3 Current maintainer: Bruce Momjian (bruce@momjian.us)
4 Last updated: Fri May 9 21:40:03 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 8.4 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 log_min_messages to be specified on a per-module basis
38 This would allow administrators to see more detailed information from
39 specific sections of the backend, e.g. checkpoints, autovacuum, etc.
40 Another idea is to allow separate configuration files for each module,
41 or allow arbitrary SET commands to be passed to them.
43 * Simplify ability to create partitioned tables
45 This would allow creation of partitioned tables without requiring
46 creation of triggers or rules for INSERT/UPDATE/DELETE, and constraints
47 for rapid partition selection. Options could include range and hash
50 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00375.php
51 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00151.php
52 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00028.php
53 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00248.php
54 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00387.php
55 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00413.php
57 * Allow auto-selection of partitioned tables for min/max() operations
58 * Allow more complex user/database default GUC settings
60 Currently ALTER USER and ALTER DATABASE support per-user and
61 per-database defaults. Consider adding per-user-and-database
62 defaults so things like search_path can be defaulted for a
63 specific user connecting to a specific database.
65 * Allow custom variable classes that can restrict who can set the values
67 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00911.php
69 * Implement the SQL standard mechanism whereby REVOKE ROLE revokes only
70 the privilege granted by the invoking role, and not those granted
73 http://archives.postgresql.org/pgsql-bugs/2007-05/msg00010.php
75 * Allow SSL authentication/encryption over unix domain sockets
77 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00924.php
79 * Allow SSL key file permission checks to be optionally disabled when
80 sharing SSL keys with other applications
82 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00069.php
84 * Allow client certificate names to be checked against the client
87 This is already implemented in
88 libpq/fe-secure.c::verify_peer_name_matches_certificate() but the code
93 o Allow pg_hba.conf to specify host names along with IP addresses
95 Host name lookup could occur when the postmaster reads the
96 pg_hba.conf file, or when the backend starts. Another
97 solution would be to reverse lookup the connection IP and
98 check that hostname against the host names in pg_hba.conf.
99 We could also then check that the host name maps to the IP
102 o %Allow postgresql.conf file values to be changed via an SQL
103 API, perhaps using SET GLOBAL
104 o Allow the server to be stopped/restarted via an SQL API
105 o Issue a warning if a change-on-restart-only postgresql.conf value
106 is modified and the server config files are reloaded
107 o Consider normalizing fractions in postgresql.conf, perhaps
110 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00550.php
112 o Allow Kerberos to disable stripping of realms so we can
113 check the username@realm against multiple realms
115 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00009.php
120 o Allow a database in tablespace t1 with tables created in
121 tablespace t2 to be used as a template for a new database created
122 with default tablespace t2
124 Currently all objects in the default database tablespace must
125 have default tablespace specifications. This is because new
126 databases are created by copying directories. If you mix default
127 tablespace tables and tablespace-specified tables in the same
128 directory, creating a new database from such a mixed directory
129 would create a new database with tables that had incorrect
130 explicit tablespaces. To fix this would require modifying
131 pg_class in the newly copied database, which we don't currently
134 o Allow reporting of which objects are in which tablespaces
136 This item is difficult because a tablespace can contain objects
137 from multiple databases. There is a server-side function that
138 returns the databases which use a specific tablespace, so this
139 requires a tool that will call that function and connect to each
140 database to find the objects in each database for that tablespace.
142 o Allow WAL replay of CREATE TABLESPACE to work when the directory
143 structure on the recovery computer is different from the original
145 o Allow per-tablespace quotas
148 * Statistics Collector
150 o Allow statistics collector information to be pulled from the collector
151 process directly, rather than requiring the collector to write a
152 filesystem file twice a second?
153 o Reduce file system activity overhead of statistics file pgstat.stat
155 http://archives.postgresql.org/pgsql-general/2007-12/msg00106.php
157 o Allow statistics last vacuum/analyze execution times to be displayed
158 without requiring stats_row_level to be enabled
160 http://archives.postgresql.org/pgsql-docs/2007-04/msg00028.php
162 o Clear table counters on TRUNCATE
164 http://archives.postgresql.org/pgsql-hackers/2008-04/msg00169.php
167 * Point-In-Time Recovery (PITR)
169 o Allow a warm standby system to also allow read-only statements
171 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00050.php
173 o %Create dump tool for write-ahead logs for use in determining
174 transaction id for point-in-time recovery
176 This is useful for checking PITR recovery.
178 o Allow recovery.conf to support the same syntax as
179 postgresql.conf, including quoting
181 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00497.php
183 o Fix server restart problem when the server was shutdown during
186 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00800.php
188 o Recreate pg_xlog/archive_status/ if it doesn't exist after
189 restoring from a PITR backup
191 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00487.php
197 * Change NUMERIC to enforce the maximum precision
198 * Reduce storage space for small NUMERICs
200 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01331.php
201 http://archives.postgresql.org/pgsql-patches/2007-02/msg00505.php
202 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00715.php
204 * Fix data types where equality comparison isn't intuitive, e.g. box
205 * Add support for public SYNONYMs
207 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00519.php
209 * Fix CREATE CAST on DOMAINs
211 http://archives.postgresql.org/pgsql-hackers/2006-05/msg00072.php
212 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01681.php
214 * Allow domains to be cast
216 http://archives.postgresql.org/pgsql-hackers/2003-06/msg01206.php
217 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00289.php
219 * Add support for SQL-standard GENERATED/IDENTITY columns
221 http://archives.postgresql.org/pgsql-hackers/2006-07/msg00543.php
222 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00038.php
223 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00344.php
224 http://archives.postgresql.org/pgsql-patches/2007-05/msg00076.php
225 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00604.php
227 * Improve XML support
229 http://developer.postgresql.org/index.php/XML_Support
231 * Consider placing all sequences in a single table, or create a system
234 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
236 * Allow the UUID type to accept non-standard formats
238 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01214.php
240 * Consider a special data type for regular expressions
242 http://archives.postgresql.org/pgsql-hackers/2007-08/msg01067.php
244 * Reduce BIT data type overhead using short varlena headers
246 http://archives.postgresql.org/pgsql-general/2007-12/msg00273.php
248 * Allow xml arrays to be cast to other data types
250 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00981.php
251 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00231.php
252 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00471.php
254 * Simplify integer cross-data-type operators
256 http://archives.postgresql.org/pgsql-bugs/2008-01/msg00189.php
258 * Allow XML to accept more liberal DOCTYPE specifications
260 http://archives.postgresql.org/pgsql-general/2008-02/msg00347.php
262 * Allow adding/renaming/removing enumerated values to an existing
265 http://archives.postgresql.org/pgsql-hackers/2008-04/msg01718.php
269 o Allow infinite dates and intervals just like infinite timestamps
270 o Merge hardwired timezone names with the TZ database; allow either
271 kind everywhere a TZ name is currently taken
272 o Allow TIMESTAMP WITH TIME ZONE to store the original timezone
273 information, either zone name or offset from UTC
275 If the TIMESTAMP value is stored with a time zone name, interval
276 computations should adjust based on the time zone rules.
277 http://archives.postgresql.org/pgsql-hackers/2004-10/msg00705.php
279 o Fix SELECT '0.01 years'::interval, '0.01 months'::interval
280 o Add a GUC variable to allow output of interval values in ISO8601
282 o Have timestamp subtraction not call justify_hours()?
284 http://archives.postgresql.org/pgsql-sql/2006-10/msg00059.php
286 o Improve timestamptz subtraction to be DST-aware
288 Currently subtracting one date from another that crosses a
289 daylight savings time adjustment can return '1 day 1 hour', but
290 adding that back to the first date returns a time one hour in
291 the future. This is caused by the adjustment of '25 hours' to
292 '1 day 1 hour', and '1 day' is the same time the next day, even
293 if daylight savings adjustments are involved.
295 o Fix interval display to support values exceeding 2^31 hours
296 o Add overflow checking to timestamp and interval arithmetic
297 o Extend timezone code to allow 64-bit values so we can
298 represent years beyond 2038
300 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01363.php
302 o Use LC_TIME for localized weekday/month names, rather than
305 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00390.php
307 o Add ISO INTERVAL handling
309 http://archives.postgresql.org/pgsql-hackers/2006-01/msg00250.php
310 http://archives.postgresql.org/pgsql-bugs/2006-04/msg00248.php
312 o Support ISO INTERVAL syntax if units cannot be determined from
313 the string, and are supplied after the string
315 The SQL standard states that the units after the string
316 specify the units of the string, e.g. INTERVAL '2' MINUTE
317 should return '00:02:00'. The current behavior has the units
318 restrict the interval value to the specified unit or unit
319 range, INTERVAL '70' SECOND returns '00:00:10'.
321 For syntax that isn't uniquely ISO or PG syntax, like '1' or
322 '1:30', treat as ISO if there is a range specification clause,
323 and as PG if there no clause is present, e.g. interpret '1:30'
324 MINUTE TO SECOND as '1 minute 30 seconds', and interpret
325 '1:30' as '1 hour, 30 minutes'.
327 This makes common cases like SELECT INTERVAL '1' MONTH
328 SQL-standard results. The SQL standard supports a limited
329 number of unit combinations and doesn't support unit names in
330 the string. The PostgreSQL syntax is more flexible in the
331 range of units supported, e.g. PostgreSQL supports '1 year 1
332 hour', while the SQL standard does not.
334 o Add support for year-month syntax, INTERVAL '50-6' YEAR
336 o Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1
337 year' AS INTERVAL MONTH), and this should return '12 months'
338 o Round or truncate values to the requested precision, e.g.
339 INTERVAL '11 months' AS YEAR should return one or zero
340 o Support precision, CREATE TABLE foo (a INTERVAL MONTH(3))
345 o Delay resolution of array expression's data type so assignment
346 coercion can be performed on empty array expressions
347 o Add support for arrays of domains
349 http://archives.postgresql.org/pgsql-patches/2007-05/msg00114.php
351 o Allow single-byte header storage for array elements
356 o Improve vacuum of large objects, like contrib/vacuumlo?
357 o Add security checking for large objects
358 o Auto-delete large objects when referencing row is deleted
360 contrib/lo offers this functionality.
362 o Allow read/write into TOAST values like large objects
364 This requires the TOAST column to be stored EXTERNAL.
366 o Add API for 64-bit large object access
368 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00781.php
372 * Add locale-aware MONEY type, and support multiple currencies
374 http://archives.postgresql.org/pgsql-general/2005-08/msg01432.php
375 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01181.php
377 * MONEY dumps in a locale-specific format making it difficult to
378 restore to a system with a different locale
379 * Allow MONEY to be easily cast to/from other numeric data types
383 o Allow dictionaries to change the token that is passed on to
386 http://archives.postgresql.org/pgsql-patches/2007-11/msg00081.php
388 o Consider a function-based API for '@@' searches
390 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00511.php
392 o Improve text search error messages
394 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00966.php
395 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01146.php
397 o Consider changing error to warning for strings larger than one
400 http://archives.postgresql.org/pgsql-bugs/2008-02/msg00190.php
401 http://archives.postgresql.org/pgsql-patches/2008-03/msg00062.php
408 * Allow INET subnet tests using non-constants to be indexed
409 * Allow to_date() and to_timestamp() accept localized month names
410 * Fix to_date()-related functions to consistently issue errors
412 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00915.php
414 * Add missing parameter handling in to_char()
416 http://archives.postgresql.org/pgsql-hackers/2005-12/msg00948.php
418 * Allow substring/replace() to get/set bit values
419 * Allow to_char() on interval values to accumulate the highest unit
422 Some special format flag would be required to request such
423 accumulation. Such functionality could also be added to EXTRACT.
424 Prevent accumulation that crosses the month/day boundary because of
425 the uneven number of days in a month.
427 o to_char(INTERVAL '1 hour 5 minutes', 'MI') => 65
428 o to_char(INTERVAL '43 hours 20 minutes', 'MI' ) => 2600
429 o to_char(INTERVAL '43 hours 20 minutes', 'WK:DD:HR:MI') => 0:1:19:20
430 o to_char(INTERVAL '3 years 5 months','MM') => 41
432 * Implement inlining of set-returning functions defined in SQL
433 * Allow SQL-language functions to return results from RETURNING queries
435 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00665.php
437 * Allow SQL-language functions to reference parameters by parameter name
439 Currently SQL-language functions can only refer to dollar parameters,
442 * Add SPI_gettypmod() to return the typemod for a TupleDesc
443 * Enforce typmod for function inputs, function results and parameters for
444 spi_prepare'd statements called from PLs
446 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01403.php
448 * Allow holdable cursors in SPI
449 * Tighten function permission checks
451 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00568.php
453 * Fix IS OF so it matches the ISO specification, and add documentation
455 http://archives.postgresql.org/pgsql-patches/2003-08/msg00060.php
456 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00060.php
458 * Add missing operators for geometric data types
460 Some geometric types do not have the full suite of geometric operators,
463 * Implement Boyer-Moore searching in strpos()
465 http://archives.postgresql.org/pgsql-patches/2007-08/msg00012.php
467 * Prevent malicious functions from being executed with the permissions
468 of unsuspecting users
470 Index functions are safe, so VACUUM and ANALYZE are safe too.
471 Triggers, CHECK and DEFAULT expressions, and rules are still vulnerable.
472 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00268.php
474 * Reduce memory usage of aggregates in set returning functions
476 http://archives.postgresql.org/pgsql-performance/2008-01/msg00031.php
478 * Add temporal versions of generate_series()
480 http://archives.postgresql.org/pgsql-hackers/2007-04/msg01180.php
482 * Add array_accum() and array_to_set() functions for arrays
484 The standards specify array_agg() and UNNEST.
485 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00464.php
487 * Fix /contrib/ltree operator
489 http://archives.postgresql.org/pgsql-bugs/2007-11/msg00044.php
491 * Fix inconsistent precedence of =, >, and < compared to <>, >=, and <=
493 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00145.php
495 * Fix regular expression bug when using complex back-references
497 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00000.php
499 * Have /contrib/dblink reuse unnamed connections
501 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00895.php
503 * Add SQL-standard array_agg() and unnest() array functions
505 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01017.php
507 * Allow calling of a procedure outside a SELECT that can control the
510 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01375.php
514 Multi-Language Support
515 ======================
517 * Add NCHAR (as distinguished from ordinary varchar),
518 * Allow locale to be set at database creation
520 Currently locale can only be set during initdb. No global tables have
521 locale-aware columns. However, the database template used during
522 database creation might have locale-aware indexes. The indexes would
523 need to be reindexed to match the new locale.
525 * Allow encoding on a per-column basis optionally using the ICU library;
528 Right now only one encoding is allowed per database.
530 http://archives.postgresql.org/pgsql-hackers/2005-03/msg00932.php
531 http://archives.postgresql.org/pgsql-patches/2005-08/msg00039.php
532 http://archives.postgresql.org/pgsql-patches/2005-08/msg00309.php
533 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00110.php
534 http://archives.postgresql.org/pgsql-patches/2005-09/msg00020.php
535 http://archives.postgresql.org/pgsql-hackers/2005-12/msg01121.php
536 http://archives.postgresql.org/pgsql-hackers/2006-01/msg00767.php
537 http://archives.postgresql.org/pgsql-patches/2006-03/msg00233.php
538 http://archives.postgresql.org/pgsql-hackers/2006-09/msg00662.php
539 http://wiki.postgresql.org/wiki/Todo:Collate
540 http://wiki.postgresql.org/wiki/Todo:ICU
542 * Support multiple simultaneous character sets, per SQL92
543 * Improve UTF8 combined character handling?
544 * Add octet_length_server() and octet_length_client()
545 * Make octet_length_client() the same as octet_length()?
546 * Fix problems with wrong runtime encoding conversion for NLS message files
547 * Add URL to more complete multi-byte regression tests
549 http://archives.postgresql.org/pgsql-hackers/2005-07/msg00272.php
551 * Fix ILIKE and regular expressions to handle case insensitivity
552 properly in multibyte encodings
554 http://archives.postgresql.org/pgsql-bugs/2005-10/msg00001.php
555 http://archives.postgresql.org/pgsql-patches/2005-11/msg00173.php
557 * Set client encoding based on the client operating system encoding
559 Currently client_encoding is set in postgresql.conf, which
560 defaults to the server encoding.
561 http://archives.postgresql.org/pgsql-hackers/2006-08/msg01696.php
563 * Change memory allocation for multi-byte functions so memory is
564 allocated inside conversion functions
566 Currently we preallocate memory based on worst-case usage.
573 * Automatically create rules on views so they are updateable, per SQL99
575 We can only auto-create rules for simple views. For more complex
576 cases users will still have to write rules manually.
578 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00586.php
579 http://archives.postgresql.org/pgsql-patches/2006-08/msg00255.php
581 * Add the functionality for WITH CHECK OPTION clause of CREATE VIEW
582 * Allow VIEW/RULE recompilation when the underlying tables change
584 Another issue is whether underlying table changes should be reflected
585 in the view, e.g. should SELECT * show additional columns if they
586 are added after the view is created.
588 * Make it possible to use RETURNING together with conditional DO INSTEAD
589 rules, such as for partitioning setups
591 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00577.php
593 * Add the ability to automatically create materialized views
595 Right now materialized views require the user to create triggers on the
596 main table to keep the summary table current. SQL syntax should be able
597 to manager the triggers and summary table automatically. A more
598 sophisticated implementation would automatically retrieve from the
599 summary table when the main table is referenced, if possible.
606 * Add CORRESPONDING BY to UNION/INTERSECT/EXCEPT
607 * Add ROLLUP, CUBE, GROUPING SETS options to GROUP BY
608 * %Allow SET CONSTRAINTS to be qualified by schema/table name
609 * %Add a separate TRUNCATE permission
611 Currently only the owner can TRUNCATE a table because triggers are not
612 called, and the table is locked in exclusive mode.
614 * Allow PREPARE of cursors
615 * Allow finer control over the caching of prepared query plans
617 Currently queries prepared via the libpq API are planned on first
618 execute using the supplied parameters --- allow SQL PREPARE to do the
619 same. Also, allow control over replanning prepared queries either
620 manually or automatically when statistics for execute parameters
621 differ dramatically from those used during planning.
623 * Improve logging of prepared transactions recovered during startup
625 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00092.php
627 * Improve failure message when DROP DATABASE is used on a database that
628 has prepared transactions
629 * Allow prepared transactions with temporary tables created and dropped
630 in the same transaction, and when an ON COMMIT DELETE ROWS temporary
633 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00047.php
635 * Add a GUC variable to warn about non-standard SQL usage in queries
636 * Add SQL-standard MERGE/REPLACE/UPSERT command
638 MERGE is typically used to merge two tables. REPLACE or UPSERT
639 command does UPDATE, or on failure, INSERT. This is similar to UPDATE,
640 then for unmatched rows, INSERT. Whether concurrent access allows
641 modifications which could cause row loss is implementation independent.
642 To implement this cleanly requires that the table have a unique index
643 so duplicate checking can be easily performed. It is possible to do it
644 without a unique index if we require the user to LOCK the table before
647 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00501.php
648 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00536.php
649 http://archives.postgresql.org/pgsql-hackers/2008-04/msg01475.php
651 * Add NOVICE output level for helpful messages like automatic sequence/index
653 * Add GUC to issue notice about statements that use unjoined tables
654 * Allow EXPLAIN to identify tables that were skipped because of
656 * Allow EXPLAIN output to be more easily processed by scripts, perhaps XML
657 * Enable standard_conforming_strings
658 * Make standard_conforming_strings the default in 8.5?
660 When this is done, backslash-quote should be prohibited in non-E''
661 strings because of possible confusion over how such strings treat
662 backslashes. Basically, '' is always safe for a literal single
663 quote, while \' might or might not be based on the backslash
666 * Simplify dropping roles that have objects in several databases
667 * Allow COMMENT ON to accept an expression rather than just a string
668 * Allow the count returned by SELECT, etc to be represented as an int64
669 to allow a higher range of values
670 * Add SQL99 WITH clause to SELECT
671 * Add SQL:2003 WITH RECURSIVE (hierarchical) queries to SELECT
673 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01375.php
674 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00642.php
675 http://archives.postgresql.org/pgsql-patches/2007-03/msg00139.php
676 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01334.php
677 http://archives.postgresql.org/pgsql-patches/2008-01/msg00105.php
678 http://archives.postgresql.org/pgsql-patches/2008-03/msg00327.php
680 * Add DEFAULT .. AS OWNER so permission checks are done as the table
683 This would be useful for SERIAL nextval() calls and CHECK constraints.
685 * Allow DISTINCT to work in multiple-argument aggregate calls
686 * Add column to pg_stat_activity that shows the progress of long-running
687 commands like CREATE INDEX and VACUUM
689 http://archives.postgresql.org/pgsql-patches/2008-04/msg00203.php
691 * Implement SQL:2003 window functions
692 * Allow INSERT/UPDATE ... RETURNING inside a SELECT 'FROM' clause
694 http://archives.postgresql.org/pgsql-general/2006-09/msg00803.php
695 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00693.php
697 * Increase locking when DROPing objects so dependent objects cannot
698 get dropped while the DROP operation is happening
700 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00937.php
702 * -Allow AS in "SELECT col AS label" to be optional in certain cases
704 * Allow INSERT ... DELETE ... RETURNING, namely allow the DELETE ...
705 RETURNING to supply values to the INSERT
706 http://archives.postgresql.org/pgsql-hackers/2008-02/thrd2.php#00979
708 * Add comments on system tables/columns using the information in
711 Ideally the information would be pulled from the SGML file
714 * Improve reporting of UNION type mismatches
716 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00944.php
717 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00597.php
722 o Allow CREATE TABLE AS to determine column lengths for complex
723 expressions like SELECT col1 || col2
725 o Have WITH CONSTRAINTS also create constraint indexes
727 http://archives.postgresql.org/pgsql-patches/2007-04/msg00149.php
729 o Have CONSTRAINT cname NOT NULL record the contraint name
731 Right now pg_attribute.attnotnull records the NOT NULL status
732 of the column, but does not record the contraint name
734 o Prevent concurrent CREATE TABLE table1 from sometimes returning
735 a cryptic error message
737 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00169.php
739 o Add CREATE SCHEMA ... LIKE that copies a schema
744 o Allow UPDATE tab SET ROW (col, ...) = (SELECT...)
746 http://archives.postgresql.org/pgsql-hackers/2006-07/msg01306.php
747 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00865.php
748 http://archives.postgresql.org/pgsql-patches/2007-04/msg00315.php
749 http://archives.postgresql.org/pgsql-patches/2008-03/msg00237.php
751 o Research self-referential UPDATEs that see inconsistent row versions
752 in read-committed mode
754 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00507.php
755 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00016.php
757 o Allow GLOBAL temporary tables to exist as empty by default in
760 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00006.php
765 o Have ALTER TABLE RENAME rename SERIAL sequence names
767 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
769 o Have ALTER SEQUENCE RENAME rename the sequence name stored
770 in the sequence table
772 http://archives.postgresql.org/pgsql-bugs/2007-09/msg00092.php
773 http://archives.postgresql.org/pgsql-bugs/2007-10/msg00007.php
774 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php
776 o Add ALTER DOMAIN to modify the underlying data type
777 o %Allow ALTER TABLE ... ALTER CONSTRAINT ... RENAME
779 http://archives.postgresql.org/pgsql-patches/2006-02/msg00168.php
781 o %Allow ALTER TABLE to change constraint deferrability and actions
782 o Add missing object types for ALTER ... SET SCHEMA
783 o Allow ALTER TABLESPACE to move to different directories
784 o Allow databases to be moved to different tablespaces
785 o Allow moving system tables to other tablespaces, where possible
787 Currently non-global system tables must be in the default database
788 tablespace. Global system tables can never be moved.
790 o -Prevent parent tables from altering or dropping constraints
791 like CHECK that are inherited by child tables unless CASCADE
793 o -Prevent child tables from altering or dropping constraints
794 like CHECK that were inherited from the parent table
795 o Have ALTER INDEX update the name of a constraint using that index
796 o Add ALTER TABLE RENAME CONSTRAINT, update index name also
797 o Allow column display reordering by recording a display,
798 storage, and permanent id for every column?
800 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00782.php
806 o Automatically maintain clustering on a table
808 This might require some background daemon to maintain clustering
809 during periods of low usage. It might also require tables to be only
810 partially filled for easier reorganization. Another idea would
811 be to create a merged heap/index data file so an index lookup would
812 automatically access the heap data too. A third idea would be to
813 store heap rows in hashed groups, perhaps using a user-supplied
815 http://archives.postgresql.org/pgsql-performance/2004-08/msg00349.php
817 o %Add default clustering to system tables
819 To do this, determine the ideal cluster index for each system
820 table and set the cluster setting during initdb.
822 o %Add VERBOSE option to report tables as they are processed,
828 o Allow COPY to report error lines and continue
830 This requires the use of a savepoint before each COPY line is
831 processed, with ROLLBACK on COPY failure.
832 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00572.php
834 o Allow COPY on a newly-created table to skip WAL logging
836 On crash recovery, the table involved in the COPY would
837 be removed or have its heap and index files truncated. One
838 issue is that no other backend should be able to add to
839 the table at the same time, which is something that is
840 currently allowed. This currently is done if the table is
841 created inside the same transaction block as the COPY because
842 no other backends can see the table.
844 o Consider using a ring buffer for COPY FROM
846 http://archives.postgresql.org/pgsql-patches/2008-02/msg00140.php
847 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01080.php
849 o Allow COPY FROM to create index entries in bulk
851 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00811.php
853 o Allow COPY in CSV mode to control whether a quoted zero-length
854 string is treated as NULL
856 Currently this is always treated as a zero-length string,
857 which generates an error when loading into an integer column
858 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00905.php
860 o Impove COPY performance
862 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00954.php
868 o Allow column-level privileges
869 o %Allow GRANT/REVOKE permissions to be applied to all schema objects
872 The proposed syntax is:
873 GRANT SELECT ON ALL TABLES IN public TO phpuser;
874 GRANT SELECT ON NEW TABLES IN public TO phpuser;
876 o Allow GRANT/REVOKE permissions to be inherited by objects based on
879 o Allow SERIAL sequences to inherit permissions from the base table?
884 o Prevent DROP TABLE from dropping a row referenced by its own open
890 o Allow INSERT/UPDATE of the system-generated oid value for a row
891 o In rules, allow VALUES() to contain a mixture of 'old' and 'new'
897 o Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM
903 o Allow LISTEN/NOTIFY to store info in memory rather than tables?
905 Currently LISTEN/NOTIFY information is stored in pg_listener.
906 Storing such information in memory would improve performance.
908 o Add optional textual message to NOTIFY
910 This would allow an informational message to be added to the notify
911 message, perhaps indicating the row modified or other custom
914 o Allow multiple identical NOTIFY events to always be communicated
915 to the client, rather than sent as a single notification to the
918 http://archives.postgresql.org/pgsql-general/2008-01/msg00057.php
920 o Allow NOTIFY in rules involving conditionals
921 o Improve LISTEN concurrency
923 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01106.php
927 Referential Integrity
928 =====================
930 * Add MATCH PARTIAL referential integrity
931 * Change foreign key constraint for array -> element to mean element
933 * Fix problem when cascading referential triggers make changes on
934 cascaded tables, seeing the tables in an intermediate state
936 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
937 http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php
939 * Allow DEFERRABLE and end-of-statement UNIQUE constraints?
941 This would allow UPDATE tab SET col = col + 1 to work if col has
942 a unique index. Currently, uniqueness checks are done while the
943 command is being executed, rather than at the end of the statement
945 http://people.planetpostgresql.org/greg/index.php?/archives/2006/06/10.html
946 http://archives.postgresql.org/pgsql-hackers/2006-09/msg01458.php
948 * Optimize referential integrity checks
950 http://archives.postgresql.org/pgsql-performance/2005-10/msg00458.php
951 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00744.php
954 Server-Side Languages
955 =====================
958 o Fix RENAME to work on variables other than OLD/NEW
960 http://archives.postgresql.org/pgsql-hackers/2002-03/msg00591.php
961 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01615.php
962 http://archives.postgresql.org/pgsql-hackers/2007-01/msg01587.php
964 o Allow function parameters to be passed by name,
965 get_employee_salary(12345 AS emp_id, 2001 AS tax_year)
966 o Allow handling of %TYPE arrays, e.g. tab.col%TYPE[]
967 o Allow listing of record column names, and access to
968 record columns via variables, e.g. columns := r.(*),
971 http://archives.postgresql.org/pgsql-patches/2005-07/msg00458.php
972 http://archives.postgresql.org/pgsql-patches/2006-05/msg00302.php
973 http://archives.postgresql.org/pgsql-patches/2006-06/msg00031.php
975 o Add support for SCROLL cursors
976 o Add support for WITH HOLD cursors
977 o Allow row and record variables to be set to NULL constants,
978 and allow NULL tests on such variables
980 Because a row is not scalar, do not allow assignment
981 from NULL-valued scalars.
983 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00070.php
985 o Review handling of MOVE and FETCH
987 http://archives.postgresql.org/pgsql-patches/2007-04/msg00527.php
989 o Improve logic of determining if an identifier is a a
990 variable or column name
992 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00436.php
994 o Consider keeping seperate cached copies when search_path changes
996 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01009.php
998 o Add CASE capability to language (already in SQL)
1000 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00696.php
1006 o Add table function support to pltcl, plpythonu
1007 o Add support for polymorphic arguments and return types to
1008 languages other than PL/PgSQL
1009 o Add capability to create and call PROCEDURES
1010 o Add support for OUT and INOUT parameters to languages other
1012 o Add PL/PythonU tracebacks
1014 http://archives.postgresql.org/pgsql-patches/2006-02/msg00288.php
1016 o Allow data to be passed in native language formats, rather
1019 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00289.php
1021 o Add ability to obfuscate function bodies
1023 http://archives.postgresql.org/pgsql-patches/2008-01/msg00125.php
1030 * Have pg_ctl look at PGHOST in case it is a socket directory?
1031 * Allow pg_ctl to work properly with configuration files located outside
1032 the PGDATA directory
1034 pg_ctl can not read the pid file because it isn't located in the
1035 config directory but in the PGDATA directory. The solution is to
1036 allow pg_ctl to read and understand postgresql.conf to find the
1037 data_directory value.
1039 * Add a function like pg_get_indexdef() that report more detailed index
1042 http://archives.postgresql.org/pgsql-bugs/2007-12/msg00166.php
1045 o Have psql show current values for a sequence
1046 o Move psql backslash database information into the backend, use
1049 This would allow non-psql clients to pull the same information out
1050 of the database as psql.
1051 http://archives.postgresql.org/pgsql-hackers/2004-01/msg00191.php
1053 o Make psql's \d commands more consistent
1055 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1056 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php
1058 o Consistently display privilege information for all objects in psql
1059 o Add auto-expanded mode so expanded output is used if the row
1060 length is wider than the screen width.
1062 Consider using auto-expanded mode for backslash commands like \df+.
1064 o Prevent tab completion of SET TRANSACTION from querying the
1065 database and therefore preventing the transaction isolation
1066 level from being set.
1068 Currently SET <tab> causes a database lookup to check all
1069 supported session variables. This query causes problems
1070 because setting the transaction isolation level must be the
1071 first statement of a transaction.
1073 o Add a \set variable to control whether \s displays line numbers
1075 Another option is to add \# which lists line numbers, and
1076 allows command execution.
1078 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00255.php
1080 o Prevent escape string warnings when object names have
1083 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00227.php
1085 o Have \d show foreign keys that reference a table's primary key
1087 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00424.php
1089 o Have \d show child tables that inherit from the specified parent
1090 o Have \l+ show database size, if permissions allow
1092 Ideally it will not generate an error for invalid permissions
1094 o Include the symbolic SQLSTATE name in verbose error reports
1096 http://archives.postgresql.org/pgsql-general/2007-09/msg00438.php
1098 o -Improve display of enums to show valid enum values
1099 o Add prompt escape to display the client and server versions
1102 * pg_dump / pg_restore
1103 o %Add dumping of comments on index columns and composite type columns
1104 o %Add full object name to the tag field. eg. for operators we need
1105 '=(integer, integer)', instead of just '='.
1106 o Add pg_dumpall custom format dumps?
1107 o Allow selection of individual object(s) of all types, not just
1109 o In a selective dump, allow dumping of an object and all its
1111 o Add options like pg_restore -l and -L to pg_dump
1112 o Stop dumping CASCADE on DROP TYPE commands in clean mode
1113 o Allow pg_dump --clean to drop roles that own objects or have
1115 o Change pg_dump so that a comment on the dumped database is
1116 applied to the loaded database, even if the database has a
1117 different name. This will require new backend syntax, perhaps
1118 COMMENT ON CURRENT DATABASE.
1119 o Remove unnecessary function pointer abstractions in pg_dump source
1121 o Allow pg_dump to utilize multiple CPUs and I/O channels by dumping
1122 multiple objects simultaneously
1124 The difficulty with this is getting multiple dump processes to
1125 produce a single dump output file. It also would require
1126 several sessions to share the same snapshot.
1127 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1129 o Allow pg_restore to utilize multiple CPUs and I/O channels by
1130 restoring multiple objects simultaneously
1132 This might require a pg_restore flag to indicate how many
1133 simultaneous operations should be performed. Only pg_dump's
1134 -Fc format has the necessary dependency information.
1135 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00963.php
1137 o To better utilize resources, allow pg_restore to check foreign
1138 keys simultaneously, where possible
1139 o Allow pg_restore to create all indexes of a table
1140 concurrently, via a single heap scan
1142 This requires a pg_dump -Fc file because that format contains
1143 the required dependency information.
1144 http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php
1146 o Allow pg_restore to load different parts of the COPY data
1148 o Prevent pg_dump/pg_restore from being affected by
1151 Using psql to restore a pg_dump dump is also affected.
1153 o Remove pre-7.3 pg_dump code that assumes pg_depend does not exit
1154 o Allow pre/data/post files when schema and data are dumped
1155 separately, for performance reasons
1157 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
1164 Document differences between ecpg and the SQL standard and
1165 information about the Informix-compatibility module.
1167 o Solve cardinality > 1 for input descriptors / variables?
1168 o Add a semantic check level, e.g. check if a table really exists
1169 o fix handling of DB attributes that are arrays
1170 o Use backend PREPARE/EXECUTE facility for ecpg where possible
1172 o Fix nested C comments
1173 o %sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified
1174 o Make SET CONNECTION thread-aware, non-standard?
1175 o Allow multidimensional arrays
1176 o Add internationalized message strings
1177 o Implement COPY FROM STDIN
1181 o Add PQescapeIdentifierConn()
1182 o Prevent PQfnumber() from lowercasing unquoted the column name
1184 PQfnumber() should never have been doing lowercasing, but
1185 historically it has so we need a way to prevent it
1187 o Allow statement results to be automatically batched to the client
1189 Currently all statement results are transferred to the libpq
1190 client before libpq makes the results available to the
1191 application. This feature would allow the application to make
1192 use of the first result rows while the rest are transferred, or
1193 held on the server waiting for them to be requested by libpq.
1194 One complexity is that a statement like SELECT 1/col could error
1195 out mid-way through the result set.
1197 o Consider disallowing multiple queries in PQexec() as an
1198 additional barrier to SQL injection attacks
1200 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00184.php
1202 o Add PQexecf() that allows complex parameter substitution
1204 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01803.php
1206 o Add SQLSTATE severity to PGconn return status
1208 http://archives.postgresql.org/pgsql-interfaces/2007-11/msg00015.php
1214 * Add deferred trigger queue file
1216 Right now all deferred trigger information is stored in backend
1217 memory. This could exhaust memory for very large trigger queues.
1218 This item involves dumping large queues into files.
1220 * Allow triggers to be disabled in only the current session.
1222 This is currently possible by starting a multi-statement transaction,
1223 modifying the system tables, performing the desired SQL, restoring the
1224 system tables, and committing the transaction. ALTER TABLE ...
1225 TRIGGER requires a table lock so it is not ideal for this usage.
1227 * With disabled triggers, allow pg_dump to use ALTER TABLE ADD FOREIGN KEY
1229 If the dump is known to be valid, allow foreign keys to be added
1230 without revalidating the data.
1232 * Allow statement-level triggers to access modified rows
1233 * Support triggers on columns
1235 http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php
1237 * Allow AFTER triggers on system tables
1239 System tables are modified in many places in the backend without going
1240 through the executor and therefore not causing triggers to fire. To
1241 complete this item, the functions that modify system tables will have
1244 * Tighten trigger permission checks
1246 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00564.php
1248 * Allow BEFORE INSERT triggers on views
1250 http://archives.postgresql.org/pgsql-general/2007-02/msg01466.php
1252 * -Add ability to trigger on TRUNCATE
1253 * Add database and transaction-level triggers
1255 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00451.php
1262 * Add UNIQUE capability to non-btree indexes
1263 * Prevent index uniqueness checks when UPDATE does not modify the column
1265 Uniqueness (index) checks are done when updating a column even if the
1266 column is not modified by the UPDATE.
1268 * Allow the creation of on-disk bitmap indexes which can be quickly
1269 combined with other bitmap indexes
1271 Such indexes could be more compact if there are only a few distinct values.
1272 Such indexes can also be compressed. Keeping such indexes updated can be
1275 http://archives.postgresql.org/pgsql-patches/2005-07/msg00512.php
1276 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01107.php
1277 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00265.php
1278 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01214.php
1279 http://archives.postgresql.org/pgsql-patches/2007-05/msg00013.php
1280 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00741.php
1282 * Allow accurate statistics to be collected on indexes with more than
1283 one column or expression indexes, perhaps using per-index statistics
1285 http://archives.postgresql.org/pgsql-performance/2006-10/msg00222.php
1286 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01131.php
1288 * Consider increasing the default and maximum number of statistics targets,
1289 and reduce statistics target overhead
1291 Also consider having a larger statistics target for indexed columns
1292 and expression indexes.
1293 http://archives.postgresql.org/pgsql-general/2007-05/msg01228.php
1294 http://archives.postgresql.org/pgsql-general/2007-06/msg00542.php
1295 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01066.php
1296 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00188.php
1298 * Consider smaller indexes that record a range of values per heap page,
1299 rather than having one index entry for every heap row
1301 This is useful if the heap is clustered by the indexed values.
1302 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00341.php
1303 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01264.php
1304 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00465.php
1305 http://archives.postgresql.org/pgsql-patches/2007-03/msg00163.php
1306 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00014.php
1307 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00487.php
1308 http://archives.postgresql.org/pgsql-hackers/2008-04/msg01589.php
1310 * Add REINDEX CONCURRENTLY, like CREATE INDEX CONCURRENTLY
1312 This is difficult because you must upgrade to an exclusive table lock
1313 to replace the existing index file. CREATE INDEX CONCURRENTLY does not
1314 have this complication. This would allow index compaction without
1316 http://archives.postgresql.org/pgsql-performance/2007-08/msg00289.php
1318 * Allow multiple indexes to be created concurrently, ideally via a
1319 single heap scan, and have pg_restore use it
1321 * Consider sorting entries before inserting into btree index
1323 http://archives.postgresql.org/pgsql-general/2008-01/msg01010.php
1325 * Allow index scans to return matching index keys, not just the matching
1328 http://archives.postgresql.org/pgsql-hackers/2008-04/msg01657.php
1334 o Allow inherited tables to inherit indexes, UNIQUE constraints,
1335 and primary/foreign keys
1336 o Honor UNIQUE INDEX on base column in INSERTs/UPDATEs
1337 on inherited table, e.g. INSERT INTO inherit_table
1338 (unique_index_col) VALUES (dup) should fail
1340 The main difficulty with this item is the problem of
1341 creating an index that can span multiple tables.
1343 o Allow SELECT ... FOR UPDATE on inherited tables
1344 o Require all CHECK constraints to be inherited
1346 http://archives.postgresql.org/pgsql-bugs/2007-04/msg00026.php
1348 o Add checks to prevent a CREATE RULE views on inherited tables
1350 http://archives.postgresql.org/pgsql-general/2008-02/msg01420.php
1351 http://archives.postgresql.org/pgsql-general/2008-03/msg00077.php
1356 o Add more GIST index support for geometric data types
1357 o Allow GIST indexes to create certain complex index types, like
1358 digital trees (see Aoki)
1363 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00051.php
1365 o Pack hash index buckets onto disk pages more efficiently
1367 Currently only one hash bucket can be stored on a page. Ideally
1368 several hash buckets could be stored on a single page and greater
1369 granularity used for the hash algorithm.
1371 http://archives.postgresql.org/pgsql-hackers/2004-06/msg00168.php
1373 o Consider sorting hash buckets so entries can be found using a
1374 binary search, rather than a linear scan
1375 o In hash indexes, consider storing the hash value with or instead
1377 o Add WAL logging for crash recovery
1378 o Allow multi-column hash indexes
1379 o -During index creation, pre-sort the tuples to improve build speed
1386 * Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
1388 Ideally this requires a separate test program that can be run
1389 at initdb time or optionally later. Consider O_SYNC when
1392 * Add program to test if fsync has a delay compared to non-fsync
1393 * Consider sorting writes during checkpoint
1395 http://archives.postgresql.org/pgsql-hackers/2007-06/msg00541.php
1404 We could use a fixed row count and a +/- count to follow MVCC
1405 visibility rules, or a single cached value could be used and
1406 invalidated if anyone modifies the table. Another idea is to
1407 get a count directly from a unique index, but for this to be
1408 faster than a sequential scan it must avoid access to the heap
1409 to obtain tuple visibility information.
1411 * Provide a way to calculate an "estimated COUNT(*)"
1413 Perhaps by using the optimizer's cardinality estimates or random
1416 http://archives.postgresql.org/pgsql-hackers/2005-11/msg00943.php
1418 * Allow data to be pulled directly from indexes
1420 Currently indexes do not have enough tuple visibility information
1421 to allow data to be pulled from the index without also accessing
1422 the heap. One way to allow this is to set a bit on index tuples
1423 to indicate if a tuple is currently visible to all transactions
1424 when the first valid heap lookup happens. This bit would have to
1425 be cleared when a heap tuple is expired.
1427 Another idea is to maintain a bitmap of heap pages where all rows
1428 are visible to all backends, and allow index lookups to reference
1429 that bitmap to avoid heap lookups, perhaps the same bitmap we might
1430 add someday to determine which heap pages need vacuuming. Frequently
1431 accessed bitmaps would have to be stored in shared memory. One 8k
1432 page of bitmaps could track 512MB of heap pages.
1434 A third idea would be for a heap scan to check if all rows are visible
1435 and if so set a per-table flag which can be checked by index scans.
1436 Any change to the table would have to clear the flag. To detect
1437 changes during the heap scan a counter could be set at the start and
1438 checked at the end --- if it is the same, the table has not been
1439 modified --- any table change would increment the counter.
1441 http://archives.postgresql.org/pgsql-patches/2007-10/msg00166.php
1442 http://archives.postgresql.org/pgsql-patches/2008-01/msg00049.php
1444 * Consider automatic caching of statements at various levels:
1447 o Query execute plan
1449 http://archives.postgresql.org/pgsql-hackers/2008-04/msg00823.php
1451 * Consider increasing internal areas when shared buffers is increased
1453 http://archives.postgresql.org/pgsql-hackers/2005-10/msg01419.php
1455 * Consider decreasing the amount of memory used by PrivateRefCount
1457 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00797.php
1458 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php
1460 * Consider allowing higher priority queries to have referenced buffer
1461 cache pages stay in memory longer
1463 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00562.php
1470 * Improve speed with indexes
1472 For large table adjustments during VACUUM FULL, it is faster to cluster
1473 or reindex rather than update the index. Also, index updates can bloat
1476 http://archives.postgresql.org/pgsql-hackers/2007-03/msg00024.php
1477 http://archives.postgresql.org/pgsql-performance/2007-05/msg00296.php
1478 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00307.php
1480 * Auto-fill the free space map by scanning the buffer cache or by
1481 checking pages written by the background writer
1483 http://archives.postgresql.org/pgsql-hackers/2006-02/msg01125.php
1484 http://archives.postgresql.org/pgsql-hackers/2006-03/msg00011.php
1486 * Create a bitmap of pages that need vacuuming
1488 Instead of sequentially scanning the entire table, have the background
1489 writer or some other process record pages that have expired rows, then
1490 VACUUM can look at just those pages rather than the entire table. In
1491 the event of a system crash, the bitmap would probably be invalidated.
1492 One complexity is that index entries still have to be vacuumed, and
1493 doing this without an index scan (by using the heap values to find the
1494 index entry) might be slow and unreliable, especially for user-defined
1497 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01188.php
1498 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00121.php
1499 http://archives.postgresql.org/pgsql-patches/2007-03/msg00508.php
1500 http://archives.postgresql.org/pgsql-patches/2007-04/msg00347.php
1501 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00156.php
1502 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00546.php
1503 http://archives.postgresql.org/pgsql-hackers/2008-04/msg00416.php
1505 * Allow FSM to return free space toward the beginning of the heap file,
1506 in hopes that empty pages at the end can be truncated by VACUUM
1507 * Allow FSM page return free space based on table clustering, to assist
1508 in maintaining clustering?
1509 * Improve dead row detection during multi-statement transactions usage
1511 http://archives.postgresql.org/pgsql-patches/2007-03/msg00358.php
1513 * Consider a more compact data representation for dead tuples
1515 http://archives.postgresql.org/pgsql-patches/2007-05/msg00143.php
1520 o %Issue log message to suggest VACUUM FULL if a table is nearly
1522 o Improve control of auto-vacuum
1524 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00876.php
1526 o Prevent long-lived temporary tables from causing frozen-xid
1527 advancement starvation
1529 The problem is that autovacuum cannot vacuum them to set frozen xids;
1530 only the session that created them can do that.
1531 http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php
1533 o Store per-table autovacuum settings in pg_class.reloptions.
1535 http://archives.postgresql.org/pgsql-hackers/2007-02/msg01440.php
1536 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00724.php
1538 o Prevent autovacuum from running if an old transaction is still
1539 running from the last vacuum
1541 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00899.php
1548 * Fix priority ordering of read and write light-weight locks (Neil)
1550 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00893.php
1551 http://archives.postgresql.org/pgsql-hackers/2004-11/msg00905.php
1553 * Fix problem when multiple subtransactions of the same outer transaction
1554 hold different types of locks, and one subtransaction aborts
1556 http://archives.postgresql.org/pgsql-hackers/2006-11/msg01011.php
1557 http://archives.postgresql.org/pgsql-hackers/2006-12/msg00001.php
1558 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00435.php
1559 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00773.php
1561 * Allow UPDATEs on only non-referential integrity columns not to conflict
1562 with referential integrity locks
1564 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00073.php
1566 * Add idle_in_transaction_timeout GUC so locks are not held for long
1569 * Improve deadlock detection when a page cleaning lock conflicts
1570 with a shared buffer that is pinned
1572 http://archives.postgresql.org/pgsql-bugs/2008-01/msg00138.php
1573 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1574 http://archives.postgresql.org/pgsql-committers/2008-01/msg00365.php
1576 * Detect deadlocks involving LockBufferForCleanup()
1578 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
1582 Startup Time Improvements
1583 =========================
1585 * Experiment with multi-threaded backend for backend creation
1587 This would prevent the overhead associated with process creation. Most
1588 operating systems have trivial process creation time compared to
1589 database startup overhead, but a few operating systems (Win32,
1590 Solaris) might benefit from threading. Also explore the idea of
1591 a single session using multiple threads to execute a statement faster.
1598 * Eliminate need to write full pages to WAL before page modification
1600 Currently, to protect against partial disk page writes, we write
1601 full page images to WAL before they are modified so we can correct any
1602 partial page writes during recovery. These pages can also be
1603 eliminated from point-in-time archive files.
1604 http://archives.postgresql.org/pgsql-hackers/2002-06/msg00655.php
1606 o When off, write CRC to WAL and check file system blocks
1609 If CRC check fails during recovery, remember the page in case
1610 a later CRC for that page properly matches.
1612 o Write full pages during file system write and not when
1613 the page is modified in the buffer cache
1615 This allows most full page writes to happen in the background
1616 writer. It might cause problems for applying WAL on recovery
1617 into a partially-written page, but later the full page will be
1620 * Allow WAL traffic to be streamed to another server for stand-by
1622 * Reduce WAL traffic so only modified values are written rather than
1625 http://archives.postgresql.org/pgsql-hackers/2007-03/msg01589.php
1627 * Allow WAL information to recover corrupted pg_controldata
1629 http://archives.postgresql.org/pgsql-patches/2006-06/msg00025.php
1631 * Find a way to reduce rotational delay when repeatedly writing
1634 Currently fsync of WAL requires the disk platter to perform a full
1635 rotation to fsync again. One idea is to write the WAL to different
1636 offsets that might reduce the rotational delay.
1637 http://archives.postgresql.org/pgsql-hackers/2002-11/msg00483.php
1639 * Allow WAL logging to be turned off for a table, but the table
1640 might be dropped or truncated during crash recovery
1642 Allow tables to bypass WAL writes and just fsync() dirty pages on
1643 commit. This should be implemented using ALTER TABLE, e.g. ALTER
1644 TABLE PERSISTENCE [ DROP | TRUNCATE | DEFAULT ]. Tables using
1645 non-default logging should not use referential integrity with
1646 default-logging tables. A table without dirty buffers during a
1647 crash could perhaps avoid the drop/truncate.
1648 http://archives.postgresql.org/pgsql-hackers/2005-12/msg01016.php
1650 * Allow WAL logging to be turned off for a table, but the table would
1651 avoid being truncated/dropped
1653 To do this, only a single writer can modify the table, and writes
1654 must happen only on new pages so the new pages can be removed during
1655 crash recovery. Readers can continue accessing the table. Such
1656 tables probably cannot have indexes. One complexity is the handling
1657 of indexes on TOAST tables.
1658 http://archives.postgresql.org/pgsql-hackers/2005-12/msg01016.php
1660 * Speed WAL recovery by allowing more than one page to be prefetched
1662 This should be done utilizing the same infrastructure used for
1663 prefetching in general to avoid introducing complex error-prone code
1665 http://archives.postgresql.org/pgsql-general/2007-12/msg00683.php
1666 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00497.php
1667 http://archives.postgresql.org/pgsql-hackers/2008-02/msg01279.php
1669 * Improve WAL concurrency by increasing lock granularity
1671 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00556.php
1673 * Be more aggressive about creating WAL files
1675 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01325.php
1676 http://archives.postgresql.org/pgsql-hackers/2004-07/msg01075.php
1677 http://archives.postgresql.org/pgsql-hackers/2005-04/msg00556.php
1679 * Have resource managers report the duration of their status changes
1681 http://archives.postgresql.org/pgsql-hackers/2007-10/msg01468.php
1683 * Move pgfoundry's xlogdump to /contrib and have it rely more closely
1684 on the WAL backend code
1686 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00035.php
1691 Optimizer / Executor
1692 ====================
1694 * Improve selectivity functions for geometric operators
1695 * Precompile SQL functions to avoid overhead
1696 * Create utility to compute accurate random_page_cost value
1697 * Improve ability to display optimizer analysis using OPTIMIZER_DEBUG
1698 * Have EXPLAIN ANALYZE issue NOTICE messages when the estimated and
1699 actual row counts differ by a specified percentage
1700 * Improve how ANALYZE computes in-doubt tuples
1702 http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php
1704 * Consider using hash buckets to do DISTINCT, rather than sorting
1706 This would be beneficial when there are few distinct values. This is
1707 already used by GROUP BY.
1709 * Log statements where the optimizer row estimates were dramatically
1710 different from the number of rows actually found?
1711 * Consider compressed annealing to search for query plans
1713 This might replace GEQO, http://sixdemonbag.org/Djinni.
1715 * Improve merge join performance by allowing mark/restore of
1718 http://archives.postgresql.org/pgsql-hackers/2007-01/msg00096.php
1720 * Consider using a hash for joining to a large IN (VALUES ...) list
1722 http://archives.postgresql.org/pgsql-hackers/2007-05/msg00450.php
1729 * Consider having the background writer update the transaction status
1730 hint bits before writing out the page
1732 Implementing this requires the background writer to have access to system
1733 catalogs and the transaction status log.
1735 * Consider adding buffers the background writer finds reusable to the
1738 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1740 * Automatically tune bgwriter_delay based on activity rather then using a
1743 http://archives.postgresql.org/pgsql-hackers/2007-04/msg00781.php
1745 * Consider wither increasing BM_MAX_USAGE_COUNT improves performance
1747 http://archives.postgresql.org/pgsql-hackers/2007-06/msg01007.php
1749 * Test to see if calling PreallocXlogFiles() from the background writer
1750 will help with WAL segment creation latency
1752 http://archives.postgresql.org/pgsql-patches/2007-06/msg00340.php
1756 Miscellaneous Performance
1757 =========================
1759 * Do async I/O for faster random read-ahead of data
1761 Async I/O allows multiple I/O requests to be sent to the disk with
1762 results coming back asynchronously.
1764 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00820.php
1765 http://archives.postgresql.org/pgsql-performance/2007-09/msg00255.php
1766 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00027.php
1767 http://archives.postgresql.org/pgsql-patches/2008-01/msg00170.php
1769 * Use mmap() rather than SYSV shared memory or to write WAL files?
1771 This would remove the requirement for SYSV SHM but would introduce
1772 portability issues. Anonymous mmap (or mmap to /dev/zero) is required
1773 to prevent I/O overhead.
1775 * Consider mmap()'ing files into a backend?
1777 Doing I/O to large tables would consume a lot of address space or
1778 require frequent mapping/unmapping. Extending the file also causes
1779 mapping problems that might require mapping only individual pages,
1780 leading to thousands of mappings. Another problem is that there is no
1781 way to _prevent_ I/O to disk from the dirty shared buffers so changes
1782 could hit disk before WAL is written.
1784 * Add a script to ask system configuration questions and tune postgresql.conf
1785 * Consider ways of storing rows more compactly on disk
1787 o Reduce the row header size?
1788 o Consider reducing on-disk varlena length from four bytes to
1789 two because a heap row cannot be more than 64k in length
1791 * Consider increasing NUM_CLOG_BUFFERS
1793 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00030.php
1794 http://archives.postgresql.org/pgsql-performance/2007-08/msg00024.php
1796 * Consider transaction start/end performance improvements
1798 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00948.php
1799 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1801 * Allow user configuration of TOAST thresholds
1803 http://archives.postgresql.org/pgsql-hackers/2007-02/msg00213.php
1804 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00082.php
1806 * Allow configuration of backend priorities via the operating system
1808 Though backend priorities make priority inversion during lock
1809 waits possible, research shows that this is not a huge problem.
1811 http://archives.postgresql.org/pgsql-general/2007-02/msg00493.php
1813 * Experiment with multi-threaded backend better I/O utilization
1815 This would allow a single query to make use of multiple I/O channels
1816 simultaneously. One idea is to create a background reader that can
1817 pre-fetch sequential and index scan pages needed by other backends.
1818 This could be expanded to allow concurrent reads from multiple devices
1819 in a partitioned table.
1821 * Experiment with multi-threaded backend better CPU utilization
1823 This would allow several CPUs to be used for a single query, such as
1824 for sorting or query execution.
1826 * Consider increasing the minimum allowed number of shared buffers
1828 http://archives.postgresql.org/pgsql-bugs/2008-02/msg00157.php
1830 * Expire published xmin for read-only and idle transactions
1832 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00343.php
1834 * Consider if CommandCounterIncrement() can avoid its
1835 AcceptInvalidationMessages() call
1837 http://archives.postgresql.org/pgsql-committers/2007-11/msg00585.php
1839 * Improve performance of shared invalidation queue for multiple CPUs
1841 http://archives.postgresql.org/pgsql-performance/2008-01/msg00023.php
1843 * Consider Cartesian joins when both relations are needed to form an
1844 indexscan qualification for a third relation
1846 http://archives.postgresql.org/pgsql-performance/2007-12/msg00090.php
1848 * Consider not storing a NULL bitmap on disk if all the NULLs are
1851 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00624.php
1852 http://archives.postgresql.org/pgsql-patches/2007-12/msg00109.php
1854 * Sort large UPDATE/DELETEs so it is done in heap order
1856 http://archives.postgresql.org/pgsql-hackers/2008-01/msg01119.php
1858 * -Avoid tuple some tuple copying in sort routines
1859 * SMP scalability improvements
1861 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php
1862 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00206.php
1863 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00361.php
1865 * Research reducing deTOASTing in more places
1867 http://archives.postgresql.org/pgsql-hackers/2007-09/msg00895.php
1869 * Consider being smarter about memory and external files used during
1872 http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php
1873 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php
1875 * Allow one transaction to see tuples using the snapshot of another
1878 This would assist multiple backends in working together.
1879 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00400.php
1885 * Add use of 'const' for variables in source tree
1886 * Move some things from contrib into main tree
1887 * %Remove warnings created by -Wcast-align
1888 * Move platform-specific ps status display info from ps_status.c to ports
1889 * Add optional CRC checksum to heap and index pages
1890 * Improve documentation to build only interfaces (Marc)
1891 * Remove or relicense modules that are not under the BSD license, if possible
1892 * Acquire lock on a relation before building a relcache entry for it
1893 * Allow cross-compiling by generating the zic database on the target system
1894 * Improve NLS maintenance of libpgport messages linked onto applications
1895 * Clean up casting in contrib/isn
1897 http://archives.postgresql.org/pgsql-hackers/2006-11/msg00245.php
1899 * Improve the /contrib installation experience
1901 http://archives.postgresql.org/pgsql-hackers/2008-04/msg00132.php
1903 * Use UTF8 encoding for NLS messages so all server encodings can
1905 * Update Bonjour to work with newer cross-platform SDK
1907 http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php
1908 http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php
1910 * Consider detoasting keys before sorting
1911 * Consider GnuTLS if OpenSSL license becomes a problem
1913 http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php
1914 http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php
1916 * Consider changing documentation format from SGML to XML
1918 http://archives.postgresql.org/pgsql-docs/2006-12/msg00152.php
1920 * Consider making NAMEDATALEN more configurable in future releases
1921 * Update our code to handle 64-bit timezone files to match the zic
1922 source code, which now uses them
1923 * Have configure choose integer datetimes by default
1925 http://archives.postgresql.org/pgsql-patches/2007-05/msg00046.php
1927 * Support scoped IPv6 addresses
1929 http://archives.postgresql.org/pgsql-bugs/2007-05/msg00111.php
1931 * Consider allowing 64-bit integers and floats to be passed by value on
1934 Also change 32-bit floats (float4) to be passed by value at the same
1937 * Research use of signals and sleep wake ups
1939 http://archives.postgresql.org/pgsql-hackers/2007-07/msg00003.php
1941 * Add automated check for invalid C++ source code constructs
1943 http://archives.postgresql.org/pgsql-patches/2007-07/msg00056.php
1945 * Consider simplifying how memory context resets handle child contexts
1947 http://archives.postgresql.org/pgsql-patches/2007-08/msg00067.php
1949 * Remove use of MAKE_PTR and MAKE_OFFSET macros
1951 http://archives.postgresql.org/pgsql-general/2007-08/msg01510.php
1953 * Convert single quotes to apostrophes in the PDF documentation
1955 http://archives.postgresql.org/pgsql-docs/2007-12/msg00059.php
1957 * Create three versions of libpgport to simplify client code
1959 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00154.php
1961 * Remove old-style routines for manipulating tuples
1963 http://archives.postgresql.org/pgsql-hackers/2007-10/msg00851.php
1965 * Improve detection of shared memory segments being used by others
1966 by checking the SysV shared memory field 'nattch'
1968 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00656.php
1969 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00673.php
1971 * Implement the non-threaded Avahi service discovery protocol
1973 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00939.php
1974 http://archives.postgresql.org/pgsql-patches/2008-02/msg00097.php
1975 http://archives.postgresql.org/pgsql-hackers/2008-03/msg01211.php
1976 http://archives.postgresql.org/pgsql-patches/2008-04/msg00001.php
1980 o Remove configure.in check for link failure when cause is found
1981 o Remove readdir() errno patch when runtime/mingwex/dirent.c rev
1983 o Remove psql newline patch when we find out why mingw outputs an
1985 o Allow psql to use readline once non-US code pages work with
1987 o Fix problem with shared memory on the Win32 Terminal Server
1988 o Diagnose problem where shared memory can sometimes not be
1989 attached by postmaster children
1991 http://archives.postgresql.org/pgsql-general/2007-08/msg01377.php
1993 o Improve signal handling
1995 http://archives.postgresql.org/pgsql-patches/2005-06/msg00027.php
1997 o Convert MSVC build system to remove most batch files
1999 http://archives.postgresql.org/pgsql-hackers/2007-08/msg00961.php
2001 o Prevent SSL from sending network packets to avoid interference
2002 with Win32 signal emulation
2004 http://archives.postgresql.org/pgsql-hackers/2007-12/msg00455.php
2006 o Support pgxs when using MSVC
2008 o Fix MSVC NLS support, like for to_char()
2010 http://archives.postgresql.org/pgsql-hackers/2008-02/msg00485.php
2011 http://archives.postgresql.org/pgsql-patches/2008-02/msg00038.php
2013 o Find a correct rint() substitute on Windows
2015 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00808.php
2019 * Wire Protocol Changes
2021 o Allow dynamic character set handling
2022 o Add decoded type, length, precision
2024 o Update clients to use data types, typmod, schema.table.column names
2025 of result sets using new statement protocol
2031 * Add pre-parsing phase that converts non-ISO syntax to supported
2034 This could allow SQL written for other databases to run without
2037 * Allow plug-in modules to emulate features from other databases
2038 * Add features of Oracle-style packages (Pavel)
2040 A package would be a schema with session-local variables,
2041 public/private functions, and initialization functions. It
2042 is also possible to implement these capabilities
2043 in any schema and not use a separate "packages"
2046 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00384.php
2048 * Consider allowing control of upper/lower case folding of unquoted
2051 http://archives.postgresql.org/pgsql-hackers/2004-04/msg00818.php
2052 http://archives.postgresql.org/pgsql-hackers/2006-10/msg01527.php
2053 http://archives.postgresql.org/pgsql-hackers/2008-03/msg00849.php
2055 * Add autonomous transactions
2057 http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.php
2061 Features We Do _Not_ Want
2062 =========================
2064 * All backends running as threads in a single process (not wanted)
2066 This eliminates the process protection we get from the current setup.
2067 Thread creation is usually the same overhead as process creation on
2068 modern systems, so it seems unwise to use a pure threaded model.
2070 * Optimizer hints (not wanted)
2072 Optimizer hints are used to work around problems in the optimizer. We
2073 would rather have the problems reported and fixed.
2075 http://archives.postgresql.org/pgsql-hackers/2006-08/msg00506.php
2076 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00517.php
2077 http://archives.postgresql.org/pgsql-hackers/2006-10/msg00663.php
2080 Because we support postfix operators, it isn't possible to make AS
2081 optional and continue to use bison.
2082 http://archives.postgresql.org/pgsql-hackers/2003-04/msg00436.php
2084 http://archives.postgresql.org/pgsql-sql/2006-08/msg00164.php
2086 * Embedded server (not wanted)
2088 While PostgreSQL clients runs fine in limited-resource environments, the
2089 server requires multiple processes and a stable pool of resources to
2090 run reliabily and efficiently. Stripping down the PostgreSQL server
2091 to run in the same process address space as the client application
2092 would add too much complexity and failure cases.