3 Current maintainer: Bruce Momjian (bruce@momjian.us)
4 Last updated: Fri Apr 11 15:14:41 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
497 Multi-Language Support
498 ======================
500 * Add NCHAR (as distinguished from ordinary varchar),
501 * Allow locale to be set at database creation
503 Currently locale can only be set during initdb. No global tables have
504 locale-aware columns. However, the database template used during
505 database creation might have locale-aware indexes. The indexes would
506 need to be reindexed to match the new locale.
508 * Allow encoding on a per-column basis optionally using the ICU library
510 Right now only one encoding is allowed per database. [locale]
512 http://archives.postgresql.org/pgsql-hackers/2005-03/msg00932.php
513 http://archives.postgresql.org/pgsql-patches/2005-08/msg00309.php
514 http://archives.postgresql.org/pgsql-patches/2006-03/msg00233.php
515 http://archives.postgresql.org/pgsql-hackers/2006-09/msg00662.php
516 http://wiki.postgresql.org/wiki/Todo:Collate
517 http://wiki.postgresql.org/wiki/Todo:ICU
519 * Add CREATE COLLATE? [locale]
520 * Support multiple simultaneous character sets, per SQL92
521 * Improve UTF8 combined character handling?
522 * Add octet_length_server() and octet_length_client()
523 * Make octet_length_client() the same as octet_length()?
524 * Fix problems with wrong runtime encoding conversion for NLS message files
525 * Add URL to more complete multi-byte regression tests
527 http://archives.postgresql.org/pgsql-hackers/2005-07/msg00272.php
529 * Fix ILIKE and regular expressions to handle case insensitivity
530 properly in multibyte encodings
532 http://archives.postgresql.org/pgsql-bugs/2005-10/msg00001.php
533 http://archives.postgresql.org/pgsql-patches/2005-11/msg00173.php
535 * Set client encoding based on the client operating system encoding
537 Currently client_encoding is set in postgresql.conf, which
538 defaults to the server encoding.
539 http://archives.postgresql.org/pgsql-hackers/2006-08/msg01696.php
541 * Change memory allocation for multi-byte functions so memory is
542 allocated inside conversion functions
544 Currently we preallocate memory based on worst-case usage.
551 * Automatically create rules on views so they are updateable, per SQL99
553 We can only auto-create rules for simple views. For more complex
554 cases users will still have to write rules manually.
556 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00586.php
557 http://archives.postgresql.org/pgsql-patches/2006-08/msg00255.php
559 * Add the functionality for WITH CHECK OPTION clause of CREATE VIEW
560 * Allow NOTIFY in rules involving conditionals
561 * Allow VIEW/RULE recompilation when the underlying tables change
563 Another issue is whether underlying table changes should be reflected
564 in the view, e.g. should SELECT * show additional columns if they
565 are added after the view is created.
567 * Make it possible to use RETURNING together with conditional DO INSTEAD
568 rules, such as for partitioning setups
570 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00577.php
572 * Add the ability to automatically create materialized views
574 Right now materialized views require the user to create triggers on the
575 main table to keep the summary table current. SQL syntax should be able
576 to manager the triggers and summary table automatically. A more
577 sophisticated implementation would automatically retrieve from the
578 summary table when the main table is referenced, if possible.
585 * Add CORRESPONDING BY to UNION/INTERSECT/EXCEPT
586 * Add ROLLUP, CUBE, GROUPING SETS options to GROUP BY
587 * %Allow SET CONSTRAINTS to be qualified by schema/table name
588 * %Add a separate TRUNCATE permission
590 Currently only the owner can TRUNCATE a table because triggers are not
591 called, and the table is locked in exclusive mode.
593 * Allow PREPARE of cursors
594 * Allow finer control over the caching of prepared query plans
596 Currently queries prepared via the libpq API are planned on first
597 execute using the supplied parameters --- allow SQL PREPARE to do the
598 same. Also, allow control over replanning prepared queries either
599 manually or automatically when statistics for execute parameters
600 differ dramatically from those used during planning.
602 * Improve logging of prepared transactions recovered during startup
604 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00092.php
606 * Allow LISTEN/NOTIFY to store info in memory rather than tables?
608 Currently LISTEN/NOTIFY information is stored in pg_listener. Storing
609 such information in memory would improve performance.
611 * Add optional textual message to NOTIFY
613 This would allow an informational message to be added to the notify
614 message, perhaps indicating the row modified or other custom
617 * Allow multiple identical NOTIFY events to always be communicated to the
618 client, rather than sent as a single notification to the listener
620 http://archives.postgresql.org/pgsql-general/2008-01/msg00057.php
622 * Add a GUC variable to warn about non-standard SQL usage in queries
623 * Add SQL-standard MERGE command, typically used to merge two tables
626 This is similar to UPDATE, then for unmatched rows, INSERT.
627 Whether concurrent access allows modifications which could cause
628 row loss is implementation independent.
630 * Add REPLACE or UPSERT command that does UPDATE, or on failure, INSERT
633 To implement this cleanly requires that the table have a unique index
634 so duplicate checking can be easily performed. It is possible to
635 do it without a unique index if we require the user to LOCK the table
638 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00501.php
639 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00536.php
641 * Add NOVICE output level for helpful messages like automatic sequence/index
643 * Add GUC to issue notice about statements that use unjoined tables
644 * Allow EXPLAIN to identify tables that were skipped because of
646 * Allow EXPLAIN output to be more easily processed by scripts, perhaps XML
647 * Enable standard_conforming_strings
648 * Make standard_conforming_strings the default in 8.5?
650 When this is done, backslash-quote should be prohibited in non-E''
651 strings because of possible confusion over how such strings treat
652 backslashes. Basically, '' is always safe for a literal single
653 quote, while \' might or might not be based on the backslash
656 * Simplify dropping roles that have objects in several databases
657 * Allow COMMENT ON to accept an expression rather than just a string
658 * Allow the count returned by SELECT, etc to be represented as an int64
659 to allow a higher range of values
660 * Add SQL99 WITH clause to SELECT
661 * Add SQL:2003 WITH RECURSIVE (hierarchical) queries to SELECT
663 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01375.php
664 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00642.php
665 http://archives.postgresql.org/pgsql-patches/2007-03/msg00139.php
666 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01334.php
667 http://archives.postgresql.org/pgsql-patches/2008-01/msg00105.php
668 http://archives.postgresql.org/pgsql-patches/2008-03/msg00327.php
670 * Add DEFAULT .. AS OWNER so permission checks are done as the table
673 This would be useful for SERIAL nextval() calls and CHECK constraints.
675 * Allow DISTINCT to work in multiple-argument aggregate calls
676 * Add column to pg_stat_activity that shows the progress of long-running
677 commands like CREATE INDEX and VACUUM
678 * Implement SQL:2003 window functions
679 * Improve failure message when DROP DATABASE is used on a database that
680 has prepared transactions
681 * Allow INSERT/UPDATE ... RETURNING inside a SELECT 'FROM' clause
683 http://archives.postgresql.org/pgsql-general/2006-09/msg00803.php
684 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00693.php
686 * Increase locking when DROPing objects so dependent objects cannot
687 get dropped while the DROP operation is happening
689 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00937.php
691 * -Allow AS in "SELECT col AS label" to be optional in certain cases
693 * Allow INSERT ... DELETE ... RETURNING, namely allow the DELETE ...
694 RETURNING to supply values to the INSERT
695 http://archives.postgresql.org/pgsql-hackers/2008-02/thrd2.php#00979
697 * Add comments on system tables/columns using the information in
700 Ideally the information would be pulled from the SGML file
703 * Improve reporting of UNION type mismatches
705 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00944.php
706 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00597.php
711 o Allow CREATE TABLE AS to determine column lengths for complex
712 expressions like SELECT col1 || col2
714 o Have WITH CONSTRAINTS also create constraint indexes
716 http://archives.postgresql.org/pgsql-patches/2007-04/msg00149.php
718 o Have CONSTRAINT cname NOT NULL record the contraint name
720 Right now pg_attribute.attnotnull records the NOT NULL status
721 of the column, but does not record the contraint name
723 o Prevent concurrent CREATE TABLE table1 from sometimes returning
724 a cryptic error message
726 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00169.php
730 o Allow UPDATE tab SET ROW (col, ...) = (SELECT...)
732 http://archives.postgresql.org/pgsql-hackers/2006-07/msg01306.php
733 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00865.php
734 http://archives.postgresql.org/pgsql-patches/2007-04/msg00315.php
735 http://archives.postgresql.org/pgsql-patches/2008-03/msg00237.php
737 o Research self-referential UPDATEs that see inconsistent row versions
738 in read-committed mode
740 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00507.php
741 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00016.php
743 o Allow GLOBAL temporary tables to exist as empty by default in
746 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00006.php
751 o Have ALTER TABLE RENAME rename SERIAL sequence names
753 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
755 o Have ALTER SEQUENCE RENAME rename the sequence name stored
756 in the sequence table
758 http://archives.postgresql.org/pgsql-bugs/2007-09/msg00092.php
759 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00007.php
760 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
762 o Add ALTER DOMAIN to modify the underlying data type
763 o %Allow ALTER TABLE ... ALTER CONSTRAINT ... RENAME
765 http://archives.postgresql.org/pgsql-patches/2006-02/msg00168.php
767 o %Allow ALTER TABLE to change constraint deferrability and actions
768 o Add missing object types for ALTER ... SET SCHEMA
769 o Allow ALTER TABLESPACE to move to different directories
770 o Allow databases to be moved to different tablespaces
771 o Allow moving system tables to other tablespaces, where possible
773 Currently non-global system tables must be in the default database
774 tablespace. Global system tables can never be moved.
776 o Prevent parent tables from altering or dropping constraints
777 like CHECK that are inherited by child tables unless CASCADE
779 o %Prevent child tables from altering or dropping constraints
780 like CHECK that were inherited from the parent table
781 o Have ALTER INDEX update the name of a constraint using that index
782 o Add ALTER TABLE RENAME CONSTRAINT, update index name also
783 o Allow column display reordering by recording a display,
784 storage, and permanent id for every column?
786 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00782.php
792 o Automatically maintain clustering on a table
794 This might require some background daemon to maintain clustering
795 during periods of low usage. It might also require tables to be only
796 partially filled for easier reorganization. Another idea would
797 be to create a merged heap/index data file so an index lookup would
798 automatically access the heap data too. A third idea would be to
799 store heap rows in hashed groups, perhaps using a user-supplied
801 http://archives.postgresql.org/pgsql-performance/2004-08/msg00349.php
803 o %Add default clustering to system tables
805 To do this, determine the ideal cluster index for each system
806 table and set the cluster setting during initdb.
808 o %Add VERBOSE option to report tables as they are processed,
814 o Allow COPY to report error lines and continue
816 This requires the use of a savepoint before each COPY line is
817 processed, with ROLLBACK on COPY failure.
818 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00572.php
820 o Allow COPY on a newly-created table to skip WAL logging
822 On crash recovery, the table involved in the COPY would
823 be removed or have its heap and index files truncated. One
824 issue is that no other backend should be able to add to
825 the table at the same time, which is something that is
826 currently allowed. This currently is done if the table is
827 created inside the same transaction block as the COPY because
828 no other backends can see the table.
830 o Consider using a ring buffer for COPY FROM
832 http://archives.postgresql.org/pgsql-patches/2008-02/msg00140.php
833 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01080.php
835 o Allow COPY FROM to create index entries in bulk
837 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00811.php
839 o Allow COPY in CSV mode to control whether a quoted zero-length
840 string is treated as NULL
842 Currently this is always treated as a zero-length string,
843 which generates an error when loading into an integer column
844 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00905.php
850 o Allow column-level privileges
851 o %Allow GRANT/REVOKE permissions to be applied to all schema objects
854 The proposed syntax is:
855 GRANT SELECT ON ALL TABLES IN public TO phpuser;
856 GRANT SELECT ON NEW TABLES IN public TO phpuser;
858 o Allow GRANT/REVOKE permissions to be inherited by objects based on
861 o Allow SERIAL sequences to inherit permissions from the base table?
866 o Prevent DROP TABLE from dropping a row referenced by its own open
872 o Allow INSERT/UPDATE of the system-generated oid value for a row
873 o In rules, allow VALUES() to contain a mixture of 'old' and 'new'
879 o Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM
884 Referential Integrity
885 =====================
887 * Add MATCH PARTIAL referential integrity
888 * Change foreign key constraint for array -> element to mean element
890 * Fix problem when cascading referential triggers make changes on
891 cascaded tables, seeing the tables in an intermediate state
893 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
894 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
896 * Allow DEFERRABLE and end-of-statement UNIQUE constraints?
898 This would allow UPDATE tab SET col = col + 1 to work if col has
899 a unique index. Currently, uniqueness checks are done while the
900 command is being executed, rather than at the end of the statement
902 http://people.planetpostgresql.org/greg/index.php?/archives/2006/06/10.html
903 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01458.php
905 * Optimize referential integrity checks
907 http://archives.postgresql.org/pgsql-performance/2005-10/msg00458.php
908 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00744.php
911 Server-Side Languages
912 =====================
915 o Fix RENAME to work on variables other than OLD/NEW
917 http://archives.postgresql.org/pgsql-hackers/2002-03/msg00591.php
918 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01615.php
919 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01587.php
921 o Allow function parameters to be passed by name,
922 get_employee_salary(12345 AS emp_id, 2001 AS tax_year)
923 o Allow handling of %TYPE arrays, e.g. tab.col%TYPE[]
924 o Allow listing of record column names, and access to
925 record columns via variables, e.g. columns := r.(*),
928 http://archives.postgresql.org/pgsql-patches/2005-07/msg00458.php
929 http://archives.postgresql.org/pgsql-patches/2006-05/msg00302.php
930 http://archives.postgresql.org/pgsql-patches/2006-06/msg00031.php
932 o Add support for SCROLL cursors
933 o Add support for WITH HOLD cursors
934 o Allow row and record variables to be set to NULL constants,
935 and allow NULL tests on such variables
937 Because a row is not scalar, do not allow assignment
938 from NULL-valued scalars.
940 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00070.php
942 o Review handling of MOVE and FETCH
944 http://archives.postgresql.org/pgsql-patches/2007-04/msg00527.php
946 o Improve logic of determining if an identifier is a a
947 variable or column name
949 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00436.php
951 o Consider keeping seperate cached copies when search_path changes
953 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01009.php
955 o Add CASE capability to language (already in SQL)
957 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00696.php
963 o Add table function support to pltcl, plpythonu
964 o Add support for polymorphic arguments and return types to
965 languages other than PL/PgSQL
966 o Add capability to create and call PROCEDURES
967 o Add support for OUT and INOUT parameters to languages other
969 o Add PL/PythonU tracebacks
971 http://archives.postgresql.org/pgsql-patches/2006-02/msg00288.php
973 o Allow data to be passed in native language formats, rather
976 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00289.php
978 o Add ability to obfuscate function bodies
980 http://archives.postgresql.org/pgsql-patches/2008-01/msg00125.php
987 * Have pg_ctl look at PGHOST in case it is a socket directory?
988 * Allow pg_ctl to work properly with configuration files located outside
991 pg_ctl can not read the pid file because it isn't located in the
992 config directory but in the PGDATA directory. The solution is to
993 allow pg_ctl to read and understand postgresql.conf to find the
994 data_directory value.
996 * Add a function like pg_get_indexdef() that report more detailed index
999 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00166.php
1002 o Have psql show current values for a sequence
1003 o Move psql backslash database information into the backend, use
1004 mnemonic commands? [psql]
1006 This would allow non-psql clients to pull the same information out
1007 of the database as psql.
1009 o Fix psql's \d commands more consistent
1011 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1012 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1014 o Consistently display privilege information for all objects in psql
1015 o Add auto-expanded mode so expanded output is used if the row
1016 length is wider than the screen width.
1018 Consider using auto-expanded mode for backslash commands like \df+.
1020 o Prevent tab completion of SET TRANSACTION from querying the
1021 database and therefore preventing the transaction isolation
1022 level from being set.
1024 Currently SET <tab> causes a database lookup to check all
1025 supported session variables. This query causes problems
1026 because setting the transaction isolation level must be the
1027 first statement of a transaction.
1029 o Add a \set variable to control whether \s displays line numbers
1031 Another option is to add \# which lists line numbers, and
1032 allows command execution.
1034 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00255.php
1036 o Prevent escape string warnings when object names have
1039 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00227.php
1041 o Have \d show foreign keys that reference a table's primary key
1043 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00424.php
1045 o Have \d show child tables that inherit from the specified parent
1046 o Have \l+ show database size, if permissions allow
1048 Ideally it will not generate an error for invalid permissions
1050 o Include the symbolic SQLSTATE name in verbose error reports
1052 http://archives.postgresql.org/pgsql-general/2007-09/msg00438.php
1054 o Improve display if enums
1056 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00826.php
1061 * pg_dump / pg_restore
1062 o %Add dumping of comments on index columns and composite type columns
1063 o %Add full object name to the tag field. eg. for operators we need
1064 '=(integer, integer)', instead of just '='.
1065 o Add pg_dumpall custom format dumps?
1066 o Allow selection of individual object(s) of all types, not just
1068 o In a selective dump, allow dumping of an object and all its
1070 o Add options like pg_restore -l and -L to pg_dump
1071 o Stop dumping CASCADE on DROP TYPE commands in clean mode
1072 o Allow pg_dump --clean to drop roles that own objects or have
1074 o Change pg_dump so that a comment on the dumped database is
1075 applied to the loaded database, even if the database has a
1076 different name. This will require new backend syntax, perhaps
1077 COMMENT ON CURRENT DATABASE.
1078 o Remove unnecessary function pointer abstractions in pg_dump source
1080 o Allow pg_dump to utilize multiple CPUs and I/O channels by dumping
1081 multiple objects simultaneously
1083 The difficulty with this is getting multiple dump processes to
1084 produce a single dump output file. It also would require
1085 several sessions to share the same snapshot.
1086 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1088 o Allow pg_restore to utilize multiple CPUs and I/O channels by
1089 restoring multiple objects simultaneously
1091 This might require a pg_restore flag to indicate how many
1092 simultaneous operations should be performed. Only pg_dump's
1093 -Fc format has the necessary dependency information.
1094 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00963.php
1096 o To better utilize resources, allow pg_restore to check foreign
1097 keys simultaneously, where possible
1098 o Allow pg_restore to create all indexes of a table
1099 concurrently, via a single heap scan
1101 This requires a pg_dump -Fc file because that format contains
1102 the required dependency information.
1103 http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php
1105 o Allow pg_restore to load different parts of the COPY data
1107 o Prevent pg_dump/pg_restore from being affected by
1110 Using psql to restore a pg_dump dump is also affected.
1112 o Remove pre-7.3 pg_dump code that assumes pg_depend does not exit
1113 o Allow pre/data/post files when schema and data are dumped
1114 separately, for performance reasons
1116 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1123 Document differences between ecpg and the SQL standard and
1124 information about the Informix-compatibility module.
1126 o Solve cardinality > 1 for input descriptors / variables?
1127 o Add a semantic check level, e.g. check if a table really exists
1128 o fix handling of DB attributes that are arrays
1129 o Use backend PREPARE/EXECUTE facility for ecpg where possible
1131 o Fix nested C comments
1132 o %sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified
1133 o Make SET CONNECTION thread-aware, non-standard?
1134 o Allow multidimensional arrays
1135 o Add internationalized message strings
1136 o Implement COPY FROM STDIN
1140 o Add PQescapeIdentifierConn()
1141 o Prevent PQfnumber() from lowercasing unquoted the column name
1143 PQfnumber() should never have been doing lowercasing, but
1144 historically it has so we need a way to prevent it
1146 o Allow statement results to be automatically batched to the client
1148 Currently all statement results are transferred to the libpq
1149 client before libpq makes the results available to the
1150 application. This feature would allow the application to make
1151 use of the first result rows while the rest are transferred, or
1152 held on the server waiting for them to be requested by libpq.
1153 One complexity is that a statement like SELECT 1/col could error
1154 out mid-way through the result set.
1156 o Consider disallowing multiple queries in PQexec() as an
1157 additional barrier to SQL injection attacks
1159 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00184.php
1161 o Add PQexecf() that allows complex parameter substitution
1163 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01803.php
1165 o Add SQLSTATE severity to PGconn return status
1167 http://archives.postgresql.org/pgsql-interfaces/2007-11/msg00015.php
1173 * Add deferred trigger queue file
1175 Right now all deferred trigger information is stored in backend
1176 memory. This could exhaust memory for very large trigger queues.
1177 This item involves dumping large queues into files.
1179 * Allow triggers to be disabled in only the current session.
1181 This is currently possible by starting a multi-statement transaction,
1182 modifying the system tables, performing the desired SQL, restoring the
1183 system tables, and committing the transaction. ALTER TABLE ...
1184 TRIGGER requires a table lock so it is not ideal for this usage.
1186 * With disabled triggers, allow pg_dump to use ALTER TABLE ADD FOREIGN KEY
1188 If the dump is known to be valid, allow foreign keys to be added
1189 without revalidating the data.
1191 * Allow statement-level triggers to access modified rows
1192 * Support triggers on columns
1194 http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php
1196 * Allow AFTER triggers on system tables
1198 System tables are modified in many places in the backend without going
1199 through the executor and therefore not causing triggers to fire. To
1200 complete this item, the functions that modify system tables will have
1203 * Tighten trigger permission checks
1205 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00564.php
1207 * Allow BEFORE INSERT triggers on views
1209 http://archives.postgresql.org/pgsql-general/2007-02/msg01466.php
1211 * -Add ability to trigger on TRUNCATE
1218 * Add UNIQUE capability to non-btree indexes
1219 * Prevent index uniqueness checks when UPDATE does not modify the column
1221 Uniqueness (index) checks are done when updating a column even if the
1222 column is not modified by the UPDATE.
1224 * Allow the creation of on-disk bitmap indexes which can be quickly
1225 combined with other bitmap indexes
1227 Such indexes could be more compact if there are only a few distinct values.
1228 Such indexes can also be compressed. Keeping such indexes updated can be
1231 http://archives.postgresql.org/pgsql-patches/2005-07/msg00512.php
1232 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01107.php
1233 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00265.php
1234 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01214.php
1235 http://archives.postgresql.org/pgsql-patches/2007-05/msg00013.php
1236 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00741.php
1238 * Allow accurate statistics to be collected on indexes with more than
1239 one column or expression indexes, perhaps using per-index statistics
1241 http://archives.postgresql.org/pgsql-performance/2006-10/msg00222.php
1242 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01131.php
1244 * Consider increasing the number of default statistics target, and
1245 reduce statistics target overhead
1247 Also consider having a larger statistics target for indexed columns
1248 and expression indexes
1249 http://archives.postgresql.org/pgsql-general/2007-05/msg01228.php
1250 http://archives.postgresql.org/pgsql-general/2007-06/msg00542.php
1251 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01066.php
1253 * Consider compressing indexes by storing key values duplicated in
1254 several rows as a single index entry
1256 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00341.php
1257 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01264.php
1258 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00465.php
1259 http://archives.postgresql.org/pgsql-patches/2007-03/msg00163.php
1260 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00014.php
1261 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00487.php
1263 * Add REINDEX CONCURRENTLY, like CREATE INDEX CONCURRENTLY
1265 This is difficult because you must upgrade to an exclusive table lock
1266 to replace the existing index file. CREATE INDEX CONCURRENTLY does not
1267 have this complication. This would allow index compaction without
1269 http://archives.postgresql.org/pgsql-performance/2007-08/msg00289.php
1271 * Allow multiple indexes to be created concurrently, ideally via a
1272 single heap scan, and have pg_restore use it
1274 * Consider sorting entries before inserting into btree index
1276 http://archives.postgresql.org/pgsql-general/2008-01/msg01010.php
1278 * Allow index scans to return matching index keys
1280 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01079.php
1285 o Allow inherited tables to inherit indexes, UNIQUE constraints,
1286 and primary/foreign keys
1287 o Honor UNIQUE INDEX on base column in INSERTs/UPDATEs
1288 on inherited table, e.g. INSERT INTO inherit_table
1289 (unique_index_col) VALUES (dup) should fail
1291 The main difficulty with this item is the problem of
1292 creating an index that can span multiple tables.
1294 o Allow SELECT ... FOR UPDATE on inherited tables
1295 o Require all CHECK constraints to be inherited
1297 http://archives.postgresql.org/pgsql-bugs/2007-04/msg00026.php
1299 o Add checks to prevent a CREATE RULE views on inherited tables
1301 http://archives.postgresql.org/pgsql-general/2008-02/msg01420.php
1302 http://archives.postgresql.org/pgsql-general/2008-03/msg00077.php
1307 o Add more GIST index support for geometric data types
1308 o Allow GIST indexes to create certain complex index types, like
1309 digital trees (see Aoki)
1314 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00051.php
1316 o Pack hash index buckets onto disk pages more efficiently
1318 Currently only one hash bucket can be stored on a page. Ideally
1319 several hash buckets could be stored on a single page and greater
1320 granularity used for the hash algorithm.
1322 http://archives.postgresql.org/pgsql-hackers/2004-06/msg00168.php
1324 o Consider sorting hash buckets so entries can be found using a
1325 binary search, rather than a linear scan
1326 o In hash indexes, consider storing the hash value with or instead
1328 o Add WAL logging for crash recovery
1329 o Allow multi-column hash indexes
1330 o -During index creation, pre-sort the tuples to improve build speed
1337 * Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
1339 Ideally this requires a separate test program that can be run
1340 at initdb time or optionally later. Consider O_SYNC when
1343 * Add program to test if fsync has a delay compared to non-fsync
1344 * Consider sorting writes during checkpoint
1346 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00541.php
1355 We could use a fixed row count and a +/- count to follow MVCC
1356 visibility rules, or a single cached value could be used and
1357 invalidated if anyone modifies the table. Another idea is to
1358 get a count directly from a unique index, but for this to be
1359 faster than a sequential scan it must avoid access to the heap
1360 to obtain tuple visibility information.
1362 * Provide a way to calculate an "estimated COUNT(*)"
1364 Perhaps by using the optimizer's cardinality estimates or random
1367 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00943.php
1369 * Allow data to be pulled directly from indexes
1371 Currently indexes do not have enough tuple visibility information
1372 to allow data to be pulled from the index without also accessing
1373 the heap. One way to allow this is to set a bit on index tuples
1374 to indicate if a tuple is currently visible to all transactions
1375 when the first valid heap lookup happens. This bit would have to
1376 be cleared when a heap tuple is expired.
1378 Another idea is to maintain a bitmap of heap pages where all rows
1379 are visible to all backends, and allow index lookups to reference
1380 that bitmap to avoid heap lookups, perhaps the same bitmap we might
1381 add someday to determine which heap pages need vacuuming. Frequently
1382 accessed bitmaps would have to be stored in shared memory. One 8k
1383 page of bitmaps could track 512MB of heap pages.
1385 A third idea would be for a heap scan to check if all rows are visible
1386 and if so set a per-table flag which can be checked by index scans.
1387 Any change to the table would have to clear the flag. To detect
1388 changes during the heap scan a counter could be set at the start and
1389 checked at the end --- if it is the same, the table has not been
1390 modified --- any table change would increment the counter.
1392 http://archives.postgresql.org/pgsql-patches/2007-10/msg00166.php
1393 http://archives.postgresql.org/pgsql-patches/2008-01/msg00049.php
1395 * Consider automatic caching of statements at various levels:
1398 o Query execute plan
1401 * Consider increasing internal areas when shared buffers is increased
1403 http://archives.postgresql.org/pgsql-hackers/2005-10/msg01419.php
1405 * Consider decreasing the amount of memory used by PrivateRefCount
1407 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00797.php
1408 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php
1410 * Consider allowing higher priority queries to have referenced buffer
1411 cache pages stay in memory longer
1413 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00562.php
1420 * Improve speed with indexes
1422 For large table adjustments during VACUUM FULL, it is faster to cluster
1423 or reindex rather than update the index. Also, index updates can bloat
1426 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00024.php
1427 http://archives.postgresql.org/pgsql-performance/2007-05/msg00296.php
1428 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00307.php
1430 * Auto-fill the free space map by scanning the buffer cache or by
1431 checking pages written by the background writer
1433 http://archives.postgresql.org/pgsql-hackers/2006-02/msg01125.php
1434 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00011.php
1436 * Create a bitmap of pages that need vacuuming
1438 Instead of sequentially scanning the entire table, have the background
1439 writer or some other process record pages that have expired rows, then
1440 VACUUM can look at just those pages rather than the entire table. In
1441 the event of a system crash, the bitmap would probably be invalidated.
1442 One complexity is that index entries still have to be vacuumed, and
1443 doing this without an index scan (by using the heap values to find the
1444 index entry) might be slow and unreliable, especially for user-defined
1447 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01188.php
1448 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00121.php
1449 http://archives.postgresql.org/pgsql-patches/2007-03/msg00508.php
1450 http://archives.postgresql.org/pgsql-patches/2007-04/msg00347.php
1451 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00156.php
1452 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00546.php
1453 http://archives.postgresql.org/pgsql-hackers/2008-04/msg00416.php
1455 * Allow FSM to return free space toward the beginning of the heap file,
1456 in hopes that empty pages at the end can be truncated by VACUUM
1457 * Allow FSM page return free space based on table clustering, to assist
1458 in maintaining clustering?
1459 * Improve dead row detection during multi-statement transactions usage
1461 http://archives.postgresql.org/pgsql-patches/2007-03/msg00358.php
1463 * Consider a more compact data representation for dead tuples
1465 http://archives.postgresql.org/pgsql-patches/2007-05/msg00143.php
1470 o %Issue log message to suggest VACUUM FULL if a table is nearly
1472 o Improve control of auto-vacuum
1474 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00876.php
1476 o Prevent long-lived temporary tables from causing frozen-xid
1477 advancement starvation
1479 The problem is that autovacuum cannot vacuum them to set frozen xids;
1480 only the session that created them can do that.
1481 http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php
1483 o Store per-table autovacuum settings in pg_class.reloptions.
1485 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01440.php
1486 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00724.php
1488 o Prevent autovacuum from running if an old transaction is still
1489 running from the last vacuum
1491 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00899.php
1498 * Fix priority ordering of read and write light-weight locks (Neil)
1500 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00893.php
1501 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00905.php
1503 * Fix problem when multiple subtransactions of the same outer transaction
1504 hold different types of locks, and one subtransaction aborts
1506 http://archives.postgresql.org/pgsql-hackers/2006-11/msg01011.php
1507 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00001.php
1508 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00435.php
1509 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00773.php
1511 * Allow UPDATEs on only non-referential integrity columns not to conflict
1512 with referential integrity locks
1514 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00073.php
1516 * Add idle_in_transaction_timeout GUC so locks are not held for long
1519 * Improve deadlock detection when a page cleaning lock conflicts
1520 with a shared buffer that is pinned
1522 http://archives.postgresql.org/pgsql-bugs/2008-01/msg00138.php
1523 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1524 http://archives.postgresql.org/pgsql-committers/2008-01/msg00365.php
1526 * Detect deadlocks involving LockBufferForCleanup()
1528 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1532 Startup Time Improvements
1533 =========================
1535 * Experiment with multi-threaded backend for backend creation [thread]
1537 This would prevent the overhead associated with process creation. Most
1538 operating systems have trivial process creation time compared to
1539 database startup overhead, but a few operating systems (Win32,
1540 Solaris) might benefit from threading. Also explore the idea of
1541 a single session using multiple threads to execute a statement faster.
1548 * Eliminate need to write full pages to WAL before page modification [wal]
1550 Currently, to protect against partial disk page writes, we write
1551 full page images to WAL before they are modified so we can correct any
1552 partial page writes during recovery. These pages can also be
1553 eliminated from point-in-time archive files.
1555 o When off, write CRC to WAL and check file system blocks
1558 If CRC check fails during recovery, remember the page in case
1559 a later CRC for that page properly matches.
1561 o Write full pages during file system write and not when
1562 the page is modified in the buffer cache
1564 This allows most full page writes to happen in the background
1565 writer. It might cause problems for applying WAL on recovery
1566 into a partially-written page, but later the full page will be
1569 * Allow WAL traffic to be streamed to another server for stand-by
1571 * Reduce WAL traffic so only modified values are written rather than
1574 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01589.php
1576 * Allow WAL information to recover corrupted pg_controldata
1578 http://archives.postgresql.org/pgsql-patches/2006-06/msg00025.php
1580 * Find a way to reduce rotational delay when repeatedly writing
1583 Currently fsync of WAL requires the disk platter to perform a full
1584 rotation to fsync again. One idea is to write the WAL to different
1585 offsets that might reduce the rotational delay.
1587 * Allow WAL logging to be turned off for a table, but the table
1588 might be dropped or truncated during crash recovery [walcontrol]
1590 Allow tables to bypass WAL writes and just fsync() dirty pages on
1591 commit. This should be implemented using ALTER TABLE, e.g. ALTER
1592 TABLE PERSISTENCE [ DROP | TRUNCATE | DEFAULT ]. Tables using
1593 non-default logging should not use referential integrity with
1594 default-logging tables. A table without dirty buffers during a
1595 crash could perhaps avoid the drop/truncate.
1597 * Allow WAL logging to be turned off for a table, but the table would
1598 avoid being truncated/dropped [walcontrol]
1600 To do this, only a single writer can modify the table, and writes
1601 must happen only on new pages so the new pages can be removed during
1602 crash recovery. Readers can continue accessing the table. Such
1603 tables probably cannot have indexes. One complexity is the handling
1604 of indexes on TOAST tables.
1606 * Speed WAL recovery by allowing more than one page to be prefetched
1608 This should be done utilizing the same infrastructure used for
1609 prefetching in general to avoid introducing complex error-prone code
1611 http://archives.postgresql.org/pgsql-general/2007-12/msg00683.php
1612 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00497.php
1613 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01279.php
1615 * Improve WAL concurrency by increasing lock granularity
1617 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00556.php
1619 * Be more aggressive about creating WAL files
1621 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01325.php
1622 http://archives.postgresql.org/pgsql-hackers/2004-07/msg01075.php
1623 http://archives.postgresql.org/pgsql-hackers/2005-04/msg00556.php
1625 * Have resource managers report the duration of their status changes
1627 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01468.php
1629 * Move pgfoundry's xlogdump to /contrib and have it rely more closely
1630 on the WAL backend code
1632 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00035.php
1637 Optimizer / Executor
1638 ====================
1640 * Improve selectivity functions for geometric operators
1641 * Precompile SQL functions to avoid overhead
1642 * Create utility to compute accurate random_page_cost value
1643 * Improve ability to display optimizer analysis using OPTIMIZER_DEBUG
1644 * Have EXPLAIN ANALYZE issue NOTICE messages when the estimated and
1645 actual row counts differ by a specified percentage
1646 * Improve how ANALYZE computes in-doubt tuples
1648 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php
1650 * Consider using hash buckets to do DISTINCT, rather than sorting
1652 This would be beneficial when there are few distinct values. This is
1653 already used by GROUP BY.
1655 * Log statements where the optimizer row estimates were dramatically
1656 different from the number of rows actually found?
1657 * Consider compressed annealing to search for query plans
1659 This might replace GEQO, http://sixdemonbag.org/Djinni.
1661 * Improve merge join performance by allowing mark/restore of
1664 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00096.php
1666 * Consider using a hash for joining to a large IN (VALUES ...) list
1668 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00450.php
1675 * Consider having the background writer update the transaction status
1676 hint bits before writing out the page
1678 Implementing this requires the background writer to have access to system
1679 catalogs and the transaction status log.
1681 * Consider adding buffers the background writer finds reusable to the
1684 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1686 * Automatically tune bgwriter_delay based on activity rather then using a
1689 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1691 * Consider wither increasing BM_MAX_USAGE_COUNT improves performance
1693 http://archives.postgresql.org/pgsql-hackers/2007-06/msg01007.php
1695 * Test to see if calling PreallocXlogFiles() from the background writer
1696 will help with WAL segment creation latency
1698 http://archives.postgresql.org/pgsql-patches/2007-06/msg00340.php
1702 Miscellaneous Performance
1703 =========================
1705 * Do async I/O for faster random read-ahead of data
1707 Async I/O allows multiple I/O requests to be sent to the disk with
1708 results coming back asynchronously.
1710 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00820.php
1711 http://archives.postgresql.org/pgsql-performance/2007-09/msg00255.php
1712 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00027.php
1713 http://archives.postgresql.org/pgsql-patches/2008-01/msg00170.php
1715 * Use mmap() rather than SYSV shared memory or to write WAL files?
1717 This would remove the requirement for SYSV SHM but would introduce
1718 portability issues. Anonymous mmap (or mmap to /dev/zero) is required
1719 to prevent I/O overhead.
1721 * Consider mmap()'ing files into a backend?
1723 Doing I/O to large tables would consume a lot of address space or
1724 require frequent mapping/unmapping. Extending the file also causes
1725 mapping problems that might require mapping only individual pages,
1726 leading to thousands of mappings. Another problem is that there is no
1727 way to _prevent_ I/O to disk from the dirty shared buffers so changes
1728 could hit disk before WAL is written.
1730 * Add a script to ask system configuration questions and tune postgresql.conf
1731 * Consider ways of storing rows more compactly on disk
1733 o Reduce the row header size?
1734 o Consider reducing on-disk varlena length from four bytes to
1735 two because a heap row cannot be more than 64k in length
1737 * Consider increasing NUM_CLOG_BUFFERS
1739 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00030.php
1740 http://archives.postgresql.org/pgsql-performance/2007-08/msg00024.php
1742 * Consider transaction start/end performance improvements
1744 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00948.php
1745 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1747 * Allow user configuration of TOAST thresholds
1749 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00213.php
1750 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00082.php
1752 * Allow configuration of backend priorities via the operating system
1754 Though backend priorities make priority inversion during lock
1755 waits possible, research shows that this is not a huge problem.
1757 http://archives.postgresql.org/pgsql-general/2007-02/msg00493.php
1759 * Experiment with multi-threaded backend better I/O utilization
1761 This would allow a single query to make use of multiple I/O channels
1762 simultaneously. One idea is to create a background reader that can
1763 pre-fetch sequential and index scan pages needed by other backends.
1764 This could be expanded to allow concurrent reads from multiple devices
1765 in a partitioned table.
1767 * Experiment with multi-threaded backend better CPU utilization
1769 This would allow several CPUs to be used for a single query, such as
1770 for sorting or query execution.
1772 * Consider increasing the minimum allowed number of shared buffers
1774 http://archives.postgresql.org/pgsql-bugs/2008-02/msg00157.php
1776 * Expire published xmin for read-only and idle transactions
1778 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00343.php
1780 * Consider if CommandCounterIncrement() can avoid its
1781 AcceptInvalidationMessages() call
1783 http://archives.postgresql.org/pgsql-committers/2007-11/msg00585.php
1785 * Improve performance of shared invalidation queue for multiple CPUs
1787 http://archives.postgresql.org/pgsql-performance/2008-01/msg00023.php
1789 * Consider Cartesian joins when both relations are needed to form an
1790 indexscan qualification for a third relation
1792 http://archives.postgresql.org/pgsql-performance/2007-12/msg00090.php
1794 * Consider not storing a NULL bitmap on disk if all the NULLs are
1797 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00624.php
1798 http://archives.postgresql.org/pgsql-patches/2007-12/msg00109.php
1800 * Sort large UPDATE/DELETEs so it is done in heap order
1802 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01119.php
1804 * -Avoid tuple some tuple copying in sort routines
1805 * SMP scalability improvements
1807 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php
1808 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00206.php
1809 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1811 * Research reducing deTOASTing in more places
1813 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00895.php
1815 * Consider being smarter about memory and external files used during
1818 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php
1819 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php
1821 * Allow one transaction to see tuples using the snapshot of another
1824 This would assist multiple backends in working together.
1825 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00400.php
1831 * Add use of 'const' for variables in source tree
1832 * Move some things from contrib into main tree
1833 * %Remove warnings created by -Wcast-align
1834 * Move platform-specific ps status display info from ps_status.c to ports
1835 * Add optional CRC checksum to heap and index pages
1836 * Improve documentation to build only interfaces (Marc)
1837 * Remove or relicense modules that are not under the BSD license, if possible
1838 * Acquire lock on a relation before building a relcache entry for it
1839 * Allow cross-compiling by generating the zic database on the target system
1840 * Improve NLS maintenance of libpgport messages linked onto applications
1841 * Clean up casting in contrib/isn
1843 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00245.php
1845 * Use UTF8 encoding for NLS messages so all server encodings can
1847 * Update Bonjour to work with newer cross-platform SDK
1849 http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php
1850 http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php
1852 * Consider detoasting keys before sorting
1853 * Consider GnuTLS if OpenSSL license becomes a problem
1855 http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php
1856 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php
1858 * Consider changing documentation format from SGML to XML
1860 http://archives.postgresql.org/pgsql-docs/2006-12/msg00152.php
1862 * Consider making NAMEDATALEN more configurable in future releases
1863 * Update our code to handle 64-bit timezone files to match the zic
1864 source code, which now uses them
1865 * Have configure choose integer datetimes by default
1867 http://archives.postgresql.org/pgsql-patches/2007-05/msg00046.php
1869 * Support scoped IPv6 addresses
1871 http://archives.postgresql.org/pgsql-bugs/2007-05/msg00111.php
1873 * Consider allowing 64-bit integers and floats to be passed by value on
1876 Also change 32-bit floats (float4) to be passed by value at the same
1879 * Research use of signals and sleep wake ups
1881 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00003.php
1883 * Add automated check for invalid C++ source code constructs
1885 http://archives.postgresql.org/pgsql-patches/2007-07/msg00056.php
1887 * Consider simplifying how memory context resets handle child contexts
1889 http://archives.postgresql.org/pgsql-patches/2007-08/msg00067.php
1891 * Remove use of MAKE_PTR and MAKE_OFFSET macros
1893 http://archives.postgresql.org/pgsql-general/2007-08/msg01510.php
1895 * Convert single quotes to apostrophes in the PDF documentation
1897 http://archives.postgresql.org/pgsql-docs/2007-12/msg00059.php
1899 * Create three versions of libpgport to simplify client code
1901 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00154.php
1903 * Remove old-style routines for manipulating tuples
1905 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00851.php
1907 * Improve detection of shared memory segments being used by other
1910 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00656.php
1916 o Remove configure.in check for link failure when cause is found
1917 o Remove readdir() errno patch when runtime/mingwex/dirent.c rev
1919 o Remove psql newline patch when we find out why mingw outputs an
1921 o Allow psql to use readline once non-US code pages work with
1923 o Fix problem with shared memory on the Win32 Terminal Server
1924 o Diagnose problem where shared memory can sometimes not be
1925 attached by postmaster children
1927 http://archives.postgresql.org/pgsql-general/2007-08/msg01377.php
1929 o Improve signal handling
1931 http://archives.postgresql.org/pgsql-patches/2005-06/msg00027.php
1933 o Convert MSVC build system to remove most batch files
1935 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00961.php
1937 o Prevent SSL from sending network packets to avoid interference
1938 with Win32 signal emulation
1940 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00455.php
1942 o Support pgxs when using MSVC
1944 o Fix MSVC NLS support, like for to_char()
1946 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00485.php
1947 http://archives.postgresql.org/pgsql-patches/2008-02/msg00038.php
1949 o Find a correct rint() substitute on Windows
1951 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00808.php
1955 * Wire Protocol Changes
1957 o Allow dynamic character set handling
1958 o Add decoded type, length, precision
1960 o Update clients to use data types, typmod, schema.table.column names
1961 of result sets using new statement protocol
1967 * Add pre-parsing phase that converts non-ISO syntax to supported
1970 This could allow SQL written for other databases to run without
1973 * Allow plug-in modules to emulate features from other databases
1974 * Add features of Oracle-style packages (Pavel)
1976 A package would be a schema with session-local variables,
1977 public/private functions, and initialization functions. It
1978 is also possible to implement these capabilities
1979 in any schema and not use a separate "packages"
1982 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00384.php
1984 * Consider allowing control of upper/lower case folding of unquoted
1987 http://archives.postgresql.org/pgsql-hackers/2004-04/msg00818.php
1988 http://archives.postgresql.org/pgsql-hackers/2006-10/msg01527.php
1989 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00849.php
1991 * Add autonomous transactions
1993 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.php
1997 Features We Do _Not_ Want
1998 =========================
2000 * All backends running as threads in a single process (not wanted)
2002 This eliminates the process protection we get from the current setup.
2003 Thread creation is usually the same overhead as process creation on
2004 modern systems, so it seems unwise to use a pure threaded model.
2006 * Optimizer hints (not wanted)
2008 Optimizer hints are used to work around problems in the optimizer. We
2009 would rather have the problems reported and fixed.
2011 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00506.php
2012 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00517.php
2013 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00663.php
2016 Because we support postfix operators, it isn't possible to make AS
2017 optional and continue to use bison.
2018 http://archives.postgresql.org/pgsql-hackers/2003-04/msg00436.php
2020 http://archives.postgresql.org/pgsql-sql/2006-08/msg00164.php
2022 * Embedded server (not wanted)
2024 While PostgreSQL clients runs fine in limited-resource environments, the
2025 server requires multiple processes and a stable pool of resources to
2026 run reliabily and efficiently. Stripping down the PostgreSQL server
2027 to run in the same process address space as the client application
2028 would add too much complexity and failure cases.