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9 <h1><a name="section_1">PostgreSQL TODO List</a></h1>
10 <p>Current maintainer: Bruce Momjian (<a href="mailto:bruce@momjian.us">bruce@momjian.us</a>)<br/>
11 Last updated: Tue Mar 4 09:38:30 EST 2008
13 <p>The most recent version of this document can be viewed at<br/>
14 <a href="http://www.postgresql.org/docs/faqs.TODO.html">http://www.postgresql.org/docs/faqs.TODO.html</a>.
16 <p><strong>A hyphen, "-", marks changes that will appear in the upcoming 8.3 release.</strong><br/>
17 <strong>A percent sign, "%", marks items that are easier to implement.</strong>
19 <p>Bracketed items, "[<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?"></a>]", have more detail.
21 <p>This list contains all known PostgreSQL bugs and feature requests. If<br/>
22 you would like to work on an item, please read the Developer's FAQ<br/>
23 first. There is also a developer's wiki at<br/>
24 <a href="http://developer.postgresql.org">http://developer.postgresql.org</a>.
26 <h1><a name="section_2">Administration</a></h1>
29 <li>Allow administrators to safely terminate individual sessions either
30 via an SQL function or SIGTERM
31 <p> Lock table corruption following SIGTERM of an individual backend
32 has been reported in 8.0. A possible cause was fixed in 8.1, but
33 it is unknown whether other problems exist. This item mostly
34 requires additional testing rather than of writing any new code.
36 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-08/msg00174.php">http://archives.postgresql.org/pgsql-hackers/2006-08/msg00174.php</a>
38 </li><li>Check for unreferenced table files created by transactions that were
39 in-progress when the server terminated abruptly
40 <p> <a href="http://archives.postgresql.org/pgsql-patches/2006-06/msg00096.php">http://archives.postgresql.org/pgsql-patches/2006-06/msg00096.php</a>
42 </li><li>Set proper permissions on non-system schemas during db creation
43 <p> Currently all schemas are owned by the super-user because they are copied
44 from the template1 database. However, since all objects are inherited
45 from the template database, it is not clear that setting schemas to the db
48 </li><li>Add function to report the time of the most recent server reload
49 </li><li>Allow statistics collector information to be pulled from the collector
50 process directly, rather than requiring the collector to write a
51 filesystem file twice a second?
52 </li><li>Allow log_min_messages to be specified on a per-module basis
53 <p> This would allow administrators to see more detailed information from
54 specific sections of the backend, e.g. checkpoints, autovacuum, etc.
55 Another idea is to allow separate configuration files for each module,
56 or allow arbitrary SET commands to be passed to them.
58 </li><li>Simplify ability to create partitioned tables
59 <p> This would allow creation of partitioned tables without requiring
60 creation of triggers or rules for INSERT/UPDATE/DELETE, and constraints
61 for rapid partition selection. Options could include range and hash
64 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-03/msg00375.php">http://archives.postgresql.org/pgsql-hackers/2007-03/msg00375.php</a>
65 <a href="http://archives.postgresql.org/pgsql-hackers/2007-04/msg00151.php">http://archives.postgresql.org/pgsql-hackers/2007-04/msg00151.php</a>
67 </li><li>Allow auto-selection of partitioned tables for min/max() operations
68 </li><li>Allow more complex user/database default GUC settings
69 <p> Currently ALTER USER and ALTER DATABASE support per-user and
70 per-database defaults. Consider adding per-user-and-database
71 defaults so things like search_path can be defaulted for a
72 specific user connecting to a specific database.
74 </li><li>Allow custom variable classes that can restrict who can set the values
75 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-11/msg00911.php">http://archives.postgresql.org/pgsql-hackers/2006-11/msg00911.php</a>
77 </li><li>Implement the SQL standard mechanism whereby REVOKE ROLE revokes only
78 the privilege granted by the invoking role, and not those granted
80 <p> <a href="http://archives.postgresql.org/pgsql-bugs/2007-05/msg00010.php">http://archives.postgresql.org/pgsql-bugs/2007-05/msg00010.php</a>
82 </li><li>Allow SSL authentication/encryption over unix domain sockets
83 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-12/msg00924.php">http://archives.postgresql.org/pgsql-hackers/2007-12/msg00924.php</a>
85 </li><li>Configuration files
87 <li>Allow pg_hba.conf to specify host names along with IP addresses
88 <p> Host name lookup could occur when the postmaster reads the
89 pg_hba.conf file, or when the backend starts. Another
90 solution would be to reverse lookup the connection IP and
91 check that hostname against the host names in pg_hba.conf.
92 We could also then check that the host name maps to the IP
95 </li><li>%Allow postgresql.conf file values to be changed via an SQL
96 API, perhaps using SET GLOBAL
97 </li><li>Allow the server to be stopped/restarted via an SQL API
98 </li><li>Issue a warning if a change-on-restart-only postgresql.conf value
99 is modified and the server config files are reloaded
103 <li>Allow a database in tablespace t1 with tables created in
104 tablespace t2 to be used as a template for a new database created
105 with default tablespace t2
106 <p> Currently all objects in the default database tablespace must
107 have default tablespace specifications. This is because new
108 databases are created by copying directories. If you mix default
109 tablespace tables and tablespace-specified tables in the same
110 directory, creating a new database from such a mixed directory
111 would create a new database with tables that had incorrect
112 explicit tablespaces. To fix this would require modifying
113 pg_class in the newly copied database, which we don't currently
116 </li><li>Allow reporting of which objects are in which tablespaces
117 <p> This item is difficult because a tablespace can contain objects
118 from multiple databases. There is a server-side function that
119 returns the databases which use a specific tablespace, so this
120 requires a tool that will call that function and connect to each
121 database to find the objects in each database for that tablespace.
123 </li><li>Allow WAL replay of CREATE TABLESPACE to work when the directory
124 structure on the recovery computer is different from the original
125 </li><li>Allow per-tablespace quotas
127 </li><li>Point-In-Time Recovery (PITR)
129 <li>Allow a warm standby system to also allow read-only statements
130 [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?pitr">pitr</a>]
131 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-03/msg00050.php">http://archives.postgresql.org/pgsql-hackers/2007-03/msg00050.php</a>
133 </li><li>%Create dump tool for write-ahead logs for use in determining
134 transaction id for point-in-time recovery
135 <p> This is useful for checking PITR recovery.
137 </li><li>Allow recovery.conf to support the same syntax as
138 postgresql.conf, including quoting
139 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg00497.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg00497.php</a>
143 <h1><a name="section_3">Data Types</a></h1>
146 <li>Change NUMERIC to enforce the maximum precision
147 </li><li>Reduce storage space for small NUMERICs
148 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-02/msg01331.php">http://archives.postgresql.org/pgsql-hackers/2007-02/msg01331.php</a>
149 <a href="http://archives.postgresql.org/pgsql-patches/2007-02/msg00505.php">http://archives.postgresql.org/pgsql-patches/2007-02/msg00505.php</a>
151 </li><li>Fix data types where equality comparison isn't intuitive, e.g. box
152 </li><li>Add support for public SYNONYMs
153 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-03/msg00519.php">http://archives.postgresql.org/pgsql-hackers/2006-03/msg00519.php</a>
155 </li><li>Fix CREATE CAST on DOMAINs
156 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-05/msg00072.php">http://archives.postgresql.org/pgsql-hackers/2006-05/msg00072.php</a>
157 <a href="http://archives.postgresql.org/pgsql-hackers/2006-09/msg01681.php">http://archives.postgresql.org/pgsql-hackers/2006-09/msg01681.php</a>
159 </li><li>Add support for SQL-standard GENERATED/IDENTITY columns
160 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-07/msg00543.php">http://archives.postgresql.org/pgsql-hackers/2006-07/msg00543.php</a>
161 <a href="http://archives.postgresql.org/pgsql-hackers/2006-08/msg00038.php">http://archives.postgresql.org/pgsql-hackers/2006-08/msg00038.php</a>
162 <a href="http://archives.postgresql.org/pgsql-hackers/2007-05/msg00344.php">http://archives.postgresql.org/pgsql-hackers/2007-05/msg00344.php</a>
163 <a href="http://archives.postgresql.org/pgsql-patches/2007-05/msg00076.php">http://archives.postgresql.org/pgsql-patches/2007-05/msg00076.php</a>
165 </li><li>Improve XML support
166 <p> <a href="http://developer.postgresql.org/index.php/XML_Support">http://developer.postgresql.org/index.php/XML_Support</a>
168 </li><li>Consider placing all sequences in a single table, or create a system
170 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php">http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php</a>
172 </li><li>Allow the UUID type to accept non-standard formats
173 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2008-02/msg01214.php">http://archives.postgresql.org/pgsql-hackers/2008-02/msg01214.php</a>
175 </li><li>Dates and Times
177 <li>Allow infinite dates and intervals just like infinite timestamps
178 </li><li>Merge hardwired timezone names with the TZ database; allow either
179 kind everywhere a TZ name is currently taken
180 </li><li>Allow TIMESTAMP WITH TIME ZONE to store the original timezone
181 information, either zone name or offset from UTC [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?timezone">timezone</a>]
182 <p> If the TIMESTAMP value is stored with a time zone name, interval
183 computations should adjust based on the time zone rules.
185 </li><li>Fix SELECT '0.01 years'::interval, '0.01 months'::interval
186 </li><li>Add a GUC variable to allow output of interval values in ISO8601
188 </li><li>Have timestamp subtraction not call justify_hours()?
189 <p> <a href="http://archives.postgresql.org/pgsql-sql/2006-10/msg00059.php">http://archives.postgresql.org/pgsql-sql/2006-10/msg00059.php</a>
191 </li><li>Improve timestamptz subtraction to be DST-aware
192 <p> Currently subtracting one date from another that crosses a
193 daylight savings time adjustment can return '1 day 1 hour', but
194 adding that back to the first date returns a time one hour in
195 the future. This is caused by the adjustment of '25 hours' to
196 '1 day 1 hour', and '1 day' is the same time the next day, even
197 if daylight savings adjustments are involved.
199 </li><li>Fix interval display to support values exceeding 2^31 hours
200 </li><li>Add overflow checking to timestamp and interval arithmetic
201 </li><li>Extend timezone code to allow 64-bit values so we can
202 represent years beyond 2038
203 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-09/msg01363.php">http://archives.postgresql.org/pgsql-hackers/2006-09/msg01363.php</a>
205 </li><li>Use LC_TIME for localized weekday/month names, rather than
207 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-11/msg00390.php">http://archives.postgresql.org/pgsql-hackers/2006-11/msg00390.php</a>
209 </li><li>Add ISO INTERVAL handling
212 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-01/msg00250.php">http://archives.postgresql.org/pgsql-hackers/2006-01/msg00250.php</a><br/>
213 <a href="http://archives.postgresql.org/pgsql-bugs/2006-04/msg00248.php">http://archives.postgresql.org/pgsql-bugs/2006-04/msg00248.php</a>
216 <li>Support ISO INTERVAL syntax if units cannot be determined from
217 the string, and are supplied after the string
218 <p> The SQL standard states that the units after the string
219 specify the units of the string, e.g. INTERVAL '2' MINUTE
220 should return '00:02:00'. The current behavior has the units
221 restrict the interval value to the specified unit or unit
222 range, INTERVAL '70' SECOND returns '00:00:10'.
224 <p> For syntax that isn't uniquely ISO or PG syntax, like '1' or
225 '1:30', treat as ISO if there is a range specification clause,
226 and as PG if there no clause is present, e.g. interpret '1:30'
227 MINUTE TO SECOND as '1 minute 30 seconds', and interpret
228 '1:30' as '1 hour, 30 minutes'.
230 <p> This makes common cases like SELECT INTERVAL '1' MONTH
231 SQL-standard results. The SQL standard supports a limited
232 number of unit combinations and doesn't support unit names in
233 the string. The PostgreSQL syntax is more flexible in the
234 range of units supported, e.g. PostgreSQL supports '1 year 1
235 hour', while the SQL standard does not.
237 </li><li>Add support for year-month syntax, INTERVAL '50-6' YEAR
239 </li><li>Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1
240 year' AS INTERVAL MONTH), and this should return '12 months'
241 </li><li>Round or truncate values to the requested precision, e.g.
242 INTERVAL '11 months' AS YEAR should return one or zero
243 </li><li>Support precision, CREATE TABLE foo (a INTERVAL MONTH(3))
247 <li>Delay resolution of array expression's data type so assignment
248 coercion can be performed on empty array expressions
249 </li><li>Add support for arrays of domains
250 <p> <a href="http://archives.postgresql.org/pgsql-patches/2007-05/msg00114.php">http://archives.postgresql.org/pgsql-patches/2007-05/msg00114.php</a>
252 </li><li>Allow single-byte header storage for array elements
256 <li>Improve vacuum of large objects, like contrib/vacuumlo?
257 </li><li>Add security checking for large objects
258 </li><li>Auto-delete large objects when referencing row is deleted
259 <p> contrib/lo offers this functionality.
261 </li><li>Allow read/write into TOAST values like large objects
262 <p> This requires the TOAST column to be stored EXTERNAL.
264 </li><li>Add API for 64-bit large object access
265 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2005-09/msg00781.php">http://archives.postgresql.org/pgsql-hackers/2005-09/msg00781.php</a>
268 </li><li>MONEY data type
270 <li>Add locale-aware MONEY type, and support multiple currencies
271 <p> <a href="http://archives.postgresql.org/pgsql-general/2005-08/msg01432.php">http://archives.postgresql.org/pgsql-general/2005-08/msg01432.php</a>
272 <a href="http://archives.postgresql.org/pgsql-hackers/2007-03/msg01181.php">http://archives.postgresql.org/pgsql-hackers/2007-03/msg01181.php</a>
274 </li><li>MONEY dumps in a locale-specific format making it difficult to
275 restore to a system with a different locale
276 </li><li>Allow MONEY to be easily cast to/from other numeric data types
280 <h1><a name="section_4">Functions</a></h1>
283 <li>Allow INET subnet tests using non-constants to be indexed
284 </li><li>Allow to_date() and to_timestamp() accept localized month names
285 </li><li>Fix to_date()-related functions to consistently issue errors
286 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-02/msg00915.php">http://archives.postgresql.org/pgsql-hackers/2007-02/msg00915.php</a>
288 </li><li>Add missing parameter handling in to_char()
289 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2005-12/msg00948.php">http://archives.postgresql.org/pgsql-hackers/2005-12/msg00948.php</a>
291 </li><li>Allow substring/replace() to get/set bit values
292 </li><li>Allow to_char() on interval values to accumulate the highest unit
294 <p> Some special format flag would be required to request such
295 accumulation. Such functionality could also be added to EXTRACT.
296 Prevent accumulation that crosses the month/day boundary because of
297 the uneven number of days in a month.
300 <li>to_char(INTERVAL '1 hour 5 minutes', 'MI') => 65
301 </li><li>to_char(INTERVAL '43 hours 20 minutes', 'MI' ) => 2600
302 </li><li>to_char(INTERVAL '43 hours 20 minutes', 'WK:DD:HR:MI') => 0:1:19:20
303 </li><li>to_char(INTERVAL '3 years 5 months','MM') => 41
305 </li><li>Implement inlining of set-returning functions defined in SQL
306 </li><li>Allow SQL-language functions to return results from RETURNING queries
307 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-10/msg00665.php">http://archives.postgresql.org/pgsql-hackers/2006-10/msg00665.php</a>
309 </li><li>Allow SQL-language functions to reference parameters by parameter name
310 <p> Currently SQL-language functions can only refer to dollar parameters,
313 </li><li>Add SPI_gettypmod() to return the typemod for a TupleDesc
314 </li><li>Enforce typmod for function inputs, function results and parameters for
315 spi_prepare'd statements called from PLs
316 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-01/msg01403.php">http://archives.postgresql.org/pgsql-hackers/2007-01/msg01403.php</a>
318 </li><li>Allow holdable cursors in SPI
319 </li><li>Tighten function permission checks
320 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg00568.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg00568.php</a>
322 </li><li>Fix IS OF so it matches the ISO specification, and add documentation
323 <p> <a href="http://archives.postgresql.org/pgsql-patches/2003-08/msg00060.php">http://archives.postgresql.org/pgsql-patches/2003-08/msg00060.php</a>
324 <a href="http://archives.postgresql.org/pgsql-hackers/2007-02/msg00060.php">http://archives.postgresql.org/pgsql-hackers/2007-02/msg00060.php</a>
326 </li><li>Add missing operators for geometric data types
327 <p> Some geometric types do not have the full suite of geometric operators,
330 </li><li>Implement Boyer-Moore searching in strpos()
331 <p> <a href="http://archives.postgresql.org/pgsql-patches/2007-08/msg00012.php">http://archives.postgresql.org/pgsql-patches/2007-08/msg00012.php</a>
334 <h1><a name="section_5">Multi-Language Support</a></h1>
337 <li>Add NCHAR (as distinguished from ordinary varchar),
338 </li><li>Allow locale to be set at database creation
339 <p> Currently locale can only be set during initdb. No global tables have
340 locale-aware columns. However, the database template used during
341 database creation might have locale-aware indexes. The indexes would
342 need to be reindexed to match the new locale.
344 </li><li>Allow encoding on a per-column basis optionally using the ICU library:
345 <p> Right now only one encoding is allowed per database. [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?locale">locale</a>]
347 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2005-03/msg00932.php">http://archives.postgresql.org/pgsql-hackers/2005-03/msg00932.php</a>
348 <a href="http://archives.postgresql.org/pgsql-patches/2005-08/msg00309.php">http://archives.postgresql.org/pgsql-patches/2005-08/msg00309.php</a>
349 <a href="http://archives.postgresql.org/pgsql-patches/2006-03/msg00233.php">http://archives.postgresql.org/pgsql-patches/2006-03/msg00233.php</a>
350 <a href="http://archives.postgresql.org/pgsql-hackers/2006-09/msg00662.php">http://archives.postgresql.org/pgsql-hackers/2006-09/msg00662.php</a>
352 </li><li>Add CREATE COLLATE? [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?locale">locale</a>]
353 </li><li>Support multiple simultaneous character sets, per SQL92
354 </li><li>Improve UTF8 combined character handling?
355 </li><li>Add octet_length_server() and octet_length_client()
356 </li><li>Make octet_length_client() the same as octet_length()?
357 </li><li>Fix problems with wrong runtime encoding conversion for NLS message files
358 </li><li>Add URL to more complete multi-byte regression tests
359 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2005-07/msg00272.php">http://archives.postgresql.org/pgsql-hackers/2005-07/msg00272.php</a>
361 </li><li>Fix ILIKE and regular expressions to handle case insensitivity
362 properly in multibyte encodings
363 <p> <a href="http://archives.postgresql.org/pgsql-bugs/2005-10/msg00001.php">http://archives.postgresql.org/pgsql-bugs/2005-10/msg00001.php</a>
364 <a href="http://archives.postgresql.org/pgsql-patches/2005-11/msg00173.php">http://archives.postgresql.org/pgsql-patches/2005-11/msg00173.php</a>
366 </li><li>Set client encoding based on the client operating system encoding
367 <p> Currently client_encoding is set in postgresql.conf, which
368 defaults to the server encoding.
370 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-08/msg01696.php">http://archives.postgresql.org/pgsql-hackers/2006-08/msg01696.php</a>
373 <h1><a name="section_6">Views / Rules</a></h1>
376 <li>Automatically create rules on views so they are updateable, per SQL99
377 <p> We can only auto-create rules for simple views. For more complex
378 cases users will still have to write rules manually.
380 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-03/msg00586.php">http://archives.postgresql.org/pgsql-hackers/2006-03/msg00586.php</a>
381 <a href="http://archives.postgresql.org/pgsql-patches/2006-08/msg00255.php">http://archives.postgresql.org/pgsql-patches/2006-08/msg00255.php</a>
383 </li><li>Add the functionality for WITH CHECK OPTION clause of CREATE VIEW
384 </li><li>Allow NOTIFY in rules involving conditionals
385 </li><li>Allow VIEW/RULE recompilation when the underlying tables change
386 <p> Another issue is whether underlying table changes should be reflected
387 in the view, e.g. should SELECT * show additional columns if they
388 are added after the view is created.
390 </li><li>Make it possible to use RETURNING together with conditional DO INSTEAD
391 rules, such as for partitioning setups
392 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-09/msg00577.php">http://archives.postgresql.org/pgsql-hackers/2007-09/msg00577.php</a>
394 </li><li>Add the ability to automatically create materialized views
395 <p> Right now materialized views require the user to create triggers on the
396 main table to keep the summary table current. SQL syntax should be able
397 to manager the triggers and summary table automatically. A more
398 sophisticated implementation would automatically retrieve from the
399 summary table when the main table is referenced, if possible.
402 <h1><a name="section_7">SQL Commands</a></h1>
405 <li>Add CORRESPONDING BY to UNION/INTERSECT/EXCEPT
406 </li><li>Add ROLLUP, CUBE, GROUPING SETS options to GROUP BY
407 </li><li>%Allow SET CONSTRAINTS to be qualified by schema/table name
408 </li><li>%Add a separate TRUNCATE permission
409 <p> Currently only the owner can TRUNCATE a table because triggers are not
410 called, and the table is locked in exclusive mode.
412 </li><li>Allow PREPARE of cursors
413 </li><li>Allow finer control over the caching of prepared query plans
414 <p> Currently queries prepared via the libpq API are planned on first
415 execute using the supplied parameters --- allow SQL PREPARE to do the
416 same. Also, allow control over replanning prepared queries either
417 manually or automatically when statistics for execute parameters
418 differ dramatically from those used during planning.
420 </li><li>Improve logging of prepared transactions recovered during startup
421 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-11/msg00092.php">http://archives.postgresql.org/pgsql-hackers/2006-11/msg00092.php</a>
423 </li><li>Allow LISTEN/NOTIFY to store info in memory rather than tables?
424 <p> Currently LISTEN/NOTIFY information is stored in pg_listener. Storing
425 such information in memory would improve performance.
427 </li><li>Add optional textual message to NOTIFY
428 <p> This would allow an informational message to be added to the notify
429 message, perhaps indicating the row modified or other custom
432 </li><li>Allow multiple identical NOTIFY events to always be communicated to the
433 client, rather than sent as a single notification to the listener
434 </li><li>Add a GUC variable to warn about non-standard SQL usage in queries
435 </li><li>Add SQL-standard MERGE command, typically used to merge two tables
436 [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?merge">merge</a>]
437 <p> This is similar to UPDATE, then for unmatched rows, INSERT.
438 Whether concurrent access allows modifications which could cause
439 row loss is implementation independent.
441 </li><li>Add REPLACE or UPSERT command that does UPDATE, or on failure, INSERT
442 [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?merge">merge</a>]
443 <p> To implement this cleanly requires that the table have a unique index
444 so duplicate checking can be easily performed. It is possible to
445 do it without a unique index if we require the user to LOCK the table
448 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2005-11/msg00501.php">http://archives.postgresql.org/pgsql-hackers/2005-11/msg00501.php</a>
449 <a href="http://archives.postgresql.org/pgsql-hackers/2005-11/msg00536.php">http://archives.postgresql.org/pgsql-hackers/2005-11/msg00536.php</a>
451 </li><li>Add NOVICE output level for helpful messages like automatic sequence/index
453 </li><li>Add GUC to issue notice about statements that use unjoined tables
454 </li><li>Allow EXPLAIN to identify tables that were skipped because of
456 </li><li>Allow EXPLAIN output to be more easily processed by scripts, perhaps XML
457 </li><li>Enable standard_conforming_strings
458 </li><li>Make standard_conforming_strings the default in 8.5?
459 <p> When this is done, backslash-quote should be prohibited in non-E''
460 strings because of possible confusion over how such strings treat
461 backslashes. Basically, '' is always safe for a literal single
462 quote, while \' might or might not be based on the backslash
465 </li><li>Simplify dropping roles that have objects in several databases
466 </li><li>Allow COMMENT ON to accept an expression rather than just a string
467 </li><li>Allow the count returned by SELECT, etc to be represented as an int64
468 to allow a higher range of values
469 </li><li>Add SQL99 WITH clause to SELECT
470 </li><li>Add SQL:2003 WITH RECURSIVE (hierarchical) queries to SELECT
471 </li><li>Add DEFAULT .. AS OWNER so permission checks are done as the table
473 <p> This would be useful for SERIAL nextval() calls and CHECK constraints.
475 </li><li>Allow DISTINCT to work in multiple-argument aggregate calls
476 </li><li>Add column to pg_stat_activity that shows the progress of long-running
477 commands like CREATE INDEX and VACUUM
478 </li><li>Implement SQL:2003 window functions
479 </li><li>Improve failure message when DROP DATABASE is used on a database that
480 has prepared transactions
481 </li><li>Allow INSERT/UPDATE ... RETURNING inside a SELECT 'FROM' clause
482 <p> <a href="http://archives.postgresql.org/pgsql-general/2006-09/msg00803.php">http://archives.postgresql.org/pgsql-general/2006-09/msg00803.php</a>
483 <a href="http://archives.postgresql.org/pgsql-hackers/2006-10/msg00693.php">http://archives.postgresql.org/pgsql-hackers/2006-10/msg00693.php</a>
485 </li><li>Increase locking when DROPing objects so dependent objects cannot
486 get dropped while the DROP operation is happening
487 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-01/msg00937.php">http://archives.postgresql.org/pgsql-hackers/2007-01/msg00937.php</a>
489 </li><li>-<em>Allow AS in "SELECT col AS label" to be optional in certain cases</em>
490 </li><li>Allow INSERT ... DELETE ... RETURNING, namely allow the DELETE ...
491 RETURNING to supply values to the INSERT
492 <a href="http://archives.postgresql.org/pgsql-hackers/2008-02/thrd2.php#00979">http://archives.postgresql.org/pgsql-hackers/2008-02/thrd2.php#00979</a>
495 <li>Allow CREATE TABLE AS to determine column lengths for complex
496 expressions like SELECT col1 || col2
497 </li><li>Have WITH CONSTRAINTS also create constraint indexes
498 <p> <a href="http://archives.postgresql.org/pgsql-patches/2007-04/msg00149.php">http://archives.postgresql.org/pgsql-patches/2007-04/msg00149.php</a>
503 <li>Allow UPDATE tab SET ROW (col, ...) = (SELECT...)
504 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-07/msg01306.php">http://archives.postgresql.org/pgsql-hackers/2006-07/msg01306.php</a>
505 <a href="http://archives.postgresql.org/pgsql-hackers/2007-03/msg00865.php">http://archives.postgresql.org/pgsql-hackers/2007-03/msg00865.php</a>
507 </li><li>Research self-referential UPDATEs that see inconsistent row versions
508 in read-committed mode
509 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-05/msg00507.php">http://archives.postgresql.org/pgsql-hackers/2007-05/msg00507.php</a>
510 <a href="http://archives.postgresql.org/pgsql-hackers/2007-06/msg00016.php">http://archives.postgresql.org/pgsql-hackers/2007-06/msg00016.php</a>
512 </li><li>Allow GLOBAL temporary tables to exist as empty by default in
514 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-07/msg00006.php">http://archives.postgresql.org/pgsql-hackers/2007-07/msg00006.php</a>
519 <li>Have ALTER TABLE RENAME rename SERIAL sequence names
520 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php">http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php</a>
522 </li><li>Have ALTER SEQUENCE RENAME rename the sequence name stored
523 in the sequence table
524 <p> <a href="http://archives.postgresql.org/pgsql-bugs/2007-09/msg00092.php">http://archives.postgresql.org/pgsql-bugs/2007-09/msg00092.php</a>
525 <a href="http://archives.postgresql.org/pgsql-bugs/2007-10/msg00007.php">http://archives.postgresql.org/pgsql-bugs/2007-10/msg00007.php</a>
526 <a href="http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php">http://archives.postgresql.org/pgsql-hackers/2008-03/msg00008.php</a>
528 </li><li>Add ALTER DOMAIN to modify the underlying data type
529 </li><li>%Allow ALTER TABLE ... ALTER CONSTRAINT ... RENAME
530 <p> <a href="http://archives.postgresql.org/pgsql-patches/2006-02/msg00168.php">http://archives.postgresql.org/pgsql-patches/2006-02/msg00168.php</a>
532 </li><li>%Allow ALTER TABLE to change constraint deferrability and actions
533 </li><li>Add missing object types for ALTER ... SET SCHEMA
534 </li><li>Allow ALTER TABLESPACE to move to different directories
535 </li><li>Allow databases to be moved to different tablespaces
536 </li><li>Allow moving system tables to other tablespaces, where possible
537 <p> Currently non-global system tables must be in the default database
538 tablespace. Global system tables can never be moved.
540 </li><li>Prevent parent tables from altering or dropping constraints
541 like CHECK that are inherited by child tables unless CASCADE
543 </li><li>%Prevent child tables from altering or dropping constraints
544 like CHECK that were inherited from the parent table
545 </li><li>Have ALTER INDEX update the name of a constraint using that index
546 </li><li>Add ALTER TABLE RENAME CONSTRAINT, update index name also
547 </li><li>Allow column display reordering by recording a display,
548 storage, and permanent id for every column?
549 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg00782.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg00782.php</a>
554 <li>Automatically maintain clustering on a table
555 <p> This might require some background daemon to maintain clustering
556 during periods of low usage. It might also require tables to be only
557 partially filled for easier reorganization. Another idea would
558 be to create a merged heap/index data file so an index lookup would
559 automatically access the heap data too. A third idea would be to
560 store heap rows in hashed groups, perhaps using a user-supplied
562 <a href="http://archives.postgresql.org/pgsql-performance/2004-08/msg00349.php">http://archives.postgresql.org/pgsql-performance/2004-08/msg00349.php</a>
564 </li><li>%Add default clustering to system tables
565 <p> To do this, determine the ideal cluster index for each system
566 table and set the cluster setting during initdb.
568 </li><li>%Add VERBOSE option to report tables as they are processed,
573 <li>Allow COPY to report error lines and continue
574 <p> This requires the use of a savepoint before each COPY line is
575 processed, with ROLLBACK on COPY failure.
577 </li><li>Allow COPY on a newly-created table to skip WAL logging
578 <p> On crash recovery, the table involved in the COPY would
579 be removed or have its heap and index files truncated. One
580 issue is that no other backend should be able to add to
581 the table at the same time, which is something that is
582 currently allowed. This currently is done if the table is
583 created inside the same transaction block as the COPY because
584 no other backends can see the table.
586 </li><li>Consider using a ring buffer for COPY FROM
587 <p> <a href="http://archives.postgresql.org/pgsql-patches/2008-02/msg00140.php">http://archives.postgresql.org/pgsql-patches/2008-02/msg00140.php</a>
588 <a href="http://archives.postgresql.org/pgsql-hackers/2008-02/msg01080.php">http://archives.postgresql.org/pgsql-hackers/2008-02/msg01080.php</a>
591 </li><li>GRANT/REVOKE
593 <li>Allow column-level privileges
594 </li><li>%Allow GRANT/REVOKE permissions to be applied to all schema objects
596 <p> The proposed syntax is:
597 </p><p> GRANT SELECT ON ALL TABLES IN public TO phpuser;
598 GRANT SELECT ON NEW TABLES IN public TO phpuser;
600 </li><li>Allow GRANT/REVOKE permissions to be inherited by objects based on
602 </li><li>Allow SERIAL sequences to inherit permissions from the base table?
606 <li>Prevent DROP TABLE from dropping a row referenced by its own open
611 <li>Allow INSERT/UPDATE of the system-generated oid value for a row
612 </li><li>In rules, allow VALUES() to contain a mixture of 'old' and 'new'
617 <li>Add SET PERFORMANCE_TIPS option to suggest INDEX, VACUUM, VACUUM
620 </li><li>Referential Integrity
622 <li>Add MATCH PARTIAL referential integrity
623 </li><li>Change foreign key constraint for array -> element to mean element
625 </li><li>Fix problem when cascading referential triggers make changes on
626 cascaded tables, seeing the tables in an intermediate state
627 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php">http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php</a>
628 <a href="http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php">http://archives.postgresql.org/pgsql-hackers/2005-09/msg00174.php</a>
630 </li><li>Allow DEFERRABLE and end-of-statement UNIQUE constraints?
631 <p> This would allow UPDATE tab SET col = col + 1 to work if col has
632 a unique index. Currently, uniqueness checks are done while the
633 command is being executed, rather than at the end of the statement
636 <p> <a href="http://people.planetpostgresql.org/greg/index.php?/archives/2006/06/10.html">http://people.planetpostgresql.org/greg/index.php?/archives/2006/06/10.html</a>
637 <a href="http://archives.postgresql.org/pgsql-hackers/2006-09/msg01458.php">http://archives.postgresql.org/pgsql-hackers/2006-09/msg01458.php</a>
640 </li><li>Server-Side Languages
644 <li>Fix RENAME to work on variables other than OLD/NEW
645 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2002-03/msg00591.php">http://archives.postgresql.org/pgsql-hackers/2002-03/msg00591.php</a>
646 <a href="http://archives.postgresql.org/pgsql-hackers/2007-01/msg01615.php">http://archives.postgresql.org/pgsql-hackers/2007-01/msg01615.php</a>
647 <a href="http://archives.postgresql.org/pgsql-hackers/2007-01/msg01587.php">http://archives.postgresql.org/pgsql-hackers/2007-01/msg01587.php</a>
649 </li><li>Allow function parameters to be passed by name,
650 get_employee_salary(12345 AS emp_id, 2001 AS tax_year)
651 </li><li>Allow handling of %TYPE arrays, e.g. tab.col%TYPE[<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?"></a>]
652 </li><li>Allow listing of record column names, and access to
653 record columns via variables, e.g. columns := r.(*),
655 <p> <a href="http://archives.postgresql.org/pgsql-patches/2005-07/msg00458.php">http://archives.postgresql.org/pgsql-patches/2005-07/msg00458.php</a>
656 <a href="http://archives.postgresql.org/pgsql-patches/2006-05/msg00302.php">http://archives.postgresql.org/pgsql-patches/2006-05/msg00302.php</a>
657 <a href="http://archives.postgresql.org/pgsql-patches/2006-06/msg00031.php">http://archives.postgresql.org/pgsql-patches/2006-06/msg00031.php</a>
659 </li><li>Add support for SCROLL cursors
660 </li><li>Add support for WITH HOLD cursors
661 </li><li>Allow row and record variables to be set to NULL constants,
662 and allow NULL tests on such variables
663 <p> Because a row is not scalar, do not allow assignment
664 from NULL-valued scalars.
666 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-10/msg00070.php">http://archives.postgresql.org/pgsql-hackers/2006-10/msg00070.php</a>
671 <li>Add table function support to pltcl, plpythonu
672 </li><li>Add support for polymorphic arguments and return types to
673 languages other than PL/PgSQL
674 </li><li>Add capability to create and call PROCEDURES
675 </li><li>Add support for OUT and INOUT parameters to languages other
677 </li><li>Add PL/PythonU tracebacks
678 <p> <a href="http://archives.postgresql.org/pgsql-patches/2006-02/msg00288.php">http://archives.postgresql.org/pgsql-patches/2006-02/msg00288.php</a>
680 </li><li>Allow data to be passed in native language formats, rather
682 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-05/msg00289.php">http://archives.postgresql.org/pgsql-hackers/2007-05/msg00289.php</a>
687 <h1><a name="section_8">Clients</a></h1>
690 <li>Have pg_ctl look at PGHOST in case it is a socket directory?
691 </li><li>Allow pg_ctl to work properly with configuration files located outside
693 <p> pg_ctl can not read the pid file because it isn't located in the
694 config directory but in the PGDATA directory. The solution is to
695 allow pg_ctl to read and understand postgresql.conf to find the
696 data_directory value.
700 <li>Have psql show current values for a sequence
701 </li><li>Move psql backslash database information into the backend, use
702 mnemonic commands? [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?psql">psql</a>]
703 <p> This would allow non-psql clients to pull the same information out
704 of the database as psql.
706 </li><li>Fix psql's \d commands more consistent
707 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php">http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php</a>
708 <a href="http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php">http://archives.postgresql.org/pgsql-hackers/2004-11/msg00014.php</a>
710 </li><li>Consistently display privilege information for all objects in psql
711 </li><li>Add auto-expanded mode so expanded output is used if the row
712 length is wider than the screen width.
713 <p> Consider using auto-expanded mode for backslash commands like \df+.
715 </li><li>Prevent tab completion of SET TRANSACTION from querying the
716 database and therefore preventing the transaction isolation
717 level from being set.
718 <p> Currently SET <tab> causes a database lookup to check all
719 supported session variables. This query causes problems
720 because setting the transaction isolation level must be the
721 first statement of a transaction.
723 </li><li>Add a \set variable to control whether \s displays line numbers
724 <p> Another option is to add \# which lists line numbers, and
725 allows command execution.
727 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg00255.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg00255.php</a>
730 </li><li>pg_dump / pg_restore
732 <li>%Add dumping of comments on index columns and composite type columns
733 </li><li>%Add full object name to the tag field. eg. for operators we need
734 '=(integer, integer)', instead of just '='.
735 </li><li>Add pg_dumpall custom format dumps?
736 </li><li>Allow selection of individual object(s) of all types, not just
738 </li><li>In a selective dump, allow dumping of an object and all its
740 </li><li>Add options like pg_restore -l and -L to pg_dump
741 </li><li>Stop dumping CASCADE on DROP TYPE commands in clean mode
742 </li><li>Allow pg_dump --clean to drop roles that own objects or have
744 </li><li>Change pg_dump so that a comment on the dumped database is
745 applied to the loaded database, even if the database has a
746 different name. This will require new backend syntax, perhaps
747 COMMENT ON CURRENT DATABASE.
748 </li><li>Remove unnecessary function pointer abstractions in pg_dump source
750 </li><li>Allow pg_dump to utilize multiple CPUs and I/O channels by dumping
751 multiple objects simultaneously
752 <p> The difficulty with this is getting multiple dump processes to
753 produce a single dump output file. It also would require
754 several sessions to share the same snapshot.
755 <a href="http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php">http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php</a>
757 </li><li>Allow pg_restore to utilize multiple CPUs and I/O channels by
758 restoring multiple objects simultaneously
759 <p> This might require a pg_restore flag to indicate how many
760 simultaneous operations should be performed. Only pg_dump's
761 -Fc format has the necessary dependency information.
762 <a href="http://archives.postgresql.org/pgsql-hackers/2008-02/msg00963.php">http://archives.postgresql.org/pgsql-hackers/2008-02/msg00963.php</a>
764 </li><li>To better utilize resources, allow pg_restore to check foreign
765 keys simultaneously, where possible
766 </li><li>Allow pg_restore to create all indexes of a table
767 concurrently, via a single heap scan
768 <p> This requires a pg_dump -Fc file because that format contains
769 the required dependency information.
770 <a href="http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php">http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php</a>
772 </li><li>Allow pg_restore to load different parts of the COPY data
778 <p> Document differences between ecpg and the SQL standard and
779 information about the Informix-compatibility module.
781 </li><li>Solve cardinality > 1 for input descriptors / variables?
782 </li><li>Add a semantic check level, e.g. check if a table really exists
783 </li><li>fix handling of DB attributes that are arrays
784 </li><li>Use backend PREPARE/EXECUTE facility for ecpg where possible
785 </li><li>Implement SQLDA
786 </li><li>Fix nested C comments
787 </li><li>%sqlwarn[<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?6">6</a>] should be 'W' if the PRECISION or SCALE value specified
788 </li><li>Make SET CONNECTION thread-aware, non-standard?
789 </li><li>Allow multidimensional arrays
790 </li><li>Add internationalized message strings
791 </li><li>Implement COPY FROM STDIN
795 <li>Add PQescapeIdentifierConn()
796 </li><li>Prevent PQfnumber() from lowercasing unquoted the column name
797 <p> PQfnumber() should never have been doing lowercasing, but
798 historically it has so we need a way to prevent it
800 </li><li>Allow statement results to be automatically batched to the client
801 <p> Currently all statement results are transferred to the libpq
802 client before libpq makes the results available to the
803 application. This feature would allow the application to make
804 use of the first result rows while the rest are transferred, or
805 held on the server waiting for them to be requested by libpq.
806 One complexity is that a statement like SELECT 1/col could error
807 out mid-way through the result set.
809 </li><li>Consider disallowing multiple queries in PQexec() as an
810 additional barrier to SQL injection attacks
811 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-01/msg00184.php">http://archives.postgresql.org/pgsql-hackers/2007-01/msg00184.php</a>
813 </li><li>Add PQexecf() that allows complex parameter substitution
814 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-03/msg01803.php">http://archives.postgresql.org/pgsql-hackers/2007-03/msg01803.php</a>
818 <h1><a name="section_9">Triggers</a></h1>
821 <li>Add deferred trigger queue file
822 <p> Right now all deferred trigger information is stored in backend
823 memory. This could exhaust memory for very large trigger queues.
824 This item involves dumping large queues into files.
826 </li><li>Allow triggers to be disabled in only the current session.
827 <p> This is currently possible by starting a multi-statement transaction,
828 modifying the system tables, performing the desired SQL, restoring the
829 system tables, and committing the transaction. ALTER TABLE ...
830 TRIGGER requires a table lock so it is not ideal for this usage.
832 </li><li>With disabled triggers, allow pg_dump to use ALTER TABLE ADD FOREIGN KEY
833 <p> If the dump is known to be valid, allow foreign keys to be added
834 without revalidating the data.
836 </li><li>Allow statement-level triggers to access modified rows
837 </li><li>Support triggers on columns
838 <p> <a href="http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php">http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php</a>
840 </li><li>Allow AFTER triggers on system tables
841 <p> System tables are modified in many places in the backend without going
842 through the executor and therefore not causing triggers to fire. To
843 complete this item, the functions that modify system tables will have
846 </li><li>Tighten trigger permission checks
847 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg00564.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg00564.php</a>
849 </li><li>Allow BEFORE INSERT triggers on views
850 <p> <a href="http://archives.postgresql.org/pgsql-general/2007-02/msg01466.php">http://archives.postgresql.org/pgsql-general/2007-02/msg01466.php</a>
852 </li><li>Add ability to trigger on TRUNCATE
853 <p> <a href="http://archives.postgresql.org/pgsql-sql/2008-01/msg00050.php">http://archives.postgresql.org/pgsql-sql/2008-01/msg00050.php</a>
856 <h1><a name="section_10">Indexes</a></h1>
859 <li>Add UNIQUE capability to non-btree indexes
860 </li><li>Prevent index uniqueness checks when UPDATE does not modify the column
861 <p> Uniqueness (index) checks are done when updating a column even if the
862 column is not modified by the UPDATE.
864 </li><li>Allow the creation of on-disk bitmap indexes which can be quickly
865 combined with other bitmap indexes
866 <p> Such indexes could be more compact if there are only a few distinct values.
867 Such indexes can also be compressed. Keeping such indexes updated can be
870 <p> <a href="http://archives.postgresql.org/pgsql-patches/2005-07/msg00512.php">http://archives.postgresql.org/pgsql-patches/2005-07/msg00512.php</a>
871 <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg01107.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg01107.php</a>
873 </li><li>Allow accurate statistics to be collected on indexes with more than
874 one column or expression indexes, perhaps using per-index statistics
875 <p> <a href="http://archives.postgresql.org/pgsql-performance/2006-10/msg00222.php">http://archives.postgresql.org/pgsql-performance/2006-10/msg00222.php</a>
876 <a href="http://archives.postgresql.org/pgsql-hackers/2007-03/msg01131.php">http://archives.postgresql.org/pgsql-hackers/2007-03/msg01131.php</a>
878 </li><li>Consider compressing indexes by storing key values duplicated in
879 several rows as a single index entry
880 </li><li>Add REINDEX CONCURRENTLY, like CREATE INDEX CONCURRENTLY
881 <p> This is difficult because you must upgrade to an exclusive table lock
882 to replace the existing index file. CREATE INDEX CONCURRENTLY does not
883 have this complication. This would allow index compaction without
886 </li><li>Allow multiple indexes to be created concurrently, ideally via a
887 single heap scan, and have pg_restore use it
890 <li>Allow inherited tables to inherit indexes, UNIQUE constraints,
891 and primary/foreign keys
892 </li><li>Honor UNIQUE INDEX on base column in INSERTs/UPDATEs
893 on inherited table, e.g. INSERT INTO inherit_table
894 (unique_index_col) VALUES (dup) should fail
895 <p> The main difficulty with this item is the problem of
896 creating an index that can span multiple tables.
898 </li><li>Allow SELECT ... FOR UPDATE on inherited tables
902 <li>Add more GIST index support for geometric data types
903 </li><li>Allow GIST indexes to create certain complex index types, like
904 digital trees (see Aoki)
908 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-09/msg00051.php">http://archives.postgresql.org/pgsql-hackers/2007-09/msg00051.php</a>
911 <li>Pack hash index buckets onto disk pages more efficiently
912 <p> Currently only one hash bucket can be stored on a page. Ideally
913 several hash buckets could be stored on a single page and greater
914 granularity used for the hash algorithm.
916 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2004-06/msg00168.php">http://archives.postgresql.org/pgsql-hackers/2004-06/msg00168.php</a>
918 </li><li>Consider sorting hash buckets so entries can be found using a
919 binary search, rather than a linear scan
920 </li><li>In hash indexes, consider storing the hash value with or instead
922 </li><li>Add WAL logging for crash recovery
923 </li><li>Allow multi-column hash indexes
924 </li><li>During index creation, pre-sort the tuples to improve build speed
925 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-03/msg01199.php">http://archives.postgresql.org/pgsql-hackers/2007-03/msg01199.php</a>
928 <h1><a name="section_11">Fsync</a></h1>
931 <li>Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
932 <p> Ideally this requires a separate test program that can be run
933 at initdb time or optionally later. Consider O_SYNC when
936 </li><li>Add program to test if fsync has a delay compared to non-fsync
938 <h1><a name="section_12">Cache Usage</a></h1>
941 <li>Speed up COUNT(*)
942 <p> We could use a fixed row count and a +/- count to follow MVCC
943 visibility rules, or a single cached value could be used and
944 invalidated if anyone modifies the table. Another idea is to
945 get a count directly from a unique index, but for this to be
946 faster than a sequential scan it must avoid access to the heap
947 to obtain tuple visibility information.
949 </li><li>Provide a way to calculate an "estimated COUNT(*)"
950 <p> Perhaps by using the optimizer's cardinality estimates or random
953 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2005-11/msg00943.php">http://archives.postgresql.org/pgsql-hackers/2005-11/msg00943.php</a>
955 </li><li>Allow data to be pulled directly from indexes
956 <p> Currently indexes do not have enough tuple visibility information
957 to allow data to be pulled from the index without also accessing
958 the heap. One way to allow this is to set a bit on index tuples
959 to indicate if a tuple is currently visible to all transactions
960 when the first valid heap lookup happens. This bit would have to
961 be cleared when a heap tuple is expired.
963 <p> Another idea is to maintain a bitmap of heap pages where all rows
964 are visible to all backends, and allow index lookups to reference
965 that bitmap to avoid heap lookups, perhaps the same bitmap we might
966 add someday to determine which heap pages need vacuuming. Frequently
967 accessed bitmaps would have to be stored in shared memory. One 8k
968 page of bitmaps could track 512MB of heap pages.
970 <p> A third idea would be for a heap scan to check if all rows are visible
971 and if so set a per-table flag which can be checked by index scans.
972 Any change to the table would have to clear the flag. To detect
973 changes during the heap scan a counter could be set at the start and
974 checked at the end --- if it is the same, the table has not been
975 modified --- any table change would increment the counter.
977 </li><li>Consider automatic caching of statements at various levels:
979 <li>Parsed query tree
980 </li><li>Query execute plan
981 </li><li>Query results
983 </li><li>Consider increasing internal areas when shared buffers is increased
984 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2005-10/msg01419.php">http://archives.postgresql.org/pgsql-hackers/2005-10/msg01419.php</a>
986 </li><li>Consider decreasing the amount of memory used by PrivateRefCount
987 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-11/msg00797.php">http://archives.postgresql.org/pgsql-hackers/2006-11/msg00797.php</a>
988 <a href="http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php">http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php</a>
991 <h1><a name="section_13">Vacuum</a></h1>
994 <li>Improve speed with indexes
995 <p> For large table adjustments during VACUUM FULL, it is faster to cluster
996 or reindex rather than update the index. Also, index updates can bloat
999 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-03/msg00024.php">http://archives.postgresql.org/pgsql-hackers/2007-03/msg00024.php</a>
1000 <a href="http://archives.postgresql.org/pgsql-performance/2007-05/msg00296.php">http://archives.postgresql.org/pgsql-performance/2007-05/msg00296.php</a>
1002 </li><li>Auto-fill the free space map by scanning the buffer cache or by
1003 checking pages written by the background writer
1004 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-02/msg01125.php">http://archives.postgresql.org/pgsql-hackers/2006-02/msg01125.php</a>
1005 <a href="http://archives.postgresql.org/pgsql-hackers/2006-03/msg00011.php">http://archives.postgresql.org/pgsql-hackers/2006-03/msg00011.php</a>
1007 </li><li>Create a bitmap of pages that need vacuuming
1008 <p> Instead of sequentially scanning the entire table, have the background
1009 writer or some other process record pages that have expired rows, then
1010 VACUUM can look at just those pages rather than the entire table. In
1011 the event of a system crash, the bitmap would probably be invalidated.
1012 One complexity is that index entries still have to be vacuumed, and
1013 doing this without an index scan (by using the heap values to find the
1014 index entry) might be slow and unreliable, especially for user-defined
1017 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg01188.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg01188.php</a>
1018 <a href="http://archives.postgresql.org/pgsql-hackers/2007-01/msg00121.php">http://archives.postgresql.org/pgsql-hackers/2007-01/msg00121.php</a>
1020 </li><li>Allow FSM to return free space toward the beginning of the heap file,
1021 in hopes that empty pages at the end can be truncated by VACUUM
1022 </li><li>Allow FSM page return free space based on table clustering, to assist
1023 in maintaining clustering?
1024 </li><li>Improve dead row detection during multi-statement transactions usage
1025 <p> <a href="http://archives.postgresql.org/pgsql-patches/2007-03/msg00358.php">http://archives.postgresql.org/pgsql-patches/2007-03/msg00358.php</a>
1027 </li><li>Auto-vacuum
1029 <li>%Issue log message to suggest VACUUM FULL if a table is nearly
1031 </li><li>Improve control of auto-vacuum
1032 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg00876.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg00876.php</a>
1034 </li><li>Prevent long-lived temporary tables from causing frozen-xid
1035 advancement starvation
1036 <p> The problem is that autovacuum cannot vacuum them to set frozen xids;
1037 only the session that created them can do that.
1038 <a href="http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php">http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php</a>
1042 <h1><a name="section_14">Locking</a></h1>
1045 <li>Fix priority ordering of read and write light-weight locks (Neil)
1046 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2004-11/msg00893.php">http://archives.postgresql.org/pgsql-hackers/2004-11/msg00893.php</a>
1047 <a href="http://archives.postgresql.org/pgsql-hackers/2004-11/msg00905.php">http://archives.postgresql.org/pgsql-hackers/2004-11/msg00905.php</a>
1049 </li><li>Fix problem when multiple subtransactions of the same outer transaction
1050 hold different types of locks, and one subtransaction aborts
1051 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-11/msg01011.php">http://archives.postgresql.org/pgsql-hackers/2006-11/msg01011.php</a>
1052 <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg00001.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg00001.php</a>
1053 <a href="http://archives.postgresql.org/pgsql-hackers/2007-02/msg00435.php">http://archives.postgresql.org/pgsql-hackers/2007-02/msg00435.php</a>
1055 </li><li>Allow UPDATEs on only non-referential integrity columns not to conflict
1056 with referential integrity locks
1057 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-02/msg00073.php">http://archives.postgresql.org/pgsql-hackers/2007-02/msg00073.php</a>
1059 </li><li>Add idle_in_transaction_timeout GUC so locks are not held for long
1061 </li><li>Improve deadlock detection when a page cleaning lock conflicts
1062 with a shared buffer that is pinned
1063 <p> <a href="http://archives.postgresql.org/pgsql-bugs/2008-01/msg00138.php">http://archives.postgresql.org/pgsql-bugs/2008-01/msg00138.php</a>
1064 <a href="http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php">http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php</a>
1065 <a href="http://archives.postgresql.org/pgsql-committers/2008-01/msg00365.php">http://archives.postgresql.org/pgsql-committers/2008-01/msg00365.php</a>
1068 <h1><a name="section_15">Startup Time Improvements</a></h1>
1071 <li>Experiment with multi-threaded backend for backend creation [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?thread">thread</a>]
1072 <p> This would prevent the overhead associated with process creation. Most
1073 operating systems have trivial process creation time compared to
1074 database startup overhead, but a few operating systems (Win32,
1075 Solaris) might benefit from threading. Also explore the idea of
1076 a single session using multiple threads to execute a statement faster.
1079 <h1><a name="section_16">Write-Ahead Log</a></h1>
1082 <li>Eliminate need to write full pages to WAL before page modification [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?wal">wal</a>]
1083 <p> Currently, to protect against partial disk page writes, we write
1084 full page images to WAL before they are modified so we can correct any
1085 partial page writes during recovery. These pages can also be
1086 eliminated from point-in-time archive files.
1089 <li>When off, write CRC to WAL and check file system blocks
1091 <p> If CRC check fails during recovery, remember the page in case
1092 a later CRC for that page properly matches.
1094 </li><li>Write full pages during file system write and not when
1095 the page is modified in the buffer cache
1096 <p> This allows most full page writes to happen in the background
1097 writer. It might cause problems for applying WAL on recovery
1098 into a partially-written page, but later the full page will be
1102 </li><li>Allow WAL traffic to be streamed to another server for stand-by
1104 </li><li>Reduce WAL traffic so only modified values are written rather than
1106 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-03/msg01589.php">http://archives.postgresql.org/pgsql-hackers/2007-03/msg01589.php</a>
1108 </li><li>Allow WAL information to recover corrupted pg_controldata
1109 <p> <a href="http://archives.postgresql.org/pgsql-patches/2006-06/msg00025.php">http://archives.postgresql.org/pgsql-patches/2006-06/msg00025.php</a>
1111 </li><li>Find a way to reduce rotational delay when repeatedly writing
1113 <p> Currently fsync of WAL requires the disk platter to perform a full
1114 rotation to fsync again. One idea is to write the WAL to different
1115 offsets that might reduce the rotational delay.
1117 </li><li>Allow WAL logging to be turned off for a table, but the table
1118 might be dropped or truncated during crash recovery [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?walcontrol">walcontrol</a>]
1119 <p> Allow tables to bypass WAL writes and just fsync() dirty pages on
1120 commit. This should be implemented using ALTER TABLE, e.g. ALTER
1121 TABLE PERSISTENCE [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo? DROP | TRUNCATE | DEFAULT "> DROP | TRUNCATE | DEFAULT </a>]. Tables using
1122 non-default logging should not use referential integrity with
1123 default-logging tables. A table without dirty buffers during a
1124 crash could perhaps avoid the drop/truncate.
1126 </li><li>Allow WAL logging to be turned off for a table, but the table would
1127 avoid being truncated/dropped [<a href="http://momjian.postgresql.org/cgi-bin/pgtodo?walcontrol">walcontrol</a>]
1128 <p> To do this, only a single writer can modify the table, and writes
1129 must happen only on new pages so the new pages can be removed during
1130 crash recovery. Readers can continue accessing the table. Such
1131 tables probably cannot have indexes. One complexity is the handling
1132 of indexes on TOAST tables.
1134 </li><li>Speed WAL recovery by allowing more than one page to be prefetched
1135 <p> This involves having a separate process that can be told which pages
1136 the recovery process will need in the near future.
1137 <a href="http://archives.postgresql.org/pgsql-hackers/2008-02/msg01279.php">http://archives.postgresql.org/pgsql-hackers/2008-02/msg01279.php</a>
1140 <h1><a name="section_17">Optimizer / Executor</a></h1>
1143 <li>Improve selectivity functions for geometric operators
1144 </li><li>Precompile SQL functions to avoid overhead
1145 </li><li>Create utility to compute accurate random_page_cost value
1146 </li><li>Improve ability to display optimizer analysis using OPTIMIZER_DEBUG
1147 </li><li>Have EXPLAIN ANALYZE issue NOTICE messages when the estimated and
1148 actual row counts differ by a specified percentage
1149 </li><li>Consider using hash buckets to do DISTINCT, rather than sorting
1150 <p> This would be beneficial when there are few distinct values. This is
1151 already used by GROUP BY.
1153 </li><li>Log statements where the optimizer row estimates were dramatically
1154 different from the number of rows actually found?
1155 </li><li>Consider compressed annealing to search for query plans
1156 <p> This might replace GEQO, <a href="http://sixdemonbag.org/Djinni">http://sixdemonbag.org/Djinni</a>.
1158 </li><li>Improve merge join performance by allowing mark/restore of
1160 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-01/msg00096.php">http://archives.postgresql.org/pgsql-hackers/2007-01/msg00096.php</a>
1163 <h1><a name="section_18">Miscellaneous Performance</a></h1>
1166 <li>Do async I/O for faster random read-ahead of data
1167 <p> Async I/O allows multiple I/O requests to be sent to the disk with
1168 results coming back asynchronously.
1170 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-10/msg00820.php">http://archives.postgresql.org/pgsql-hackers/2006-10/msg00820.php</a>
1171 <a href="http://archives.postgresql.org/pgsql-hackers/2007-12/msg00027.php">http://archives.postgresql.org/pgsql-hackers/2007-12/msg00027.php</a>
1173 </li><li>Use mmap() rather than SYSV shared memory or to write WAL files?
1174 <p> This would remove the requirement for SYSV SHM but would introduce
1175 portability issues. Anonymous mmap (or mmap to /dev/zero) is required
1176 to prevent I/O overhead.
1178 </li><li>Consider mmap()'ing files into a backend?
1179 <p> Doing I/O to large tables would consume a lot of address space or
1180 require frequent mapping/unmapping. Extending the file also causes
1181 mapping problems that might require mapping only individual pages,
1182 leading to thousands of mappings. Another problem is that there is no
1183 way to <u>prevent</u> I/O to disk from the dirty shared buffers so changes
1184 could hit disk before WAL is written.
1186 </li><li>Add a script to ask system configuration questions and tune postgresql.conf
1187 </li><li>Consider ways of storing rows more compactly on disk
1189 <li>Reduce the row header size?
1190 </li><li>Consider reducing on-disk varlena length from four bytes to
1191 two because a heap row cannot be more than 64k in length
1193 </li><li>Consider increasing NUM_CLOG_BUFFERS
1194 </li><li>Consider having the background writer update the transaction status
1195 hint bits before writing out the page
1196 <p> Implementing this requires the background writer to have access to system
1197 catalogs and the transaction status log.
1199 </li><li>Allow user configuration of TOAST thresholds
1200 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-02/msg00213.php">http://archives.postgresql.org/pgsql-hackers/2007-02/msg00213.php</a>
1202 </li><li>Allow configuration of backend priorities via the operating system
1203 <p> Though backend priorities make priority inversion during lock
1204 waits possible, research shows that this is not a huge problem.
1206 <p> <a href="http://archives.postgresql.org/pgsql-general/2007-02/msg00493.php">http://archives.postgresql.org/pgsql-general/2007-02/msg00493.php</a>
1208 </li><li>Experiment with multi-threaded backend better resource utilization
1209 <p> This would allow a single query to make use of multiple CPU's or
1210 multiple I/O channels simultaneously. One idea is to create a
1211 background reader that can pre-fetch sequential and index scan
1212 pages needed by other backends. This could be expanded to allow
1213 concurrent reads from multiple devices in a partitioned table.
1216 <h1><a name="section_19">Source Code</a></h1>
1219 <li>Add use of 'const' for variables in source tree
1220 </li><li>Move some things from contrib into main tree
1221 </li><li>%Remove warnings created by -Wcast-align
1222 </li><li>Move platform-specific ps status display info from ps_status.c to ports
1223 </li><li>Add optional CRC checksum to heap and index pages
1224 </li><li>Improve documentation to build only interfaces (Marc)
1225 </li><li>Remove or relicense modules that are not under the BSD license, if possible
1226 </li><li>Acquire lock on a relation before building a relcache entry for it
1227 </li><li>Allow cross-compiling by generating the zic database on the target system
1228 </li><li>Improve NLS maintenance of libpgport messages linked onto applications
1229 </li><li>Clean up casting in contrib/isn
1230 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-11/msg00245.php">http://archives.postgresql.org/pgsql-hackers/2006-11/msg00245.php</a>
1232 </li><li>Use UTF8 encoding for NLS messages so all server encodings can
1234 </li><li>Update Bonjour to work with newer cross-platform SDK
1235 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php">http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php</a>
1236 <a href="http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php">http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php</a>
1238 </li><li>Consider detoasting keys before sorting
1239 </li><li>Consider GnuTLS if OpenSSL license becomes a problem
1240 <p> <a href="http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php">http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php</a>
1241 <a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php</a>
1243 </li><li>Consider changing documentation format from SGML to XML
1244 <p> <a href="http://archives.postgresql.org/pgsql-docs/2006-12/msg00152.php">http://archives.postgresql.org/pgsql-docs/2006-12/msg00152.php</a>
1246 </li><li>Consider making NAMEDATALEN more configurable in future releases
1247 </li><li>Update our code to handle 64-bit timezone files to match the zic
1248 source code, which now uses them
1249 </li><li>Have configure choose integer datetimes by default
1250 <p> <a href="http://archives.postgresql.org/pgsql-patches/2007-05/msg00046.php">http://archives.postgresql.org/pgsql-patches/2007-05/msg00046.php</a>
1252 </li><li>Support scoped IPv6 addresses
1253 <p> <a href="http://archives.postgresql.org/pgsql-bugs/2007-05/msg00111.php">http://archives.postgresql.org/pgsql-bugs/2007-05/msg00111.php</a>
1255 </li><li>Consider allowing 64-bit integers and floats to be passed by value on
1257 <p> Also change 32-bit floats (float4) to be passed by value at the same
1262 <li>Remove configure.in check for link failure when cause is found
1263 </li><li>Remove readdir() errno patch when runtime/mingwex/dirent.c rev
1265 </li><li>Remove psql newline patch when we find out why mingw outputs an
1267 </li><li>Allow psql to use readline once non-US code pages work with
1269 </li><li>Fix problem with shared memory on the Win32 Terminal Server
1270 </li><li>Improve signal handling
1271 <p> <a href="http://archives.postgresql.org/pgsql-patches/2005-06/msg00027.php">http://archives.postgresql.org/pgsql-patches/2005-06/msg00027.php</a>
1274 </li><li>Wire Protocol Changes
1276 <li>Allow dynamic character set handling
1277 </li><li>Add decoded type, length, precision
1278 </li><li>Use compression?
1279 </li><li>Update clients to use data types, typmod, schema.table.column names
1280 of result sets using new statement protocol
1283 <h1><a name="section_20">Exotic Features</a></h1>
1286 <li>Add pre-parsing phase that converts non-ISO syntax to supported
1288 <p> This could allow SQL written for other databases to run without
1291 </li><li>Allow plug-in modules to emulate features from other databases
1292 </li><li>Add features of Oracle-style packages (Pavel)
1293 <p> A package would be a schema with session-local variables,
1294 public/private functions, and initialization functions. It
1295 is also possible to implement these capabilities
1296 in any schema and not use a separate "packages"
1299 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-08/msg00384.php">http://archives.postgresql.org/pgsql-hackers/2006-08/msg00384.php</a>
1301 </li><li>Consider allowing control of upper/lower case folding of unquoted
1303 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2004-04/msg00818.php">http://archives.postgresql.org/pgsql-hackers/2004-04/msg00818.php</a>
1304 <a href="http://archives.postgresql.org/pgsql-hackers/2006-10/msg01527.php">http://archives.postgresql.org/pgsql-hackers/2006-10/msg01527.php</a>
1306 </li><li>Add autonomous transactions
1307 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.php">http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.php</a>
1310 <h1><a name="section_21">Features We Do <u>Not</u> Want</a></h1>
1313 <li>All backends running as threads in a single process (not wanted)
1314 <p> This eliminates the process protection we get from the current setup.
1315 Thread creation is usually the same overhead as process creation on
1316 modern systems, so it seems unwise to use a pure threaded model.
1318 </li><li>Optimizer hints (not wanted)
1319 <p> Optimizer hints are used to work around problems in the optimizer. We
1320 would rather have the problems reported and fixed.
1322 <p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-08/msg00506.php">http://archives.postgresql.org/pgsql-hackers/2006-08/msg00506.php</a>
1323 <a href="http://archives.postgresql.org/pgsql-hackers/2006-10/msg00517.php">http://archives.postgresql.org/pgsql-hackers/2006-10/msg00517.php</a>
1324 <a href="http://archives.postgresql.org/pgsql-hackers/2006-10/msg00663.php">http://archives.postgresql.org/pgsql-hackers/2006-10/msg00663.php</a>
1326 <p> Because we support postfix operators, it isn't possible to make AS
1327 optional and continue to use bison.
1328 <a href="http://archives.postgresql.org/pgsql-hackers/2003-04/msg00436.php">http://archives.postgresql.org/pgsql-hackers/2003-04/msg00436.php</a>
1330 <p> <a href="http://archives.postgresql.org/pgsql-sql/2006-08/msg00164.php">http://archives.postgresql.org/pgsql-sql/2006-08/msg00164.php</a>
1332 </li><li>Embedded server (not wanted)
1333 <p> While PostgreSQL clients runs fine in limited-resource environments, the
1334 server requires multiple processes and a stable pool of resources to
1335 run reliabily and efficiently. Stripping down the PostgreSQL server
1336 to run in the same process address space as the client application
1337 would add too much complexity and failure cases.</p>