diff options
| author | Bruce Momjian | 2003-06-02 18:16:56 +0000 |
|---|---|---|
| committer | Bruce Momjian | 2003-06-02 18:16:56 +0000 |
| commit | 7facd5d10c3f5913224f598af57f4a78819a827d (patch) | |
| tree | 5737f6dd0c699e291c7a1fad81f4964e01d96ce0 /doc/src | |
| parent | 202f77fe6d5973816483ef1a6653a054e7768124 (diff) | |
Add Turkish FAQ, from Devrim GUNDUZ.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/FAQ/FAQ_turkish.html | 1255 |
1 files changed, 1255 insertions, 0 deletions
diff --git a/doc/src/FAQ/FAQ_turkish.html b/doc/src/FAQ/FAQ_turkish.html new file mode 100644 index 00000000000..38944666bb8 --- /dev/null +++ b/doc/src/FAQ/FAQ_turkish.html @@ -0,0 +1,1255 @@ +
+ PostgreSQL i�in S�k�a Sorulan Sorular (SSS)
+
+Son g�ncelleme : 19 May�s 2003 Pazartesi - 03:05:21
+
+Current maintainer: Bruce Momjian ([email protected]
+<mailto:[email protected]>)
+
+�eviren : Devrim G�ND�Z ([email protected] <mailto:[email protected]>)
+Nicolai Tufar ([email protected] <mailto:[email protected]>)
+
+Bu belgenin en g�ncel hali,
+http://www.PostgreSQL.org/docs/faqs/FAQ_turkish.html ve
+http://www.gunduz.org/seminer/pg/FAQ_turkish adreslerinde g�r�lebilir.
+
+Platforma �zel sorular�n�z,http://www.PostgreSQL.org/docs/index.html
+adresinde yan�tlan�r..
+
+------------------------------------------------------------------------
+
+
+ Genel Sorular
+
+1.1 <#1.1>) PostgreSQL nedir? Nas�l okunur?
+1.2 <#1.2>) PostgreSQL' in haklar� nedir?
+1.3 <#1.3>) PostgreSQL, hangi Unix platformlar�nda �al�s�r?
+1.4 <#1.4>) Hangi Unix olmayan uyarlamalar� bulunmaktad�r?
+1.5 <#1.5>) PostgreSQL'i nereden indirebilirim?
+1.6 <#1.6>) Deste�i nereden alabilirim?
+1.7 <#1.7>) En son s�r�m� nedir?
+1.8 <#1.8>) Hangi belgelere ulasabilirim?
+1.9 <#1.9>) Bilinen hatalar ya da eksik �zelliklere nereden ulasabilirim?
+1.10 <#1.10>) Nas�l SQL ��renebilirim?
+1.11 <#1.11>) PostgreSQL 2000 y�l�na uyumlu mudur?
+1.12 <#1.12>) Geli�tirme tak�m�na nas�l kat�labilirim??
+1.13 <#1.13>) Bir hata raporunu nas�l g�nderebilirim?
+1.14 <#1.14>) PostgreSQL, diger VTYS(DBMS lerle nas�l kar��la�t�r�labilir?
+1.15 <#1.15>) PostgreSQL'e maddi a��dan nas�l destek olabilirim?
+
+
+ Kullan�c�/istemci Sorular�
+
+2.1 <#2.1>) Are there ODBC drivers for PostgreSQL?
+2.2 <#2.2>) What tools are available for using PostgreSQL with Web pages?
+2.3 <#2.3>) Does PostgreSQL have a graphical user interface?
+2.4 <#2.4>) What languages are available to communicate with PostgreSQL?
+
+
+ Administrative Questions
+
+3.1 <#3.1>) How do I install PostgreSQL somewhere other than
+//usr/local/pgsql/?
+3.2 <#3.2>) When I start /postmaster/, I get a /Bad System Call/ or core
+dumped message. Why?
+3.3 <#3.3>) When I try to start /postmaster/, I get /IpcMemoryCreate/
+errors. Why?
+3.4 <#3.4>) When I try to start /postmaster/, I get /IpcSemaphoreCreate/
+errors. Why?
+3.5 <#3.5>) How do I control connections from other hosts?
+3.6 <#3.6>) How do I tune the database engine for better performance?
+3.7 <#3.7>) What debugging features are available?
+3.8 <#3.8>) Why do I get /"Sorry, too many clients"/ when trying to connect?
+3.9 <#3.9>) What is in the /pgsql_tmp/ directory?
+3.10 <#3.10>) Why do I need to do a dump and restore to upgrade
+PostgreSQL releases?
+
+
+ Operational Questions
+
+4.1 <#4.1>) What is the difference between binary cursors and normal
+cursors?
+4.2 <#4.2>) How do I SELECT only the first few rows of a query?
+4.3 <#4.3>) How do I get a list of tables or other things I can see in
+/psql/?
+4.4 <#4.4>) How do you remove a column from a table?
+4.5 <#4.5>) What is the maximum size for a row, a table, and a database?
+4.6 <#4.6>) How much database disk space is required to store data from
+a typical text file?
+4.7 <#4.7>) How do I find out what tables, indexes, databases, and users
+are defined?
+4.8 <#4.8>) My queries are slow or don't make use of the indexes. Why?
+4.9 <#4.9>) How do I see how the query optimizer is evaluating my query?
+4.10 <#4.10>) What is an R-tree index?
+4.11 <#4.11>) What is the Genetic Query Optimizer?
+4.12 <#4.12>) How do I perform regular expression searches and
+case-insensitive regular expression searches? How do I use an index for
+case-insensitive searches?
+4.13 <#4.13>) In a query, how do I detect if a field is NULL?
+4.14 <#4.14>) What is the difference between the various character types?
+4.15.1 <#4.15.1>) How do I create a serial/auto-incrementing field?
+4.15.2 <#4.15.2>) How do I get the value of a SERIAL insert?
+4.15.3 <#4.15.3>) Don't /currval()/ and /nextval()/ lead to a race
+condition with other users?
+4.15.4 <#4.15.4>) Why aren't my sequence numbers reused on transaction
+abort? Why are there gaps in the numbering of my sequence/SERIAL column?
+4.16 <#4.16>) What is an OID? What is a TID?
+4.17 <#4.17>) What is the meaning of some of the terms used in PostgreSQL?
+4.18 <#4.18>) Why do I get the error /"ERROR: Memory exhausted in
+AllocSetAlloc()"/?
+4.19 <#4.19>) How do I tell what PostgreSQL version I am running?
+4.20 <#4.20>) Why does my large-object operations get /"invalid large
+obj descriptor"/?
+4.21 <#4.21>) How do I create a column that will default to the current
+time?
+4.22 <#4.22>) Why are my subqueries using |IN| so slow?
+4.23 <#4.23>) How do I perform an outer join?
+4.24 <#4.24>) How do I perform queries using multiple databases?
+4.25 <#4.25>) How do I return multiple rows or columns from a function?
+4.26 <#4.26>) Why can't I reliably create/drop temporary tables in
+PL/PgSQL functions?
+4.27 <#4.27>) What replication options are available?
+4.28 <#4.28>) What encryption options are available?
+
+
+ Extending PostgreSQL
+
+5.1 <#5.1>) I wrote a user-defined function. When I run it in /psql/,
+why does it dump core?
+5.2 <#5.2>) How can I contribute some nifty new types and functions to
+PostgreSQL?
+5.3 <#5.3>) How do I write a C function to return a tuple?
+5.4 <#5.4>) I have changed a source file. Why does the recompile not see
+the change?
+------------------------------------------------------------------------
+
+
+ General Questions
+
+
+ 1.1) What is PostgreSQL? How is it pronounced?
+
+PostgreSQL is pronounced /Post-Gres-Q-L/.
+
+PostgreSQL is an enhancement of the POSTGRES database management system,
+a next-generation DBMS research prototype. While PostgreSQL retains the
+powerful data model and rich data types of POSTGRES, it replaces the
+PostQuel query language with an extended subset of SQL. PostgreSQL is
+free and the complete source is available.
+
+PostgreSQL development is performed by a team of developers who all
+subscribe to the PostgreSQL development mailing list. The current
+coordinator is Marc G. Fournier ([email protected]
+<mailto:[email protected]>). (See section 1.6 <#1.6> on how to
+join). This team is now responsible for all development of PostgreSQL.
+
+The authors of PostgreSQL 1.01 were Andrew Yu and Jolly Chen. Many
+others have contributed to the porting, testing, debugging, and
+enhancement of the code. The original Postgres code, from which
+PostgreSQL is derived, was the effort of many graduate students,
+undergraduate students, and staff programmers working under the
+direction of Professor Michael Stonebraker at the University of
+California, Berkeley.
+
+The original name of the software at Berkeley was Postgres. When SQL
+functionality was added in 1995, its name was changed to Postgres95. The
+name was changed at the end of 1996 to PostgreSQL.
+
+
+ 1.2) What is the copyright on PostgreSQL?
+
+PostgreSQL is subject to the following COPYRIGHT:
+
+PostgreSQL Data Base Management System
+
+Portions copyright (c) 1996-2002, PostgreSQL Global Development Group
+Portions Copyright (c) 1994-6 Regents of the University of California
+
+Permission to use, copy, modify, and distribute this software and its
+documentation for any purpose, without fee, and without a written
+agreement is hereby granted, provided that the above copyright notice
+and this paragraph and the following two paragraphs appear in all copies.
+
+IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
+FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
+INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
+DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF
+THE POSSIBILITY OF SUCH DAMAGE.
+
+THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS
+TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+
+The above is the BSD license, the classic open-source license. It has no
+restrictions on how the source code may be used. We like it and have no
+intention of changing it.
+
+
+ 1.3) What Unix platforms does PostgreSQL run on?
+
+In general, a modern Unix-compatible platform should be able to run
+PostgreSQL. The platforms that had received explicit testing at the time
+of release are listed in the installation instructions.
+
+
+ 1.4) What non-Unix ports are available?
+
+*Client*
+
+It is possible to compile the /libpq/ C library, psql, and other
+interfaces and client applications to run on MS Windows platforms. In
+this case, the client is running on MS Windows, and communicates via
+TCP/IP to a server running on one of our supported Unix platforms. A
+file /win32.mak/ is included in the distribution for making a Win32
+/libpq/ library and /psql/. PostgreSQL also communicates with ODBC clients.
+
+*Server*
+
+The database server can run on Windows NT and Win2k using Cygwin, the
+Cygnus Unix/NT porting library. See /pgsql/doc/FAQ_MSWIN/ in the
+distribution or the MS Windows FAQ at
+http://www.PostgreSQL.org/docs/faqs/text/FAQ_MSWIN
+<http://www.PostgreSQL.org/docs/faqs/text/FAQ_MSWIN>.
+
+A native port to MS Win NT/2000/XP is currently being worked on. For
+more details on the current status of PostgreSQL on Windows see
+http://techdocs.postgresql.org/guides/Windows
+<http://techdocs.postgresql.org/guides/Windows>.
+
+There is also a Novell Netware 6 port at http://forge.novell.com.
+
+
+ 1.5) Where can I get PostgreSQL?
+
+The primary anonymous ftp site for PostgreSQL is
+ftp://ftp.PostgreSQL.org/pub. For mirror sites, see our main web site.
+
+
+ 1.6) Where can I get support?
+
+The main mailing list is: [email protected]
+<mailto:[email protected]>. It is available for discussion of
+matters pertaining to PostgreSQL. To subscribe, send mail with the
+following lines in the body (not the subject line):
+
+ subscribe
+ end
+
+<mailto:[email protected]>.
+
+There is also a digest list available. To subscribe to this list, send
+email to: [email protected]
+<mailto:[email protected]> with a body of:
+
+ subscribe
+ end
+
+Digests are sent out to members of this list whenever the main list has
+received around 30k of messages.
+
+The bugs mailing list is available. To subscribe to this list, send
+email to [email protected]
+<mailto:[email protected]> with a body of:
+
+ subscribe
+ end
+
+There is also a developers discussion mailing list available. To
+subscribe to this list, send email to
+<mailto:[email protected]> with a body of:
+
+ subscribe
+ end
+
+Additional mailing lists and information about PostgreSQL can be found
+via the PostgreSQL WWW home page at:
+
+ http://www.PostgreSQL.org
+
+There is also an IRC channel on EFNet and OpenProjects, channel
+/#PostgreSQL/. I use the Unix command |irc -c '#PostgreSQL' "$USER"
+irc.phoenix.net.|
+
+A list of commercial support companies is available at
+http://www.ca.PostgreSQL.org/users-lounge/commercial-support.html.
+
+
+ 1.7) What is the latest release?
+
+The latest release of PostgreSQL is version 7.3.3.
+
+We plan to have major releases every four months.
+
+
+ 1.8) What documentation is available?
+
+Several manuals, manual pages, and some small test examples are included
+in the distribution. See the //doc/ directory. You can also browse the
+manuals online at http://www.PostgreSQL.org/docs.
+
+There are two PostgreSQL books available online at
+http://www.PostgreSQL.org/docs/awbook.html and
+http://www.commandprompt.com/ppbook/. There is a list of PostgreSQL
+books available for purchase at http://www.ca.PostgreSQL.org/books/.
+There is also a collection of PostgreSQL technical articles at
+http://techdocs.PostgreSQL.org/.
+
+/psql/ has some nice \d commands to show information about types,
+operators, functions, aggregates, etc.
+
+Our web site contains even more documentation.
+
+
+ 1.9) How do I find out about known bugs or missing features?
+
+PostgreSQL supports an extended subset of SQL-92. See our TODO
+<http://developer.PostgreSQL.org/todo.php> list for known bugs, missing
+features, and future plans.
+
+
+ 1.10) How can I learn SQL?
+
+The PostgreSQL book at http://www.PostgreSQL.org/docs/awbook.html
+teaches SQL. There is another PostgreSQL book at
+http://www.commandprompt.com/ppbook.
+<http://www.commandprompt.com/ppbook/> There is a nice tutorial at
+http://www.intermedia.net/support/sql/sqltut.shtm,
+<http://www.intermedia.net/support/sql/sqltut.shtm> at
+http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM,
+<http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM>
+and at http://sqlcourse.com. <http://sqlcourse.com/>
+
+Another one is "Teach Yourself SQL in 21 Days, Second Edition" at
+http://members.tripod.com/er4ebus/sql/index.htm
+
+Many of our users like /The Practical SQL Handbook/, Bowman, Judith S.,
+et al., Addison-Wesley. Others like /The Complete Reference SQL/, Groff
+et al., McGraw-Hill.
+
+
+ 1.11) Is PostgreSQL Y2K compliant?
+
+Yes, we easily handle dates past the year 2000 AD, and before 2000 BC.
+
+
+ 1.12) How do I join the development team?
+
+First, download the latest source and read the PostgreSQL Developers
+documentation on our web site, or in the distribution. Second, subscribe
+to the /pgsql-hackers/ and /pgsql-patches/ mailing lists. Third, submit
+high quality patches to pgsql-patches.
+
+There are about a dozen people who have commit privileges to the
+PostgreSQL CVS archive. They each have submitted so many high-quality
+patches that it was impossible for the existing committers to keep up,
+and we had confidence that patches they committed were of high quality.
+
+
+ 1.13) How do I submit a bug report?
+
+Please visit the PostgreSQL BugTool page at
+http://www.PostgreSQL.org/bugs/bugs.php, which gives guidelines and
+directions on how to submit a bug report.
+
+Also check out our ftp site ftp://ftp.PostgreSQL.org/pub to see if there
+is a more recent PostgreSQL version or patches.
+
+
+ 1.14) How does PostgreSQL compare to other DBMSs?
+
+There are several ways of measuring software: features, performance,
+reliability, support, and price.
+
+*Features*
+ PostgreSQL has most features present in large commercial DBMSs, like
+ transactions, subselects, triggers, views, foreign key referential
+ integrity, and sophisticated locking. We have some features they do
+ not have, like user-defined types, inheritance, rules, and
+ multi-version concurrency control to reduce lock contention.
+
+*Performance*
+ PostgreSQL has performance similar to other commercial and open
+ source databases. it is faster for some things, slower for others.
+ In comparison to MySQL or leaner database systems, we are slower on
+ inserts/updates because of transaction overhead. Of course, MySQL
+ does not have any of the features mentioned in the /Features/
+ section above. We are built for reliability and features, though we
+ continue to improve performance in every release. There is an
+ interesting Web page comparing PostgreSQL to MySQL at
+ http://openacs.org/philosophy/why-not-mysql.html
+ <http://openacs.org/philosophy/why-not-mysql.html>
+
+*Reliability*
+ We realize that a DBMS must be reliable, or it is worthless. We
+ strive to release well-tested, stable code that has a minimum of
+ bugs. Each release has at least one month of beta testing, and our
+ release history shows that we can provide stable, solid releases
+ that are ready for production use. We believe we compare favorably
+ to other database software in this area.
+
+*Support*
+ Our mailing lists provide contact with a large group of developers
+ and users to help resolve any problems encountered. While we cannot
+ guarantee a fix, commercial DBMSs do not always supply a fix either.
+ Direct access to developers, the user community, manuals, and the
+ source code often make PostgreSQL support superior to other DBMSs.
+ There is commercial per-incident support available for those who
+ need it. (See FAQ section 1.6 <#1.6>.)
+
+*Price*
+ We are free for all use, both commercial and non-commercial. You can
+ add our code to your product with no limitations, except those
+ outlined in our BSD-style license stated above.
+
+
+ 1.15) How can I financially assist PostgreSQL?
+
+PostgreSQL has had a first-class infrastructure since we started in
+1996. This is all thanks to Marc Fournier, who has created and managed
+this infrastructure over the years.
+
+Quality infrastructure is very important to an open-source project. It
+prevents disruptions that can greatly delay forward movement of the project.
+
+Of course, this infrastructure is not cheap. There are a variety of
+monthly and one-time expenses that are required to keep it going. If you
+or your company has money it can donate to help fund this effort, please
+go to http://store.pgsql.com/shopping/ and make a donation.
+
+Although the web page mentions PostgreSQL, Inc, the "contributions" item
+is solely to support the PostgreSQL project and does not fund any
+specific company. If you prefer, you can also send a check to the
+contact address.
+
+------------------------------------------------------------------------
+
+
+ User Client Questions
+
+
+ 2.1) Are there ODBC drivers for PostgreSQL?
+
+There are two ODBC drivers available, PsqlODBC and OpenLink ODBC.
+
+You can download PsqlODBC from
+http://gborg.postgresql.org/project/psqlodbc/projdisplay.php
+<http://gborg.postgresql.org/project/psqlodbc/projdisplay.php>.
+
+OpenLink ODBC can be gotten from http://www.openlinksw.com
+<http://www.openlinksw.com/>. It works with their standard ODBC client
+software so you'll have PostgreSQL ODBC available on every client
+platform they support (Win, Mac, Unix, VMS).
+
+They will probably be selling this product to people who need
+commercial-quality support, but a freeware version will always be
+available. Please send questions to [email protected]
+<mailto:[email protected]>.
+
+
+ 2.2) What tools are available for using PostgreSQL with Web pages?
+
+A nice introduction to Database-backed Web pages can be seen at:
+http://www.webreview.com
+
+For Web integration, PHP is an excellent interface. It is at
+http://www.php.net.
+
+For complex cases, many use the Perl interface and CGI.pm or mod_perl.
+
+
+ 2.3) Does PostgreSQL have a graphical user interface?
+
+Yes, there are several graphical interfaces to PostgreSQL available.
+These include PgAccess http://www.pgaccess.org
+<http://www.pgaccess.org>), PgAdmin II (http://www.pgadmin.org,
+Win32-only), RHDB Admin (http://sources.redhat.com/rhdb/ ) and Rekall (
+http://www.thekompany.com/products/rekall/
+<http://www.thekompany.com/products/rekall/>, proprietary). There is
+also PHPPgAdmin ( http://phppgadmin.sourceforge.net/
+<http://phppgadmin.sourceforge.net/>), a web-based interface to PostgreSQL.
+
+See http://techdocs.postgresql.org/guides/GUITools for a more detailed list.
+
+
+ 2.4) What languages are able to communicate with PostgreSQL?
+
+Most popular programming languages contain an interface to PostgreSQL.
+Check your programming language's list of extension modules.
+
+The following interfaces are included in the PostgreSQL distribution:
+
+ * C (libpq)
+ * Embedded C (ecpg)
+ * Java (jdbc)
+ * Python (PyGreSQL)
+ * TCL (libpgtcl)
+
+Additional interfaces are available at http://gborg.postgresql.org in
+the /Drivers/Interfaces/ section.
+
+------------------------------------------------------------------------
+
+
+ Administrative Questions
+
+
+ 3.1) How do I install PostgreSQL somewhere other than
+ //usr/local/pgsql/?
+
+Specify the /--prefix/ option when running /configure/.
+
+
+ 3.2) When I start /postmaster/, I get a /Bad System Call/ or
+ core dumped message. Why?
+
+It could be a variety of problems, but first check to see that you have
+System V extensions installed in your kernel. PostgreSQL requires kernel
+support for shared memory and semaphores.
+
+
+ 3.3) When I try to start /postmaster/, I get /IpcMemoryCreate/
+ errors. Why?
+
+You either do not have shared memory configured properly in your kernel
+or you need to enlarge the shared memory available in the kernel. The
+exact amount you need depends on your architecture and how many buffers
+and backend processes you configure for /postmaster/. For most systems,
+with default numbers of buffers and processes, you need a minimum of ~1
+MB. See the PostgreSQL Administrator's Guide
+<http://www.PostgreSQL.org/docs/view.php?version=current&idoc=1&file=kernel-resources.html>
+for more detailed information about shared memory and semaphores.
+
+
+ 3.4) When I try to start /postmaster/, I get
+ /IpcSemaphoreCreate/ errors. Why?
+
+If the error message is /IpcSemaphoreCreate: semget failed (No space
+left on device)/ then your kernel is not configured with enough
+semaphores. Postgres needs one semaphore per potential backend process.
+A temporary solution is to start /postmaster/ with a smaller limit on
+the number of backend processes. Use /-N/ with a parameter less than the
+default of 32. A more permanent solution is to increase your kernel's
+SEMMNS and SEMMNI parameters.
+
+Inoperative semaphores can also cause crashes during heavy database access.
+
+If the error message is something else, you might not have semaphore
+support configured in your kernel at all. See the PostgreSQL
+Administrator's Guide for more detailed information about shared memory
+and semaphores.
+
+
+ 3.5) How do I control connections from other hosts?
+
+By default, PostgreSQL only allows connections from the local machine
+using Unix domain sockets. Other machines will not be able to connect
+unless you add the /-i/ flag to /postmaster/, *and* enable host-based
+authentication by modifying the file /$PGDATA/pg_hba.conf/ accordingly.
+This will allow TCP/IP connections.
+
+
+ 3.6) How do I tune the database engine for better performance?
+
+Certainly, indexes can speed up queries. The EXPLAIN command allows you
+to see how PostgreSQL is interpreting your query, and which indexes are
+being used.
+
+If you are doing many INSERTs, consider doing them in a large batch
+using the COPY command. This is much faster than individual INSERTS.
+Second, statements not in a BEGIN WORK/COMMIT transaction block are
+considered to be in their own transaction. Consider performing several
+statements in a single transaction block. This reduces the transaction
+overhead. Also, consider dropping and recreating indexes when making
+large data changes.
+
+There are several tuning options. You can disable /fsync()/ by starting
+/postmaster/ with a /-o -F/ option. This will prevent /fsync()/s from
+flushing to disk after every transaction.
+
+You can also use the /postmaster/ /-B/ option to increase the number of
+shared memory buffers used by the backend processes. If you make this
+parameter too high, the /postmaster/ may not start because you have
+exceeded your kernel's limit on shared memory space. Each buffer is 8K
+and the default is 64 buffers.
+
+You can also use the backend /-S/ option to increase the maximum amount
+of memory used by the backend process for temporary sorts. The /-S/
+value is measured in kilobytes, and the default is 512 (i.e. 512K).
+
+You can also use the CLUSTER command to group data in tables to match an
+index. See the CLUSTER manual page for more details.
+
+
+ 3.7) What debugging features are available?
+
+PostgreSQL has several features that report status information that can
+be valuable for debugging purposes.
+
+First, by running /configure/ with the --enable-cassert option, many
+/assert()/s monitor the progress of the backend and halt the program
+when something unexpected occurs.
+
+Both /postmaster/ and /postgres/ have several debug options available.
+First, whenever you start /postmaster/, make sure you send the standard
+output and error to a log file, like:
+
+ cd /usr/local/pgsql
+ ./bin/postmaster >server.log 2>&1 &
+
+This will put a server.log file in the top-level PostgreSQL directory.
+This file contains useful information about problems or errors
+encountered by the server. /Postmaster/ has a /-d/ option that allows
+even more detailed information to be reported. The /-d/ option takes a
+number that specifies the debug level. Be warned that high debug level
+values generate large log files.
+
+If /postmaster/ is not running, you can actually run the /postgres/
+backend from the command line, and type your SQL statement directly.
+This is recommended *only* for debugging purposes. Note that a newline
+terminates the query, not a semicolon. If you have compiled with
+debugging symbols, you can use a debugger to see what is happening.
+Because the backend was not started from /postmaster/, it is not running
+in an identical environment and locking/backend interaction problems may
+not be duplicated.
+
+If /postmaster/ is running, start /psql/ in one window, then find the
+PID of the /postgres/ process used by /psql/. Use a debugger to attach
+to the /postgres/ PID. You can set breakpoints in the debugger and issue
+queries from /psql/. If you are debugging /postgres/ startup, you can
+set PGOPTIONS="-W n", then start /psql/. This will cause startup to
+delay for /n/ seconds so you can attach to the process with the
+debugger, set any breakpoints, and continue through the startup sequence.
+
+The /postgres/ program has /-s, -A/, and /-t/ options that can be very
+useful for debugging and performance measurements.
+
+You can also compile with profiling to see what functions are taking
+execution time. The backend profile files will be deposited in the
+/pgsql/data/base/dbname/ directory. The client profile file will be put
+in the client's current directory. Linux requires a compile with
+/-DLINUX_PROFILE/ for proper profiling.
+
+
+ 3.8) Why do I get /"Sorry, too many clients"/ when trying to
+ connect?
+
+You need to increase /postmaster/'s limit on how many concurrent backend
+processes it can start.
+
+The default limit is 32 processes. You can increase it by restarting
+/postmaster/ with a suitable /-N/ value or modifying /postgresql.conf/.
+
+Note that if you make /-N/ larger than 32, you must also increase /-B/
+beyond its default of 64; /-B/ must be at least twice /-N/, and probably
+should be more than that for best performance. For large numbers of
+backend processes, you are also likely to find that you need to increase
+various Unix kernel configuration parameters. Things to check include
+the maximum size of shared memory blocks, SHMMAX; the maximum number of
+semaphores, SEMMNS and SEMMNI; the maximum number of processes, NPROC;
+the maximum number of processes per user, MAXUPRC; and the maximum
+number of open files, NFILE and NINODE. The reason that PostgreSQL has a
+limit on the number of allowed backend processes is so your system won't
+run out of resources.
+
+
+ 3.9) What is in the /pgsql_tmp/ directory?
+
+This directory contains temporary files generated by the query executor.
+For example, if a sort needs to be done to satisfy an ORDER BY and the
+sort requires more space than the backend's /-S/ parameter allows, then
+temporary files are created here to hold the extra data.
+
+The temporary files are usually deleted automatically, but might remain
+if a backend crashes during a sort. A stop and restart of the
+/postmaster/ will remove files from those directories.
+
+
+ 3.10) Why do I need to do a dump and restore to upgrade between
+ major PostgreSQL releases?
+
+The PostgreSQL team makes only small changes between minor releases, so
+upgrading from 7.2 to 7.2.1 does not require a dump and restore.
+However, major releases (e.g. from 7.2 to 7.3) often change the internal
+format of system tables and data files. These changes are often complex,
+so we don't maintain backward compatability for data files. A dump
+outputs data in a generic format that can then be loaded in using the
+new internal format.
+
+In releases where the on-disk format does not change, the /pg_upgrade/
+script can be used to upgrade without a dump/restore. The release notes
+mention whether /pg_upgrade/ is available for the release.
+
+------------------------------------------------------------------------
+
+
+ Operational Questions
+
+
+ 4.1) What is the difference between binary cursors and normal
+ cursors?
+
+See the DECLARE manual page for a description.
+
+
+ 4.2) How do I SELECT only the first few rows of a query?
+
+See the FETCH manual page, or use SELECT ... LIMIT....
+
+The entire query may have to be evaluated, even if you only want the
+first few rows. Consider using a query that has an ORDER BY. If there is
+an index that matches the ORDER BY, PostgreSQL may be able to evaluate
+only the first few records requested, or the entire query may have to be
+evaluated until the desired rows have been generated.
+
+
+ 4.3) How do I get a list of tables or other things I can see in
+ /psql/?
+
+You can read the source code for /psql/ in file
+/pgsql/src/bin/psql/describe.c/. It contains SQL commands that generate
+the output for psql's backslash commands. You can also start /psql/ with
+the /-E/ option so it will print out the queries it uses to execute the
+commands you give.
+
+
+ 4.4) How do you remove a column from a table?
+
+This functionality was added in release 7.3 with ALTER TABLE DROP
+COLUMN. In earlier versions, you can do this:
+
+ BEGIN;
+ LOCK TABLE old_table;
+ SELECT ... -- select all columns but the one you want to remove
+ INTO TABLE new_table
+ FROM old_table;
+ DROP TABLE old_table;
+ ALTER TABLE new_table RENAME TO old_table;
+ COMMIT;
+
+
+ 4.5) What is the maximum size for a row, a table, and a database?
+
+These are the limits:
+
+ Maximum size for a database? unlimited (4 TB databases exist)
+ Maximum size for a table? 16 TB
+ Maximum size for a row? 1.6TB
+ Maximum size for a field? 1 GB
+ Maximum number of rows in a table? unlimited
+ Maximum number of columns in a table? 250-1600 depending on column types
+ Maximum number of indexes on a table? unlimited
+
+Of course, these are not actually unlimited, but limited to available
+disk space and memory/swap space. Performance may suffer when these
+values get unusually large.
+
+The maximum table size of 16 TB does not require large file support from
+the operating system. Large tables are stored as multiple 1 GB files so
+file system size limits are not important.
+
+The maximum table size and maximum number of columns can be increased if
+the default block size is increased to 32k.
+
+
+ 4.6) How much database disk space is required to store data from
+ a typical text file?
+
+A PostgreSQL database may require up to five times the disk space to
+store data from a text file.
+
+As an example, consider a file of 100,000 lines with an integer and text
+description on each line. Suppose the text string avergages twenty bytes
+in length. The flat file would be 2.8 MB. The size of the PostgreSQL
+database file containing this data can be estimated as 6.4 MB:
+
+ 36 bytes: each row header (approximate)
+ 24 bytes: one int field and one text field
+ + 4 bytes: pointer on page to tuple
+ ----------------------------------------
+ 64 bytes per row
+
+ The data page size in PostgreSQL is 8192 bytes (8 KB), so:
+
+ 8192 bytes per page
+ ------------------- = 128 rows per database page (rounded down)
+ 64 bytes per row
+
+ 100000 data rows
+ -------------------- = 782 database pages (rounded up)
+ 128 rows per page
+
+782 database pages * 8192 bytes per page = 6,406,144 bytes (6.4 MB)
+
+Indexes do not require as much overhead, but do contain the data that is
+being indexed, so they can be large also.
+
+NULLs are stored in bitmaps, so they use very little space.
+
+
+ 4.7) How do I find out what tables, indexes, databases, and
+ users are defined?
+
+/psql/ has a variety of backslash commands to show such information. Use
+\? to see them. There are also system tables beginning with /pg_/ that
+describe these too. Also, /psql -l/ will list all databases.
+
+Also try the file /pgsql/src/tutorial/syscat.source/. It illustrates
+many of the SELECTs needed to get information from the database system
+tables.
+
+
+ 4.8) My queries are slow or don't make use of the indexes. Why?
+
+Indexes are not automatically used by every query. Indexes are only used
+if the table is larger than a minimum size, and the query selects only a
+small percentage of the rows in the table. This is because the random
+disk access caused by an index scan can be slower than a straight read
+through the table, or sequential scan.
+
+To determine if an index should be used, PostgreSQL must have statistics
+about the table. These statistics are collected using VACUUM ANALYZE, or
+simply ANALYZE. Using statistics, the optimizer knows how many rows are
+in the table, and can better determine if indexes should be used.
+Statistics are also valuable in determining optimal join order and join
+methods. Statistics collection should be performed periodically as the
+contents of the table change.
+
+Indexes are normally not used for ORDER BY or to perform joins. A
+sequential scan followed by an explicit sort is usually faster than an
+index scan of a large table.
+
+However, LIMIT combined with ORDER BY often will use an index because
+only a small portion of the table is returned. In fact, though MAX() and
+MIN() don't use indexes, it is possible to retrieve such values using an
+index with ORDER BY and LIMIT:
+
+ SELECT col
+ FROM tab
+ ORDER BY col [ DESC ]
+ LIMIT 1;
+
+If you believe the optimizer is incorrect in choosing a sequential scan,
+use |SET enable_seqscan TO 'off'| and run tests to see if an index scan
+is indeed faster.
+
+When using wild-card operators such as LIKE or /~/, indexes can only be
+used in certain circumstances:
+
+ * The beginning of the search string must be anchored to the start
+ of the string, i.e.
+ o LIKE patterns must not start with /%/.
+ o /~/ (regular expression) patterns must start with /^/.
+ * The search string can not start with a character class, e.g. [a-e].
+ * Case-insensitive searches such as ILIKE and /~*/ do not utilise
+ indexes. Instead, use functional indexes, which are described in
+ section 4.12 <#4.12>.
+ * The default /C/ locale must be used during /initdb/.
+
+
+ 4.9) How do I see how the query optimizer is evaluating my query?
+
+See the EXPLAIN manual page.
+
+
+ 4.10) What is an R-tree index?
+
+An R-tree index is used for indexing spatial data. A hash index can't
+handle range searches. A B-tree index only handles range searches in a
+single dimension. R-trees can handle multi-dimensional data. For
+example, if an R-tree index can be built on an attribute of type
+/point/, the system can more efficiently answer queries such as "select
+all points within a bounding rectangle."
+
+The canonical paper that describes the original R-tree design is:
+
+Guttman, A. "R-trees: A Dynamic Index Structure for Spatial Searching."
+Proceedings of the 1984 ACM SIGMOD Int'l Conf on Mgmt of Data, 45-57.
+
+You can also find this paper in Stonebraker's "Readings in Database
+Systems".
+
+Built-in R-trees can handle polygons and boxes. In theory, R-trees can
+be extended to handle higher number of dimensions. In practice,
+extending R-trees requires a bit of work and we don't currently have any
+documentation on how to do it.
+
+
+ 4.11) What is the Genetic Query Optimizer?
+
+The GEQO module speeds query optimization when joining many tables by
+means of a Genetic Algorithm (GA). It allows the handling of large join
+queries through nonexhaustive search.
+
+
+ 4.12) How do I perform regular expression searches and
+ case-insensitive regular expression searches? How do I use an
+ index for case-insensitive searches?
+
+The /~/ operator does regular expression matching, and /~*/ does
+case-insensitive regular expression matching. The case-insensitive
+variant of LIKE is called ILIKE.
+
+Case-insensitive equality comparisons are normally expressed as:
+
+ SELECT *
+ FROM tab
+ WHERE lower(col) = 'abc';
+
+This will not use an standard index. However, if you create a functional
+index, it will be used:
+
+ CREATE INDEX tabindex ON tab (lower(col));
+
+
+ 4.13) In a query, how do I detect if a field is NULL?
+
+You test the column with IS NULL and IS NOT NULL.
+
+
+ 4.14) What is the difference between the various character types?
+
+Type Internal Name Notes
+--------------------------------------------------
+VARCHAR(n) varchar size specifies maximum length, no padding
+CHAR(n) bpchar blank padded to the specified fixed length
+TEXT text no specific upper limit on length
+BYTEA bytea variable-length byte array (null-byte safe)
+"char" char one character
+
+You will see the internal name when examining system catalogs and in
+some error messages.
+
+The first four types above are "varlena" types (i.e., the first four
+bytes on disk are the length, followed by the data). Thus the actual
+space used is slightly greater than the declared size. However, these
+data types are also subject to compression or being stored out-of-line
+by TOAST, so the space on disk might also be less than expected.
+
+VARCHAR(n) is best when storing variable-length strings and it limits
+how long a string can be. TEXT is for strings of unlimited length, with
+a maximum of one gigabyte.
+
+CHAR(n) is for storing strings that are all the same length. CHAR(n)
+pads with blanks to the specified length, while VARCHAR(n) only stores
+the characters supplied. BYTEA is for storing binary data, particularly
+values that include NULL bytes. All the types described here have
+similar performance characteristics.
+
+
+ 4.15.1) How do I create a serial/auto-incrementing field?
+
+PostgreSQL supports a SERIAL data type. It auto-creates a sequence and
+index on the column. For example, this:
+
+ CREATE TABLE person (
+ id SERIAL,
+ name TEXT
+ );
+
+is automatically translated into this:
+
+ CREATE SEQUENCE person_id_seq;
+ CREATE TABLE person (
+ id INT4 NOT NULL DEFAULT nextval('person_id_seq'),
+ name TEXT
+ );
+ CREATE UNIQUE INDEX person_id_key ON person ( id );
+
+See the /create_sequence/ manual page for more information about
+sequences. You can also use each row's /OID/ field as a unique value.
+However, if you need to dump and reload the database, you need to use
+/pg_dump/'s /-o/ option or COPY WITH OIDS option to preserve the OIDs.
+
+
+ 4.15.2) How do I get the value of a SERIAL insert?
+
+One approach is to retrieve the next SERIAL value from the sequence
+object with the /nextval()/ function /before/ inserting and then insert
+it explicitly. Using the example table in 4.15.1 <#4.15.1>, an example
+in a pseudo-language would look like this:
+
+ new_id = execute("SELECT nextval('person_id_seq')");
+ execute("INSERT INTO person (id, name) VALUES (new_id, 'Blaise Pascal')");
+
+You would then also have the new value stored in |new_id| for use in
+other queries (e.g., as a foreign key to the |person| table). Note that
+the name of the automatically created SEQUENCE object will be named
+</table/>_</serialcolumn/>_/seq/, where /table/ and /serialcolumn/ are
+the names of your table and your SERIAL column, respectively.
+
+Alternatively, you could retrieve the assigned SERIAL value with the
+/currval()/ function /after/ it was inserted by default, e.g.,
+
+ execute("INSERT INTO person (name) VALUES ('Blaise Pascal')");
+ new_id = execute("SELECT currval('person_id_seq')");
+
+Finally, you could use the OID <#4.16> returned from the INSERT
+statement to look up the default value, though this is probably the
+least portable approach. In Perl, using DBI with Edmund Mergl's DBD::Pg
+module, the oid value is made available via /$sth->{pg_oid_status}/
+after /$sth->execute()/.
+
+
+ 4.15.3) Don't /currval()/ and /nextval()/ lead to a race
+ condition with other users?
+
+No. /currval()/ returns the current value assigned by your backend, not
+by all users.
+
+
+ 4.15.4) Why aren't my sequence numbers reused on transaction
+ abort? Why are there gaps in the numbering of my sequence/SERIAL
+ column?
+
+To improve concurrency, sequence values are given out to running
+transactions as needed and are not locked until the transaction
+completes. This causes gaps in numbering from aborted transactions.
+
+
+ 4.16) What is an OID? What is a TID?
+
+OIDs are PostgreSQL's answer to unique row ids. Every row that is
+created in PostgreSQL gets a unique OID. All OIDs generated during
+/initdb/ are less than 16384 (from /include/access/transam.h/). All
+user-created OIDs are equal to or greater than this. By default, all
+these OIDs are unique not only within a table or database, but unique
+within the entire PostgreSQL installation.
+
+PostgreSQL uses OIDs in its internal system tables to link rows between
+tables. These OIDs can be used to identify specific user rows and used
+in joins. It is recommended you use column type OID to store OID values.
+You can create an index on the OID field for faster access.
+
+OIDs are assigned to all new rows from a central area that is used by
+all databases. If you want to change the OID to something else, or if
+you want to make a copy of the table, with the original OIDs, there is
+no reason you can't do it:
+
+ CREATE TABLE new_table(old_oid oid, mycol int);
+ SELECT old_oid, mycol INTO new FROM old;
+ COPY new TO '/tmp/pgtable';
+ DELETE FROM new;
+ COPY new WITH OIDS FROM '/tmp/pgtable';
+
+OIDs are stored as 4-byte integers, and will overflow at 4 billion. No
+one has reported this ever happening, and we plan to have the limit
+removed before anyone does.
+
+TIDs are used to identify specific physical rows with block and offset
+values. TIDs change after rows are modified or reloaded. They are used
+by index entries to point to physical rows.
+
+
+ 4.17) What is the meaning of some of the terms used in PostgreSQL?
+
+Some of the source code and older documentation use terms that have more
+common usage. Here are some:
+
+ * table, relation, class
+ * row, record, tuple
+ * column, field, attribute
+ * retrieve, select
+ * replace, update
+ * append, insert
+ * OID, serial value
+ * portal, cursor
+ * range variable, table name, table alias
+
+A list of general database terms can be found at:
+http://hea-www.harvard.edu/MST/simul/software/docs/pkgs/pgsql/glossary/glossary.html
+
+
+ 4.18) Why do I get the error /"ERROR: Memory exhausted in
+ AllocSetAlloc()"/?
+
+You probably have run out of virtual memory on your system, or your
+kernel has a low limit for certain resources. Try this before starting
+/postmaster/:
+
+ ulimit -d 262144
+ limit datasize 256m
+
+Depending on your shell, only one of these may succeed, but it will set
+your process data segment limit much higher and perhaps allow the query
+to complete. This command applies to the current process, and all
+subprocesses created after the command is run. If you are having a
+problem with the SQL client because the backend is returning too much
+data, try it before starting the client.
+
+
+ 4.19) How do I tell what PostgreSQL version I am running?
+
+From /psql/, type |SELECT version();|
+
+
+ 4.20) Why does my large-object operations get /"invalid large
+ obj descriptor"/?
+
+You need to put |BEGIN WORK| and |COMMIT| around any use of a large
+object handle, that is, surrounding |lo_open| ... |lo_close.|
+
+Currently PostgreSQL enforces the rule by closing large object handles
+at transaction commit. So the first attempt to do anything with the
+handle will draw /invalid large obj descriptor/. So code that used to
+work (at least most of the time) will now generate that error message if
+you fail to use a transaction.
+
+If you are using a client interface like ODBC you may need to set
+|auto-commit off.|
+
+
+ 4.21) How do I create a column that will default to the current
+ time?
+
+Use /CURRENT_TIMESTAMP/:
+
+|CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP );
+|
+
+
+ 4.22) Why are my subqueries using |IN| so slow?
+
+Currently, we join subqueries to outer queries by sequentially scanning
+the result of the subquery for each row of the outer query. If the
+subquery returns only a few rows and the outer query returns many rows,
+|IN| is fastest. To speed up other queries, replace |IN| with |EXISTS|:
+
+ SELECT *
+ FROM tab
+ WHERE col IN (SELECT subcol FROM subtab);
+
+to:
+
+ SELECT *
+ FROM tab
+ WHERE EXISTS (SELECT subcol FROM subtab WHERE subcol = col);
+
+For this to be fast, |subcol| should be an indexed column. This
+preformance problem will be fixed in 7.4.
+
+
+ 4.23) How do I perform an outer join?
+
+PostgreSQL supports outer joins using the SQL standard syntax. Here are
+two examples:
+
+ SELECT *
+ FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col);
+
+or
+
+ SELECT *
+ FROM t1 LEFT OUTER JOIN t2 USING (col);
+
+These identical queries join t1.col to t2.col, and also return any
+unjoined rows in t1 (those with no match in t2). A RIGHT join would add
+unjoined rows of t2. A FULL join would return the matched rows plus all
+unjoined rows from t1 and t2. The word OUTER is optional and is assumed
+in LEFT, RIGHT, and FULL joins. Ordinary joins are called INNER joins.
+
+In previous releases, outer joins can be simulated using UNION and NOT
+IN. For example, when joining /tab1/ and /tab2/, the following query
+does an /outer/ join of the two tables:
+
+ SELECT tab1.col1, tab2.col2
+ FROM tab1, tab2
+ WHERE tab1.col1 = tab2.col1
+ UNION ALL
+ SELECT tab1.col1, NULL
+ FROM tab1
+ WHERE tab1.col1 NOT IN (SELECT tab2.col1 FROM tab2)
+ ORDER BY col1
+
+
+ 4.24) How do I perform queries using multiple databases?
+
+There is no way to query a database other than the current one. Because
+PostgreSQL loads database-specific system catalogs, it is uncertain how
+a cross-database query should even behave.
+
+/contrib/dblink/ allows cross-database queries using function calls. Of
+course, a client can make simultaneous connections to different
+databases and merge the results on the client side.
+
+
+ 4.25) How do I return multiple rows or columns from a function?
+
+In 7.3, you can easily return multiple rows or columns from a function,
+http://techdocs.postgresql.org/guides/SetReturningFunctions
+<http://techdocs.postgresql.org/guides/SetReturningFunctions>.
+
+
+ 4.26) Why can't I reliably create/drop temporary tables in
+ PL/PgSQL functions?
+
+PL/PgSQL caches function contents, and an unfortunate side effect is
+that if a PL/PgSQL function accesses a temporary table, and that table
+is later dropped and recreated, and the function called again, the
+function will fail because the cached function contents still point to
+the old temporary table. The solution is to use EXECUTE for temporary
+table access in PL/PgSQL. This will cause the query to be reparsed every
+time.
+
+
+ 4.27) What replication options are available?
+
+There are several master/slave replication options available. These
+allow only the master to make database changes and the slave can only do
+database reads. The bottom of
+http://gborg.PostgreSQL.org/genpage?replication_research
+<http://gborg.PostgreSQL.org/genpage?replication_research> lists them. A
+multi-master replication solution is being worked on at
+http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php.
+
+
+ 4.28) What encryption options are available?
+
+ * /contrib/pgcrypto/ contains many encryption functions for use in
+ SQL queries.
+ * The only way to encrypt transmission from the client to the server
+ is by using /hostssl/ in /pg_hba.conf/.
+ * Database user passwords are automatically encrypted when stored in
+ version 7.3. In previous versions, you must enable the option
+ /PASSWORD_ENCRYPTION/ in /postgresql.conf/.
+ * The server can run using an encrypted file system.
+
+------------------------------------------------------------------------
+
+
+ Extending PostgreSQL
+
+
+ 5.1) I wrote a user-defined function. When I run it in /psql/,
+ why does it dump core?
+
+The problem could be a number of things. Try testing your user-defined
+function in a stand-alone test program first.
+
+
+ 5.2) How can I contribute some nifty new types and functions to
+ PostgreSQL?
+
+Send your extensions to the /pgsql-hackers/ mailing list, and they will
+eventually end up in the /contrib// subdirectory.
+
+
+ 5.3) How do I write a C function to return a tuple?
+
+In versions of PostgreSQL beginning with 7.3, table-returning functions
+are fully supported in C, PL/PgSQL, and SQL. See the Programmer's Guide
+for more information. An example of a table-returning function defined
+in C can be found in /contrib/tablefunc/.
+
+
+ 5.4) I have changed a source file. Why does the recompile not
+ see the change?
+
+The /Makefiles/ do not have the proper dependencies for include files.
+You have to do a /make clean/ and then another /make/. If you are using
+GCC you can use the /--enable-depend/ option of /configure/ to have the
+compiler compute the dependencies automatically.
+
|