TODO list for PostgreSQL
========================
Last updated: Tue Feb 12 17:24:00 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 7.3 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 http://gborg.postgresql.org/project/pgreplication/projdisplay.php
* Point-in-time data recovery using backup and write-ahead log
REPORTING
---------
* Allow elog() to return error codes, module name, file name, line
number, not just messages (Peter E)
* Add error codes (Peter E)
* Change DEBUG startup tag to NOTICE; change NOTICE to output to client
only if client exists (Bruce)
* Show location of syntax error in query [yacc]
PERMISSIONS
-----------
* Improve control over user privileges, including table creation and
lock use [privileges] (Karel, others)
* Allow usernames to be specified directly in pg_hba.conf (Bruce)
* Add PGPASSWORDFILE environment variable or ~/.pgpass to store
user/host/password combinations
* Remove PGPASSWORD because is insecure on some OS's
* Make single-user local access permissions the default (Peter E)
* Use thread-safe crypt() in libpq, if available
ADMIN
-----
* Incremental backups
* Make it easier to create a database owned by someone who can't createdb,
perhaps CREATE DATABASE dbname WITH OWNER = "user" (Gavin)
* Make equals sign optional in CREATE DATABASE WITH param = 'val'
* Remove unreferenced table files and temp tables during database vacuum
or postmaster startup (Bruce)
* Add table name mapping for numeric file names (Bruce)
* Remove behavior of postmaster -o after making postmaster/postgres
flags unique
* Allow logging of query durations
* Prevent SIGHUP and 'pg_ctl reload' from changing command line
specified parameters to postgresql.conf defaults
DATA TYPES
----------
* Add domain capability [domain]
* Add IPv6 capability to INET/CIDR types
* Remove Money type, add money formatting for decimal type
* SELECT cash_out(2) crashes because of opaque
* Declare typein/out functions in pg_proc with a special "C string" data type
* Functions returning sets do not totally work
* Change factorial to return a numeric
* Add function to return compressed length of TOAST data values (Tom)
* CONVERSION
o Store binary-compatible type information in the system
o Allow better handling of numeric constants, type conversion
[typeconv]
o SELECT col FROM tab WHERE numeric_col = 10.1 fails, requires quotes
* ARRAYS
o Allow nulls in arrays
o Allow arrays to be ORDER'ed
o Ensure we have array-eq operators for every built-in array type
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
* Allow setting database character set without multibyte enabled
* 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() (?)
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
* Allow temporary views
* Move psql backslash information into views
* Allow RULE recompilation
* Remove brackets as multi-statement rule grouping, must use parens
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]
* Allow UPDATE/DELETE on inherited table
* Have UPDATE/DELETE clean out indexes
* 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. oid indexes with many inserts
* 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
* Add deleted bit to index tuples to reduce heap access
* Prevent index uniqueness checks when UPDATE does not modifying column
* Add bitmap 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]
* Improve concurrency in GIST
* Add FILLFACTOR to index creation
COMMANDS
--------
* Add SIMILAR TO to allow character classes, 'pg_[a-c]%'
* Add BETWEEN ASYMMETRIC/SYMMETRIC
* Remove LIMIT #,# and force use LIMIT and OFFSET clauses in 7.3 (Bruce)
* Allow LIMIT/OFFSET to use expressions
* Disallow TRUNCATE on tables that are involved in referential constraints
* Add OR REPLACE clauses to non-FUNCTION object creation
* CREATE TABLE AS can not determine column lengths from expressions [atttypmod]
* Allow UPDATE to handle complex aggregates [update]
* Prevent create/drop scripts from allowing extra args (Bruce)
* Allow command blocks to ignore certain types of errors
* ALTER
o ALTER TABLE ADD COLUMN does not honor DEFAULT and non-CHECK CONSTRAINT
o ALTER TABLE ADD COLUMN to inherited table put column in wrong place
[inheritance]
o Add ALTER TABLE DROP COLUMN feature [drop] (Bruce)
o Add ALTER FUNCTION
o Add ALTER TABLE DROP non-CHECK CONSTRAINT
o ALTER TABLE ADD PRIMARY KEY (Christopher Kings-Lynne)
o ALTER TABLE ADD UNIQUE (Christopher Kings-Lynne)
o ALTER TABLE ADD COLUMN column SERIAL doesn't create sequence
o ALTER TABLE ADD COLUMN column SET DEFAULT should fill existing
rows with DEFAULT value
o Have ALTER TABLE OWNER change all dependant objects like indexes
* CLUSTER
o cluster all tables at once
o prevent loss of indexes, permissions, inheritance (Bruce)
o Automatically maintain clustering on a table
* COPY
o Allow specification of column names
o Allow dump/load of CSV format
o Change syntax to WITH DELIMITER, (keep old syntax around?)
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
* CURSOR
o Allow BINARY option to SELECT, just like DECLARE
o MOVE 0 should not move to end of cursor
o Allow cursors to be DECLAREd/OPENed/CLOSEed outside transactions
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
* 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 INTO my_table VALUES (a, b, c, DEFAULT, x, y, z, ...)
o Disallow missing columns in INSERT ... VALUES, per ANSI
o Allow INSERT/UPDATE ... RETURNING new.col or old.col; handle
RULE cases (Philip)
* SHOW/SET
o Add SHOW command to display locks
o Add SET or BEGIN timeout parameter to cancel query
o Add SET REAL_FORMAT and SET DOUBLE_PRECISION_FORMAT using printf args
o Remove SET KSQO option now that OR processing is improved (Tom)
o Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM
ANALYZE, and CLUSTER
o Add SHOW command to see locale
* SERVER-SIDE LANGUAGES
o Allow PL/PgSQL's RAISE function to take expressions
o Fix PL/PgSQL to handle quoted mixed-case identifiers
o Change PL/PgSQL to use palloc() instead of malloc()
o Add untrusted version of plpython
o Add plsh server-side shell language (Peter E)
o Allow Java server-side programming (?) [java]
CLIENTS
-------
* Have pg_dump use LEFT OUTER JOIN in multi-table SELECTs
or multiple SELECTS to avoid bad system catalog entries
* Have pg_dump -C dump database location and encoding information
* Allow psql \d to show foreign keys
* Allow psql \d to show temporary table structure
* Add XML interface: psql, pg_dump, COPY, separate server (?)
* Add config file check for $ODBCINI, $HOME/.odbc.ini, installpath/etc/odbc.ini
* JDBC
o Comprehensive test suite. This may be available already.
o Updateable resultSet (must be done in backend code)
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 Implement cancel() method on Statement
o Use cursors implicitly to avoid large results (see setCursorName())
o Add support for CallableStatements
* ECPG
o Implement set descriptor, using descriptor
o Make casts work in variable initializations
o Implement SQLDA
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)
* Allow oid to act as a foreign key
* Implement dirty reads and use them in RI triggers
* Make triggers refer to columns by number, not name
* Enforce referential integrity for system tables
* Allow user to control trigger firing order
* Change foreign key constraint for array -> element to mean element
in array
* Fix foreign key constraints to not error on intermediate db states (Stephan)
DEPENDENCY CHECKING
-------------------
* Add pg_depend table for dependency recording; use sysrelid, oid,
depend_sysrelid, depend_oid, name
* Auto-destroy sequence on DROP of table with SERIAL; perhaps a separate
SERIAL type
* Have SERIAL generate non-colliding sequence names when we have
auto-destruction
* Prevent column dropping if column is used by foreign key
* Propagate column or table renaming to foreign key constraints
* Automatically drop constraints/functions when object is dropped
* Make constraints clearer in dump file
* Make foreign keys easier to identify
* Flush cached query plans when their underlying catalog data changes
TRANSACTIONS
------------
* Allow autocommit so always in a transaction block
* Overhaul bufmgr/lockmgr/transaction manager
* Allow savepoints / nested transactions [transactions]
EXOTIC FEATURES
---------------
* Add sql3 recursive unions
* Add the concept of dataspaces/tablespaces [tablespaces]
* Allow SQL92 schemas [schema]
* 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
-----
* Cache most recent query plan(s) (Karel) [prepare]
* 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]
* Add LAZY VACUUM (Vadim) [performance]
* Provide automatic scheduling of background vacuum (Tom)
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
* Cache system catalog information in per-database files (Tom)
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
* Turn off after-change writes if fsync is disabled (?)
* Add WAL index reliability improvement to non-btree indexes
* Reorder postgresql.conf WAL items in order of importance
* Remove wal_files postgresql.conf option because WAL files are now recycled
* Find proper defaults for postgresql.conf WAL entries
* Add checkpoint_min_warning postgresql.conf option to warn about checkpoints
that are too frequent
OPTIMIZER / EXECUTOR
--------------------
* Improve Subplan list handling
* Allow Subplans to use efficient joins(hash, merge) with upper variable
* Improve dynamic memory allocation by introducing tuple-context memory
allocation (Tom)
* Add hash for evaluating GROUP BY aggregates
* Nested FULL OUTER JOINs don't work (Tom)
* Allow merge and hash joins on expressions not just simple variables (Tom)
* Add new pg_proc cachable settings to specify whether function can be
evaluated only once or once per query
* Change FIXED_CHAR_SEL to 0.20 from 0.04 to give better selectivity (Bruce)
* 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
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]
SOURCE CODE
===========
* Add use of 'const' for variables in source tree
* Fix problems with libpq non-blocking/async code [async]
* Make sure all block numbers are unsigned to increase maximum table size
* Use BlockNumber rather than int where appropriate
* Merge LockMethodCtl and LockMethodTable into one shared structure (Bruce)
* HOLDER/HOLDERTAB rename to PROCLOCK/PROCLOCKTAG (Bruce)
* Remove LockMethodTable.prio field, not used (Bruce)
* Add version file format stamp to heap and other table types
* 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
* Allow ps status display to work on Solaris/SVr4-based systems
* Make one version of simple_prompt() in code (Bruce, Tom)
* Compile in syslog functionaility by default (?)
* Modify regression tests to prevent failures do to minor numeric rounding
* Remove USING clause from pg_get_indexdef() if index is btree (Bruce)
* Use our own getopt() for FreeBSD/OpenBSD to allow --xxx flags (Bruce)
* Add OpenBSD's getpeereid() call for local socket authentication (Bruce)
* Improve access-permissions check on data directory in Cygwin (Tom)
* Report failure to find readline or zlib at end of configure run
* Add --port flag to regression tests
* Increase identifier length (NAMEDATALEN) if small performance hit,
perhaps to standard length of 128; change struct pgNotify to use pid
first, breaks notify API;
* Increase maximum number of function parameters if little wasted space
* 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
* Evaluate AIX cs() spinlock macro for performance optimizations (Tatsuo)
---------------------------------------------------------------------------
Developers who have claimed items are:
--------------------------------------
* Billy is Billy G. Allie <Bill.Allie@mug.org>
* Bruce is Bruce Momjian<pgman@candle.pha.pa.us>
* D'Arcy is D'Arcy J.M. Cain <darcy@druid.net>
* Edmund is Edmund Mergl <E.Mergl@bawue.de>
* 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>
* 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>
* 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>
