postgres/doc/TODO

TODO list for PostgreSQL
========================
Last updated:		Wed Jan 12 22:36:16 EST 2000

Current maintainer:	Bruce Momjian (pgman@candle.pha.pa.us)

The most recent version of this document can be viewed at
the PostgreSQL web site, http://www.PostgreSQL.org.

A dash(-) marks changes that will appear in the next release.

Names in brackets "[]" indicate more detailed information is available in
the directory pgsql/doc/TODO.detail/ under that name.


RELIABILITY
-----------

RESOURCES

* -Elog() does not free all its memory
* spinlock stuck problem when elog(FATAL) and elog(ERROR) inside bufmgr
* -Recover or force failure when disk space is exhausted(Hiroshi)

PARSER

* Disallow inherited columns with the same name as new columns
* -INSERT INTO ... SELECT with AS columns matching result columns problem
* SELECT pg_class FROM pg_class generates strange error
* Alter TABLE ADD COLUMN does not honor DEFAULT, add CONSTRAINT
* Do not allow bpchar column creation without length
* -Select a[1] FROM test fails, it needs test.a[1](Tom)
* -Array index references without table name cause problems [array](Tom)
* Update table SET table.value = 3 fails(SQL standard says this is OK)
* Creating index of TIMESTAMP & RELTIME fails, or rename to DATETIME(Thomas)
* SELECT foo UNION SELECT foo is incorrectly simplified to SELECT foo
* -INSERT ... SELECT ... GROUP BY groups by target columns not source columns(Tom)
* -CREATE TABLE test (a char(5) DEFAULT text '', b int4) fails on INSERT(Tom)
* -UNION with LIMIT fails
* Unique index on base column not honored on inserts from inherited table
  INSERT INTO inherit_table (unique_index_col) VALUES (dup) should fail
  [inherit] 
* -CREATE TABLE x AS SELECT 1 UNION SELECT 2 fails
* -CREATE TABLE test(col char(2) DEFAULT user) fails in length restriction
* -mismatched types in CREATE TABLE ... DEFAULT causes problems [default]
* SELECT ... UNION ... ORDER BY fails when sort expr not in result list
* Be smarter about promoting types when UNION merges different data types
* SELECT ... UNION ... GROUP BY fails if column types disagree
* redesign INSERT ... SELECT to have two levels of target list
* -select * from pg_class where oid in (0,-1)
* have INTERSECT/EXCEPT prevent duplicates unless ALL is specified
* -prevent primary key that exceeds max index columns [primary]
* -SELECT COUNT('asdf') FROM pg_class WHERE oid=12 crashes
* SELECT DISTINCT ON col1 col1 col2 FROM tab1 is broken [distinct]
* -require SELECT DISTINCT target list to have all ORDER BY columns
* -When using aggregates + GROUP BY, no rows in should yield no rows out(Tom)
* -Allow HAVING to use comparisons that have no aggregates(Tom)
* -Allow COUNT(DISTINCT col))(TOm)

VIEWS

* Views containing aggregates sometimes fail(Jan)
* Views with spaces in view name fail when referenced
* Creating view and inheriting the view causes view* to show
  duplicates(inherit) 

MISC

* User who can create databases can modify pg_database table
* Plpgsql does not handle quoted mixed-case identifiers
* -Fix btree to give a useful elog when key > 1/2 (page - overhead)(Tom)
* -pg_dump should preserve primary key information
* plpgsql regression tests fails on BSD/OS
* -database names with spaces fail
* insert of 0.0 into DECIMAL(4,4) field fails
* Interlock to prevent DROP DATABASE on a database with running backends
* Buffer reference counting bugfixes
* Fix libpq bug that causes it to drop backend error message sent
  just before connection closure (ie, any FATAL error message

ENHANCEMENTS
------------

URGENT

* -Add referential integrity(Jan)[primary]
* Add OUTER joins, left and right[outer](Thomas, Bruce)
* Allow long tuples by chaining or auto-storing outside db (TOAST)(Jan)
* -Eliminate limits on query length
* Fix memory leak for expressions[memory](Tom?) 
* -Fix memory leak for aggregates(Tom)

ADMIN

* Better interface for adding to pg_group
* More access control over who can create tables and access the database
* Test syslog functionality
* Allow elog() to return error codes, not just messages
* Allow international error message support and add error codes
* -Generate postmaster pid file and remove flock/fcntl lock code[flock](Tatsuo)
* Add ability to specifiy location of lock/socket files [flock]

TYPES

* -Add BIT, BIT VARYING
* Nchar (as distinguished from ordinary varchar),
* Domain capability
* Add STDDEV/VARIANCE() function for standard deviation computation/variance
* Allow compression of large fields or a compressed field type
* Large objects
	o Fix large object mapping scheme, own typeid or reltype(Peter)
	o Not to stuff everything as files in a single directory, hash dirs
	o Allow large object vacuuming
	o Tables that start with xinv confused to be large objects
* -Allow pg_descriptions when creating tables
* -Allow pg_descriptions when creating types, columns, and functions
* Add IPv6 capability to INET/CIDR types
* Make a separate SERIAL type?
* Store binary-compatible type information in the system
* Allow user to define char1 column
* Add support for & operator
* Allow LOCALE on a per-column basis, default to ASCII
* -Allow LOCALE to use indexes in regular expression searches(Tom)
* Allow array on int8[]
* Allow nulls in arrays
* Allow arrays to be ORDER'ed
* Remove Money type, add money formatting for decimal type
* Declare typein/out functions in pg_proc with a special "C string" data type
* Add non-large-object binary field
* -Add index on NUMERIC/DECIMAL type(Jan)
* Make Absolutetime/Relativetime int4 because time_t can be int8 on some ports
* Functions returning sets don't really work right[function]
* Make type equivalency apply to aggregates

VIEWS

* Allow DISTINCT on views
* Allow views of aggregate columns
* Allow views with subselects

INDEXES

* Allow CREATE INDEX zman_index ON test (date_trunc( 'day', zman ) datetime_ops)
  fails index can't store constant parameters
* Allow creation of functional indexes to use default types
* Permissions on indexes, prevent them?
* Allow SQL function indexes
* Add FILLFACTOR to index creation
* -Allow indexing of LIKE with localle character sets
* -Allow indexing of more than eight columns

COMMANDS

* ALTER TABLE ADD COLUMN to inherited table put column in wrong place [inherit]
* Add ALTER TABLE DROP/ALTER COLUMN feature
* Allow CLUSTER on all tables at once, and improve CLUSTER, loses NOT
	NULL specification, indexes, permissions, etc on table[cluster]
* Add SIMILAR TO to allow character classes, 'pg_[a-c]%'
* Auto-destroy sequence on DROP of table with SERIAL(Ryan)
* Allow LOCK TABLE tab1, tab2, tab3 so all tables locked in unison
* Allow INSERT/UPDATE of system-generated oid value for a row
* Allow ESCAPE '\' at the end of LIKE for ANSI compliance [like]
* Rewrite the LIKE handling by rewriting the user string with the 
  supplied ESCAPE [like]
* -Move LIKE index optimization handling to the optimizer(Tom)
* Allow RULE recompilation
* Support UNION/INTERSECT/EXCEPT in sub-selects
* Allow DELETE and UPDATE to use inheritance using tablename*
  
CLIENTS

* Make NULL's come out at the beginning or end depending on the 
  ORDER BY direction
* -Allow flag to control COPY input/output of NULLs
* Update reltuples from COPY command
* -Allow psql \copy to allow delimiters
* -Add a function to return the last inserted oid, for use in psql
	scripts (Peter E)
* -Allow psql to print nulls as distinct from "" [null]

EXOTIC FEATURES

* Add sql3 recursive unions
* Add the concept of dataspaces
* Add replication of distributed databases
* Allow queries across multiple databases
* Allow nested transactions

MISC

* Increase identifier length(NAMEDATALEN) if small performance hit
* Allow row re-use without vacuum(Vadim)
* Create a background process for each database that runs while
  database is idle, finding superceeded rows, gathering stats and vacuuming
* Add UNIQUE capability to non-btree indexes
* -Certain indexes will not shrink, i.e. oid indexes with many inserts(Vadim)
* Restore unused oid's on backend exit if no one else has gotten oids
* Have UPDATE/DELETE clean out indexes
* -Allow WHERE restriction on ctid(Hiroshi)
* Allow cursors to be DECLAREd/OPENed/CLOSEed outside transactions
* Allow DELETE WHERE CURRENT OF cursor
* Allow PQrequestCancel() to terminate when in waiting-for-lock state
* Transaction log, so re-do log can be on a separate disk by
  with after-row images(Vadim) [logging](Vadim)(in-progress)
* Populate backend status area and write program to dump status data
* Make oid use unsigned int more reliably, pg_atoi()
* -Allow subqueries in target list(Tom)
* Put sort files, large objects in their own directory
* Do autocommit so always in a transaction block(?)
* Show location of syntax error in query [yacc]
* Redesign the function call interface to handle NULLs better[function](Tom)
* -Document/trigger/rule so changes to pg_shadow recreate pg_pwd [pg_shadow]
* Missing optimizer selectivities for date, r-tree, etc. [optimizer]
* -Overhaul mdmgr/smgr to fix double unlinking and double opens, cleanup
* Overhaul bufmgr/lockmgr/transaction manager
* Add PL/Perl(Mark Hollomon)
* Make postgres user have a password by default
* Add configure test to check for C++ need for *.h and namespaces
* Allow BLCKSZ <= 64k, not <= 32k
* redesign UNION structures to have separarate target lists
* Allow multi-level query trees for INSERT INTO ... SELECT

PERFORMANCE
-----------

FSYNC

* -Allow transaction commits with rollback with no-fsync performance [fsync](Vadim)
* -Prevent fsync in SELECT-only queries(Vadim)

INDEXES

* Use indexes in ORDER BY for min(), max()
* Use index to restrict rows returned by multi-key index when used with
  non-consecutive keys or OR clauses, so fewer heap accesses
* -Convert function(constant) into a constant for index use(Bernard Frankpitt)
* Improve LIMIT processing by using index to limit rows processed [limit]
* Have optimizer take LIMIT into account when considering index scans [limit]
* -Make index creation use psort code, because it is now faster(Tom)
* -Allow creation of sort temp tables > 1 Gig
* -Create more system table indexes for faster cache lookups
* -fix indexscan() so it does leak memory by not requiring caller to
free(Tom)
* -Improve _bt_binsrch() to handle equal keys better, remove _bt_firsteq()(Tom)
* Allow SELECT * FROM tab WHERE int2col = 4 use int2col index, int8,
  float4, numeric/decimal too [optimizer]
* -Allow optimizer to prefer plans that match ORDER BY(Tom)
* Include heap CTID in btree index keys, remove equal-key cruft from btree

CACHE

* Cache most recent query plan(s) [prepare]
* Shared catalog cache, reduce lseek()'s by caching table size in shared area
* -elog() flushes cache, try invalidating just entries from current xact,
  perhaps using invalidation cache


MISC

* Allow compression of log and meta data
* Allow char() not to use variable-sized header to reduce disk size
* Do async I/O to do better read-ahead of data
* -Fix memory exhaustion when using many OR's [cnfify](Tom)
* Get faster regex() code from Henry Spencer <henry@zoo.utoronto.ca>
  when it is available
* Use mmap() rather than SYSV shared memory(?)
* -Process const = const parts of OR clause in separate pass(Bernard Frankpitt)
* Make oid use oidin/oidout not int4in/int4out in pg_type.h
* Improve Subplan list handling
* Allow Subplans to use efficient joins(hash, merge) with upper variable
  [subquery]
* use fmgr_info()/fmgr_faddr() instead of fmgr() calls in high-traffic
  places, like GROUP BY, UNIQUE, index processing, etc.
* improve dynamic memory allocation by introducing tuple-context memory
  allocation [memory]
* -fix memory leak in cache code when non-existant table is referenced
  In WHERE tab1.x=3 AND tab1.x=tab2.y, add tab2.y=3
* pass atttypmod through parser in more cases [atttypmod]
* -remove duplicate type in/out functions for disk and net
* Allow persistent backends [persistent]
* others [performance]

SOURCE CODE
-----------
* Add use of 'const' for variables in source tree
* Fix C optimizer problem where fmgr_ptr calls return different types [alpha]
* -Add needed includes and removed unneeded include files(Bruce)
* -Make configure --enable-debug add -g on compile line
* Does Mariposa source contain any other bug fixes?
* Remove SET KSQO option if OR processing is improved(Tom)

---------------------------------------------------------------------------


Developers who have claimed items are:
--------------------------------------
	* Billy is Billy G. Allie <Bill.Allie@mug.org>
	* Brook is Brook Milligan <brook@trillium.NMSU.Edu>
	* Bruce is Bruce Momjian<pgman@candle.pha.pa.us>
	* Bryan is Bryan Henderson<bryanh@giraffe.netgate.net>
	* D'Arcy is D'Arcy J.M. Cain <darcy@druid.net>
	* David is David Hartwig <daveh@insightdist.com>
	* Edmund is Edmund Mergl <E.Mergl@bawue.de>
	* Goran is Goran Thyni <goran@kyla.kiruna.se>
      >::	* Hiroshi is Hiroshi Inoue<Inoue@tpf.co.jp>
	* Jan is Jan Wieck <wieck@sapserv.debis.de>
 	* Marc is Marc Fournier <scrappy@hub.org>
	* Massimo Dal Zotto <dz@cs.unitn.it>
	* Michael is Michael Meskes <meskes@postgresql.org>
	* Oleg is Oleg Bartunov <oleg@sai.msu.su>
	* Peter is Peter T Mount <peter@retep.org.uk>
	* Ryan is Ryan Bradetich <rbrad@hpb50023.boi.hp.com>
	* Stefan Simkovics <ssimkovi@rainbow.studorg.tuwien.ac.at>
	* Tatsuo is Tatsuo Ishii <t-ishii@sra.co.jp>
	* Tom is Tom Lane <tgl@sss.pgh.pa.us>
	* Thomas is Thomas Lockhart <lockhart@alumni.caltech.edu>
	* TomH is Tom I Helbekkmo <tih@Hamartun.Priv.NO>
	* Vadim is "Vadim B. Mikheev" <vadim@krs.ru>