diff --git a/doc/FAQ b/doc/FAQ
index 4888cb649d34d255991106d6c550c52c378e1bde..9092c0a49af88f905924e418ddc0f5a42eb6d814 100644
--- a/doc/FAQ
+++ b/doc/FAQ
@@ -1,7 +1,7 @@
Frequently Asked Questions (FAQ) for PostgreSQL
- Last updated: Fri Oct 11 13:54:56 EDT 2002
+ Last updated: Sun Oct 13 22:49:56 EDT 2002
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
@@ -112,7 +112,7 @@
General Questions
- 1.1) What is PostgreSQL?
+ 1.1) What is PostgreSQL? How is it pronounced?
PostgreSQL is pronounced Post-Gres-Q-L.
@@ -122,11 +122,11 @@
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 Internet developers
- who all subscribe to the PostgreSQL development mailing list. The
- current coordinator is Marc G. Fournier (scrappy@PostgreSQL.org). (See
- below on how to join). This team is now responsible for all
- development of PostgreSQL.
+ 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 (scrappy@PostgreSQL.org). (See section
+ 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
@@ -183,18 +183,22 @@
Client
It is possible to compile the libpq C library, psql, and other
- interfaces and binaries 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
- win31.mak is included in the distribution for making a Win32 libpq
- library and psql. PostgreSQL also communicates with ODBC clients.
+ 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 on our web site. We have no plan to
- do a native port to any Microsoft platform.
+ distribution or the MS Windows FAQ at
+ http://www.PostgreSQL.org/docs/faq-mswin.html.
+
+ A native port to some Microsoft platforms is currently being worked
+ upon.
1.5) Where can I get PostgreSQL?
@@ -240,7 +244,7 @@
Unix command irc -c '#PostgreSQL' "$USER" irc.phoenix.net.
A list of commercial support companies is available at
- http://www.postgresql.org/users-lounge/commercial-support.html.
+ http://www.PostgreSQL.org/users-lounge/commercial-support.html.
1.7) What is the latest release?
@@ -258,9 +262,9 @@
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.postgresql.org/books/.
+ 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/.
+ http://techdocs.PostgreSQL.org/.
psql has some nice \d commands to show information about types,
operators, functions, aggregates, etc.
@@ -307,8 +311,9 @@
1.13) How do I submit a bug report?
- Please visit the PostgreSQL BugTool page, which gives guidelines and
- directions on how to submit a bug.
+ 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.
@@ -346,14 +351,14 @@
compare favorably to other database software in this area.
Support
- Our mailing list provides a large group of developers and users
- to help resolve any problems encountered. While we can not
- 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 support FAQ
- item.)
+ 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.)
Price
We are free for all use, both commercial and non-commercial.
@@ -362,9 +367,9 @@
1.15) How can I financially assist PostgreSQL?
- PostgreSQL has had a first-class infrastructure since we started six
- years ago. This is all thanks to Marc Fournier, who has created and
- managed this infrastructure over the years.
+ PostgreSQL has had a first-class infrastructure since we started in
+ 1994. 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
@@ -373,8 +378,7 @@
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 https://store.pgsql.com/shopping/index.php?id=1 and make
- a donation.
+ 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
@@ -407,39 +411,37 @@
A nice introduction to Database-backed Web pages can be seen at:
http://www.webreview.com
- There is also one at http://www.phone.net/home/mwm/hotlist/.
-
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.
+ For complex cases, many use the Perl interface and CGI.pm or mod_perl.
2.3) Does PostgreSQL have a graphical user interface? A report generator?
An embedded query language interface?
- We have a nice graphical user interface called pgaccess, which is
- shipped as part of the distribution. pgaccess also has a report
- generator. The Web page is http://www.flex.ro/pgaccess
+ We have a nice graphical user interface called PgAccess, which is
+ shipped as part of the distribution. PgAccess also has a report
+ generator. The Web page is http://www.pgaccess.org/.
We also include ecpg, which is an embedded SQL query language
interface for C.
- 2.4) What languages are available to communicate with PostgreSQL?
+ 2.4) What languages are able to communicate with PostgreSQL?
We have:
* C (libpq)
* C++ (libpq++)
* Embedded C (ecpg)
* Java (jdbc)
- * Perl (perl5)
+ * Perl (DBD::Pg)
* ODBC (odbc)
* Python (PyGreSQL)
* TCL (libpgtcl)
* C Easy API (libpgeasy)
- * Embedded HTML (PHP from http://www.php.net)
+ * PHP ('pg_' functions, Pear::DB)
Additional interfaces are available at
- http://www.postgresql.org/interfaces.html.
+ http://www.PostgreSQL.org/interfaces.html.
_________________________________________________________________
Administrative Questions
@@ -594,7 +596,7 @@
was 64, and changing it required a rebuild after altering the
MaxBackendId constant in include/storage/sinvaladt.h.
- 3.9) What are the pg_sorttempNNN.NN files in my database directory?
+ 3.9) What are the pg_tempNNN.NN files in my database directory?
They are temporary files generated by the query executor. For example,
if a sort needs to be done to satisfy an ORDER BY, and the sort
@@ -610,11 +612,11 @@
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 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.
+ 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
@@ -632,10 +634,10 @@
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 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.
+ 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?
@@ -647,7 +649,8 @@
4.4) How do you remove a column from a table?
- We do not support ALTER TABLE DROP COLUMN, but do this:
+ Prior to version 7.3, ALTER TABLE DROP COLUMN is not supported. You
+ can do this instead:
BEGIN;
LOCK TABLE old_table;
SELECT ... -- select all columns but the one you want to remove
@@ -691,7 +694,7 @@
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 filed
+ 24 bytes: one int field and one text field
+ 4 bytes: pointer on page to tuple
----------------------------------------
64 bytes per row
@@ -750,7 +753,7 @@
SELECT col
FROM tab
ORDER BY col [ DESC ]
- LIMIT 1
+ LIMIT 1;
When using wild-card operators such as LIKE or ~, indexes can only be
used in certain circumstances:
@@ -762,11 +765,11 @@
The search string can not start with a character class, e.g. [a-e].
- Case-insensitive searches like ILIKE and ~* can not be used.
- Instead, use functional indexes, which are described later in this
- FAQ.
+ Case-insensitive searches such as ILIKE and ~* do not utilise
+ indexes. Instead, use functional indexes, which are described in
+ section 4.12.
- The default C local must be used during initdb.
+ The default C locale must be used during initdb.
4.9) How do I see how the query optimizer is evaluating my query?
@@ -812,11 +815,11 @@
Case-insensitive equality comparisons are normally expressed as:
SELECT *
FROM tab
- WHERE lower(col) = 'abc'
+ 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));
+ CREATE INDEX tabindex ON tab (LOWER(col));
4.13) In a query, how do I detect if a field is NULL?
@@ -827,8 +830,8 @@
Type Internal Name Notes
--------------------------------------------------
"char" char 1 character
-CHAR(#) bpchar blank padded to the specified fixed length
-VARCHAR(#) varchar size specifies maximum length, no padding
+CHAR(n) bpchar blank padded to the specified fixed length
+VARCHAR(n) varchar size specifies maximum length, no padding
TEXT text no specific upper limit on length
BYTEA bytea variable-length byte array (null-byte safe)
@@ -841,8 +844,8 @@ BYTEA bytea variable-length byte array (null-byte safe)
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.
- CHAR() is best when storing strings that are usually the same length.
- VARCHAR() is best when storing variable-length strings but it limits
+ CHAR(n) is best when storing strings that are usually the same length.
+ VARCHAR(n) is best when storing variable-length strings but it limits
how long a string can be. TEXT is for strings of unlimited length,
maximum 1 gigabyte. BYTEA is for storing binary data, particularly
values that include NULL bytes.
@@ -873,10 +876,10 @@ BYTEA bytea variable-length byte array (null-byte safe)
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, that might look like
- this in Perl:
- new_id = output of "SELECT nextval('person_id_seq')"
- INSERT INTO person (id, name) VALUES (new_id, 'Blaise Pascal');
+ explicitly. Using the example table in 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
@@ -886,8 +889,8 @@ BYTEA bytea variable-length byte array (null-byte safe)
Alternatively, you could retrieve the assigned SERIAL value with the
currval() function after it was inserted by default, e.g.,
- INSERT INTO person (name) VALUES ('Blaise Pascal');
- new_id = output of "SELECT currval('person_id_seq')";
+ execute("INSERT INTO person (name) VALUES ('Blaise Pascal')");
+ new_id = execute("SELECT currval('person_id_seq')");
Finally, you could use the OID returned from the INSERT statement to
look up the default value, though this is probably the least portable
@@ -898,7 +901,7 @@ BYTEA bytea variable-length byte array (null-byte safe)
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
+ 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
@@ -912,7 +915,7 @@ BYTEA bytea variable-length byte array (null-byte safe)
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 backend/access/transam.h). All
+ 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.
@@ -956,7 +959,8 @@ BYTEA bytea variable-length byte array (null-byte safe)
* range variable, table name, table alias
A list of general database terms can be found at:
- http://www.comptechnews.com/~reaster/dbdesign.html
+ 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()"?
@@ -975,7 +979,7 @@ BYTEA bytea variable-length byte array (null-byte safe)
4.19) How do I tell what PostgreSQL version I am running?
- From psql, type select version();
+ From psql, type SELECT version();
4.20) Why does my large-object operations get "invalid large obj
descriptor"?
@@ -1004,14 +1008,14 @@ CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP );
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 *
+ SELECT *
FROM tab
- WHERE col IN (SELECT subcol FROM subtab)
+ WHERE col IN (SELECT subcol FROM subtab);
to:
-SELECT *
+ SELECT *
FROM tab
- WHERE EXISTS (SELECT subcol FROM subtab WHERE subcol = col)
+ WHERE EXISTS (SELECT subcol FROM subtab WHERE subcol = col);
For this to be fast, subcol should be an indexed column. We hope to
fix this limitation in a future release.
@@ -1059,8 +1063,7 @@ SELECT *
4.25) How do I return multiple rows or columns from a function?
You can return result sets from PL/pgSQL functions using refcursors.
- See
- http://developer.postgresql.org/docs/postgres/plpgsql-cursors.html,
+ See http://www.PostgreSQL.org/idocs/index.php?plpgsql-cursors.html,
section 23.7.3.3.
4.26) Why can't I reliably create/drop temporary tables in PL/PgSQL
@@ -1079,19 +1082,19 @@ SELECT *
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 lists them. A
+ 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.
+ http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php.
- 4.27) What encryption options are available?
+ 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
- password_encryption in postgresql.conf.
+ 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.
_________________________________________________________________
diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html
index 7553a988db3d9f7c02bf6fbcaad440c46fc7a71a..042a4984ee4a6878355421fadf8adb10e386aea0 100644
--- a/doc/src/FAQ/FAQ.html
+++ b/doc/src/FAQ/FAQ.html
@@ -14,7 +14,7 @@
alink="#0000ff">
<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
- <P>Last updated: Fri Oct 11 13:54:56 EDT 2002</P>
+ <P>Last updated: Sun Oct 13 22:49:56 EDT 2002</P>
<P>Current maintainer: Bruce Momjian (<A href=
"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
@@ -22,15 +22,14 @@
<P>The most recent version of this document can be viewed at <A
href=
- "http://www.Postgresql.org/docs/faq-english.html">http://www.PostgreSQL.org/docs/faq-english.html</A>.</P>
+ "http://www.PostgreSQL.org/docs/faq-english.html">http://www.PostgreSQL.org/docs/faq-english.html</A>.</P>
<P>Platform-specific questions are answered at <A href=
"http://www.PostgreSQL.org/users-lounge/docs/faq.html">http://www.PostgreSQL.org/users-lounge/docs/faq.html</A>.</P>
<HR>
<H2 align="center">General Questions</H2>
- <A href="#1.1">1.1</A>) What is PostgreSQL? How is it
- pronounced?<BR>
+ <A href="#1.1">1.1</A>) What is PostgreSQL? How is it pronounced?<BR>
<A href="#1.2">1.2</A>) What is the copyright on PostgreSQL?<BR>
<A href="#1.3">1.3</A>) What Unix platforms does PostgreSQL run
on?<BR>
@@ -161,7 +160,7 @@
<H2 align="center">General Questions</H2>
- <H4><A name="1.1">1.1</A>) What is PostgreSQL?</H4>
+ <H4><A name="1.1">1.1</A>) What is PostgreSQL? How is it pronounced?</H4>
<P>PostgreSQL is pronounced <I>Post-Gres-Q-L</I>.</P>
@@ -172,12 +171,12 @@
extended subset of <SMALL>SQL</SMALL>. PostgreSQL is free and the
complete source is available.</P>
- <P>PostgreSQL development is performed by a team of Internet
+ <P>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 (<A href=
"mailto:scrappy@PostgreSQL.org">scrappy@PostgreSQL.org</A>). (See
- below on how to join). This team is now responsible for all
- development of PostgreSQL.</P>
+ section <a href="#1.6">1.6</a> on how to join). This team is now
+ responsible for all development of PostgreSQL.</P>
<P>The authors of PostgreSQL 1.01 were Andrew Yu and Jolly Chen.
Many others have contributed to the porting, testing, debugging,
@@ -239,10 +238,10 @@
<P><STRONG>Client</STRONG></P>
<P>It is possible to compile the <I>libpq</I> C library, psql, and
- other interfaces and binaries to run on MS Windows platforms. In
- this case, the client is running on MS Windows, and communicates
+ 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 <I>win31.mak</I> is included in the distribution
+ platforms. A file <I>win32.mak</I> is included in the distribution
for making a Win32 <I>libpq</I> library and <I>psql</I>. PostgreSQL
also communicates with <SMALL>ODBC</SMALL> clients.</P>
@@ -250,10 +249,11 @@
<P>The database server can run on Windows NT and Win2k using
Cygwin, the Cygnus Unix/NT porting library. See
- <I>pgsql/doc/FAQ_MSWIN</I> in the distribution or the <A href=
- "http://www.postgresql.org/docs/faq-mswin.html">MS Windows FAQ</A>
- on our web site. We have no plan to do a native port to any
- Microsoft platform.</P>
+ <I>pgsql/doc/FAQ_MSWIN</I> in the distribution or the MS Windows FAQ
+ at <A href="http://www.PostgreSQL.org/docs/faq-mswin.html">http://www.PostgreSQL.org/docs/faq-mswin.html</A>.</P>
+
+ <p>A native port to some Microsoft platforms is currently being worked
+ upon.</p>
<H4><A name="1.5">1.5</A>) Where can I get PostgreSQL?</H4>
@@ -318,7 +318,7 @@
'#PostgreSQL' "$USER" irc.phoenix.net.</CODE></P>
<P>A list of commercial support companies is available at <A href=
- "http://www.postgresql.org/users-lounge/commercial-support.html">http://www.postgresql.org/users-lounge/commercial-support.html</A>.</P>
+ "http://www.PostgreSQL.org/users-lounge/commercial-support.html">http://www.PostgreSQL.org/users-lounge/commercial-support.html</A>.</P>
<H4><A name="1.7">1.7</A>) What is the latest release?</H4>
@@ -339,10 +339,10 @@
"http://www.commandprompt.com/ppbook/">http://www.commandprompt.com/ppbook/</A>.
There is a list of PostgreSQL books available for purchase at <A
href=
- "http://www.postgresql.org/books/">http://www.postgresql.org/books/</A>.
+ "http://www.ca.PostgreSQL.org/books/">http://www.ca.PostgreSQL.org/books/</A>.
There is also a collection of PostgreSQL technical articles at <A
href=
- "http://techdocs.postgresql.org/">http://techdocs.postgresql.org/</A>.</P>
+ "http://techdocs.PostgreSQL.org/">http://techdocs.PostgreSQL.org/</A>.</P>
<P><I>psql</I> has some nice \d commands to show information about
types, operators, functions, aggregates, etc.</P>
@@ -402,10 +402,10 @@
<H4><A name="1.13">1.13</A>) How do I submit a bug report?</H4>
- <P>Please visit the <A href=
- "http://www.postgresql.org/bugs/bugs.php">PostgreSQL BugTool</A>
- page, which gives guidelines and directions on how to submit a
- bug.</P>
+ <P>Please visit the PostgreSQL BugTool page at <A href=
+ "http://www.PostgreSQL.org/bugs/bugs.php">http://www.PostgreSQL.org/bugs/bugs.php</A>,
+ which gives guidelines and directions on how to submit a
+ bug report.</P>
<P>Also check out our ftp site <A href=
"ftp://ftp.PostgreSQL.org/pub">ftp://ftp.PostgreSQL.org/pub</A> to
@@ -460,14 +460,14 @@
<DT><B>Support</B></DT>
- <DD>Our mailing list provides a large group of developers and
- users to help resolve any problems encountered. While we can not
+ <DD>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 <SMALL>DBMS</SMALL>s 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 <SMALL>DBMS</SMALL>s. There is
commercial per-incident support available for those who need it.
- (See <A href="#1.6">support FAQ item</A>.)<BR>
+ (See <A href="#1.6">FAQ section 1.6</A>.)<BR>
<BR>
</DD>
@@ -484,7 +484,7 @@
PostgreSQL?</H4>
<P>PostgreSQL has had a first-class infrastructure since we started
- six years ago. This is all thanks to Marc Fournier, who has created
+ in 1994. This is all thanks to Marc Fournier, who has created
and managed this infrastructure over the years.</P>
<P>Quality infrastructure is very important to an open-source
@@ -494,9 +494,7 @@
<P>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 <A href=
- "https://store.pgsql.com/shopping/index.php?id=1">
- https://store.pgsql.com/shopping/index.php?id=1</A>
+ this effort, please go to <A href="http://store.pgsql.com/shopping/">http://store.pgsql.com/shopping/</A>
and make a donation.</P>
<P>Although the web page mentions PostgreSQL, Inc, the
@@ -538,28 +536,23 @@
<P>A nice introduction to Database-backed Web pages can be seen at:
<A href="http://www.webreview.com">http://www.webreview.com</A></P>
- <P>There is also one at <A href=
- "http://www.phone.net/home/mwm/hotlist/">http://www.phone.net/home/mwm/hotlist/.</A></P>
-
<P>For Web integration, PHP is an excellent interface. It is at <A
href="http://www.php.net">http://www.php.net</A>.</P>
- <P>For complex cases, many use the Perl interface and CGI.pm.</P>
+ <P>For complex cases, many use the Perl interface and CGI.pm or mod_perl.</P>
<H4><A name="2.3">2.3</A>) Does PostgreSQL have a graphical user
interface? A report generator? An embedded query language
interface?</H4>
- <P>We have a nice graphical user interface called <I>pgaccess</I>,
- which is shipped as part of the distribution. <I>pgaccess</I> also
- has a report generator. The Web page is <A href=
- "http://www.flex.ro/pgaccess">http://www.flex.ro/pgaccess</A></P>
+ <P>We have a nice graphical user interface called PgAccess, which is
+ shipped as part of the distribution. PgAccess also has a report
+ generator. The Web page is <A href="http://www.pgaccess.org/">http://www.pgaccess.org/</A>.</P>
<P>We also include <I>ecpg</I>, which is an embedded SQL query
language interface for C.</P>
- <H4><A name="2.4">2.4</A>) What languages are available to
- communicate with PostgreSQL?</H4>
+ <H4><A name="2.4">2.4</A>) What languages are able to communicate with PostgreSQL?</H4>
<P>We have:</P>
@@ -572,7 +565,7 @@
<LI>Java (jdbc)</LI>
- <LI>Perl (perl5)</LI>
+ <LI>Perl (DBD::Pg)</LI>
<LI>ODBC (odbc)</LI>
@@ -582,12 +575,10 @@
<LI>C Easy API (libpgeasy)</LI>
- <LI>Embedded <SMALL>HTML</SMALL> (<A href=
- "http://www.php.net">PHP from http://www.php.net</A>)</LI>
+ <LI>PHP ('pg_' functions, Pear::DB)</LI>
</UL>
- <P>Additional interfaces are available at <a
- href="http://www.postgresql.org/interfaces.html">
- http://www.postgresql.org/interfaces.html.</A>
+ <P>Additional interfaces are available at
+ <a href="http://www.PostgreSQL.org/interfaces.html">http://www.PostgreSQL.org/interfaces.html</A>.
</P>
<HR>
@@ -774,7 +765,7 @@
the MaxBackendId constant in
<I>include/storage/sinvaladt.h</I>.</P>
- <H4><A name="3.9">3.9</A>) What are the <I>pg_sorttempNNN.NN</I>
+ <H4><A name="3.9">3.9</A>) What are the <I>pg_tempNNN.NN</I>
files in my database directory?</H4>
<P>They are temporary files generated by the query executor. For
@@ -793,16 +784,16 @@
<P>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 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.
+ 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.</P>
- <P>In releases where the on-disk format does not change, the
+ <p>In releases where the on-disk format does not change, the
<i>pg_upgrade</i> script can be used to upgrade without a dump/restore.
The release notes mention whether <i>pg_upgrade</i> is available for the
- release.
+ release.</p>
<HR>
@@ -821,7 +812,7 @@
<SMALL>SELECT</SMALL> ... <SMALL>LIMIT</SMALL>....</P>
<P>The entire query may have to be evaluated, even if you only want
- the first few rows. Consider a query that has an <SMALL>ORDER
+ the first few rows. Consider using a query that has an <SMALL>ORDER
BY.</SMALL> If there is an index that matches the <SMALL>ORDER
BY</SMALL>, PostgreSQL may be able to evaluate only the first few
records requested, or the entire query may have to be evaluated
@@ -840,8 +831,8 @@
<H4><A name="4.4">4.4</A>) How do you remove a column from a
table?</H4>
- <P>We do not support <SMALL>ALTER TABLE DROP COLUMN,</SMALL> but do
- this:</P>
+ <P>Prior to version 7.3, <SMALL>ALTER TABLE DROP COLUMN</SMALL> is not supported.
+ You can do this instead:</P>
<PRE>
BEGIN;
LOCK TABLE old_table;
@@ -892,7 +883,7 @@
be estimated as 6.4 MB:</P>
<PRE>
36 bytes: each row header (approximate)
- 24 bytes: one int field and one text filed
+ 24 bytes: one int field and one text field
+ 4 bytes: pointer on page to tuple
----------------------------------------
64 bytes per row
@@ -957,7 +948,7 @@
SELECT col
FROM tab
ORDER BY col [ DESC ]
- LIMIT 1
+ LIMIT 1;
</PRE>
<P>When using wild-card operators such as <SMALL>LIKE</SMALL> or
@@ -972,10 +963,10 @@
</UL>
<LI>The search string can not start with a character class,
e.g. [a-e].</LI>
- <LI>Case-insensitive searches like <SMALL>ILIKE</SMALL> and
- <I>~*</I> can not be used. Instead, use functional
- indexes, which are described later in this FAQ.</LI>
- <LI>The default <I>C</I> local must be used during
+ <LI>Case-insensitive searches such as <SMALL>ILIKE</SMALL> and
+ <I>~*</I> do not utilise indexes. Instead, use functional
+ indexes, which are described in section <a href="#4.12">4.12</a>.</LI>
+ <LI>The default <I>C</I> locale must be used during
<i>initdb.</i></LI>
</UL>
<P>
@@ -1032,13 +1023,13 @@
<PRE>
SELECT *
FROM tab
- WHERE lower(col) = 'abc'
+ WHERE LOWER(col) = 'abc';
</PRE>
This will not use an standard index. However, if you create a
functional index, it will be used:
<PRE>
- CREATE INDEX tabindex on tab (lower(col));
+ CREATE INDEX tabindex ON tab (LOWER(col));
</PRE>
<H4><A name="4.13">4.13</A>) In a query, how do I detect if a field
@@ -1053,8 +1044,8 @@
Type Internal Name Notes
--------------------------------------------------
"char" char 1 character
-CHAR(#) bpchar blank padded to the specified fixed length
-VARCHAR(#) varchar size specifies maximum length, no padding
+CHAR(n) bpchar blank padded to the specified fixed length
+VARCHAR(n) varchar size specifies maximum length, no padding
TEXT text no specific upper limit on length
BYTEA bytea variable-length byte array (null-byte safe)
</PRE>
@@ -1069,8 +1060,8 @@ BYTEA bytea variable-length byte array (null-byte safe)
stored out-of-line by <SMALL>TOAST</SMALL>, so the space on disk
might also be less than expected.</P>
- <P><SMALL>CHAR()</SMALL> is best when storing strings that are
- usually the same length. <SMALL>VARCHAR()</SMALL> is best when
+ <P><SMALL>CHAR(n)</SMALL> is best when storing strings that are
+ usually the same length. <SMALL>VARCHAR(n)</SMALL> is best when
storing variable-length strings but it limits how long a string can
be. <SMALL>TEXT</SMALL> is for strings of unlimited length, maximum
1 gigabyte. <SMALL>BYTEA</SMALL> is for storing binary data,
@@ -1111,11 +1102,11 @@ BYTEA bytea variable-length byte array (null-byte safe)
<P>One approach is to retrieve the next <SMALL>SERIAL</SMALL> value
from the sequence object with the <I>nextval()</I> function
<I>before</I> inserting and then insert it explicitly. Using the
- example table in <A href="#4.15.1">4.15.1</A>, that might look like
- this in Perl:</P>
+ example table in <A href="#4.15.1">4.15.1</A>, an example in a
+ pseudo-language would look like this:</P>
<PRE>
- new_id = output of "SELECT nextval('person_id_seq')"
- INSERT INTO person (id, name) VALUES (new_id, 'Blaise Pascal');
+ new_id = execute("SELECT nextval('person_id_seq')");
+ execute("INSERT INTO person (id, name) VALUES (new_id, 'Blaise Pascal')");
</PRE>
You would then also have the new value stored in
@@ -1124,14 +1115,14 @@ BYTEA bytea variable-length byte array (null-byte safe)
automatically created <SMALL>SEQUENCE</SMALL> object will be named
<<I>table</I>>_<<I>serialcolumn</I>>_<I>seq</I>, where
<I>table</I> and <I>serialcolumn</I> are the names of your table
- and your <SMALL>SERIAL</SMALL> column, respectively.
+ and your <SMALL>SERIAL</SMALL> column, respectively.
<P>Alternatively, you could retrieve the assigned
<SMALL>SERIAL</SMALL> value with the <I>currval</I>() function
<I>after</I> it was inserted by default, e.g.,</P>
<PRE>
- INSERT INTO person (name) VALUES ('Blaise Pascal');
- new_id = output of "SELECT currval('person_id_seq')";
+ execute("INSERT INTO person (name) VALUES ('Blaise Pascal')");
+ new_id = execute("SELECT currval('person_id_seq')");
</PRE>
Finally, you could use the <A href="#4.16"><SMALL>OID</SMALL></A>
@@ -1139,12 +1130,12 @@ BYTEA bytea variable-length byte array (null-byte safe)
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 <I>$sth->{pg_oid_status}</I> after
- <I>$sth->execute()</I>.
+ <I>$sth->execute()</I>.
<H4><A name="4.15.3">4.15.3</A>) Don't <I>currval()</I> and
<I>nextval()</I> lead to a race condition with other users?</H4>
- <P>No. Currval() returns the current value assigned by your
+ <P>No. <i>currval</i>() returns the current value assigned by your
backend, not by all users.</P>
<H4><A name="4.15.4">4.15.4</A>) Why aren't my sequence numbers
@@ -1163,7 +1154,7 @@ BYTEA bytea variable-length byte array (null-byte safe)
Every row that is created in PostgreSQL gets a unique
<SMALL>OID</SMALL>. All <SMALL>OID</SMALL>s generated during
<I>initdb</I> are less than 16384 (from
- <I>backend/access/transam.h</I>). All user-created
+ <I>include/access/transam.h</I>). All user-created
<SMALL>OID</SMALL>s are equal to or greater than this. By default,
all these <SMALL>OID</SMALL>s are unique not only within a table or
database, but unique within the entire PostgreSQL installation.</P>
@@ -1186,12 +1177,11 @@ BYTEA bytea variable-length byte array (null-byte safe)
COPY new TO '/tmp/pgtable';
DELETE FROM new;
COPY new WITH OIDS FROM '/tmp/pgtable';
+</PRE>
<!--
CREATE TABLE new_table (mycol int);
INSERT INTO new_table (oid, mycol) SELECT oid, mycol FROM old_table;
-->
-</PRE>
-
<P>O<SMALL>ID</SMALL>s 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.</P>
@@ -1228,7 +1218,7 @@ BYTEA bytea variable-length byte array (null-byte safe)
</UL>
<P>A list of general database terms can be found at: <A href=
- "http://www.comptechnews.com/~reaster/dbdesign.html">http://www.comptechnews.com/~reaster/dbdesign.html</A></P>
+ "http://hea-www.harvard.edu/MST/simul/software/docs/pkgs/pgsql/glossary/glossary.html">http://hea-www.harvard.edu/MST/simul/software/docs/pkgs/pgsql/glossary/glossary.html</A></P>
<H4><A name="4.18">4.18</A>) Why do I get the error <I>"ERROR:
Memory exhausted in AllocSetAlloc()"</I>?</H4>
@@ -1247,12 +1237,12 @@ BYTEA bytea variable-length byte array (null-byte safe)
and all subprocesses created after the command is run. If you are
having a problem with the <SMALL>SQL</SMALL> client because the
backend is returning too much data, try it before starting the
- client.
+ client.
<H4><A name="4.19">4.19</A>) How do I tell what PostgreSQL version
I am running?</H4>
- <P>From <I>psql</I>, type <CODE>select version();</CODE></P>
+ <P>From <I>psql</I>, type <CODE>SELECT version();</CODE></P>
<H4><A name="4.20">4.20</A>) Why does my large-object operations
get <I>"invalid large obj descriptor"</I>?</H4>
@@ -1288,22 +1278,18 @@ BYTEA bytea variable-length byte array (null-byte safe)
returns many rows, <CODE><SMALL>IN</SMALL></CODE> is fastest. To
speed up other queries, replace <CODE>IN</CODE> with
<CODE>EXISTS</CODE>:</P>
-<PRE>
-<CODE>SELECT *
+<PRE> SELECT *
FROM tab
- WHERE col IN (SELECT subcol FROM subtab)
-</CODE>
+ WHERE col IN (SELECT subcol FROM subtab);
</PRE>
- to:
-<PRE>
-<CODE>SELECT *
+ to:
+<PRE> SELECT *
FROM tab
- WHERE EXISTS (SELECT subcol FROM subtab WHERE subcol = col)
-</CODE>
+ WHERE EXISTS (SELECT subcol FROM subtab WHERE subcol = col);
</PRE>
For this to be fast, <CODE>subcol</CODE> should be an indexed column.
- We hope to fix this limitation in a future release.
+ We hope to fix this limitation in a future release.
<H4><A name="4.23">4.23</A>) How do I perform an outer join?</H4>
@@ -1362,8 +1348,8 @@ BYTEA bytea variable-length byte array (null-byte safe)
<P>You can return result sets from PL/pgSQL functions using
<I>refcursors</I>. See <A href=
- "http://developer.postgresql.org/docs/postgres/plpgsql-cursors.html">
- http://developer.postgresql.org/docs/postgres/plpgsql-cursors.html,</A>
+ "http://www.PostgreSQL.org/idocs/index.php?plpgsql-cursors.html">
+ http://www.PostgreSQL.org/idocs/index.php?plpgsql-cursors.html</A>,
section 23.7.3.3.</P>
<H4><A name="4.26">4.26</A>) Why can't I reliably create/drop
@@ -1381,13 +1367,12 @@ BYTEA bytea variable-length byte array (null-byte safe)
<P>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 <a
- href="http://gborg.postgresql.org/genpage?replication_research">
- http://gborg.postgresql.org/genpage?replication_research</a> lists
+ href="http://gborg.PostgreSQL.org/genpage?replication_research">
+ http://gborg.PostgreSQL.org/genpage?replication_research</a> lists
them. A multi-master replication solution is being worked on at <a
- href="http://gborg.postgresql.org/project/pgreplication/projdisplay.
- php">http://gborg.postgresql.org/project/pgreplication/projdisplay.php</a>.</P>
+ href="http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php">http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php</a>.</P>
- <H4><A name="4.27">4.27</A>) What encryption options are available?
+ <H4><A name="4.28">4.28</A>) What encryption options are available?
</H4>
<UL>
<LI><I>/contrib/pgcrypto</I> contains many encryption functions for
@@ -1395,8 +1380,8 @@ BYTEA bytea variable-length byte array (null-byte safe)
<LI>The only way to encrypt transmission from the client to the
server is by using <I>hostssl</I> in <I>pg_hba.conf</I>.</LI>
<LI>Database user passwords are automatically encrypted when stored
- in version 7.3. In previous versions, you must enable
- <I>password_encryption</I> in <I>postgresql.conf</I>.</LI>
+ in version 7.3. In previous versions, you must enable the option
+ <i>PASSWORD_ENCRYPTION</i> in <i>postgresql.conf</i>.</LI>
<LI>The server can run using an encrypted file system.</LI>
</UL>