
1784 * Consider if CommandCounterIncrement() can avoid its
1785 AcceptInvalidationMessages() call
1787 http://archives.postgresql.org/pgsql-committers/2007-11/msg00585.php
1789 * Improve performance of shared invalidation queue for multiple CPUs
1791 http://archives.postgresql.org/pgsql-performance/2008-01/msg00023.php
1793 * Consider Cartesian joins when both relations are needed to form an
1794 indexscan qualification for a third relation
1796 http://archives.postgresql.org/pgsql-performance/2007-12/msg00090.php
1798 * Consider not storing a NULL bitmap on disk if all the NULLs are
1801 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00624.php
1802 http://archives.postgresql.org/pgsql-patches/2007-12/msg00109.php
1804 * Sort large UPDATE/DELETEs so it is done in heap order
1806 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01119.php
1808 * -Avoid tuple some tuple copying in sort routines
1809 * SMP scalability improvements
1811 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php
1812 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00206.php
1813 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1815 * Research reducing deTOASTing in more places
1817 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00895.php
1819 * Consider being smarter about memory and external files used during
1822 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php
1823 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php
1825 * Allow one transaction to see tuples using the snapshot of another
1828 This would assist multiple backends in working together.
1829 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00400.php
1835 * Add use of 'const' for variables in source tree
1836 * Move some things from contrib into main tree
1837 * %Remove warnings created by -Wcast-align
1838 * Move platform-specific ps status display info from ps_status.c to ports
1839 * Add optional CRC checksum to heap and index pages
1840 * Improve documentation to build only interfaces (Marc)
1841 * Remove or relicense modules that are not under the BSD license, if possible
1842 * Acquire lock on a relation before building a relcache entry for it
1843 * Allow cross-compiling by generating the zic database on the target system
1844 * Improve NLS maintenance of libpgport messages linked onto applications
1845 * Clean up casting in contrib/isn
1847 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00245.php
1849 * Use UTF8 encoding for NLS messages so all server encodings can
1851 * Update Bonjour to work with newer cross-platform SDK
1853 http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php
1854 http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php
1856 * Consider detoasting keys before sorting
1857 * Consider GnuTLS if OpenSSL license becomes a problem
1859 http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php
1860 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php
1862 * Consider changing documentation format from SGML to XML
1864 http://archives.postgresql.org/pgsql-docs/2006-12/msg00152.php
1866 * Consider making NAMEDATALEN more configurable in future releases
1867 * Update our code to handle 64-bit timezone files to match the zic
1868 source code, which now uses them
1869 * Have configure choose integer datetimes by default
1871 http://archives.postgresql.org/pgsql-patches/2007-05/msg00046.php
1873 * Support scoped IPv6 addresses
1875 http://archives.postgresql.org/pgsql-bugs/2007-05/msg00111.php
1877 * Consider allowing 64-bit integers and floats to be passed by value on
1880 Also change 32-bit floats (float4) to be passed by value at the same
1883 * Research use of signals and sleep wake ups
1885 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00003.php
1887 * Add automated check for invalid C++ source code constructs
1889 http://archives.postgresql.org/pgsql-patches/2007-07/msg00056.php
1891 * Consider simplifying how memory context resets handle child contexts
1893 http://archives.postgresql.org/pgsql-patches/2007-08/msg00067.php
1895 * Remove use of MAKE_PTR and MAKE_OFFSET macros
1897 http://archives.postgresql.org/pgsql-general/2007-08/msg01510.php
1899 * Convert single quotes to apostrophes in the PDF documentation
1901 http://archives.postgresql.org/pgsql-docs/2007-12/msg00059.php
1903 * Create three versions of libpgport to simplify client code
1905 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00154.php
1907 * Remove old-style routines for manipulating tuples
1909 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00851.php
1911 * Improve detection of shared memory segments being used by other
1914 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00656.php
1920 o Remove configure.in check for link failure when cause is found
1921 o Remove readdir() errno patch when runtime/mingwex/dirent.c rev
1923 o Remove psql newline patch when we find out why mingw outputs an
1925 o Allow psql to use readline once non-US code pages work with
1927 o Fix problem with shared memory on the Win32 Terminal Server
1928 o Diagnose problem where shared memory can sometimes not be
1929 attached by postmaster children
1931 http://archives.postgresql.org/pgsql-general/2007-08/msg01377.php
1933 o Improve signal handling
1935 http://archives.postgresql.org/pgsql-patches/2005-06/msg00027.php
1937 o Convert MSVC build system to remove most batch files
1939 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00961.php
1941 o Prevent SSL from sending network packets to avoid interference
1942 with Win32 signal emulation
1944 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00455.php
1946 o Support pgxs when using MSVC
1948 o Fix MSVC NLS support, like for to_char()
1950 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00485.php
1951 http://archives.postgresql.org/pgsql-patches/2008-02/msg00038.php
1953 o Find a correct rint() substitute on Windows
1955 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00808.php
1959 * Wire Protocol Changes
1961 o Allow dynamic character set handling
1962 o Add decoded type, length, precision
1964 o Update clients to use data types, typmod, schema.table.column names
1965 of result sets using new statement protocol
1971 * Add pre-parsing phase that converts non-ISO syntax to supported
1974 This could allow SQL written for other databases to run without
1977 * Allow plug-in modules to emulate features from other databases
1978 * Add features of Oracle-style packages (Pavel)
1980 A package would be a schema with session-local variables,
1981 public/private functions, and initialization functions. It
1982 is also possible to implement these capabilities
1983 in any schema and not use a separate "packages"
1986 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00384.php
1988 * Consider allowing control of upper/lower case folding of unquoted
1991 http://archives.postgresql.org/pgsql-hackers/2004-04/msg00818.php
1992 http://archives.postgresql.org/pgsql-hackers/2006-10/msg01527.php
1993 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00849.php
1995 * Add autonomous transactions
1997 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.php
2001 Features We Do _Not_ Want
2002 =========================
2004 * All backends running as threads in a single process (not wanted)
2006 This eliminates the process protection we get from the current setup.
2007 Thread creation is usually the same overhead as process creation on
2008 modern systems, so it seems unwise to use a pure threaded model.
2010 * Optimizer hints (not wanted)
2012 Optimizer hints are used to work around problems in the optimizer. We
2013 would rather have the problems reported and fixed.
2015 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00506.php
2016 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00517.php
2017 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00663.php
2020 Because we support postfix operators, it isn't possible to make AS
2021 optional and continue to use bison.
2022 http://archives.postgresql.org/pgsql-hackers/2003-04/msg00436.php
2024 http://archives.postgresql.org/pgsql-sql/2006-08/msg00164.php
2026 * Embedded server (not wanted)
2028 While PostgreSQL clients runs fine in limited-resource environments, the
2029 server requires multiple processes and a stable pool of resources to
2030 run reliabily and efficiently. Stripping down the PostgreSQL server
2031 to run in the same process address space as the client application
2032 would add too much complexity and failure cases.