postgresql/doc/TODO

TODO list for PostgreSQL
========================
Last updated:		Tue Sep 21 15:54:14 EDT 1999

Current maintainer:	Bruce Momjian (maillist@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.


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

RESOURCES

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

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]
* -Array index references without table name cause problems
	(see TODO.detail/array)
* Update table SET table.value = 3 fails
* 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
* -CREATE TABLE test (a char(5) DEFAULT text '', b int4) fails on INSERT
* 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
  (see TODO.detail/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
	(see TODO.detail/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

VIEWS

* Views containing aggregates sometimes fail(Jan)
* Views with spaces in view name fail when referenced

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)
* pg_dump should preserve primary key information

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

URGENT

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

ADMIN

* Better interface for adding to pg_group
* More access control over who can create tables and access the database
* Add 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
	(see TODO.detail/flock)
* Add ability to specifiy location of lock/socket files (see TODO.detail/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 Allow large text type to use large objects(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 types, tables, 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 array on int8[]
* Allow nulls in arrays
* 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
* Make Absolutetime/Relativetime int4 because time_t can be int8 on some ports
* Functions returning sets don't really work right(see TODO.detail/functions)

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
	(see TODO.detail/inherit)
* Add ALTER TABLE DROP/ALTER COLUMN feature
* Allow CLUSTER on all tables at once, and improve CLUSTER, loses NOT
	NULL specification on table(see TODO.detail/cluster)
* Generate error on CREATE OPERATOR of ~~, ~ and and ~*
* 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(see TODO.detail/like)
* Rewrite the LIKE handling by rewriting the user string with the 
  supplied ESCAPE(see TODO.detail/like)
* Move LIKE index optimization handling to the optimizer
* Allow RULE recompilation
* Support UNION/INTERSECT/EXCEPT in sub-selects
  
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
* Allow psql to print nulls as distinct from ""(see TODO.detail/nulls)
* PQrequestCancel() be able to terminate backend waiting for lock

EXOTIC FEATURES

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

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
* 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
* Allow cursors to be DECLAREd/OPENed/CLOSEed outside transactions
* 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) (see TODO.detail/logging)
* 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
* Put sort files, large objects in their own directory
* Do autocommit so always in a transaction block(?)
* Show location of syntax error in query (see TODO.detail/yacc)
* Redesign the function call interface to handle NULLs better
	(see TODO.detail/function)
* Document/trigger/rule so changes to pg_shadow recreate pg_pwd
	(see TODO.detail/pg_shadow)
* Missing optimizer selectivities for date, r-tree, etc.
	(see TODO.detail/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
	(see TODO.detail/fsync)
* -Prevent fsync in SELECT-only queries

INDEXES

* Use indexes in ORDER BY for restrictive data sets, min(), max()
* Pull requested data directly from indexes, bypassing heap data
* 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
* Allow LIMIT ability on single-table queries that have no ORDER BY to use
  a matching index(see TODO.detail/limit)
* Improve LIMIT processing by using index to limit rows processed
	(see TODO.detail/limit) 
* Have optimizer take LIMIT into account when considering index scans
	(see TODO.detail/limit)
* Make index creation use psort code, because it is now faster(Vadim)
* 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
* Improve _bt_binsrch() to handle equal keys better, remove _bt_firsteq()(Tom)
* Allow SELECT * FROM tab WHERE int2col = 4 use int2col index
	(see TODO.detail/optimizer)
* Allow optimizer to prefer plans that match ORDER BY

CACHE

* Cache most recent query plan(s)(see TODO.detail/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
* Update pg_statistic table to remove operator column
* 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(see TODO.detail/cnfify)
* 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
* 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
* 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(see TODO.detail/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(see TODO.detail/atttypmod)
* remove duplicate type in/out functions for disk and net
* change VACUUM ANALYZE to use btree comparison functions, not <,=,> calls
* Allow persistent backends(see TODO.detail/persistent)
* Misc(see TODO.detail/performance)

SOURCE CODE
-----------
* Add use of 'const' for varibles in source tree
* Fix C optimizer problem where fmgr_ptr calls return different types
	(see TODO.detail/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

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


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<maillist@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>