3 Current maintainer: Bruce Momjian (bruce@momjian.us)
4 Last updated: Wed Apr 23 22:24:23 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 This list contains all known PostgreSQL bugs and feature requests. If
13 you would like to work on an item, please read the Developer's FAQ
14 first. There is also a developer's wiki at
15 http://developer.postgresql.org.
21 * -Allow administrators to safely terminate individual sessions either
22 via an SQL function or SIGTERM
23 * Check for unreferenced table files created by transactions that were
24 in-progress when the server terminated abruptly
26 http://archives.postgresql.org/pgsql-patches/2006-06/msg00096.php
28 * Set proper permissions on non-system schemas during db creation
30 Currently all schemas are owned by the super-user because they are copied
31 from the template1 database. However, since all objects are inherited
32 from the template database, it is not clear that setting schemas to the db
35 * Add function to report the time of the most recent server reload
36 * Allow statistics collector information to be pulled from the collector
37 process directly, rather than requiring the collector to write a
38 filesystem file twice a second?
39 * Reduce file system activity overhead of statistics file pgstat.stat
41 http://archives.postgresql.org/pgsql-general/2007-12/msg00106.php
43 * Allow statistics last vacuum/analyze execution times to be displayed
44 without requiring stats_row_level to be enabled
46 http://archives.postgresql.org/pgsql-docs/2007-04/msg00028.php
48 * Allow log_min_messages to be specified on a per-module basis
50 This would allow administrators to see more detailed information from
51 specific sections of the backend, e.g. checkpoints, autovacuum, etc.
52 Another idea is to allow separate configuration files for each module,
53 or allow arbitrary SET commands to be passed to them.
55 * Simplify ability to create partitioned tables
57 This would allow creation of partitioned tables without requiring
58 creation of triggers or rules for INSERT/UPDATE/DELETE, and constraints
59 for rapid partition selection. Options could include range and hash
62 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00375.php
63 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00151.php
64 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00028.php
65 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00248.php
66 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00387.php
67 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00413.php
69 * Allow auto-selection of partitioned tables for min/max() operations
70 * Allow more complex user/database default GUC settings
72 Currently ALTER USER and ALTER DATABASE support per-user and
73 per-database defaults. Consider adding per-user-and-database
74 defaults so things like search_path can be defaulted for a
75 specific user connecting to a specific database.
77 * Allow custom variable classes that can restrict who can set the values
79 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00911.php
81 * Implement the SQL standard mechanism whereby REVOKE ROLE revokes only
82 the privilege granted by the invoking role, and not those granted
85 http://archives.postgresql.org/pgsql-bugs/2007-05/msg00010.php
87 * Allow SSL authentication/encryption over unix domain sockets
89 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00924.php
91 * Allow SSL key file permission checks to be optionally disabled when
92 sharing SSL keys with other applications
94 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00069.php
96 * Allow client certificate names to be checked against the client
99 This is already implemented in
100 libpq/fe-secure.c::verify_peer_name_matches_certificate() but the code
103 * Configuration files
105 o Allow pg_hba.conf to specify host names along with IP addresses
107 Host name lookup could occur when the postmaster reads the
108 pg_hba.conf file, or when the backend starts. Another
109 solution would be to reverse lookup the connection IP and
110 check that hostname against the host names in pg_hba.conf.
111 We could also then check that the host name maps to the IP
114 o %Allow postgresql.conf file values to be changed via an SQL
115 API, perhaps using SET GLOBAL
116 o Allow the server to be stopped/restarted via an SQL API
117 o Issue a warning if a change-on-restart-only postgresql.conf value
118 is modified and the server config files are reloaded
119 o Consider normalizing fractions in postgresql.conf, perhaps
122 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00550.php
124 o Allow Kerberos to disable stripping of realms so we can
125 check the username@realm against multiple realms
127 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00009.php
132 o Allow a database in tablespace t1 with tables created in
133 tablespace t2 to be used as a template for a new database created
134 with default tablespace t2
136 Currently all objects in the default database tablespace must
137 have default tablespace specifications. This is because new
138 databases are created by copying directories. If you mix default
139 tablespace tables and tablespace-specified tables in the same
140 directory, creating a new database from such a mixed directory
141 would create a new database with tables that had incorrect
142 explicit tablespaces. To fix this would require modifying
143 pg_class in the newly copied database, which we don't currently
146 o Allow reporting of which objects are in which tablespaces
148 This item is difficult because a tablespace can contain objects
149 from multiple databases. There is a server-side function that
150 returns the databases which use a specific tablespace, so this
151 requires a tool that will call that function and connect to each
152 database to find the objects in each database for that tablespace.
154 o Allow WAL replay of CREATE TABLESPACE to work when the directory
155 structure on the recovery computer is different from the original
157 o Allow per-tablespace quotas
160 * Point-In-Time Recovery (PITR)
162 o Allow a warm standby system to also allow read-only statements
164 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00050.php
166 o %Create dump tool for write-ahead logs for use in determining
167 transaction id for point-in-time recovery
169 This is useful for checking PITR recovery.
171 o Allow recovery.conf to support the same syntax as
172 postgresql.conf, including quoting
174 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00497.php
176 o Fix server restart problem when the server was shutdown during
179 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00800.php
181 o Recreate pg_xlog/archive_status/ if it doesn't exist after
182 restoring from a PITR backup
184 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00487.php
190 * Change NUMERIC to enforce the maximum precision
191 * Reduce storage space for small NUMERICs
193 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01331.php
194 http://archives.postgresql.org/pgsql-patches/2007-02/msg00505.php
195 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00715.php
197 * Fix data types where equality comparison isn't intuitive, e.g. box
198 * Add support for public SYNONYMs
200 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00519.php
202 * Fix CREATE CAST on DOMAINs
204 http://archives.postgresql.org/pgsql-hackers/2006-05/msg00072.php
205 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01681.php
207 * Allow domains to be cast
209 http://archives.postgresql.org/pgsql-hackers/2003-06/msg01206.php
210 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00289.php
212 * Add support for SQL-standard GENERATED/IDENTITY columns
214 http://archives.postgresql.org/pgsql-hackers/2006-07/msg00543.php
215 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00038.php
216 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00344.php
217 http://archives.postgresql.org/pgsql-patches/2007-05/msg00076.php
218 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00604.php
220 * Improve XML support
222 http://developer.postgresql.org/index.php/XML_Support
224 * Consider placing all sequences in a single table, or create a system
227 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
229 * Allow the UUID type to accept non-standard formats
231 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01214.php
233 * Allow text search dictionary to filter out only stop words
235 http://archives.postgresql.org/pgsql-patches/2007-11/msg00081.php
237 * Consider a function-based API for '@@' full text searches
239 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00511.php
241 * Improve text search error messages
243 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00966.php
244 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01146.php
246 * Consider a special data type for regular expressions
248 http://archives.postgresql.org/pgsql-hackers/2007-08/msg01067.php
250 * Reduce BIT data type overhead using short varlena headers
252 http://archives.postgresql.org/pgsql-general/2007-12/msg00273.php
254 * Allow xml arrays to be cast to other data types
256 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00981.php
257 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00231.php
258 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00471.php
260 * Simplify integer cross-data-type operators
262 http://archives.postgresql.org/pgsql-bugs/2008-01/msg00189.php
264 * Allow XML to accept more liberal DOCTYPE specifications
266 http://archives.postgresql.org/pgsql-general/2008-02/msg00347.php
271 o Allow infinite dates and intervals just like infinite timestamps
272 o Merge hardwired timezone names with the TZ database; allow either
273 kind everywhere a TZ name is currently taken
274 o Allow TIMESTAMP WITH TIME ZONE to store the original timezone
275 information, either zone name or offset from UTC
277 If the TIMESTAMP value is stored with a time zone name, interval
278 computations should adjust based on the time zone rules.
279 http://archives.postgresql.org/pgsql-hackers/2004-10/msg00705.php
281 o Fix SELECT '0.01 years'::interval, '0.01 months'::interval
282 o Add a GUC variable to allow output of interval values in ISO8601
284 o Have timestamp subtraction not call justify_hours()?
286 http://archives.postgresql.org/pgsql-sql/2006-10/msg00059.php
288 o Improve timestamptz subtraction to be DST-aware
290 Currently subtracting one date from another that crosses a
291 daylight savings time adjustment can return '1 day 1 hour', but
292 adding that back to the first date returns a time one hour in
293 the future. This is caused by the adjustment of '25 hours' to
294 '1 day 1 hour', and '1 day' is the same time the next day, even
295 if daylight savings adjustments are involved.
297 o Fix interval display to support values exceeding 2^31 hours
298 o Add overflow checking to timestamp and interval arithmetic
299 o Extend timezone code to allow 64-bit values so we can
300 represent years beyond 2038
302 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01363.php
304 o Use LC_TIME for localized weekday/month names, rather than
307 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00390.php
309 o Add ISO INTERVAL handling
311 http://archives.postgresql.org/pgsql-hackers/2006-01/msg00250.php
312 http://archives.postgresql.org/pgsql-bugs/2006-04/msg00248.php
314 o Support ISO INTERVAL syntax if units cannot be determined from
315 the string, and are supplied after the string
317 The SQL standard states that the units after the string
318 specify the units of the string, e.g. INTERVAL '2' MINUTE
319 should return '00:02:00'. The current behavior has the units
320 restrict the interval value to the specified unit or unit
321 range, INTERVAL '70' SECOND returns '00:00:10'.
323 For syntax that isn't uniquely ISO or PG syntax, like '1' or
324 '1:30', treat as ISO if there is a range specification clause,
325 and as PG if there no clause is present, e.g. interpret '1:30'
326 MINUTE TO SECOND as '1 minute 30 seconds', and interpret
327 '1:30' as '1 hour, 30 minutes'.
329 This makes common cases like SELECT INTERVAL '1' MONTH
330 SQL-standard results. The SQL standard supports a limited
331 number of unit combinations and doesn't support unit names in
332 the string. The PostgreSQL syntax is more flexible in the
333 range of units supported, e.g. PostgreSQL supports '1 year 1
334 hour', while the SQL standard does not.
336 o Add support for year-month syntax, INTERVAL '50-6' YEAR
338 o Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1
339 year' AS INTERVAL MONTH), and this should return '12 months'
340 o Round or truncate values to the requested precision, e.g.
341 INTERVAL '11 months' AS YEAR should return one or zero
342 o Support precision, CREATE TABLE foo (a INTERVAL MONTH(3))
347 o Delay resolution of array expression's data type so assignment
348 coercion can be performed on empty array expressions
349 o Add support for arrays of domains
351 http://archives.postgresql.org/pgsql-patches/2007-05/msg00114.php
353 o Allow single-byte header storage for array elements
358 o Improve vacuum of large objects, like contrib/vacuumlo?
359 o Add security checking for large objects
360 o Auto-delete large objects when referencing row is deleted
362 contrib/lo offers this functionality.
364 o Allow read/write into TOAST values like large objects
366 This requires the TOAST column to be stored EXTERNAL.
368 o Add API for 64-bit large object access
370 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00781.php
374 * Add locale-aware MONEY type, and support multiple currencies
376 http://archives.postgresql.org/pgsql-general/2005-08/msg01432.php
377 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01181.php
379 * MONEY dumps in a locale-specific format making it difficult to
380 restore to a system with a different locale
381 * Allow MONEY to be easily cast to/from other numeric data types
387 * Allow INET subnet tests using non-constants to be indexed
388 * Allow to_date() and to_timestamp() accept localized month names
389 * Fix to_date()-related functions to consistently issue errors
391 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00915.php
393 * Add missing parameter handling in to_char()
395 http://archives.postgresql.org/pgsql-hackers/2005-12/msg00948.php
397 * Allow substring/replace() to get/set bit values
398 * Allow to_char() on interval values to accumulate the highest unit
401 Some special format flag would be required to request such
402 accumulation. Such functionality could also be added to EXTRACT.
403 Prevent accumulation that crosses the month/day boundary because of
404 the uneven number of days in a month.
406 o to_char(INTERVAL '1 hour 5 minutes', 'MI') => 65
407 o to_char(INTERVAL '43 hours 20 minutes', 'MI' ) => 2600
408 o to_char(INTERVAL '43 hours 20 minutes', 'WK:DD:HR:MI') => 0:1:19:20
409 o to_char(INTERVAL '3 years 5 months','MM') => 41
411 * Implement inlining of set-returning functions defined in SQL
412 * Allow SQL-language functions to return results from RETURNING queries
414 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00665.php
416 * Allow SQL-language functions to reference parameters by parameter name
418 Currently SQL-language functions can only refer to dollar parameters,
421 * Add SPI_gettypmod() to return the typemod for a TupleDesc
422 * Enforce typmod for function inputs, function results and parameters for
423 spi_prepare'd statements called from PLs
425 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01403.php
427 * Allow holdable cursors in SPI
428 * Tighten function permission checks
430 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00568.php
432 * Fix IS OF so it matches the ISO specification, and add documentation
434 http://archives.postgresql.org/pgsql-patches/2003-08/msg00060.php
435 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00060.php
437 * Add missing operators for geometric data types
439 Some geometric types do not have the full suite of geometric operators,
442 * Implement Boyer-Moore searching in strpos()
444 http://archives.postgresql.org/pgsql-patches/2007-08/msg00012.php
446 * Prevent malicious functions from being executed with the permissions
447 of unsuspecting users
449 Index functions are safe, so VACUUM and ANALYZE are safe too.
450 Triggers, CHECK and DEFAULT expressions, and rules are still vulnerable.
451 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00268.php
453 * Reduce memory usage of aggregates in set returning functions
455 http://archives.postgresql.org/pgsql-performance/2008-01/msg00031.php
457 * Add temporal versions of generate_series()
459 http://archives.postgresql.org/pgsql-hackers/2007-04/msg01180.php
461 * Add array_accum() and array_to_set() functions for arrays
463 The standards specify array_agg() and UNNEST.
464 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00464.php
466 * Fix /contrib/ltree operator
468 http://archives.postgresql.org/pgsql-bugs/2007-11/msg00044.php
470 * Fix inconsistent precedence of =, >, and < compared to <>, >=, and <=
472 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00145.php
474 * Fix regular expression bug when using complex back-references
476 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00000.php
478 * Have /contrib/dblink reuse unnamed connections
480 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00895.php
482 * Add SQL-standard array_agg() and unnest() array functions
484 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01017.php
486 * Allow calling of a procedure outside a SELECT that can control the
489 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01375.php
493 Multi-Language Support
494 ======================
496 * Add NCHAR (as distinguished from ordinary varchar),
497 * Allow locale to be set at database creation
499 Currently locale can only be set during initdb. No global tables have
500 locale-aware columns. However, the database template used during
501 database creation might have locale-aware indexes. The indexes would
502 need to be reindexed to match the new locale.
504 * Allow encoding on a per-column basis optionally using the ICU library;
507 Right now only one encoding is allowed per database.
509 http://archives.postgresql.org/pgsql-hackers/2005-03/msg00932.php
510 http://archives.postgresql.org/pgsql-patches/2005-08/msg00039.php
511 http://archives.postgresql.org/pgsql-patches/2005-08/msg00309.php
512 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00110.php
513 http://archives.postgresql.org/pgsql-patches/2005-09/msg00020.php
514 http://archives.postgresql.org/pgsql-hackers/2005-12/msg01121.php
515 http://archives.postgresql.org/pgsql-hackers/2006-01/msg00767.php
516 http://archives.postgresql.org/pgsql-patches/2006-03/msg00233.php
517 http://archives.postgresql.org/pgsql-hackers/2006-09/msg00662.php
518 http://wiki.postgresql.org/wiki/Todo:Collate
519 http://wiki.postgresql.org/wiki/Todo:ICU
521 * Support multiple simultaneous character sets, per SQL92
522 * Improve UTF8 combined character handling?
523 * Add octet_length_server() and octet_length_client()
524 * Make octet_length_client() the same as octet_length()?
525 * Fix problems with wrong runtime encoding conversion for NLS message files
526 * Add URL to more complete multi-byte regression tests
528 http://archives.postgresql.org/pgsql-hackers/2005-07/msg00272.php
530 * Fix ILIKE and regular expressions to handle case insensitivity
531 properly in multibyte encodings
533 http://archives.postgresql.org/pgsql-bugs/2005-10/msg00001.php
534 http://archives.postgresql.org/pgsql-patches/2005-11/msg00173.php
536 * Set client encoding based on the client operating system encoding
538 Currently client_encoding is set in postgresql.conf, which
539 defaults to the server encoding.
540 http://archives.postgresql.org/pgsql-hackers/2006-08/msg01696.php
542 * Change memory allocation for multi-byte functions so memory is
543 allocated inside conversion functions
545 Currently we preallocate memory based on worst-case usage.
552 * Automatically create rules on views so they are updateable, per SQL99
554 We can only auto-create rules for simple views. For more complex
555 cases users will still have to write rules manually.
557 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00586.php
558 http://archives.postgresql.org/pgsql-patches/2006-08/msg00255.php
560 * Add the functionality for WITH CHECK OPTION clause of CREATE VIEW
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 * Add a GUC variable to warn about non-standard SQL usage in queries
607 * Add SQL-standard MERGE/REPLACE/UPSERT command
609 MERGE is typically used to merge two tables. REPLACE or UPSERT
610 command does UPDATE, or on failure, INSERT. This is similar to UPDATE,
611 then for unmatched rows, INSERT. Whether concurrent access allows
612 modifications which could cause row loss is implementation independent.
613 To implement this cleanly requires that the table have a unique index
614 so duplicate checking can be easily performed. It is possible to do it
615 without a unique index if we require the user to LOCK the table before
618 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00501.php
619 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00536.php
620 http://archives.postgresql.org/pgsql-hackers/2008-04/msg01475.php
622 * Add NOVICE output level for helpful messages like automatic sequence/index
624 * Add GUC to issue notice about statements that use unjoined tables
625 * Allow EXPLAIN to identify tables that were skipped because of
627 * Allow EXPLAIN output to be more easily processed by scripts, perhaps XML
628 * Enable standard_conforming_strings
629 * Make standard_conforming_strings the default in 8.5?
631 When this is done, backslash-quote should be prohibited in non-E''
632 strings because of possible confusion over how such strings treat
633 backslashes. Basically, '' is always safe for a literal single
634 quote, while \' might or might not be based on the backslash
637 * Simplify dropping roles that have objects in several databases
638 * Allow COMMENT ON to accept an expression rather than just a string
639 * Allow the count returned by SELECT, etc to be represented as an int64
640 to allow a higher range of values
641 * Add SQL99 WITH clause to SELECT
642 * Add SQL:2003 WITH RECURSIVE (hierarchical) queries to SELECT
644 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01375.php
645 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00642.php
646 http://archives.postgresql.org/pgsql-patches/2007-03/msg00139.php
647 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01334.php
648 http://archives.postgresql.org/pgsql-patches/2008-01/msg00105.php
649 http://archives.postgresql.org/pgsql-patches/2008-03/msg00327.php
651 * Add DEFAULT .. AS OWNER so permission checks are done as the table
654 This would be useful for SERIAL nextval() calls and CHECK constraints.
656 * Allow DISTINCT to work in multiple-argument aggregate calls
657 * Add column to pg_stat_activity that shows the progress of long-running
658 commands like CREATE INDEX and VACUUM
659 * Implement SQL:2003 window functions
660 * Improve failure message when DROP DATABASE is used on a database that
661 has prepared transactions
662 * Allow INSERT/UPDATE ... RETURNING inside a SELECT 'FROM' clause
664 http://archives.postgresql.org/pgsql-general/2006-09/msg00803.php
665 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00693.php
667 * Increase locking when DROPing objects so dependent objects cannot
668 get dropped while the DROP operation is happening
670 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00937.php
672 * -Allow AS in "SELECT col AS label" to be optional in certain cases
674 * Allow INSERT ... DELETE ... RETURNING, namely allow the DELETE ...
675 RETURNING to supply values to the INSERT
676 http://archives.postgresql.org/pgsql-hackers/2008-02/thrd2.php#00979
678 * Add comments on system tables/columns using the information in
681 Ideally the information would be pulled from the SGML file
684 * Improve reporting of UNION type mismatches
686 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00944.php
687 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00597.php
692 o Allow CREATE TABLE AS to determine column lengths for complex
693 expressions like SELECT col1 || col2
695 o Have WITH CONSTRAINTS also create constraint indexes
697 http://archives.postgresql.org/pgsql-patches/2007-04/msg00149.php
699 o Have CONSTRAINT cname NOT NULL record the contraint name
701 Right now pg_attribute.attnotnull records the NOT NULL status
702 of the column, but does not record the contraint name
704 o Prevent concurrent CREATE TABLE table1 from sometimes returning
705 a cryptic error message
707 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00169.php
711 o Allow UPDATE tab SET ROW (col, ...) = (SELECT...)
713 http://archives.postgresql.org/pgsql-hackers/2006-07/msg01306.php
714 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00865.php
715 http://archives.postgresql.org/pgsql-patches/2007-04/msg00315.php
716 http://archives.postgresql.org/pgsql-patches/2008-03/msg00237.php
718 o Research self-referential UPDATEs that see inconsistent row versions
719 in read-committed mode
721 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00507.php
722 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00016.php
724 o Allow GLOBAL temporary tables to exist as empty by default in
727 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00006.php
732 o Have ALTER TABLE RENAME rename SERIAL sequence names
734 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
736 o Have ALTER SEQUENCE RENAME rename the sequence name stored
737 in the sequence table
739 http://archives.postgresql.org/pgsql-bugs/2007-09/msg00092.php
740 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00007.php
741 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
743 o Add ALTER DOMAIN to modify the underlying data type
744 o %Allow ALTER TABLE ... ALTER CONSTRAINT ... RENAME
746 http://archives.postgresql.org/pgsql-patches/2006-02/msg00168.php
748 o %Allow ALTER TABLE to change constraint deferrability and actions
749 o Add missing object types for ALTER ... SET SCHEMA
750 o Allow ALTER TABLESPACE to move to different directories
751 o Allow databases to be moved to different tablespaces
752 o Allow moving system tables to other tablespaces, where possible
754 Currently non-global system tables must be in the default database
755 tablespace. Global system tables can never be moved.
757 o Prevent parent tables from altering or dropping constraints
758 like CHECK that are inherited by child tables unless CASCADE
760 o %Prevent child tables from altering or dropping constraints
761 like CHECK that were inherited from the parent table
762 o Have ALTER INDEX update the name of a constraint using that index
763 o Add ALTER TABLE RENAME CONSTRAINT, update index name also
764 o Allow column display reordering by recording a display,
765 storage, and permanent id for every column?
767 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00782.php
773 o Automatically maintain clustering on a table
775 This might require some background daemon to maintain clustering
776 during periods of low usage. It might also require tables to be only
777 partially filled for easier reorganization. Another idea would
778 be to create a merged heap/index data file so an index lookup would
779 automatically access the heap data too. A third idea would be to
780 store heap rows in hashed groups, perhaps using a user-supplied
782 http://archives.postgresql.org/pgsql-performance/2004-08/msg00349.php
784 o %Add default clustering to system tables
786 To do this, determine the ideal cluster index for each system
787 table and set the cluster setting during initdb.
789 o %Add VERBOSE option to report tables as they are processed,
795 o Allow COPY to report error lines and continue
797 This requires the use of a savepoint before each COPY line is
798 processed, with ROLLBACK on COPY failure.
799 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00572.php
801 o Allow COPY on a newly-created table to skip WAL logging
803 On crash recovery, the table involved in the COPY would
804 be removed or have its heap and index files truncated. One
805 issue is that no other backend should be able to add to
806 the table at the same time, which is something that is
807 currently allowed. This currently is done if the table is
808 created inside the same transaction block as the COPY because
809 no other backends can see the table.
811 o Consider using a ring buffer for COPY FROM
813 http://archives.postgresql.org/pgsql-patches/2008-02/msg00140.php
814 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01080.php
816 o Allow COPY FROM to create index entries in bulk
818 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00811.php
820 o Allow COPY in CSV mode to control whether a quoted zero-length
821 string is treated as NULL
823 Currently this is always treated as a zero-length string,
824 which generates an error when loading into an integer column
825 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00905.php
831 o Allow column-level privileges
832 o %Allow GRANT/REVOKE permissions to be applied to all schema objects
835 The proposed syntax is:
836 GRANT SELECT ON ALL TABLES IN public TO phpuser;
837 GRANT SELECT ON NEW TABLES IN public TO phpuser;
839 o Allow GRANT/REVOKE permissions to be inherited by objects based on
842 o Allow SERIAL sequences to inherit permissions from the base table?
847 o Prevent DROP TABLE from dropping a row referenced by its own open
853 o Allow INSERT/UPDATE of the system-generated oid value for a row
854 o In rules, allow VALUES() to contain a mixture of 'old' and 'new'
860 o Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM
866 o Allow LISTEN/NOTIFY to store info in memory rather than tables?
868 Currently LISTEN/NOTIFY information is stored in pg_listener.
869 Storing such information in memory would improve performance.
871 o Add optional textual message to NOTIFY
873 This would allow an informational message to be added to the notify
874 message, perhaps indicating the row modified or other custom
877 o Allow multiple identical NOTIFY events to always be communicated
878 to the client, rather than sent as a single notification to the
881 http://archives.postgresql.org/pgsql-general/2008-01/msg00057.php
883 o Allow NOTIFY in rules involving conditionals
884 o Improve LISTEN concurrency
886 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01106.php
890 Referential Integrity
891 =====================
893 * Add MATCH PARTIAL referential integrity
894 * Change foreign key constraint for array -> element to mean element
896 * Fix problem when cascading referential triggers make changes on
897 cascaded tables, seeing the tables in an intermediate state
899 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
900 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
902 * Allow DEFERRABLE and end-of-statement UNIQUE constraints?
904 This would allow UPDATE tab SET col = col + 1 to work if col has
905 a unique index. Currently, uniqueness checks are done while the
906 command is being executed, rather than at the end of the statement
908 http://people.planetpostgresql.org/greg/index.php?/archives/2006/06/10.html
909 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01458.php
911 * Optimize referential integrity checks
913 http://archives.postgresql.org/pgsql-performance/2005-10/msg00458.php
914 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00744.php
917 Server-Side Languages
918 =====================
921 o Fix RENAME to work on variables other than OLD/NEW
923 http://archives.postgresql.org/pgsql-hackers/2002-03/msg00591.php
924 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01615.php
925 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01587.php
927 o Allow function parameters to be passed by name,
928 get_employee_salary(12345 AS emp_id, 2001 AS tax_year)
929 o Allow handling of %TYPE arrays, e.g. tab.col%TYPE[]
930 o Allow listing of record column names, and access to
931 record columns via variables, e.g. columns := r.(*),
934 http://archives.postgresql.org/pgsql-patches/2005-07/msg00458.php
935 http://archives.postgresql.org/pgsql-patches/2006-05/msg00302.php
936 http://archives.postgresql.org/pgsql-patches/2006-06/msg00031.php
938 o Add support for SCROLL cursors
939 o Add support for WITH HOLD cursors
940 o Allow row and record variables to be set to NULL constants,
941 and allow NULL tests on such variables
943 Because a row is not scalar, do not allow assignment
944 from NULL-valued scalars.
946 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00070.php
948 o Review handling of MOVE and FETCH
950 http://archives.postgresql.org/pgsql-patches/2007-04/msg00527.php
952 o Improve logic of determining if an identifier is a a
953 variable or column name
955 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00436.php
957 o Consider keeping seperate cached copies when search_path changes
959 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01009.php
961 o Add CASE capability to language (already in SQL)
963 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00696.php
969 o Add table function support to pltcl, plpythonu
970 o Add support for polymorphic arguments and return types to
971 languages other than PL/PgSQL
972 o Add capability to create and call PROCEDURES
973 o Add support for OUT and INOUT parameters to languages other
975 o Add PL/PythonU tracebacks
977 http://archives.postgresql.org/pgsql-patches/2006-02/msg00288.php
979 o Allow data to be passed in native language formats, rather
982 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00289.php
984 o Add ability to obfuscate function bodies
986 http://archives.postgresql.org/pgsql-patches/2008-01/msg00125.php
993 * Have pg_ctl look at PGHOST in case it is a socket directory?
994 * Allow pg_ctl to work properly with configuration files located outside
997 pg_ctl can not read the pid file because it isn't located in the
998 config directory but in the PGDATA directory. The solution is to
999 allow pg_ctl to read and understand postgresql.conf to find the
1000 data_directory value.
1002 * Add a function like pg_get_indexdef() that report more detailed index
1005 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00166.php
1008 o Have psql show current values for a sequence
1009 o Move psql backslash database information into the backend, use
1012 This would allow non-psql clients to pull the same information out
1013 of the database as psql.
1014 http://archives.postgresql.org/pgsql-hackers/2004-01/msg00191.php
1016 o Make psql's \d commands more consistent
1018 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1019 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1021 o Consistently display privilege information for all objects in psql
1022 o Add auto-expanded mode so expanded output is used if the row
1023 length is wider than the screen width.
1025 Consider using auto-expanded mode for backslash commands like \df+.
1027 o Prevent tab completion of SET TRANSACTION from querying the
1028 database and therefore preventing the transaction isolation
1029 level from being set.
1031 Currently SET <tab> causes a database lookup to check all
1032 supported session variables. This query causes problems
1033 because setting the transaction isolation level must be the
1034 first statement of a transaction.
1036 o Add a \set variable to control whether \s displays line numbers
1038 Another option is to add \# which lists line numbers, and
1039 allows command execution.
1041 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00255.php
1043 o Prevent escape string warnings when object names have
1046 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00227.php
1048 o Have \d show foreign keys that reference a table's primary key
1050 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00424.php
1052 o Have \d show child tables that inherit from the specified parent
1053 o Have \l+ show database size, if permissions allow
1055 Ideally it will not generate an error for invalid permissions
1057 o Include the symbolic SQLSTATE name in verbose error reports
1059 http://archives.postgresql.org/pgsql-general/2007-09/msg00438.php
1061 o Improve display if enums
1063 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00826.php
1065 o Add prompt escape to display the client and server versions
1068 * pg_dump / pg_restore
1069 o %Add dumping of comments on index columns and composite type columns
1070 o %Add full object name to the tag field. eg. for operators we need
1071 '=(integer, integer)', instead of just '='.
1072 o Add pg_dumpall custom format dumps?
1073 o Allow selection of individual object(s) of all types, not just
1075 o In a selective dump, allow dumping of an object and all its
1077 o Add options like pg_restore -l and -L to pg_dump
1078 o Stop dumping CASCADE on DROP TYPE commands in clean mode
1079 o Allow pg_dump --clean to drop roles that own objects or have
1081 o Change pg_dump so that a comment on the dumped database is
1082 applied to the loaded database, even if the database has a
1083 different name. This will require new backend syntax, perhaps
1084 COMMENT ON CURRENT DATABASE.
1085 o Remove unnecessary function pointer abstractions in pg_dump source
1087 o Allow pg_dump to utilize multiple CPUs and I/O channels by dumping
1088 multiple objects simultaneously
1090 The difficulty with this is getting multiple dump processes to
1091 produce a single dump output file. It also would require
1092 several sessions to share the same snapshot.
1093 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1095 o Allow pg_restore to utilize multiple CPUs and I/O channels by
1096 restoring multiple objects simultaneously
1098 This might require a pg_restore flag to indicate how many
1099 simultaneous operations should be performed. Only pg_dump's
1100 -Fc format has the necessary dependency information.
1101 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00963.php
1103 o To better utilize resources, allow pg_restore to check foreign
1104 keys simultaneously, where possible
1105 o Allow pg_restore to create all indexes of a table
1106 concurrently, via a single heap scan
1108 This requires a pg_dump -Fc file because that format contains
1109 the required dependency information.
1110 http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php
1112 o Allow pg_restore to load different parts of the COPY data
1114 o Prevent pg_dump/pg_restore from being affected by
1117 Using psql to restore a pg_dump dump is also affected.
1119 o Remove pre-7.3 pg_dump code that assumes pg_depend does not exit
1120 o Allow pre/data/post files when schema and data are dumped
1121 separately, for performance reasons
1123 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1130 Document differences between ecpg and the SQL standard and
1131 information about the Informix-compatibility module.
1133 o Solve cardinality > 1 for input descriptors / variables?
1134 o Add a semantic check level, e.g. check if a table really exists
1135 o fix handling of DB attributes that are arrays
1136 o Use backend PREPARE/EXECUTE facility for ecpg where possible
1138 o Fix nested C comments
1139 o %sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified
1140 o Make SET CONNECTION thread-aware, non-standard?
1141 o Allow multidimensional arrays
1142 o Add internationalized message strings
1143 o Implement COPY FROM STDIN
1147 o Add PQescapeIdentifierConn()
1148 o Prevent PQfnumber() from lowercasing unquoted the column name
1150 PQfnumber() should never have been doing lowercasing, but
1151 historically it has so we need a way to prevent it
1153 o Allow statement results to be automatically batched to the client
1155 Currently all statement results are transferred to the libpq
1156 client before libpq makes the results available to the
1157 application. This feature would allow the application to make
1158 use of the first result rows while the rest are transferred, or
1159 held on the server waiting for them to be requested by libpq.
1160 One complexity is that a statement like SELECT 1/col could error
1161 out mid-way through the result set.
1163 o Consider disallowing multiple queries in PQexec() as an
1164 additional barrier to SQL injection attacks
1166 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00184.php
1168 o Add PQexecf() that allows complex parameter substitution
1170 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01803.php
1172 o Add SQLSTATE severity to PGconn return status
1174 http://archives.postgresql.org/pgsql-interfaces/2007-11/msg00015.php
1180 * Add deferred trigger queue file
1182 Right now all deferred trigger information is stored in backend
1183 memory. This could exhaust memory for very large trigger queues.
1184 This item involves dumping large queues into files.
1186 * Allow triggers to be disabled in only the current session.
1188 This is currently possible by starting a multi-statement transaction,
1189 modifying the system tables, performing the desired SQL, restoring the
1190 system tables, and committing the transaction. ALTER TABLE ...
1191 TRIGGER requires a table lock so it is not ideal for this usage.
1193 * With disabled triggers, allow pg_dump to use ALTER TABLE ADD FOREIGN KEY
1195 If the dump is known to be valid, allow foreign keys to be added
1196 without revalidating the data.
1198 * Allow statement-level triggers to access modified rows
1199 * Support triggers on columns
1201 http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php
1203 * Allow AFTER triggers on system tables
1205 System tables are modified in many places in the backend without going
1206 through the executor and therefore not causing triggers to fire. To
1207 complete this item, the functions that modify system tables will have
1210 * Tighten trigger permission checks
1212 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00564.php
1214 * Allow BEFORE INSERT triggers on views
1216 http://archives.postgresql.org/pgsql-general/2007-02/msg01466.php
1218 * -Add ability to trigger on TRUNCATE
1225 * Add UNIQUE capability to non-btree indexes
1226 * Prevent index uniqueness checks when UPDATE does not modify the column
1228 Uniqueness (index) checks are done when updating a column even if the
1229 column is not modified by the UPDATE.
1231 * Allow the creation of on-disk bitmap indexes which can be quickly
1232 combined with other bitmap indexes
1234 Such indexes could be more compact if there are only a few distinct values.
1235 Such indexes can also be compressed. Keeping such indexes updated can be
1238 http://archives.postgresql.org/pgsql-patches/2005-07/msg00512.php
1239 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01107.php
1240 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00265.php
1241 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01214.php
1242 http://archives.postgresql.org/pgsql-patches/2007-05/msg00013.php
1243 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00741.php
1245 * Allow accurate statistics to be collected on indexes with more than
1246 one column or expression indexes, perhaps using per-index statistics
1248 http://archives.postgresql.org/pgsql-performance/2006-10/msg00222.php
1249 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01131.php
1251 * Consider increasing the number of default statistics target, and
1252 reduce statistics target overhead
1254 Also consider having a larger statistics target for indexed columns
1255 and expression indexes
1256 http://archives.postgresql.org/pgsql-general/2007-05/msg01228.php
1257 http://archives.postgresql.org/pgsql-general/2007-06/msg00542.php
1258 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01066.php
1260 * Consider compressing indexes by storing key values duplicated in
1261 several rows as a single index entry
1263 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00341.php
1264 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01264.php
1265 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00465.php
1266 http://archives.postgresql.org/pgsql-patches/2007-03/msg00163.php
1267 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00014.php
1268 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00487.php
1269 http://archives.postgresql.org/pgsql-hackers/2008-04/msg01589.php
1271 * Add REINDEX CONCURRENTLY, like CREATE INDEX CONCURRENTLY
1273 This is difficult because you must upgrade to an exclusive table lock
1274 to replace the existing index file. CREATE INDEX CONCURRENTLY does not
1275 have this complication. This would allow index compaction without
1277 http://archives.postgresql.org/pgsql-performance/2007-08/msg00289.php
1279 * Allow multiple indexes to be created concurrently, ideally via a
1280 single heap scan, and have pg_restore use it
1282 * Consider sorting entries before inserting into btree index
1284 http://archives.postgresql.org/pgsql-general/2008-01/msg01010.php
1286 * Allow index scans to return matching index keys
1288 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01079.php
1293 o Allow inherited tables to inherit indexes, UNIQUE constraints,
1294 and primary/foreign keys
1295 o Honor UNIQUE INDEX on base column in INSERTs/UPDATEs
1296 on inherited table, e.g. INSERT INTO inherit_table
1297 (unique_index_col) VALUES (dup) should fail
1299 The main difficulty with this item is the problem of
1300 creating an index that can span multiple tables.
1302 o Allow SELECT ... FOR UPDATE on inherited tables
1303 o Require all CHECK constraints to be inherited
1305 http://archives.postgresql.org/pgsql-bugs/2007-04/msg00026.php
1307 o Add checks to prevent a CREATE RULE views on inherited tables
1309 http://archives.postgresql.org/pgsql-general/2008-02/msg01420.php
1310 http://archives.postgresql.org/pgsql-general/2008-03/msg00077.php
1315 o Add more GIST index support for geometric data types
1316 o Allow GIST indexes to create certain complex index types, like
1317 digital trees (see Aoki)
1322 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00051.php
1324 o Pack hash index buckets onto disk pages more efficiently
1326 Currently only one hash bucket can be stored on a page. Ideally
1327 several hash buckets could be stored on a single page and greater
1328 granularity used for the hash algorithm.
1330 http://archives.postgresql.org/pgsql-hackers/2004-06/msg00168.php
1332 o Consider sorting hash buckets so entries can be found using a
1333 binary search, rather than a linear scan
1334 o In hash indexes, consider storing the hash value with or instead
1336 o Add WAL logging for crash recovery
1337 o Allow multi-column hash indexes
1338 o -During index creation, pre-sort the tuples to improve build speed
1345 * Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
1347 Ideally this requires a separate test program that can be run
1348 at initdb time or optionally later. Consider O_SYNC when
1351 * Add program to test if fsync has a delay compared to non-fsync
1352 * Consider sorting writes during checkpoint
1354 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00541.php
1363 We could use a fixed row count and a +/- count to follow MVCC
1364 visibility rules, or a single cached value could be used and
1365 invalidated if anyone modifies the table. Another idea is to
1366 get a count directly from a unique index, but for this to be
1367 faster than a sequential scan it must avoid access to the heap
1368 to obtain tuple visibility information.
1370 * Provide a way to calculate an "estimated COUNT(*)"
1372 Perhaps by using the optimizer's cardinality estimates or random
1375 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00943.php
1377 * Allow data to be pulled directly from indexes
1379 Currently indexes do not have enough tuple visibility information
1380 to allow data to be pulled from the index without also accessing
1381 the heap. One way to allow this is to set a bit on index tuples
1382 to indicate if a tuple is currently visible to all transactions
1383 when the first valid heap lookup happens. This bit would have to
1384 be cleared when a heap tuple is expired.
1386 Another idea is to maintain a bitmap of heap pages where all rows
1387 are visible to all backends, and allow index lookups to reference
1388 that bitmap to avoid heap lookups, perhaps the same bitmap we might
1389 add someday to determine which heap pages need vacuuming. Frequently
1390 accessed bitmaps would have to be stored in shared memory. One 8k
1391 page of bitmaps could track 512MB of heap pages.
1393 A third idea would be for a heap scan to check if all rows are visible
1394 and if so set a per-table flag which can be checked by index scans.
1395 Any change to the table would have to clear the flag. To detect
1396 changes during the heap scan a counter could be set at the start and
1397 checked at the end --- if it is the same, the table has not been
1398 modified --- any table change would increment the counter.
1400 http://archives.postgresql.org/pgsql-patches/2007-10/msg00166.php
1401 http://archives.postgresql.org/pgsql-patches/2008-01/msg00049.php
1403 * Consider automatic caching of statements at various levels:
1406 o Query execute plan
1408 http://archives.postgresql.org/pgsql-hackers/2008-04/msg00823.php
1410 * Consider increasing internal areas when shared buffers is increased
1412 http://archives.postgresql.org/pgsql-hackers/2005-10/msg01419.php
1414 * Consider decreasing the amount of memory used by PrivateRefCount
1416 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00797.php
1417 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php
1419 * Consider allowing higher priority queries to have referenced buffer
1420 cache pages stay in memory longer
1422 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00562.php
1429 * Improve speed with indexes
1431 For large table adjustments during VACUUM FULL, it is faster to cluster
1432 or reindex rather than update the index. Also, index updates can bloat
1435 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00024.php
1436 http://archives.postgresql.org/pgsql-performance/2007-05/msg00296.php
1437 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00307.php
1439 * Auto-fill the free space map by scanning the buffer cache or by
1440 checking pages written by the background writer
1442 http://archives.postgresql.org/pgsql-hackers/2006-02/msg01125.php
1443 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00011.php
1445 * Create a bitmap of pages that need vacuuming
1447 Instead of sequentially scanning the entire table, have the background
1448 writer or some other process record pages that have expired rows, then
1449 VACUUM can look at just those pages rather than the entire table. In
1450 the event of a system crash, the bitmap would probably be invalidated.
1451 One complexity is that index entries still have to be vacuumed, and
1452 doing this without an index scan (by using the heap values to find the
1453 index entry) might be slow and unreliable, especially for user-defined
1456 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01188.php
1457 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00121.php
1458 http://archives.postgresql.org/pgsql-patches/2007-03/msg00508.php
1459 http://archives.postgresql.org/pgsql-patches/2007-04/msg00347.php
1460 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00156.php
1461 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00546.php
1462 http://archives.postgresql.org/pgsql-hackers/2008-04/msg00416.php
1464 * Allow FSM to return free space toward the beginning of the heap file,
1465 in hopes that empty pages at the end can be truncated by VACUUM
1466 * Allow FSM page return free space based on table clustering, to assist
1467 in maintaining clustering?
1468 * Improve dead row detection during multi-statement transactions usage
1470 http://archives.postgresql.org/pgsql-patches/2007-03/msg00358.php
1472 * Consider a more compact data representation for dead tuples
1474 http://archives.postgresql.org/pgsql-patches/2007-05/msg00143.php
1479 o %Issue log message to suggest VACUUM FULL if a table is nearly
1481 o Improve control of auto-vacuum
1483 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00876.php
1485 o Prevent long-lived temporary tables from causing frozen-xid
1486 advancement starvation
1488 The problem is that autovacuum cannot vacuum them to set frozen xids;
1489 only the session that created them can do that.
1490 http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php
1492 o Store per-table autovacuum settings in pg_class.reloptions.
1494 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01440.php
1495 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00724.php
1497 o Prevent autovacuum from running if an old transaction is still
1498 running from the last vacuum
1500 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00899.php
1507 * Fix priority ordering of read and write light-weight locks (Neil)
1509 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00893.php
1510 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00905.php
1512 * Fix problem when multiple subtransactions of the same outer transaction
1513 hold different types of locks, and one subtransaction aborts
1515 http://archives.postgresql.org/pgsql-hackers/2006-11/msg01011.php
1516 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00001.php
1517 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00435.php
1518 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00773.php
1520 * Allow UPDATEs on only non-referential integrity columns not to conflict
1521 with referential integrity locks
1523 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00073.php
1525 * Add idle_in_transaction_timeout GUC so locks are not held for long
1528 * Improve deadlock detection when a page cleaning lock conflicts
1529 with a shared buffer that is pinned
1531 http://archives.postgresql.org/pgsql-bugs/2008-01/msg00138.php
1532 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1533 http://archives.postgresql.org/pgsql-committers/2008-01/msg00365.php
1535 * Detect deadlocks involving LockBufferForCleanup()
1537 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1541 Startup Time Improvements
1542 =========================
1544 * Experiment with multi-threaded backend for backend creation
1546 This would prevent the overhead associated with process creation. Most
1547 operating systems have trivial process creation time compared to
1548 database startup overhead, but a few operating systems (Win32,
1549 Solaris) might benefit from threading. Also explore the idea of
1550 a single session using multiple threads to execute a statement faster.
1557 * Eliminate need to write full pages to WAL before page modification
1559 Currently, to protect against partial disk page writes, we write
1560 full page images to WAL before they are modified so we can correct any
1561 partial page writes during recovery. These pages can also be
1562 eliminated from point-in-time archive files.
1563 http://archives.postgresql.org/pgsql-hackers/2002-06/msg00655.php
1565 o When off, write CRC to WAL and check file system blocks
1568 If CRC check fails during recovery, remember the page in case
1569 a later CRC for that page properly matches.
1571 o Write full pages during file system write and not when
1572 the page is modified in the buffer cache
1574 This allows most full page writes to happen in the background
1575 writer. It might cause problems for applying WAL on recovery
1576 into a partially-written page, but later the full page will be
1579 * Allow WAL traffic to be streamed to another server for stand-by
1581 * Reduce WAL traffic so only modified values are written rather than
1584 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01589.php
1586 * Allow WAL information to recover corrupted pg_controldata
1588 http://archives.postgresql.org/pgsql-patches/2006-06/msg00025.php
1590 * Find a way to reduce rotational delay when repeatedly writing
1593 Currently fsync of WAL requires the disk platter to perform a full
1594 rotation to fsync again. One idea is to write the WAL to different
1595 offsets that might reduce the rotational delay.
1596 http://archives.postgresql.org/pgsql-hackers/2002-11/msg00483.php
1598 * Allow WAL logging to be turned off for a table, but the table
1599 might be dropped or truncated during crash recovery
1601 Allow tables to bypass WAL writes and just fsync() dirty pages on
1602 commit. This should be implemented using ALTER TABLE, e.g. ALTER
1603 TABLE PERSISTENCE [ DROP | TRUNCATE | DEFAULT ]. Tables using
1604 non-default logging should not use referential integrity with
1605 default-logging tables. A table without dirty buffers during a
1606 crash could perhaps avoid the drop/truncate.
1607 http://archives.postgresql.org/pgsql-hackers/2005-12/msg01016.php
1609 * Allow WAL logging to be turned off for a table, but the table would
1610 avoid being truncated/dropped
1612 To do this, only a single writer can modify the table, and writes
1613 must happen only on new pages so the new pages can be removed during
1614 crash recovery. Readers can continue accessing the table. Such
1615 tables probably cannot have indexes. One complexity is the handling
1616 of indexes on TOAST tables.
1617 http://archives.postgresql.org/pgsql-hackers/2005-12/msg01016.php
1619 * Speed WAL recovery by allowing more than one page to be prefetched
1621 This should be done utilizing the same infrastructure used for
1622 prefetching in general to avoid introducing complex error-prone code
1624 http://archives.postgresql.org/pgsql-general/2007-12/msg00683.php
1625 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00497.php
1626 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01279.php
1628 * Improve WAL concurrency by increasing lock granularity
1630 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00556.php
1632 * Be more aggressive about creating WAL files
1634 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01325.php
1635 http://archives.postgresql.org/pgsql-hackers/2004-07/msg01075.php
1636 http://archives.postgresql.org/pgsql-hackers/2005-04/msg00556.php
1638 * Have resource managers report the duration of their status changes
1640 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01468.php
1642 * Move pgfoundry's xlogdump to /contrib and have it rely more closely
1643 on the WAL backend code
1645 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00035.php
1650 Optimizer / Executor
1651 ====================
1653 * Improve selectivity functions for geometric operators
1654 * Precompile SQL functions to avoid overhead
1655 * Create utility to compute accurate random_page_cost value
1656 * Improve ability to display optimizer analysis using OPTIMIZER_DEBUG
1657 * Have EXPLAIN ANALYZE issue NOTICE messages when the estimated and
1658 actual row counts differ by a specified percentage
1659 * Improve how ANALYZE computes in-doubt tuples
1661 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php
1663 * Consider using hash buckets to do DISTINCT, rather than sorting
1665 This would be beneficial when there are few distinct values. This is
1666 already used by GROUP BY.
1668 * Log statements where the optimizer row estimates were dramatically
1669 different from the number of rows actually found?
1670 * Consider compressed annealing to search for query plans
1672 This might replace GEQO, http://sixdemonbag.org/Djinni.
1674 * Improve merge join performance by allowing mark/restore of
1677 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00096.php
1679 * Consider using a hash for joining to a large IN (VALUES ...) list
1681 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00450.php
1688 * Consider having the background writer update the transaction status
1689 hint bits before writing out the page
1691 Implementing this requires the background writer to have access to system
1692 catalogs and the transaction status log.
1694 * Consider adding buffers the background writer finds reusable to the
1697 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1699 * Automatically tune bgwriter_delay based on activity rather then using a
1702 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1704 * Consider wither increasing BM_MAX_USAGE_COUNT improves performance
1706 http://archives.postgresql.org/pgsql-hackers/2007-06/msg01007.php
1708 * Test to see if calling PreallocXlogFiles() from the background writer
1709 will help with WAL segment creation latency
1711 http://archives.postgresql.org/pgsql-patches/2007-06/msg00340.php
1715 Miscellaneous Performance
1716 =========================
1718 * Do async I/O for faster random read-ahead of data
1720 Async I/O allows multiple I/O requests to be sent to the disk with
1721 results coming back asynchronously.
1723 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00820.php
1724 http://archives.postgresql.org/pgsql-performance/2007-09/msg00255.php
1725 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00027.php
1726 http://archives.postgresql.org/pgsql-patches/2008-01/msg00170.php
1728 * Use mmap() rather than SYSV shared memory or to write WAL files?
1730 This would remove the requirement for SYSV SHM but would introduce
1731 portability issues. Anonymous mmap (or mmap to /dev/zero) is required
1732 to prevent I/O overhead.
1734 * Consider mmap()'ing files into a backend?
1736 Doing I/O to large tables would consume a lot of address space or
1737 require frequent mapping/unmapping. Extending the file also causes
1738 mapping problems that might require mapping only individual pages,
1739 leading to thousands of mappings. Another problem is that there is no
1740 way to _prevent_ I/O to disk from the dirty shared buffers so changes
1741 could hit disk before WAL is written.
1743 * Add a script to ask system configuration questions and tune postgresql.conf
1744 * Consider ways of storing rows more compactly on disk
1746 o Reduce the row header size?
1747 o Consider reducing on-disk varlena length from four bytes to
1748 two because a heap row cannot be more than 64k in length
1750 * Consider increasing NUM_CLOG_BUFFERS
1752 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00030.php
1753 http://archives.postgresql.org/pgsql-performance/2007-08/msg00024.php
1755 * Consider transaction start/end performance improvements
1757 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00948.php
1758 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1760 * Allow user configuration of TOAST thresholds
1762 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00213.php
1763 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00082.php
1765 * Allow configuration of backend priorities via the operating system
1767 Though backend priorities make priority inversion during lock
1768 waits possible, research shows that this is not a huge problem.
1770 http://archives.postgresql.org/pgsql-general/2007-02/msg00493.php
1772 * Experiment with multi-threaded backend better I/O utilization
1774 This would allow a single query to make use of multiple I/O channels
1775 simultaneously. One idea is to create a background reader that can
1776 pre-fetch sequential and index scan pages needed by other backends.
1777 This could be expanded to allow concurrent reads from multiple devices
1778 in a partitioned table.
1780 * Experiment with multi-threaded backend better CPU utilization
1782 This would allow several CPUs to be used for a single query, such as
1783 for sorting or query execution.
1785 * Consider increasing the minimum allowed number of shared buffers
1787 http://archives.postgresql.org/pgsql-bugs/2008-02/msg00157.php
1789 * Expire published xmin for read-only and idle transactions
1791 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00343.php
1793 * Consider if CommandCounterIncrement() can avoid its
1794 AcceptInvalidationMessages() call
1796 http://archives.postgresql.org/pgsql-committers/2007-11/msg00585.php
1798 * Improve performance of shared invalidation queue for multiple CPUs
1800 http://archives.postgresql.org/pgsql-performance/2008-01/msg00023.php
1802 * Consider Cartesian joins when both relations are needed to form an
1803 indexscan qualification for a third relation
1805 http://archives.postgresql.org/pgsql-performance/2007-12/msg00090.php
1807 * Consider not storing a NULL bitmap on disk if all the NULLs are
1810 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00624.php
1811 http://archives.postgresql.org/pgsql-patches/2007-12/msg00109.php
1813 * Sort large UPDATE/DELETEs so it is done in heap order
1815 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01119.php
1817 * -Avoid tuple some tuple copying in sort routines
1818 * SMP scalability improvements
1820 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php
1821 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00206.php
1822 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1824 * Research reducing deTOASTing in more places
1826 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00895.php
1828 * Consider being smarter about memory and external files used during
1831 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php
1832 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php
1834 * Allow one transaction to see tuples using the snapshot of another
1837 This would assist multiple backends in working together.
1838 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00400.php
1844 * Add use of 'const' for variables in source tree
1845 * Move some things from contrib into main tree
1846 * %Remove warnings created by -Wcast-align
1847 * Move platform-specific ps status display info from ps_status.c to ports
1848 * Add optional CRC checksum to heap and index pages
1849 * Improve documentation to build only interfaces (Marc)
1850 * Remove or relicense modules that are not under the BSD license, if possible
1851 * Acquire lock on a relation before building a relcache entry for it
1852 * Allow cross-compiling by generating the zic database on the target system
1853 * Improve NLS maintenance of libpgport messages linked onto applications
1854 * Clean up casting in contrib/isn
1856 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00245.php
1858 * Use UTF8 encoding for NLS messages so all server encodings can
1860 * Update Bonjour to work with newer cross-platform SDK
1862 http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php
1863 http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php
1865 * Consider detoasting keys before sorting
1866 * Consider GnuTLS if OpenSSL license becomes a problem
1868 http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php
1869 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php
1871 * Consider changing documentation format from SGML to XML
1873 http://archives.postgresql.org/pgsql-docs/2006-12/msg00152.php
1875 * Consider making NAMEDATALEN more configurable in future releases
1876 * Update our code to handle 64-bit timezone files to match the zic
1877 source code, which now uses them
1878 * Have configure choose integer datetimes by default
1880 http://archives.postgresql.org/pgsql-patches/2007-05/msg00046.php
1882 * Support scoped IPv6 addresses
1884 http://archives.postgresql.org/pgsql-bugs/2007-05/msg00111.php
1886 * Consider allowing 64-bit integers and floats to be passed by value on
1889 Also change 32-bit floats (float4) to be passed by value at the same
1892 * Research use of signals and sleep wake ups
1894 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00003.php
1896 * Add automated check for invalid C++ source code constructs
1898 http://archives.postgresql.org/pgsql-patches/2007-07/msg00056.php
1900 * Consider simplifying how memory context resets handle child contexts
1902 http://archives.postgresql.org/pgsql-patches/2007-08/msg00067.php
1904 * Remove use of MAKE_PTR and MAKE_OFFSET macros
1906 http://archives.postgresql.org/pgsql-general/2007-08/msg01510.php
1908 * Convert single quotes to apostrophes in the PDF documentation
1910 http://archives.postgresql.org/pgsql-docs/2007-12/msg00059.php
1912 * Create three versions of libpgport to simplify client code
1914 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00154.php
1916 * Remove old-style routines for manipulating tuples
1918 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00851.php
1920 * Improve detection of shared memory segments being used by other
1923 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00656.php
1925 * Implement the non-threaded Avahi service discovery protocol
1927 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00939.php
1928 http://archives.postgresql.org/pgsql-patches/2008-02/msg00097.php
1929 http://archives.postgresql.org/pgsql-hackers/2008-03/msg01211.php
1930 http://archives.postgresql.org/pgsql-patches/2008-04/msg00001.php
1934 o Remove configure.in check for link failure when cause is found
1935 o Remove readdir() errno patch when runtime/mingwex/dirent.c rev
1937 o Remove psql newline patch when we find out why mingw outputs an
1939 o Allow psql to use readline once non-US code pages work with
1941 o Fix problem with shared memory on the Win32 Terminal Server
1942 o Diagnose problem where shared memory can sometimes not be
1943 attached by postmaster children
1945 http://archives.postgresql.org/pgsql-general/2007-08/msg01377.php
1947 o Improve signal handling
1949 http://archives.postgresql.org/pgsql-patches/2005-06/msg00027.php
1951 o Convert MSVC build system to remove most batch files
1953 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00961.php
1955 o Prevent SSL from sending network packets to avoid interference
1956 with Win32 signal emulation
1958 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00455.php
1960 o Support pgxs when using MSVC
1962 o Fix MSVC NLS support, like for to_char()
1964 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00485.php
1965 http://archives.postgresql.org/pgsql-patches/2008-02/msg00038.php
1967 o Find a correct rint() substitute on Windows
1969 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00808.php
1973 * Wire Protocol Changes
1975 o Allow dynamic character set handling
1976 o Add decoded type, length, precision
1978 o Update clients to use data types, typmod, schema.table.column names
1979 of result sets using new statement protocol
1985 * Add pre-parsing phase that converts non-ISO syntax to supported
1988 This could allow SQL written for other databases to run without
1991 * Allow plug-in modules to emulate features from other databases
1992 * Add features of Oracle-style packages (Pavel)
1994 A package would be a schema with session-local variables,
1995 public/private functions, and initialization functions. It
1996 is also possible to implement these capabilities
1997 in any schema and not use a separate "packages"
2000 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00384.php
2002 * Consider allowing control of upper/lower case folding of unquoted
2005 http://archives.postgresql.org/pgsql-hackers/2004-04/msg00818.php
2006 http://archives.postgresql.org/pgsql-hackers/2006-10/msg01527.php
2007 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00849.php
2009 * Add autonomous transactions
2011 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.php
2015 Features We Do _Not_ Want
2016 =========================
2018 * All backends running as threads in a single process (not wanted)
2020 This eliminates the process protection we get from the current setup.
2021 Thread creation is usually the same overhead as process creation on
2022 modern systems, so it seems unwise to use a pure threaded model.
2024 * Optimizer hints (not wanted)
2026 Optimizer hints are used to work around problems in the optimizer. We
2027 would rather have the problems reported and fixed.
2029 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00506.php
2030 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00517.php
2031 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00663.php
2034 Because we support postfix operators, it isn't possible to make AS
2035 optional and continue to use bison.
2036 http://archives.postgresql.org/pgsql-hackers/2003-04/msg00436.php
2038 http://archives.postgresql.org/pgsql-sql/2006-08/msg00164.php
2040 * Embedded server (not wanted)
2042 While PostgreSQL clients runs fine in limited-resource environments, the
2043 server requires multiple processes and a stable pool of resources to
2044 run reliabily and efficiently. Stripping down the PostgreSQL server
2045 to run in the same process address space as the client application
2046 would add too much complexity and failure cases.