TODO list for PostgreSQL
========================
Last updated: Tue Nov 26 17:05:35 EST 2002
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 upcoming 7.4 release.
Bracketed items "[]" have more detailed.
Urgent
======
* Add replication of distributed databases [replication]
o automatic failover
o load balancing
o master/slave replication
o multi-master replication
o partition data across servers
o sample implementation in contrib/rserv
o queries across databases or servers (two-phase commit)
o allow replication over unreliable or non-persistent links
o http://gborg.postgresql.org/project/pgreplication/projdisplay.php
* Point-in-time data recovery using backup and write-ahead log
* Create native Win32 port [win32]
Reporting
=========
* Allow elog() to return error codes, module name, file name, line
number, not just messages (Peter E)
* Add error codes (Peter E)
* Make error messages more consistent [error]
* Show location of syntax error in query [yacc]
Administration
==============
* Incremental backups
* Remove unreferenced table files and temp tables during database vacuum
or postmaster startup (Bruce)
* Remove behavior of postmaster -o after making postmaster/postgres
flags unique
* Allow easy display of usernames in a group
* Allow configuration files to be specified in a different directory
* Add start time to pg_stat_activity
* Allow limits on per-db/user connections
* Have standalone backend read postgresql.conf
Data Types
==========
* Add IPv6 capability to INET/CIDR types
* Remove Money type, add money formatting for decimal type
* Change factorial to return a numeric
* Change NUMERIC data type to use base 10,000 internally
* Change NUMERIC to enforce the maximum precision, and increase it
* Add function to return compressed length of TOAST data values (Tom)
* Allow INET subnet tests using non-constants
* Add now("transaction|statement|clock") functionality
* -Add GUC variables to control floating number output digits (Pedro Ferreira)
* Have sequence dependency track use of DEFAULT sequences, seqname.nextval
* CONVERSION
o Allow better handling of numeric constants, type conversion
[typeconv]
* ARRAYS
o Allow nulls in arrays
o Allow arrays to be ORDER'ed
o Support construction of array result values in expressions
* BINARY DATA
o Improve vacuum of large objects, like /contrib/vacuumlo
o Add security checking for large objects
o Make file in/out interface for TOAST columns, similar to large object
interface (force out-of-line storage and no compression)
o Auto-delete large objects when referencing row is deleted
Multi-Language Support
======================
* Add NCHAR (as distinguished from ordinary varchar),
* Allow LOCALE on a per-column basis, default to ASCII
* Support multiple simultaneous character sets, per SQL92
* Improve Unicode combined character handling
* Optimize locale to have minimal performance impact when not used (Peter E)
* Add octet_length_server() and octet_length_client() (Thomas, Tatsuo)
* Make octet_length_client the same as octet_length() (?)
* Prevent mismatch of frontend/backend encodings from converting bytea
data from being interpreted as encoded strings
* Remove Cyrillic recode support
Views / Rules
=============
* Automatically create rules on views so they are updateable, per SQL92 [view]
* Add the functionality for WITH CHECK OPTION clause of CREATE VIEW
* Allow NOTIFY in rules involving conditionals
* Have views on temporary tables exist in the temporary namespace
* Move psql backslash information into views
* Allow RULE recompilation
Indexes
=======
* Allow CREATE INDEX zman_index ON test (date_trunc( 'day', zman ) datetime_ops)
fails index can't store constant parameters
* Order duplicate index entries by tid for faster heap lookups
* Allow inherited tables to inherit index, UNIQUE constraint, and primary
key, foreign key [inheritance]
* UNIQUE INDEX on base column not honored on inserts from inherited table
INSERT INTO inherit_table (unique_index_col) VALUES (dup) should fail
[inheritance]
* Add UNIQUE capability to non-btree indexes
* Add btree index support for reltime, tinterval, regproc
* Add rtree index support for line, lseg, path, point
* Certain indexes will not shrink, e.g. indexes on ever-increasing
columns and indexes with many duplicate keys
* Use indexes for min() and max() or convert to SELECT col FROM tab ORDER
BY col DESC LIMIT 1 if appropriate index exists and WHERE clause acceptible
* Allow LIKE indexing optimization for non-ASCII locales
* Use index to restrict rows returned by multi-key index when used with
non-consecutive keys or OR clauses, so fewer heap accesses
* Be smarter about insertion of already-ordered data into btree index
* Prevent index uniqueness checks when UPDATE does not modifying column
* Use bitmaps to fetch heap pages in sequential order [performance]
* Use bitmaps to combine existing indexes [performance]
* Improve handling of index scans for NULL
* Allow SELECT * FROM tab WHERE int2col = 4 to use int2col index, int8,
float4, numeric/decimal too [optimizer]
* Add FILLFACTOR to btree index creation
* Add concurrency to GIST
* Improve concurrency of hash indexes (Neil)
Commands
========
* Add BETWEEN ASYMMETRIC/SYMMETRIC (Christopher)
* Allow LIMIT/OFFSET to use expressions
* CREATE TABLE AS can not determine column lengths from expressions [atttypmod]
* Allow UPDATE to handle complex aggregates [update]
* Allow command blocks to ignore certain types of errors
* Allow backslash handling in quoted strings to be disabled for portability
* Return proper effected tuple count from complex commands [return]
* Allow DELETE to handle table aliases for self-joins [delete]
* Add CORRESPONDING BY to UNION/INTERSECT/EXCEPT
* Allow REINDEX to rebuild all indexes, remove /contrib/reindex
* Make a transaction-safe TRUNCATE
* Fix SELECT ... INTO and CREATE TABLE AS to have appopriate OID column
* ALTER
o ALTER TABLE ADD COLUMN does not honor DEFAULT and non-CHECK CONSTRAINT
o ALTER TABLE ADD COLUMN column DEFAULT should fill existing
rows with DEFAULT value
o ALTER TABLE ADD COLUMN column SERIAL doesn't create sequence because
of the item above
o Add ALTER TABLE tab SET WITHOUT OIDS
* CLUSTER
o Automatically maintain clustering on a table
o Allow CLUSTER to cluster all tables, remove clusterdb
* COPY
o Allow psql \copy to specify column names
o Allow dump/load of CSV format
o Allow COPY to report error lines and continue; optionally
allow error codes to be specified; requires savepoints or can
not be run in a multi-statement transaction
o Allow copy to understand \x as hex
* CURSOR
o Allow BINARY option to SELECT, just like DECLARE
o -MOVE 0 should not move to end of cursor (Bruce)
o Allow UPDATE/DELETE WHERE CURRENT OF cursor using per-cursor tid
stored in the backend
o Prevent DROP of table being referenced by our own open cursor
o Allow cursors outside transactions [cursor]
* INSERT
o Allow INSERT/UPDATE of system-generated oid value for a row
o Allow INSERT INTO tab (col1, ..) VALUES (val1, ..), (val2, ..)
o Allow INSERT/UPDATE ... RETURNING new.col or old.col; handle
RULE cases (Philip)
* SHOW/SET
o Add SET REAL_FORMAT and SET DOUBLE_PRECISION_FORMAT using printf args
o Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM
ANALYZE, and CLUSTER
o Add SET SCHEMA
o Allow EXPLAIN EXECUTE to see prepared plans
o Allow SHOW of non-modifiable variables, like pg_controldata
o Add GUC parameter to control the maximum number of rewrite cycles
* SERVER-SIDE LANGUAGES
o Allow PL/PgSQL's RAISE function to take expressions
o Change PL/PgSQL to use palloc() instead of malloc()
o Add untrusted version of plpython
o Allow Java server-side programming, http://pljava.sourceforge.net
[java]
o Fix problems with complex temporary table creation/destruction
without using PL/PgSQL EXECUTE, needs cache prevention/invalidation
o Fix PL/pgSQL RENAME to work on variables other than OLD/NEW
o Improve PL/PgSQL exception handling
o Allow parameters to be specified by name and type during
definition
o Allow function parameters to be passed by name,
get_employee_salary(emp_id => 12345, tax_year => 2001)
o Add PL/PgSQL packages
o Allow array declarations and other data types in PL/PgSQL DECLARE
o Add PL/PgSQL PROCEDURES that can return multiple values
o Add table function support to pltcl, plperl, plpython
o Make PL/PgSQL %TYPE schema-aware
Clients
=======
* Allow psql to show transaction status if backend protocol changes made
* Add XML interface: psql, pg_dump, COPY, separate server (?)
* Add schema, cast, and conversion backslash commands to psql
* Allow pg_dump to dump a specific schema
* Allow psql to do table completion for SELECT * FROM schema_part and
table completion for SELECT * FROM schema_name.
* JDBC
o Comprehensive test suite. This may be available already.
o JDBC-standard BLOB support
o Error Codes (pending backend implementation)
o Support both 'make' and 'ant'
o Fix LargeObject API to handle OIDs as unsigned ints
o Use cursors implicitly to avoid large results (see setCursorName())
o Add LISTEN/NOTIFY support to the JDBC driver (Barry)
* ECPG
o Implement set descriptor, using descriptor
o Make casts work in variable initializations
o Implement SQLDA
o Allow multi-threaded use of SQLCA
o Solve cardinality > 1 for input descriptors / variables
o Understand structure definitions outside a declare section
o sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified
o Improve error handling
o Allow :var[:index] or :var[<integer>] as cvariable for an array var
o Add a semantic check level, e.g. check if a table really exists
o Fix nested C comments
o Add SQLSTATE
o fix handling of DB attributes that are arrays
Referential Integrity
=====================
* Add MATCH PARTIAL referential integrity [foreign]
* Add deferred trigger queue file (Jan)
* Implement dirty reads and use them in RI triggers
* Enforce referential integrity for system tables
* Change foreign key constraint for array -> element to mean element
in array
* Allow DEFERRABLE UNIQUE constraints
* Allow triggers to be disabled [trigger]
* -Support statement-level triggers (Neil)
* Support triggers on columns (Neil)
Dependency Checking
===================
* Flush cached query plans when their underlying catalog data changes
* Use dependency information to dump data in proper order
Transactions
============
* Overhaul bufmgr/lockmgr/transaction manager
* Allow savepoints / nested transactions [transactions] (Bruce)
Exotic Features
===============
* Add sql3 recursive unions
* Add the concept of dataspaces/tablespaces [tablespaces]
* Allow queries across multiple databases [crossdb]
* Add pre-parsing phase that converts non-ANSI features to supported features
* Allow plug-in modules to emulate features from other databases
* SQL*Net listener that makes PostgreSQL appear as an Oracle database
to clients
PERFORMANCE
===========
Fsync
=====
* Delay fsync() when other backends are about to commit too [fsync]
o Determine optimal commit_delay value
* Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
o Allow multiple blocks to be written to WAL with one write()
Cache
=====
* Shared catalog cache, reduce lseek()'s by caching table size in shared area
* Add free-behind capability for large sequential scans (Bruce)
* Allow binding query args over FE/BE protocol
* Consider use of open/fcntl(O_DIRECT) to minimize OS caching
* Make blind writes go through the file descriptor cache
Vacuum
======
* Improve speed with indexes (perhaps recreate index instead) [vacuum]
* Reduce lock time by moving tuples with read lock, then write
lock and truncate table [vacuum]
* Provide automatic running of vacuum in the background (Tom) [vacuum]
* Allow free space map to be auto-sized or warn when it is too small
Locking
=======
* Make locking of shared data structures more fine-grained
* Add code to detect an SMP machine and handle spinlocks accordingly
from distributted.net, http://www1.distributed.net/source,
in client/common/cpucheck.cpp
* Research use of sched_yield() for spinlock acquisition failure
Startup Time
============
* Experiment with multi-threaded backend [thread]
* Add connection pooling [pool]
* Allow persistent backends [persistent]
* Create a transaction processor to aid in persistent connections and
connection pooling
* Do listen() in postmaster and accept() in pre-forked backend
* Have pre-forked backend pre-connect to last requested database or pass
file descriptor to backend pre-forked for matching database
Write-Ahead Log
===============
* Have after-change WAL write()'s write only modified data to kernel
* Reduce number of after-change WAL writes; they exist only to gaurd against
partial page writes [wal]
* Turn off after-change writes if fsync is disabled (?)
* Add WAL index reliability improvement to non-btree indexes
* Find proper defaults for postgresql.conf WAL entries
* Add checkpoint_min_warning postgresql.conf option to warn about checkpoints
that are too frequent
* Allow xlog directory location to be specified during initdb, perhaps
using symlinks
* Allow pg_xlog to be moved without symlinks
Optimizer / Executor
====================
* Improve Subplan list handling
* Allow Subplans to use efficient joins(hash, merge) with upper variable
* -Add hash for evaluating GROUP BY aggregates (Tom)
* Allow merge and hash joins on expressions not just simple variables (Tom)
* Make IN/NOT IN have similar performance to EXISTS/NOT EXISTS [exists]
* Missing optimizer selectivities for date, r-tree, etc. [optimizer]
* Allow ORDER BY ... LIMIT to select top values without sort or index
using a sequential scan for highest/lowest values (Oleg)
* Inline simple SQL functions to avoid overhead (Tom)
* Precompile SQL functions to avoid overhead (Neil)
* Add utility to compute accurate random_page_cost value
* Improve ability to display optimizer analysis using OPTIMIZER_DEBUG
* Use CHECK constraints to improve optimizer decisions
* Check GUC geqo_threshold to see if it is still accurate
* Allow sorting, temp files, temp tables to use multiple work directories
Miscellaneous
=============
* Do async I/O for faster random read-ahead of data
* Get faster regex() code from Henry Spencer <henry@zoo.utoronto.ca>
when it is available
* Use mmap() rather than SYSV shared memory or to write WAL files (?) [mmap]
* Improve caching of attribute offsets when NULLs exist in the row
Source Code
===========
* Add use of 'const' for variables in source tree
* Rename some /contrib modules from pg* to pg_*
* Move some things from /contrib into main tree
* Remove warnings created by -Wcast-align
* Move platform-specific ps status display info from ps_status.c to ports
* Modify regression tests to prevent failures do to minor numeric rounding
* Add OpenBSD's getpeereid() call for local socket authentication (Bruce)
* Improve access-permissions check on data directory in Cygwin (Tom)
* Add --port flag to regression tests
* Add documentation for perl, including mention of DBI/DBD perl location
* Add optional CRC checksum to heap and index pages
* Change representation of whole-tuple parameters to functions
* Clarify use of 'application' and 'command' tags in SGML docs
* Better document ability to build only certain interfaces (Marc)
* Remove or relicense modules that are not under the BSD license, if possible
* Remove memory/file descriptor freeing befor elog(ERROR) (Bruce)
* Acquire lock on a relation before building a relcache entry for it
* Research interaction of setitimer() and sleep() used by statement_timeout
---------------------------------------------------------------------------
Developers who have claimed items are:
--------------------------------------
* Barry is Barry Lind <barry@xythos.com>
* Billy is Billy G. Allie <Bill.Allie@mug.org>
* Bruce is Bruce Momjian <pgman@candle.pha.pa.us>
* Christopher is Christopher Kings-Lynne <chriskl@familyhealth.com.au>
* D'Arcy is D'Arcy J.M. Cain <darcy@druid.net>
* Dave is Dave Cramer <dave@fastcrypt.com>
* Edmund is Edmund Mergl <E.Mergl@bawue.de>
* Gavin Sherry <swm@linuxworld.com.au>
* Hiroshi is Hiroshi Inoue <Inoue@tpf.co.jp>
* Karel is Karel Zak <zakkr@zf.jcu.cz>
* Jan is Jan Wieck <wieck@sapserv.debis.de>
* Liam is Liam Stewart <liams@redhat.com>
* Marc is Marc Fournier <scrappy@hub.org>
* Mark is Mark Hollomon <mhh@mindspring.com>
* Marko is Marko Kreen <marko@l-t.ee>
* Michael is Michael Meskes <meskes@postgresql.org>
* Neil is Neil Conway <neilc@samurai.com>
* Oleg is Oleg Bartunov <oleg@sai.msu.su>
* Peter M is Peter T Mount <peter@retep.org.uk>
* Peter E is Peter Eisentraut <peter_e@gmx.net>
* Philip is Philip Warner <pjw@rhyme.com.au>
* Rod is Rod Taylor <rbt@zort.ca>
* Ross is Ross J. Reedstrom <reedstrm@wallace.ece.rice.edu>
* Ryan is Ryan Bradetich <rbrad@hpb50023.boi.hp.com>
* Stephan is Stephan Szabo <sszabo@megazone23.bigpanda.com>
* Tatsuo is Tatsuo Ishii <t-ishii@sra.co.jp>
* Thomas is Thomas Lockhart <lockhart@fourpalms.org>
* Tom is Tom Lane <tgl@sss.pgh.pa.us>
* TomH is Tom I Helbekkmo <tih@Hamartun.Priv.no>
* Vadim is Vadim B. Mikheev <vadim4o@email.com>
