Difference between revisions of "TodoDone90"

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This list contains '''all known PostgreSQL bugs and feature requests'''. If you would like to work on an item, please read the [[Developer FAQ]] first. There is also a [[Development_information|development information page]].
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This list contains '''all PostgreSQL bugs and features requests that were solved in 9.0'''. There is a [[Todo]] page too for '''bugs and features that are still not solved'''.
 
 
* {{TodoPending}} - marks ordinary, incomplete items
 
* {{TodoEasy}} - marks items that are easier to implement
 
* {{TodoDone}} - marks changes that are done, and will appear in the next major release
 
 
 
For help on editing this list, please see [[Talk:Todo]]. <b>Please do not add items here without discussion on the mailing list.</b>
 
  
 
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Revision as of 00:44, 10 August 2010

This list contains all PostgreSQL bugs and features requests that were solved in 9.0. There is a Todo page too for bugs and features that are still not solved.

Administration

Incomplete item Allow administrators to cancel multi-statement idle transactions
This allows locks to be released, but it is complex to report the cancellation back to the client.
Incomplete item Check for unreferenced table files created by transactions that were in-progress when the server terminated abruptly
Incomplete item Set proper permissions on non-system schemas during db creation
Currently all schemas are owned by the super-user because they are copied from the template1 database. However, since all objects are inherited from the template database, it is not clear that setting schemas to the db owner is correct.
Incomplete item Allow log_min_messages to be specified on a per-module basis
This would allow administrators to see more detailed information from specific sections of the backend, e.g. checkpoints, autovacuum, etc. Another idea is to allow separate configuration files for each module, or allow arbitrary SET commands to be passed to them. See also Logging Brainstorm.
Incomplete item Simplify ability to create partitioned tables
This would allow creation of partitioned tables without requiring creation of triggers or rules for INSERT/UPDATE/DELETE, and constraints for rapid partition selection. Options could include range and hash partition selection. See also Table partitioning
Incomplete item Allow auto-selection of partitioned tables for min/max() operations
There was a patch on -hackers from July 2009, but it has not been merged: MIN/MAX optimization for partitioned table
[D] Completed itemAllow more complex user/database default GUC settings
Currently ALTER USER and ALTER DATABASE support per-user and per-database defaults. Consider adding per-user-and-database defaults so things like search_path can be defaulted for a specific user connecting to a specific database.
Incomplete item Allow custom variables to appear in pg_settings()
Incomplete item Have custom variables be transaction safe
[D] Completed itemAllow custom variables to be created only by super-users but modified by ordinary uses, where appropriate
Incomplete item Implement the SQL standard mechanism whereby REVOKE ROLE revokes only the privilege granted by the invoking role, and not those granted by other roles
Incomplete item Improve server security options
Incomplete item Prevent query cancel packets from being replayed by an attacker, especially when using SSL
Incomplete item Provide a way to query the log collector subprocess to determine what the currently active log file is
Incomplete item Allow the client to authenticate the server in a Unix-domain socket connection, e.g., using SO_PEERCRED
[D] Completed itemAllow the client to set an application_name to appear in pg_stat_activity
[D] Completed itemAllow server-side enforcement of password policies
Password checks might include password complexity or non-reuse of passwords. This facility will require the client to send password creation/changes to the server in plain-text, not MD5.
Incomplete item Allow custom daemons to be automatically stopped/started along postmaster
This allows easier administration of daemons like user job schedulers or replication-related daemons.

Configuration files

Incomplete item Allow pg_hba.conf to specify host names along with IP addresses
Host name lookup could occur when the postmaster reads the pg_hba.conf file, or when the backend starts. Another solution would be to reverse lookup the connection IP and check that hostname against the host names in pg_hba.conf. We could also then check that the host name maps to the IP address.
Incomplete item Allow postgresql.conf file values to be changed via an SQL API, perhaps using SET GLOBAL
Incomplete item Allow the server to be stopped/restarted via an SQL API
Incomplete item Consider normalizing fractions in postgresql.conf, perhaps using '%'
Incomplete item Allow Kerberos to disable stripping of realms so we can check the username@realm against multiple realms
Incomplete item Add functions to check correctness of configuration files before they are loaded "live"
Incomplete item Improve LDAP authentication configuration options
Incomplete item Add external tool to auto-tune some postgresql.conf parameters
Incomplete item Add 'hostgss' pg_hba.conf option to allow GSS link-level encryption
Incomplete item Process pg_hba.conf keywords as case-insensitive

Tablespaces

Incomplete item Allow a database in tablespace t1 with tables created in tablespace t2 to be used as a template for a new database created with default tablespace t2
Currently all objects in the default database tablespace must have default tablespace specifications. This is because new databases are created by copying directories. If you mix default tablespace tables and tablespace-specified tables in the same directory, creating a new database from such a mixed directory would create a new database with tables that had incorrect explicit tablespaces. To fix this would require modifying pg_class in the newly copied database, which we don't currently do.
Incomplete item Allow reporting of which objects are in which tablespaces
This item is difficult because a tablespace can contain objects from multiple databases. There is a server-side function that returns the databases which use a specific tablespace, so this requires a tool that will call that function and connect to each database to find the objects in each database for that tablespace.
Incomplete item Allow WAL replay of CREATE TABLESPACE to work when the directory structure on the recovery computer is different from the original
Incomplete item Allow per-tablespace quotas
[D] Completed itemAllow per-tablespace random_page_cost

Statistics Collector

Incomplete item Allow statistics last vacuum/analyze execution times to be displayed without requiring track_counts to be enabled
Incomplete item Clear table counters on TRUNCATE
Incomplete item  Allow the clearing of cluster-level statistics

Point-In-Time Recovery (PITR)

[D] Completed itemAllow a warm standby system to also allow read-only statements
[E] Incomplete item Create dump tool for write-ahead logs for use in determining transaction id for point-in-time recovery
This is useful for checking PITR recovery.
Incomplete item Allow recovery.conf to support the same syntax as postgresql.conf, including quoting
Incomplete item Allow archive_mode to be changed without server restart?
Incomplete item Consider avoiding WAL switching via archive_timeout if there has been no database activity
[E] Incomplete item Expose pg_controldata via SQL interface
Helpful for monitoring replicated databases; initial patch

SSL

Incomplete item Allow SSL authentication/encryption over unix domain sockets
Incomplete item Allow SSL key file permission checks to be optionally disabled when sharing SSL keys with other applications
Incomplete item Allow SSL CRL files to be re-read during configuration file reload, rather than requiring a server restart
Unlike SSL CRT files, CRL (Certificate Revocation List) files are updated frequently Alternatively or additionally supporting OCSP (online certificate security protocol) would provide real-time revocation discovery without reloading
Incomplete item  Allow automatic selection of SSL client certificates from a certificate store
Incomplete item  Send full certificate server chain to client

Standby server mode

Incomplete item  Allow pg_xlogfile_name() to be used in recovery mode
[D] Completed item Redefine smart shutdown in standby mode to exist as soon as all read-only connections are gone.
Incomplete item  Fix things so that any such variables inherited from the server environment are intentionally *NOT* used for making SR connections.
[D] Completed item Consider changing the calculation of superused_reserved_connections so that replication connections don't consume superuser_reserved_connections slots.
Incomplete item  Add a new privilege for connecting for streaming replication
Incomplete item  Add support for synchronous replication.
Incomplete item  Add capability to take and send a base backup over the streaming replication connection, making it possible to initialize a new standby server from a running primary server without a WAL archive or other access to the primary server.


Data Types

Incomplete item Change NUMERIC to enforce the maximum precision
Incomplete item Reduce storage space for small NUMERICs
Incomplete item Fix data types where equality comparison isn't intuitive, e.g. box
Incomplete item Add support for public SYNONYMs
Incomplete item Add support for SQL-standard GENERATED/IDENTITY columns
Incomplete item Consider placing all sequences in a single table, or create a system view
Incomplete item Consider a special data type for regular expressions
Incomplete item Reduce BIT data type overhead using short varlena headers
Incomplete item Allow adding/renaming/removing enumerated values to an existing enumerated data type
Incomplete item Support scoped IPv6 addresses in inet type
Incomplete item Add JSON (JavaScript Object Notation) data type
This would behave similar to the XML data type, which is stored as text, but allows element lookup and conversion functions.
Incomplete item Considering improving performance of computing CHAR() value lengths

Domains

Dates and Times

Incomplete item Allow infinite intervals just like infinite timestamps
Incomplete item Allow TIMESTAMP WITH TIME ZONE to store the original timezone information, either zone name or offset from UTC
If the TIMESTAMP value is stored with a time zone name, interval computations should adjust based on the time zone rules.
Incomplete item Fix SELECT '0.01 years'::interval, '0.01 months'::interval
Incomplete item Have timestamp subtraction not call justify_hours()?
Incomplete item Improve timestamptz subtraction to be DST-aware
Currently subtracting one date from another that crosses a daylight savings time adjustment can return '1 day 1 hour', but adding that back to the first date returns a time one hour in the future. This is caused by the adjustment of '25 hours' to '1 day 1 hour', and '1 day' is the same time the next day, even if daylight savings adjustments are involved.
Incomplete item Fix interval display to support values exceeding 2^31 hours
Incomplete item Add overflow checking to timestamp and interval arithmetic
[D] Completed itemRevise the src/timezone/tznames abbreviation files:
Incomplete item Add function to allow the creation of timestamps using parameters

Arrays

Incomplete item Add support for arrays of domains
Incomplete item Allow single-byte header storage for array elements
Incomplete item Add function to detect if an array is empty
Incomplete item Improve handling of empty arrays
Incomplete item Improve handling of NULLs in arrays

Binary Data

Incomplete item Improve vacuum of large objects, like contrib/vacuumlo?
[D] Completed itemAdd security checks for large objects
Incomplete item Auto-delete large objects when referencing row is deleted
contrib/lo offers this functionality.
Incomplete item Allow read/write into TOAST values like large objects
This requires the TOAST column to be stored EXTERNAL.
Incomplete item Add API for 64-bit large object access

MONEY Data Type

Incomplete item Add locale-aware MONEY type, and support multiple currencies
Incomplete item MONEY dumps in a locale-specific format making it difficult to restore to a system with a different locale
Incomplete item Allow MONEY to be easily cast to/from other numeric data types

Text Search

Incomplete item Allow dictionaries to change the token that is passed on to later dictionaries
Incomplete item Consider a function-based API for '@@' searches
Incomplete item Improve text search error messages
Incomplete item Consider changing error to warning for strings larger than one megabyte
Incomplete item tsearch and tsdicts regression tests fail in Turkish locale on glibc
Incomplete item tsquery negator operator treated as part of lexeme

XML

Incomplete item Allow xml arrays to be cast to other data types
Incomplete item Add XML Schema validation and xmlvalidate function (SQL:2008)
Incomplete item Add xmlvalidatedtd variant to support validating against a DTD?
Incomplete item Relax-NG validation; libxml2 supports this already
Incomplete item Make it work reliably for non-UTF8 server encoding (xpath()) in particular is known to not work)
Incomplete item Extra functions from SQL:2006: XMLDOCUMENT, XMLCAST, XMLTEXT
[D] Completed itemInline ORDER BY for XMLAGG. Example: "... XMLAGG(XMLELEMENT(...) ORDER BY col1) ..." (should be made to work with all aggregate functions)
Incomplete item XMLNAMESPACES support in XMLELEMENT and elsewhere
Incomplete item XSLT support; already available in contrib/xml2, but needs API fixes and adaptation to xml type.
Incomplete item XML Canonical: Convert XML documents to canonical form to compare them. libxml2 has support for this.
Incomplete item Pretty-printing XML: Parse a document and serialize it back in some indented form. libxml2 might support this.
Incomplete item XMLQUERY (from SQL/XML standard)
Incomplete item In some cases shredding could be better option (if there is no need in keeping XML docs entirely; if we have already developed tools that understand only relational data; etc) -- it would be a separate module that implements annotated schema decomposition technique, similar to DB2 and SQL Server functionality.
Incomplete item  Nested or repeated xpath() apparently mess up namespaces [1] [2] [3] [4] [5]
Incomplete item XPath: Adding the <x> at the root causes problems [6] [7] [8]
Incomplete item xpath_table needs to be implemented/implementable to get rid of contrib/xml2 [9]
Incomplete item xpath_table is pretty broken anyway [10]
Incomplete item better handling of XPath data types [11] [12]
Incomplete item xpath_exists() is needed. It checks, whether or not the path specified exists in the XML value. (W/o this function we need to use weird "array_dims(xpath(...)) IS NOT NULL" syntax.)
Incomplete item better handling of PIs and DTDs in xmlconcat() [13]

Functions

Incomplete item Allow INET subnet tests using non-constants to be indexed
Incomplete item Add INET overlaps operator, for use by exclusion constraints
Incomplete item Allow to_date() and to_timestamp() to accept localized month names
Incomplete item Add missing parameter handling in to_char()
Incomplete item Throw an error from to_char() instead of printing a string of "#" when a number doesn't fit in the desired output format.
[D] Completed itemAdd functions to get/set bit values
Incomplete item Allow to_char() on interval values to accumulate the highest unit requested
Some special format flag would be required to request such accumulation. Such functionality could also be added to EXTRACT. Prevent accumulation that crosses the month/day boundary because of the uneven number of days in a month.
  • to_char(INTERVAL '1 hour 5 minutes', 'MI') => 65
  • to_char(INTERVAL '43 hours 20 minutes', 'MI' ) => 2600
  • to_char(INTERVAL '43 hours 20 minutes', 'WK:DD:HR:MI') => 0:1:19:20
  • to_char(INTERVAL '3 years 5 months','MM') => 41
Incomplete item Allow SQL-language functions to reference parameters by parameter name
Currently SQL-language functions can only refer to dollar parameters, e.g. $1
Incomplete item Add SPI_gettypmod() to return the typemod for a TupleDesc
Incomplete item Enforce typmod for function inputs, function results and parameters for spi_prepare'd statements called from PLs
Incomplete item Allow holdable cursors in SPI
Incomplete item Tighten function permission checks
Incomplete item Fix IS OF so it matches the ISO specification, and add documentation
[D] Completed itemAdd missing operators for geometric data types
Some geometric types do not have the full suite of geometric operators, e.g. box @> point
Incomplete item Add overlaps geometric operators that ignore point overlaps
Incomplete item Implement Boyer-Moore searching in LIKE queries
Incomplete item Prevent malicious functions from being executed with the permissions of unsuspecting users
Index functions are safe, so VACUUM and ANALYZE are safe too. Triggers, CHECK and DEFAULT expressions, and rules are still vulnerable.
Incomplete item Reduce memory usage of aggregates in set returning functions
Incomplete item Fix /contrib/ltree operator
Incomplete item Fix inconsistent precedence of =, >, and < compared to <>, >=, and <=
Incomplete item Fix regular expression bug when using complex back-references
Incomplete item Have /contrib/dblink reuse unnamed connections
Incomplete item Allow calling of a procedure outside a SELECT that can control the transaction state
[D] Completed itemAdd has_sequence_privilege()
Incomplete item Improve formatting of pg_get_viewdef() output
Incomplete item Add printf()-like functionality
Incomplete item Fix to_number() handling for values not matching the format string
Incomplete item Add function to dump pg_depend information cleanly

Multi-Language Support

Incomplete item Add NCHAR (as distinguished from ordinary varchar),
Incomplete item Allow more fine-grained collation selection; add CREATE COLLATION.
Right now the collation is fixed at database creation time.
Incomplete item Add a LOCALE option to CREATE DATABASE, as a shorthand
Incomplete item Support multiple simultaneous character sets, per SQL:2008
Incomplete item Improve UTF8 combined character handling?
Incomplete item Add octet_length_server() and octet_length_client()
Incomplete item Make octet_length_client() the same as octet_length()?
Incomplete item Fix problems with wrong runtime encoding conversion for NLS message files
Incomplete item Add URL to more complete multi-byte regression tests
Incomplete item Fix contrib/fuzzystrmatch to work with multibyte encodings
Incomplete item Set client encoding based on the client operating system encoding
Currently client_encoding is set in postgresql.conf, which defaults to the server encoding.
Incomplete item Change memory allocation for multi-byte functions so memory is allocated inside conversion functions
Currently we preallocate memory based on worst-case usage.
Incomplete item Add ability to use case-insensitive regular expressions on multi-byte characters
ILIKE already works with multi-byte characters
Incomplete item Improve encoding of connection startup messages sent to the client
Currently some authentication error messages are sent in the server encoding
Incomplete item Have pg_stat_activity display query strings in the correct client encoding
Incomplete item More sensible support for Unicode combining characters, normal forms

Views / Rules

Incomplete item Automatically create rules on views so they are updateable, per SQL:2008
We can only auto-create rules for simple views. For more complex cases users will still have to write rules manually.
Incomplete item Add the functionality for WITH CHECK OPTION clause of CREATE VIEW
Incomplete item Allow VIEW/RULE recompilation when the underlying tables change
This is both difficult and controversial.
Incomplete item Make it possible to use RETURNING together with conditional DO INSTEAD rules, such as for partitioning setups
Incomplete item Add the ability to automatically create materialized views
Right now materialized views require the user to create triggers on the main table to keep the summary table current. SQL syntax should be able to manage the triggers and summary table automatically. A more sophisticated implementation would automatically retrieve from the summary table when the main table is referenced, if possible. See Materialized Views for implementation details
Incomplete item Improve ability to modify views via ALTER TABLE
Incomplete item Prevent low-cost functions from seeing unauthorized view rows

SQL Commands

Incomplete item Add CORRESPONDING BY to UNION/INTERSECT/EXCEPT
Incomplete item Add ROLLUP, CUBE, GROUPING SETS options to GROUP BY
[E] Incomplete item Allow SET CONSTRAINTS to be qualified by schema/table name
[E] Incomplete item Fix TRUNCATE ... RESTART IDENTITY so its effect on sequences is rolled back on transaction abort
Incomplete item Allow PREPARE of cursors
Incomplete item Allow finer control over the caching of prepared query plans
Currently anonymous (un-named) queries prepared via the wire protocol are replanned every time bind parameters are supplied --- allow SQL PREPARE to do the same. Also, allow control over replanning prepared queries either manually or automatically when statistics for execute parameters differ dramatically from those used during planning.
Incomplete item Improve logging of prepared transactions recovered during startup
Incomplete item Allow prepared transactions with temporary tables created and dropped in the same transaction, and when an ON COMMIT DELETE ROWS temporary table is accessed
Incomplete item Add a GUC variable to warn about non-standard SQL usage in queries
Incomplete item Add SQL-standard MERGE/REPLACE/UPSERT command
MERGE is typically used to merge two tables. REPLACE or UPSERT command does UPDATE, or on failure, INSERT. See SQL MERGE for notes on the implementation details.
Incomplete item Add NOVICE output level for helpful messages like automatic sequence/index creation
Incomplete item Add GUC to issue notice about statements that use unjoined tables
Incomplete item Allow EXPLAIN to identify tables that were skipped because of constraint_exclusion
[D] Completed itemAllow EXPLAIN output to be more easily processed by scripts, perhaps XML
Incomplete item Enable standard_conforming_strings by default in 9.1?
When this is done, backslash-quote should be prohibited in non-E'' strings because of possible confusion over how such strings treat backslashes. Basically, '' is always safe for a literal single quote, while \' might or might not be based on the backslash handling rules.
Incomplete item Simplify dropping roles that have objects in several databases
Incomplete item Allow the count returned by SELECT, etc to be represented as an int64 to allow a higher range of values
Incomplete item Add support for WITH RECURSIVE ... CYCLE
Incomplete item Add DEFAULT .. AS OWNER so permission checks are done as the table owner
This would be useful for SERIAL nextval() calls and CHECK constraints.
Incomplete item Allow DISTINCT to work in multiple-argument aggregate calls
Incomplete item Add column to pg_stat_activity that shows the progress of long-running commands like CREATE INDEX and VACUUM
Incomplete item Allow INSERT/UPDATE/DELETE ... RETURNING inside a SELECT 'FROM' clause or target list
Actually it would be saner to allow this in WITH
Incomplete item Allow INSERT/UPDATE/DELETE ... RETURNING in common table expressions
Incomplete item Add comments on system tables/columns using the information in catalogs.sgml
Ideally the information would be pulled from the SGML file automatically.
Incomplete item Prevent the specification of conflicting transaction read/write options
Incomplete item Support LATERAL subqueries
Lateral subqueries can reference columns of tables defined outside the subquery at the same level, i.e. laterally. For example, a LATERAL subquery in a FROM clause could reference tables defined in the same FROM clause. Currently only the columns of tables defined above subqueries are recognized.
[D] Completed itemForbid COMMENT on columns of an index
Postgres currently allows comments to be placed on the columns of an index, but pg_dump doesn't handle them and the column names themselves are implementation-dependent.
Incomplete item Add support for functional dependencies
This would allow omitting GROUP BY columns when grouping by the primary key.
Incomplete item Optimize ON COMMIT DELETE ROWS
Currently deletions are excessively performed

CREATE

Incomplete item Allow CREATE TABLE AS to determine column lengths for complex expressions like SELECT col1
Incomplete item Have WITH CONSTRAINTS also create constraint indexes
Incomplete item Move NOT NULL constraint information to pg_constraint
Currently NOT NULL constraints are stored in pg_attribute without any designation of their origins, e.g. primary keys. One manifest problem is that dropping a PRIMARY KEY constraint does not remove the NOT NULL constraint designation. Another issue is that we should probably force NOT NULL to be propagated from parent tables to children, just as CHECK constraints are. (But then does dropping PRIMARY KEY affect children?)
Incomplete item Prevent concurrent CREATE TABLE from sometimes returning a cryptic error message
[D] Completed itemAdd CREATE TABLE LIKE ... INCLUDING COMMENTS
Incomplete item Allow CREATE TABLE to optionally create a table if it does not already exist, without throwing an error
The fact that tables contain data makes this more complex than other CREATE OR REPLACE operations.
Incomplete item Add CREATE SCHEMA ... LIKE that copies a schema
[D] Completed itemHave CREATE TABLE LIKE copy column storage parameters
Incomplete item CREATE OR REPLACE FUNCTION might leave dependent objects depending on the function in inconsistent state
Incomplete item Allow temporary tables to exist as empty by default in all sessions
[D] Completed itemAdd OR REPLACE to CREATE LANGUAGE
Incomplete item Allow the creation of "distinct" types
Incomplete item Consider analyzing temporary tables when they are first used in a query
Autovacuum cannot analyze or vacuum temporary tables.

UPDATE

Incomplete item Allow UPDATE tab SET ROW (col, ...) = (SELECT...)
Incomplete item Research self-referential UPDATEs that see inconsistent row versions in read-committed mode
Incomplete item Improve performance of EvalPlanQual mechanism that rechecks already-updated rows
This is related to the previous item, which questions whether it even has the right semantics

ALTER

Incomplete item Have ALTER TABLE RENAME rename SERIAL sequence names
[E] Incomplete item Allow ALTER TABLE ... ALTER CONSTRAINT ... RENAME
Incomplete item Add ALTER TABLE RENAME CONSTRAINT
Incomplete item Have ALTER SEQUENCE RENAME rename the sequence name stored in the sequence table
Incomplete item Add ALTER DOMAIN to modify the underlying data type
[E] Incomplete item Allow ALTER TABLE to change constraint deferrability and actions
Incomplete item Add missing object types for ALTER ... SET SCHEMA
Incomplete item Allow ALTER TABLESPACE to move to different directories
Incomplete item Allow moving system tables to other tablespaces, where possible
Currently non-global system tables must be in the default database tablespace. Global system tables can never be moved.
Incomplete item Have ALTER INDEX update the name of a constraint using that index
Incomplete item Allow column display reordering by recording a display, storage, and permanent id for every column?
Incomplete item Allow an existing index to be marked as a table's primary key
Incomplete item Allow ALTER TYPE on composite types to perform operations similar to ALTER TABLE
Incomplete item Don't require table rewrite on ALTER TABLE ... ALTER COLUMN TYPE, when the old and new data types are binary compatible
Incomplete item Reduce locking required for ALTER commands

CLUSTER

Incomplete item Automatically maintain clustering on a table
This might require some background daemon to maintain clustering during periods of low usage. It might also require tables to be only partially filled for easier reorganization. Another idea would be to create a merged heap/index data file so an index lookup would automatically access the heap data too. A third idea would be to store heap rows in hashed groups, perhaps using a user-supplied hash function.
[E] Incomplete item Add default clustering to system tables
To do this, determine the ideal cluster index for each system table and set the cluster setting during initdb.
Incomplete item Improve CLUSTER performance by sorting to reduce random I/O
[E] Incomplete item Make CLUSTER VERBOSE more verbose.
It is also used by new VACUUM FULL VERBOSE.

COPY

Incomplete item Allow COPY to report error lines and continue
This requires the use of a savepoint before each COPY line is processed, with ROLLBACK on COPY failure.
Incomplete item Allow COPY on a newly-created table to skip WAL logging
On crash recovery, the table involved in the COPY would be removed or have its heap and index files truncated. One issue is that no other backend should be able to add to the table at the same time, which is something that is currently allowed. This currently is done if the table is created inside the same transaction block as the COPY because no other backends can see the table.
Incomplete item Allow COPY FROM to create index entries in bulk
Incomplete item Allow COPY in CSV mode to control whether a quoted zero-length string is treated as NULL
Currently this is always treated as a zero-length string, which generates an error when loading into an integer column
Incomplete item Improve COPY performance
Incomplete item Allow COPY to report errors sooner
[D] Completed itemImprove bytea COPY format
Incomplete item Allow COPY to handle other number formats eg. the German notation. Best would be something like WITH DECIMAL ','.
Incomplete item Allow a stalled COPY to exit if the backend is terminated

GRANT/REVOKE

[D] Completed itemAllow GRANT/REVOKE permissions to be applied to all schema objects with one command
The proposed syntax is: GRANT SELECT ON ALL TABLES IN public TO phpuser; GRANT SELECT ON NEW TABLES IN public TO phpuser;
[D] Completed itemAllow GRANT/REVOKE permissions to be inherited by objects based on schema permissions
Incomplete item Allow SERIAL sequences to inherit permissions from the base table?
Incomplete item Allow dropping of a role that has connection rights

DECLARE CURSOR

Incomplete item Prevent DROP TABLE from dropping a table referenced by its own open cursor?
Incomplete item Provide some guarantees about the behavior of cursors that invoke volatile functions

INSERT

Incomplete item Allow INSERT/UPDATE of the system-generated oid value for a row
Incomplete item In rules, allow VALUES() to contain a mixture of 'old' and 'new' references

SHOW/SET

Incomplete item Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM ANALYZE, and CLUSTER
Incomplete item Rationalize the discrepancy between settings that use values in bytes and SHOW that returns the object count

LISTEN/NOTIFY

[D] Completed itemAllow LISTEN/NOTIFY to store info in memory rather than tables
Currently LISTEN/NOTIFY information is stored in pg_listener. Storing such information in memory would improve performance.
[D] Completed itemAdd optional textual message to NOTIFY
This would allow an informational message to be added to the notify message, perhaps indicating the row modified or other custom information.
Incomplete item Allow NOTIFY in rules involving conditionals

Window Functions

See TODO items for window functions.

Incomplete item Support creation of user-defined window functions.
We have the ability to create new window functions written in C. Is it worth the effort to create an API that would let them be written in PL/pgsql, etc?
Incomplete item Implement full support for window framing clauses.
In addition to done clauses described in the latest doc, these clauses are not implemented yet.
  • RANGE BETWEEN ... PRECEDING/FOLLOWING
  • EXCLUDE
Incomplete item Look at tuplestore performance issues.
The tuplestore_in_memory() thing is just a band-aid, we ought to try to solve it properly. tuplestore_advance seems like a weak spot as well.
Incomplete item Do we really need so much duplicated code between Agg and WindowAgg?
Incomplete item Teach planner to evaluate multiple windows in the optimal order.
Currently windows are always evaluated in the query-specified order.
Incomplete item Implement DISTINCT clause in window aggregates.
Some proprietary RDBMSs have implemented it already, so it helps with porting from those.

Integrity Constraints

Keys

[D] Completed itemAllow DEFERRABLE UNIQUE constraints
This would allow UPDATE tab SET col = col + 1 to work if col has a unique index. Currently, uniqueness checks are done while the command is being executed, rather than at the end of the statement or transaction.
Incomplete item Improve deferrable unique constraints for cases with many conflicts
The current implementation fires a trigger for each potentially conflicting row. This might not scale well for an update that changes many key values at once.

Referential Integrity

Incomplete item Add MATCH PARTIAL referential integrity
Incomplete item Change foreign key constraint for array -> element to mean element in array?
Incomplete item Fix problem when cascading referential triggers make changes on cascaded tables, seeing the tables in an intermediate state
Incomplete item Optimize referential integrity checks

Server-Side Languages

Incomplete item Add support for polymorphic arguments and return types to languages other than PL/PgSQL
Incomplete item Add capability to create and call PROCEDURES
Incomplete item Add support for OUT and INOUT parameters to languages other than PL/PgSQL
Incomplete item Add more fine-grained specification of functions taking arbitrary data types
Incomplete item Add support for returning multiple result sets?

PL/pgSQL

[D] Completed itemAllow function parameters to be passed by name, get_employee_salary(12345 AS emp_id, 2001 AS tax_year)
Incomplete item Allow handling of %TYPE arrays, e.g. tab.col%TYPE[]
Incomplete item Allow listing of record column names, and access to record columns via variables, e.g. columns := r.(*), tval2 := r.(colname)
Incomplete item Add support for SCROLL cursors
Incomplete item Add support for WITH HOLD cursors
Incomplete item Allow row and record variables to be set to NULL constants, and allow NULL tests on such variables
Because a row is not scalar, do not allow assignment from NULL-valued scalars.
[D] Completed itemReview handling of MOVE and FETCH
[D] Completed itemImprove logic of determining if an identifier is a variable or a column name
Incomplete item Consider keeping separate cached copies when search_path changes
[D] Completed itemImprove PL/pgSQL's ability to cope with rowtypes containing dropped columns
Incomplete item Improve handling of NULL row values vs. NULL rows

PL/Perl

Incomplete item Allow data to be passed in native language formats, rather than only text
Incomplete item Allow regex operations in plperl using UTF8 characters in non-UTF8 encoded databases.

PL/Python

Incomplete item Add table function support
Incomplete item Add tracebacks
[D] Completed itemAdd support for Python 3
Incomplete item Develop a trusted variant of PL/Python.
[D] Completed itemAllow arrays as function arguments and return values.
Incomplete item Create a new restricted execution class that will allow passing function arguments in as locals. Passing them as globals means functions cannot be called recursively.
Incomplete item Functions cache the input and output functions for their arguments, so the following will make PostgreSQL unhappy: create table users (first_name text, last_name text); create function user_name(user) returns text as 'mycode' language plpython; select user_name(user) from users; alter table add column user_id integer; select user_name(user) from users; You have to drop and create the function(s) each time its arguments are modified (not nice), or don't cache the input and output functions (slower?), or check if the structure of the argument has been altered (is this possible, easy, quick?) and recreate cache.
Incomplete item Better documentation
Incomplete item Add a DB-API compliant interface on top of the SPI interface.
[D] Completed itemcheck encoding validity of values passed back to Postgres in function returns, trigger tuple changes, or SPI calls.

PL/Tcl

Incomplete item Add table function support
Incomplete item check encoding validity of values passed back to Postgres in function returns, trigger tuple changes, or SPI calls.

Clients

Incomplete item Add a function like pg_get_indexdef() that report more detailed index information

pg_ctl

Incomplete item Allow pg_ctl to work properly with configuration files located outside the PGDATA directory
pg_ctl can not read the pid file because it isn't located in the config directory but in the PGDATA directory. The solution is to allow pg_ctl to read and understand postgresql.conf to find the data_directory value.
Incomplete item Have the postmaster write a random number to a file on startup that pg_ctl checks against the contents of a pg_ping response on its initial connection (without login)
This will protect against connecting to an old instance of the postmaster in a different or deleted subdirectory.
Incomplete item Modify pg_ctl behavior and exit codes to make it easier to write an LSB conforming init script
It may be desirable to condition some of the changes on a command-line switch, to avoid breaking existing scripts. A Linux shell (sh) script is referenced which has been tested and seems to provide a high degree of conformance in multiple environments. Study of this script might suggest areas where pg_ctl could be modified to make writing an LSB conforming script easier; however, some aspects of that script would be unnecessary with other suggested changes to pg_ctl, and discussion on the lists did not reach consensus on support for all aspects of this script. Further discussion of particular changes is needed before beginning any work. These threads should be studied for other ideas on improvements:

psql

Incomplete item Have psql \ds show all sequences and their settings
Incomplete item Have \d on a sequence indicate if the sequences is owned by a table
Incomplete item Move psql backslash database information into the backend, use mnemonic commands?
This would allow non-psql clients to pull the same information out of the database as psql.
Incomplete item Make psql's \d commands more consistent in its handling of schemas
Incomplete item Consistently display privilege information for all objects in psql
Incomplete item Add auto-expanded mode so expanded output is used if the row length is wider than the screen width.
Consider using auto-expanded mode for backslash commands like \df+.
Incomplete item Prevent tab completion of SET TRANSACTION from querying the database and therefore preventing the transaction isolation level from being set.
Currently SET <tab> causes a database lookup to check all supported session variables. This query causes problems because setting the transaction isolation level must be the first statement of a transaction.
Incomplete item Add a \set variable to control whether \s displays line numbers
Another option is to add \# which lists line numbers, and allows command execution.
Incomplete item Prevent escape string warnings when object names have backslashes
Incomplete item Have \d show child tables that inherit from the specified parent
Incomplete item Include the symbolic SQLSTATE name in verbose error reports
Incomplete item Add prompt escape to display the client and server versions
Incomplete item Add option to wrap column values at whitespace boundaries, rather than chopping them at a fixed width.
Currently, "wrapped" format chops values into fixed widths. Perhaps the word wrapping could use the same algorithm documented in the W3C specification.
Incomplete item Add "auto" expanded mode that outputs in expanded format if "wrapped" mode can't wrap the output to the screen width
Incomplete item Support the ReST table output format
Details about the ReST format: http://docutils.sourceforge.net/rst.html#reference-documentation
Incomplete item Add option to print advice for people familiar with other databases
Incomplete item Consider showing TOAST and index sizes in \dt+
Incomplete item Allow \dd to show constraint comments
Incomplete item Add ability to edit views with \ev
Incomplete item Add \dL to show languages
[E] Incomplete item Distinguish between unique indexes and unique constraints in \d+
Incomplete item Fix FETCH_COUNT to handle SELECT ... INTO and WITH queries
Incomplete item Prevent psql from sending remaining single-line multi-statement queries after reconnecting

pg_dump / pg_restore

[D] Completed itemAdd dumping of comments on composite type columns
[E] Incomplete item Add full object name to the tag field. eg. for operators we need '=(integer, integer)', instead of just '='.
[D] Completed item Add comments to output indicating version of pg_dump and of the database server
Incomplete item Add pg_dumpall custom format dumps?
Incomplete item Avoid using platform-dependent locale names in pg_dumpall output
Using native locale names puts roadblocks in the way of porting a dump to another platform. One possible solution is to get CREATE DATABASE to accept some agreed-on set of locale names and fix them up to meet the platform's requirements.
Incomplete item Allow selection of individual object(s) of all types, not just tables
Incomplete item In a selective dump, allow dumping of an object and all its dependencies
Incomplete item Add options like pg_restore -l and -L to pg_dump
Incomplete item Add support for multiple pg_restore -t options, like pg_dump
pg_restore's -t switch is less useful than pg_dump's in quite a few ways: no multiple switches, no pattern matching, no ability to pick up indexes and other dependent items for a selected table. It should be made to handle this switch just like pg_dump does.
Incomplete item Stop dumping CASCADE on DROP TYPE commands in clean mode
Incomplete item Allow pg_dump --clean to drop roles that own objects or have privileges
tgl says: if this is about pg_dumpall, it's done as of 8.4. If it's really about pg_dump, what does it mean? pg_dump has no business dropping roles.
Incomplete item Remove unnecessary function pointer abstractions in pg_dump source code
Incomplete item Allow pg_dump to utilize multiple CPUs and I/O channels by dumping multiple objects simultaneously
The difficulty with this is getting multiple dump processes to produce a single dump output file. It also would require several sessions to share the same snapshot.
Incomplete item Allow pg_restore to load different parts of the COPY data for a single table simultaneously
Incomplete item Remove support for dumping from pre-7.3 servers
In 7.3 and later, we can get accurate dependency information from the server. pg_dump still contains a lot of crufty code to try to deal with the lack of dependency info in older servers, but the usefulness of maintaining that code grows small.
Incomplete item Allow pre/data/post files when schema and data are dumped separately, for performance reasons
Incomplete item Refactor handling of database attributes between pg_dump and pg_dumpall
Currently only pg_dumpall emits database attributes, such as ALTER DATABASE SET commands and database-level GRANTs. Many people wish that pg_dump would do that. One proposal is to let pg_dump issue such commands if the -C switch was used, but it's unclear whether that will satisfy the demand.
Incomplete item Change pg_dump so that a comment on the dumped database is applied to the loaded database, even if the database has a different name.
This will require new backend syntax, perhaps COMMENT ON CURRENT DATABASE. This is related to the previous item.
Incomplete item Allow parallel restore of tar dumps

ecpg

Incomplete item Docs
Document differences between ecpg and the SQL standard and information about the Informix-compatibility module.
Incomplete item Solve cardinality > 1 for input descriptors / variables?
Incomplete item Add a semantic check level, e.g. check if a table really exists
Incomplete item fix handling of DB attributes that are arrays
[D] Completed itemImplement SQLDA
add sqlda support to ecpg in both native and compatibility mode
Incomplete item Fix nested C comments
[E] Incomplete item sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified
Incomplete item Make SET CONNECTION thread-aware, non-standard?
Incomplete item Allow multidimensional arrays
Incomplete item Implement COPY FROM STDIN
Incomplete item Provide a way to specify size of a bytea parameter
[E] Incomplete item Fix small memory leaks in ecpg
Memory leaks in a short running application like ecpg are not really a problem, but make debugging more complicated
Incomplete item Allow re-usage of cursor name variables

libpq

[D] Completed itemAdd PQescapeIdentifier()
Incomplete item Prevent PQfnumber() from lowercasing unquoted column names
PQfnumber() should never have been doing lowercasing, but historically it has so we need a way to prevent it
Incomplete item Allow statement results to be automatically batched to the client
Currently all statement results are transferred to the libpq client before libpq makes the results available to the application. This feature would allow the application to make use of the first result rows while the rest are transferred, or held on the server waiting for them to be requested by libpq. One complexity is that a statement like SELECT 1/col could error out mid-way through the result set.
Incomplete item Consider disallowing multiple queries in PQexec() as an additional barrier to SQL injection attacks
Incomplete item Add PQexecf() that allows complex parameter substitution
Incomplete item Add SQLSTATE and severity to errors generated within libpq itself
Incomplete item Add code to detect client encoding and locale from the operating system environment
[D] Completed itemAdd keepalive support to libpq
Incomplete item Add support for interface/ipaddress binding to libpq

Triggers

Incomplete item Improve storage of deferred trigger queue
Right now all deferred trigger information is stored in backend memory. This could exhaust memory for very large trigger queues. This item involves dumping large queues into files, or doing some kind of join to process all the triggers, some bulk operation, or a bitmap.
Incomplete item Allow triggers to be disabled in only the current session.
This is currently possible by starting a multi-statement transaction, modifying the system tables, performing the desired SQL, restoring the system tables, and committing the transaction. ALTER TABLE ... TRIGGER requires a table lock so it is not ideal for this usage.
Incomplete item With disabled triggers, allow pg_dump to use ALTER TABLE ADD FOREIGN KEY
If the dump is known to be valid, allow foreign keys to be added without revalidating the data.
Incomplete item Allow statement-level triggers to access modified rows
Incomplete item When statement-level triggers are defined on a parent table, have them fire only on the parent table, and fire child table triggers only where appropriate
[D] Completed itemSupport triggers on columns
Incomplete item Allow AFTER triggers on system tables
System tables are modified in many places in the backend without going through the executor and therefore not causing triggers to fire. To complete this item, the functions that modify system tables will have to fire triggers.
Incomplete item Tighten trigger permission checks
Incomplete item Allow BEFORE INSERT triggers on views
Incomplete item Add database and transaction-level triggers
Incomplete item Reduce locking requirements for creating a trigger

Inheritance

Incomplete item Allow inherited tables to inherit indexes, UNIQUE constraints, and primary/foreign keys
Incomplete item Honor UNIQUE INDEX on base column in INSERTs/UPDATEs on inherited table, e.g. INSERT INTO inherit_table (unique_index_col) VALUES (dup) should fail
The main difficulty with this item is the problem of creating an index that can span multiple tables.
Incomplete item Determine whether ALTER TABLE / SET SCHEMA should work on inheritance hierarchies (and thus support ONLY). If yes, implement it.
Incomplete item ALTER TABLE variants sometimes support recursion and sometimes not, but this is poorly/not documented, and the ONLY marker would then be silently ignored. Clarify the documentation, and reject ONLY if it is not supported.

Indexes

Incomplete item Prevent index uniqueness checks when UPDATE does not modify the column
Uniqueness (index) checks are done when updating a column even if the column is not modified by the UPDATE. However, HOT already short-circuits this in common cases, so more work might not be helpful.
Incomplete item Allow the creation of on-disk bitmap indexes which can be quickly combined with other bitmap indexes
Such indexes could be more compact if there are only a few distinct values. Such indexes can also be compressed. Keeping such indexes updated can be costly.
Incomplete item Allow accurate statistics to be collected on indexes with more than one column or expression indexes, perhaps using per-index statistics
Incomplete item Consider having a larger statistics target for indexed columns and expression indexes.
Incomplete item Consider smaller indexes that record a range of values per heap page, rather than having one index entry for every heap row
This is useful if the heap is clustered by the indexed values.
Incomplete item Add REINDEX CONCURRENTLY, like CREATE INDEX CONCURRENTLY
This is difficult because you must upgrade to an exclusive table lock to replace the existing index file. CREATE INDEX CONCURRENTLY does not have this complication. This would allow index compaction without downtime.
Incomplete item Allow multiple indexes to be created concurrently, ideally via a single heap scan
pg_restore allows parallel index builds, but it is done via subprocesses, and there is no SQL interface for this.
Incomplete item Consider sorting entries before inserting into btree index
Incomplete item Allow index scans to return matching index keys, not just the matching heap locations
Incomplete item Allow creation of an index that can do comparisons to test if a value is between two column values
Incomplete item Consider using "effective_io_concurrency" for index scans
  • Currently only bitmap scans use this, which might be fine because most multi-row index scans use bitmap scans.

GIST

Incomplete item Add more GIST index support for geometric data types
Incomplete item Allow GIST indexes to create certain complex index types, like digital trees (see Aoki)
Incomplete item Fix performance issues in contrib/seg and contrib/cube GiST support

GIN

Incomplete item Support empty indexed values (such as zero-element arrays) properly
Incomplete item Behave correctly for cases where some elements of an indexed value are NULL
Incomplete item Support queries that require a full scan

Hash

Incomplete item Add UNIQUE capability to hash indexes
[D] Completed itemPack hash index buckets onto disk pages more efficiently
Currently only one hash bucket can be stored on a page. Ideally several hash buckets could be stored on a single page and greater granularity used for the hash algorithm. However, the binary searching within a hash page probably renders this issue moot.
Incomplete item Add hash WAL logging for crash recovery
Incomplete item Allow multi-column hash indexes

Catalogs

[D] Completed itemImprove performance of information_schema views
[D] Completed itemImprove information_schema's entries for precision and scale

Sorting

Incomplete item Consider whether duplicate keys should be sorted by block/offset
Incomplete item Consider being smarter about memory and external files used during sorts
Incomplete item Consider detoasting keys before sorting

Fsync

Incomplete item Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
Ideally this requires a separate test program that can be run at initdb time or optionally later. Consider O_SYNC when O_DIRECT exists.
Incomplete item Add program to test if fsync has a delay compared to non-fsync
Incomplete item Consider sorting writes during checkpoint

Cache Usage

Incomplete item Speed up COUNT(*)
We could use a fixed row count and a +/- count to follow MVCC visibility rules, or a single cached value could be used and invalidated if anyone modifies the table. Another idea is to get a count directly from a unique index, but for this to be faster than a sequential scan it must avoid access to the heap to obtain tuple visibility information.
Incomplete item Provide a way to calculate an "estimated COUNT(*)"
Perhaps by using the optimizer's cardinality estimates or random sampling.
Incomplete item Allow data to be pulled directly from indexes
Currently indexes do not have enough tuple visibility information to allow data to be pulled from the index without also accessing the heap. One way to allow this is to set a bit on index tuples to indicate if a tuple is currently visible to all transactions when the first valid heap lookup happens. This bit would have to be cleared when a heap tuple is expired. Another idea is to maintain a bitmap of heap pages where all rows are visible to all backends, and allow index lookups to reference that bitmap to avoid heap lookups, perhaps the same bitmap we might add someday to determine which heap pages need vacuuming. Frequently accessed bitmaps would have to be stored in shared memory. One 8k page of bitmaps could track 512MB of heap pages. A third idea would be for a heap scan to check if all rows are visible and if so set a per-table flag which can be checked by index scans. Any change to the table would have to clear the flag. To detect changes during the heap scan a counter could be set at the start and checked at the end --- if it is the same, the table has not been modified --- any table change would increment the counter.
Incomplete item Consider automatic caching of statements at various levels:
  • Parsed query tree
  • Query execute plan
  • Query results
Incomplete item Consider increasing internal areas (NUM_CLOG_BUFFERS) when shared buffers is increased
Incomplete item Consider decreasing the amount of memory used by PrivateRefCount
Incomplete item Consider allowing higher priority queries to have referenced buffer cache pages stay in memory longer

Vacuum

[D] Completed itemImprove VACUUM FULL's speed when major data movement is needed
For large table adjustments during VACUUM FULL, it would be faster to cluster or reindex rather than update the indexes piecemeal as it does now. Also, this behavior tends to bloat the indexes.
Incomplete item Auto-fill the free space map by scanning the buffer cache or by checking pages written by the background writer
Incomplete item Consider having single-page pruning update the visibility map
Incomplete item Improve tracking of total relation tuple counts now that vacuum doesn't always scan the whole heap
Incomplete item Bias FSM towards returning free space near the beginning of the heap file, in hopes that empty pages at the end can be truncated by VACUUM
Incomplete item Make FSM return free space based on table clustering, to assist in maintaining clustering?
Incomplete item Consider a more compact data representation for dead tuple locations within VACUUM
Incomplete item Provide more information in order to improve user-side estimates of dead space bloat in relations

Auto-vacuum

[E] Incomplete item Issue log message to suggest VACUUM FULL if a table is nearly empty?
Incomplete item Prevent long-lived temporary tables from causing frozen-xid advancement starvation
The problem is that autovacuum cannot vacuum them to set frozen xids; only the session that created them can do that.
Incomplete item Prevent autovacuum from running if an old transaction is still running from the last vacuum
Incomplete item Have free space allocation bias away from using trailing table pages
This improves the chances of truncating the table during vacuum
Incomplete item Have autoanalyze of parent tables occur when child tables are modified

Locking

Incomplete item Fix priority ordering of read and write light-weight locks
Incomplete item Fix problem when multiple subtransactions of the same outer transaction hold different types of locks, and one subtransaction aborts
Incomplete item Allow UPDATEs on only non-referential integrity columns not to conflict with referential integrity locks
Incomplete item Add idle_in_transaction_timeout GUC so locks are not held for long periods of time
Incomplete item Improve deadlock detection when a page cleaning lock conflicts with a shared buffer that is pinned
Incomplete item Detect deadlocks involving LockBufferForCleanup()
Incomplete item Consider a lock timeout parameter
Incomplete item Consider improving serialized transaction behavior to avoid anomalies

Startup Time Improvements

Incomplete item Experiment with multi-threaded backend for backend creation
This would prevent the overhead associated with process creation. Most operating systems have trivial process creation time compared to database startup overhead, but a few operating systems (Win32, Solaris) might benefit from threading. Also explore the idea of a single session using multiple threads to execute a statement faster.

Write-Ahead Log

Incomplete item Eliminate need to write full pages to WAL before page modification
Currently, to protect against partial disk page writes, we write full page images to WAL before they are modified so we can correct any partial page writes during recovery. These pages can also be eliminated from point-in-time archive files.
Incomplete item When full page writes are off, write CRC to WAL and check file system blocks on recovery
If CRC check fails during recovery, remember the page in case a later CRC for that page properly matches.
Incomplete item Write full pages during file system write and not when the page is modified in the buffer cache
This allows most full page writes to happen in the background writer. It might cause problems for applying WAL on recovery into a partially-written page, but later the full page will be replaced from WAL.
[D] Completed itemAllow WAL traffic to be streamed to another server for stand-by replication
Incomplete item Reduce WAL traffic so only modified values are written rather than entire rows
Incomplete item Allow WAL information to recover corrupted pg_controldata
Incomplete item Find a way to reduce rotational delay when repeatedly writing last WAL page
Currently fsync of WAL requires the disk platter to perform a full rotation to fsync again. One idea is to write the WAL to different offsets that might reduce the rotational delay.
Incomplete item Allow WAL logging to be turned off for a table, but the table might be dropped or truncated during crash recovery
Allow tables to bypass WAL writes and just fsync() dirty pages on commit. This should be implemented using ALTER TABLE, e.g. ALTER TABLE PERSISTENCE [ DROP | TRUNCATE | DEFAULT ]. Tables using non-default logging should not use referential integrity with default-logging tables. A table without dirty buffers during a crash could perhaps avoid the drop/truncate.
Incomplete item Allow WAL logging to be turned off for a table, but the table would avoid being truncated/dropped
To do this, only a single writer can modify the table, and writes must happen only on new pages so the new pages can be removed during crash recovery. Readers can continue accessing the table. Such tables probably cannot have indexes. One complexity is the handling of indexes on TOAST tables.
Incomplete item Speed WAL recovery by allowing more than one page to be prefetched
This should be done utilizing the same infrastructure used for prefetching in general to avoid introducing complex error-prone code in WAL replay.
Incomplete item Improve WAL concurrency by increasing lock granularity
Incomplete item Be more aggressive about creating WAL files
Incomplete item Have resource managers report the duration of their status changes
Incomplete item Move pgfoundry's xlogdump to /contrib and have it rely more closely on the WAL backend code
Incomplete item Close deleted WAL files held open in *nix by long-lived read-only backends

Optimizer / Executor

Incomplete item Improve selectivity functions for geometric operators
Incomplete item Precompile SQL functions to avoid overhead
Incomplete item Create utility to compute accurate random_page_cost value
Incomplete item Consider increasing the default values of from_collapse_limit, join_collapse_limit, and/or geqo_threshold
Incomplete item Improve ability to display optimizer analysis using OPTIMIZER_DEBUG
Incomplete item Have EXPLAIN ANALYZE issue NOTICE messages when the estimated and actual row counts differ by a specified percentage
Incomplete item Have EXPLAIN ANALYZE report rows as floating-point numbers
Incomplete item Log statements where the optimizer row estimates were dramatically different from the number of rows actually found?
Incomplete item Improve how ANALYZE computes in-doubt tuples
Incomplete item Consider compressed annealing to search for query plans
This might replace GEQO.
Incomplete item Consider using a hash for joining to a large IN (VALUES ...) list
Incomplete item Allow single batch hash joins to preserve outer pathkeys
Incomplete item "lazy" hash tables - look up only the tuples that are actually requested
Incomplete item Avoid building the same hash table more than once during the same query
Incomplete item Avoid hashing for distinct and then re-hashing for hash join
Incomplete item Allow hashing to be used on arrays, if the element type is hashable
Incomplete item Improve use of expression indexes for ORDER BY

Background Writer

Incomplete item Consider having the background writer update the transaction status hint bits before writing out the page
Implementing this requires the background writer to have access to system catalogs and the transaction status log.
Incomplete item Consider adding buffers the background writer finds reusable to the free list
Incomplete item Automatically tune bgwriter_delay based on activity rather then using a fixed interval
Incomplete item Consider whether increasing BM_MAX_USAGE_COUNT improves performance
Incomplete item Test to see if calling PreallocXlogFiles() from the background writer will help with WAL segment creation latency

Concurrent Use of Resources

Incomplete item Do async I/O for faster random read-ahead of data
Async I/O allows multiple I/O requests to be sent to the disk with results coming back asynchronously. The above patch is already applied as of 8.4, but it still remains to figure out how to handle plain indexscans effectively.
Incomplete item Experiment with multi-threaded backend for better I/O utilization
This would allow a single query to make use of multiple I/O channels simultaneously. One idea is to create a background reader that can pre-fetch sequential and index scan pages needed by other backends. This could be expanded to allow concurrent reads from multiple devices in a partitioned table.
Incomplete item Experiment with multi-threaded backend for better CPU utilization
This would allow several CPUs to be used for a single query, such as for sorting or query execution.
Incomplete item SMP scalability improvements

TOAST

Incomplete item Allow user configuration of TOAST thresholds
Incomplete item Reduce unnecessary cases of deTOASTing
Incomplete item Reduce costs of repeat de-TOASTing of values

Miscellaneous Performance

Incomplete item Use mmap() rather than SYSV shared memory or to write WAL files?
This would remove the requirement for SYSV SHM but would introduce portability issues. Anonymous mmap (or mmap to /dev/zero) is required to prevent I/O overhead.
Incomplete item Consider mmap()'ing files into a backend?
Doing I/O to large tables would consume a lot of address space or require frequent mapping/unmapping. Extending the file also causes mapping problems that might require mapping only individual pages, leading to thousands of mappings. Another problem is that there is no way to _prevent_ I/O to disk from the dirty shared buffers so changes could hit disk before WAL is written.
Incomplete item Add a script to ask system configuration questions and tune postgresql.conf
Incomplete item Consider ways of storing rows more compactly on disk:
  • Reduce the row header size?
  • Consider reducing on-disk varlena length from four bytes to two because a heap row cannot be more than 64k in length
Incomplete item Consider transaction start/end performance improvements
Incomplete item Allow configuration of backend priorities via the operating system
Though backend priorities make priority inversion during lock waits possible, research shows that this is not a huge problem.
Incomplete item Consider increasing the minimum allowed number of shared buffers
Incomplete item Consider if CommandCounterIncrement() can avoid its AcceptInvalidationMessages() call
Incomplete item Consider Cartesian joins when both relations are needed to form an indexscan qualification for a third relation
Incomplete item Consider not storing a NULL bitmap on disk if all the NULLs are trailing
Incomplete item Sort large UPDATE/DELETEs so it is done in heap order
Incomplete item Allow one transaction to see tuples using the snapshot of another transaction
This would assist multiple backends in working together.
Incomplete item Consider decreasing the I/O caused by updating tuple hint bits
Incomplete item Avoid the requirement of freezing pages that are infrequently modified
If all rows on a page are visible, it is possible to set a bit in the visibility map (once the visibility map is 100% reliable) and not need to freeze the page, avoiding a page rewrite
Incomplete item Avoid reading in b-tree pages when replaying vacuum records in hot standby mode

Miscellaneous Other

Incomplete item Deal with encoding issues for filenames in the server filesystem
Incomplete item Deal with encoding issues in the output of localeconv()
Incomplete item Provide schema name and other fields available from SQL GET DIAGNOSTICS in error reports
[E] Incomplete item  Provide fallback_application_name in contrib/pgbench, oid2name, and dblink.

Source Code

Incomplete item Add use of 'const' for variables in source tree
[E] Incomplete item Remove warnings created by -Wcast-align
Incomplete item Move platform-specific ps status display info from ps_status.c to ports
Incomplete item Add optional CRC checksum to heap and index pages
One difficulty is how to prevent hint bit changes from affecting the computed CRC checksum.
Incomplete item Consider a faster CRC32 algorithm
Incomplete item Allow cross-compiling by generating the zic database on the target system
Incomplete item Improve NLS maintenance of libpgport messages linked onto applications
Incomplete item Improve the module installation experience (/contrib, etc)
Incomplete item Use UTF8 encoding for NLS messages so all server encodings can read them properly
[D] Completed itemUpdate Bonjour to work with newer cross-platform SDK
Incomplete item Allow creation of universal binaries for Darwin
Incomplete item Consider GnuTLS if OpenSSL license becomes a problem
Incomplete item Consider making NAMEDATALEN more configurable in future releases
Incomplete item Research use of signals and sleep wake ups
[D] Completed itemAdd automated check for invalid C++ source code constructs
Incomplete item Allow C++ code to more easily access backend code
Incomplete item Consider simplifying how memory context resets handle child contexts
Incomplete item Create three versions of libpgport to simplify client code
Incomplete item Improve detection of shared memory segments being used by others by checking the SysV shared memory field 'nattch'
Incomplete item Implement the non-threaded Avahi service discovery protocol
[D] Completed itemAllow table and index WITH options to be specified via hooks, for use with plugins like GiST index methods
Incomplete item Reduce data row alignment requirements on some 64-bit systems
Incomplete item Restructure TOAST internal storage format for greater flexibility
[D] Completed itemAllow setting of system oids during object creation, for use by pg_migrator
Incomplete item  Add regression tests for pg_dump/restore

Documentation

Incomplete item Convert single quotes to apostrophes in the PDF documentation
Incomplete item Provide a manpage for postgresql.conf
Incomplete item Change the manpage-generating toolchain to use the new XML-based docbook2x tools
Incomplete item Consider changing documentation format from SGML to XML
Incomplete item Document support for N' ' national character string literals, if it matches the SQL standard

/contrib/pg_upgrade

Incomplete item Remove copy_dir() code, or use it
Incomplete item Handle large object comments
This is difficult to do because the large object doesn't exist when --schema-only is loaded.
Incomplete item Consider using pg_depend for checking object usage in version.c
Incomplete item If reindex is necessary, allow it to be done in parallel with pg_dump custom format
Incomplete item Migrate pg_statistic by dumping it out as a flat file, so analyze is not necessary
pg_class.oid is not preserved so schema.tablename must be used.
Incomplete item Improve testing, perhaps using the buildfarm
The buildfarm has access to multiple versions of PostgreSQL.

Windows

Incomplete item Remove configure.in check for link failure when cause is found
Incomplete item Remove readdir() errno patch when runtime/mingwex/dirent.c rev 1.4 is released
Incomplete item Allow psql to use readline once non-US code pages work with backslashes
Incomplete item Fix problem with shared memory on the Win32 Terminal Server
[D] Completed itemDiagnose problem where shared memory can sometimes not be attached by postmaster children
Incomplete item Improve signal handling
Incomplete item Convert MSVC build system to remove most batch files
Incomplete item Support pgxs when using MSVC
Incomplete item Fix MSVC NLS support, like for to_char()
[D] Completed itemFix locale-aware handling (e.g. monetary) for specific server/client encoding combinations
Incomplete item Find a correct rint() substitute on Windows
[D] Completed itemReduce compiler warnings on 64-bit Windows
Incomplete item Fix global namespace issues when using multiple terminal server sessions
Incomplete item Change from the current autoconf/gmake build system to cmake
Incomplete item Improve consistency of path separator usage
[D] Completed itemAllow compilation using MSVC 2008

Wire Protocol Changes

Incomplete item Allow dynamic character set handling
Incomplete item Add decoded type, length, precision
Incomplete item Use compression?
Incomplete item Update clients to use data types, typmod, schema.table.column names of result sets using new statement protocol

Exotic Features

Incomplete item Add pre-parsing phase that converts non-ISO syntax to supported syntax
This could allow SQL written for other databases to run without modification.
Incomplete item Allow plug-in modules to emulate features from other databases
Incomplete item Add features of Oracle-style packages
A package would be a schema with session-local variables, public/private functions, and initialization functions. It is also possible to implement these capabilities in any schema and not use a separate "packages" syntax at all.
Incomplete item Consider allowing control of upper/lower case folding of unquoted identifiers
Incomplete item Add autonomous transactions
Incomplete item Give query progress indication
Incomplete item Rethink our type system

Features We Do Not Want

Incomplete item All backends running as threads in a single process (not wanted)
This eliminates the process protection we get from the current setup. Thread creation is usually the same overhead as process creation on modern systems, so it seems unwise to use a pure threaded model, and MySQL and DB2 have demonstrated that threads introduce as many issues as they solve. Threading specific operations such as I/O, seq scans, and connection management has been discussed and will probably be implemented to enable specific performance features. Moving to a threaded engine would also require halting all other work on PostgreSQL for one to two years.
Incomplete item Optimizer hints (not wanted)
Optimizer hints are used to work around problems in the optimizer and introduce upgrade and maintenance issues. We would rather have the problems reported and fixed. We have discussed a more sophisticated system of per-class cost adjustment instead, but a specification remains to be developed.
Incomplete item Embedded server (not wanted)
While PostgreSQL clients runs fine in limited-resource environments, the server requires multiple processes and a stable pool of resources to run reliably and efficiently. Stripping down the PostgreSQL server to run in the same process address space as the client application would add too much complexity and failure cases. Besides, there are several very mature embedded SQL databases already available.
Incomplete item Obfuscated function source code (not wanted)
Obfuscating function source code has minimal protective benefits because anyone with super-user access can find a way to view the code. At the same time, it would greatly complicate backups and other administrative tasks. To prevent non-super-users from viewing function source code, remove SELECT permission on pg_proc.
Incomplete item Indeterminate behavior for the GROUP BY clause (not wanted)
At least one other database product allows specification of a subset of the result columns which GROUP BY would need to be able to provide predictable results; the server is free to return any value from the group. This is not viewed as a desirable feature.