Backpatch FAQ's to 8.0.X for release.

1 files changed, 175 insertions, 297 deletions

diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html
index f6bef3c6a15..1c6f3d9ccf8 100644
--- a/doc/src/FAQ/FAQ.html
+++ b/doc/src/FAQ/FAQ.html
@@ -10,7 +10,7 @@
   alink="#0000ff">
     <H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
 
-    <P>Last updated: Tue Mar 15 17:38:18 EST 2005</P>
+    <P>Last updated: Mon May  9 13:15:04 EDT 2005</P>
 
     <P>Current maintainer: Bruce Momjian (<A href=
     "mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)
@@ -40,6 +40,7 @@
      <A href="#1.11">1.11</A>) How do I join the development team?<BR>
      <A href="#1.12">1.12</A>) How does PostgreSQL compare to other
     <SMALL>DBMS</SMALL>s?<BR>
+     <A href="#1.13">1.13</A>) Who controls PostgreSQL?<BR>
      
 
     <H2 align="center">User Client Questions</H2>
@@ -99,41 +100,29 @@
     reused on transaction abort? Why are there gaps in the numbering of
     my sequence/SERIAL column?<BR>
      <A href="#4.12">4.12</A>) What is an <SMALL>OID</SMALL>? What is a
-    <SMALL>TID</SMALL>?<BR>
-     <A href="#4.12">4.13</A>) Why do I get the error <I>"ERROR: Memory
+    <SMALL>CTID</SMALL>?<BR>
+     <A href="#4.13">4.13</A>) Why do I get the error <I>"ERROR: Memory
     exhausted in AllocSetAlloc()"</I>?<BR>
      <A href="#4.14">4.14</A>) How do I tell what PostgreSQL version I
     am running?<BR>
-     <A href="#4.15">4.15</A>) Why does my large-object operations get
-    <I>"invalid large obj descriptor"</I>?<BR>
-     <A href="#4.16">4.16</A>) How do I create a column that will
+     <A href="#4.15">4.15</A>) How do I create a column that will
     default to the current time?<BR>
-     <A href="#4.17">4.17</A>) How do I perform an outer join?<BR>
-     <A href="#4.18">4.18</A>) How do I perform queries using multiple
+     <A href="#4.16">4.16</A>) How do I perform an outer join?<BR>
+     <A href="#4.17">4.17</A>) How do I perform queries using multiple
     databases?<BR>
-     <A href="#4.19">4.19</A>) How do I return multiple rows or columns
+     <A href="#4.18">4.18</A>) How do I return multiple rows or columns
     from a function?<BR>
-     <A href="#4.20">4.20</A>) Why do I get "relation with OID #####
+     <A href="#4.19">4.19</A>) Why do I get "relation with OID #####
     does not exist" errors when accessing temporary tables in PL/PgSQL
     functions?<BR>
-     <A href="#4.21">4.21</A>) What encryption options are available?<BR>
+     <A href="#4.20">4.20</A>) What replication solutions are available?<BR>
      
 
-    <H2 align="center">Extending PostgreSQL</H2>
-    <A href="#5.1">5.1</A>) I wrote a user-defined function. When I run
-    it in <I>psql</I>, why does it dump core?<BR>
-     <A href="#5.2">5.2</A>) How can I contribute some nifty new types
-    and functions to PostgreSQL?<BR>
-     <A href="#5.3">5.3</A>) How do I write a C function to return a
-    tuple?<BR>
-     <A href="#5.4">5.4</A>) I have changed a source file. Why does the
-    recompile not see the change?<BR>
-     
     <HR>
 
     <H2 align="center">General Questions</H2>
 
-    <H4><A name="1.1">1.1</A>) What is PostgreSQL? How is it pronounced?</H4>
+    <H3><A name="1.1">1.1</A>) What is PostgreSQL? How is it pronounced?</H3>
 
     <P>PostgreSQL is pronounced <I>Post-Gres-Q-L</I>, also called just
     <I>Postgres</I>.</P>
@@ -152,8 +141,8 @@
     http://www.postgresql.org/files/documentation/faqs/FAQ_DEV.html</A>
     </P>
 
-    <H4><A name="1.2">1.2</A>) What is the copyright of
-    PostgreSQL?</H4>
+    <H3><A name="1.2">1.2</A>) What is the copyright of
+    PostgreSQL?</H3>
 
     <P>PostgreSQL is distributed under the classic BSD license. It has
     no restrictions on how the source code can be used. We like it and
@@ -185,17 +174,16 @@
     UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
     SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.</P>
 
-    <H4><A name="1.3">1.3</A>) What platforms does PostgreSQL support?</H4>
+    <H3><A name="1.3">1.3</A>) What platforms does PostgreSQL support?</H3>
 
     <P>In general, any 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.</P>
 
-    <P>Starting with version 8.0, PostgreSQL now runs natively on
-    Microsoft Windows NT-based operating systems like Win2000, WinXP,
-    and Win2003.  A prepackaged installer is available at <a href=
-    "http://pgfoundry.org/projects/pginstaller">
+    <P>PostgreSQL also runs natively on Microsoft Windows NT-based operating
+    systems like Win2000, WinXP, and Win2003.  A prepackaged installer is
+    available at <a href= "http://pgfoundry.org/projects/pginstaller">
     http://pgfoundry.org/projects/pginstaller</a>.  MSDOS-based versions
     of Windows (Win95, Win98, WinMe) can run PostgreSQL using Cygwin.</P>
 
@@ -205,13 +193,14 @@
     "http://hobbes.nmsu.edu/cgi-bin/h-search?sh=1&amp;button=Search&amp;key=postgreSQL&amp;stype=all&amp;sort=type&amp;dir=%2F">
     http://hobbes.nmsu.edu/cgi-bin/h-search?sh=1&amp;button=Search&amp;key=postgreSQL&amp;stype=all&amp;sort=type&amp;dir=%2F</a>.</p>
 
-    <H4><A name="1.4">1.4</A>) Where can I get PostgreSQL?</H4>
+    <H3><A name="1.4">1.4</A>) Where can I get PostgreSQL?</H3>
 
-    <P>The primary anonymous ftp site for PostgreSQL is <A href=
-    "ftp://ftp.PostgreSQL.org/pub/">ftp://ftp.PostgreSQL.org/pub/</A>.
-    For mirror sites, see our main web site.</P>
+    <P>Via web browser, use <a href="http://www.postgresql.org/ftp/">
+    http://www.postgresql.org/ftp/</a>, and via ftp, use
+    <A href="ftp://ftp.PostgreSQL.org/pub/">
+    ftp://ftp.PostgreSQL.org/pub/</A>.</P>
 
-    <H4><A name="1.5">1.5</A>) Where can I get support?</H4>
+    <H3><A name="1.5">1.5</A>) Where can I get support?</H3>
 
     <P>The PostgreSQL community provides assistance to many of its users
     via email.  The main web site to subscribe to the email lists is
@@ -222,7 +211,7 @@
     <P>The major IRC channel is <I>#postgresql</I> on Freenode
     (<I>irc.freenode.net</I>).  To connect you can use the Unix
     program <CODE>irc -c '#postgresql' "$USER" irc.freenode.net</CODE>
-    or use any of the other popular IRC clients.  A Spanish one also exists
+    or use any other IRC clients.  A Spanish one also exists
     on the same network, (<I>#postgresql-es</I>), and a French one,
     (<I>#postgresqlfr</I>).  There is also a PostgreSQL channel on EFNet.</P>
 
@@ -230,7 +219,7 @@
     "http://techdocs.postgresql.org/companies.php">
     http://techdocs.postgresql.org/companies.php</A>.</P>
 
-    <H4><A name="1.6">1.6</A>) How do I submit a bug report?</H4>
+    <H3><A name="1.6">1.6</A>) How do I submit a bug report?</H3>
 
     <P>Visit the PostgreSQL bug form at <A href=
     "http://www.postgresql.org/support/submitbug">
@@ -240,13 +229,14 @@
     "ftp://ftp.PostgreSQL.org/pub/">ftp://ftp.PostgreSQL.org/pub/</A> to
     see if there is a more recent PostgreSQL version.</P>
 
-    <H4><A name="1.7">1.7</A>) What is the latest release?</H4>
+    <H3><A name="1.7">1.7</A>) What is the latest release?</H3>
 
-    <P>The latest release of PostgreSQL is version 8.0.1.</P>
+    <P>The latest release of PostgreSQL is version 8.0.2.</P>
 
-    <P>We plan to have major releases every ten to twelve months.</P>
+    <P>We plan to have a major release every year, with minor releases
+    every few months.</P>
 
-    <H4><A name="1.8">1.8</A>) What documentation is available?</H4>
+    <H3><A name="1.8">1.8</A>) What documentation is available?</H3>
 
     <P>PostgreSQL includes extensive documentation, including a large
     manual, manual pages, and some test examples. See the <I>/doc</I>
@@ -258,8 +248,9 @@
     "http://www.postgresql.org/docs/books/awbook.html">http://www.postgresql.org/docs/books/awbook.html</A>
     and <A href=
     "http://www.commandprompt.com/ppbook/">http://www.commandprompt.com/ppbook/</A>.
-    There is a list of PostgreSQL books available for purchase at <A
-    href=
+    There are a number of PostgreSQL books available for purchase.  One
+    of the most popular ones is by Korry Douglas.  A list of book reviews
+    can be found at <A href=
     "http://techdocs.postgresql.org/techdocs/bookreviews.php">http://techdocs.PostgreSQL.org/techdocs/bookreviews.php</A>.
     There is also a collection of PostgreSQL technical articles at <A
     href=
@@ -271,22 +262,25 @@
 
     <P>Our web site contains even more documentation.</P>
 
-    <H4><A name="1.9">1.9</A>) How do I find out about known bugs or
-    missing features?</H4>
+    <H3><A name="1.9">1.9</A>) How do I find out about known bugs or
+    missing features?</H3>
 
     <P>PostgreSQL supports an extended subset of <SMALL>SQL</SMALL>-92.
-    See our <A href="http://developer.PostgreSQL.org/todo.php">TODO</A>
+    See our <A href="http://www.postgresql.org/docs/faqs.TODO.html">TODO</A>
     list for known bugs, missing features, and future plans.</P>
 
-    <H4><A name="1.10">1.10</A>) How can I learn
-    <SMALL>SQL</SMALL>?</H4>
+    <H3><A name="1.10">1.10</A>) How can I learn
+    <SMALL>SQL</SMALL>?</H3>
 
-    <P>The PostgreSQL book at <A href=
-    "http://www.postgresql.org/docs/books/awbook.html">http://www.postgresql.org/docs/books/awbook.html</A>
-    teaches <SMALL>SQL</SMALL>. There is another PostgreSQL book at <A
-    href=
-    "http://www.commandprompt.com/ppbook/">http://www.commandprompt.com/ppbook.</A>
-    There is a nice tutorial at <A href=
+    <P>First, consider the PostgreSQL-specific books mentioned above.
+    Another one is "Teach Yourself SQL in 21 Days, Second Edition"
+    at <A href=
+    "http://members.tripod.com/er4ebus/sql/index.htm">http://members.tripod.com/er4ebus/sql/index.htm</A>.
+    Many of our users like <I>The Practical SQL Handbook</I>,
+    Bowman, Judith S., et al., Addison-Wesley. Others like <I>The
+    Complete Reference SQL</I>, Groff et al., McGraw-Hill.</P>
+
+    <P>There is also a nice tutorial at <A href=
     "http://www.intermedia.net/support/sql/sqltut.shtm">http://www.intermedia.net/support/sql/sqltut.shtm,</A>
     at <A href=
     "http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM">
@@ -294,31 +288,14 @@
     and at <A href=
     "http://sqlcourse.com/">http://sqlcourse.com.</A></P>
 
-    <P>Another one is "Teach Yourself SQL in 21 Days, Second Edition"
-    at <A href=
-    "http://members.tripod.com/er4ebus/sql/index.htm">http://members.tripod.com/er4ebus/sql/index.htm</A></P>
-
-    <P>Many of our users like <I>The Practical SQL Handbook</I>,
-    Bowman, Judith S., et al., Addison-Wesley. Others like <I>The
-    Complete Reference SQL</I>, Groff et al., McGraw-Hill.</P>
+    <H3><A name="1.11">1.11</A>) How do I join the development
+    team?</H3>
 
-    <H4><A name="1.11">1.11</A>) How do I join the development
-    team?</H4>
+    <P>See the <a href="http://www.postgresql.org/docs/faqs.FAQ_DEV.html">
+    Developer's FAQ</A>.
 
-    <P>First, download the latest source and read the PostgreSQL
-    Developers FAQ and documentation on our web site, or in the
-    distribution. Second, subscribe to the <I>pgsql-hackers</I> and
-    <I>pgsql-patches</I> mailing lists. Third, submit high quality
-    patches to pgsql-patches.</P>
-
-    <P>There are about a dozen people who have commit privileges to the
-    PostgreSQL <SMALL>CVS</SMALL> 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.</P>
-
-    <H4><A name="1.12">1.12</A>) How does PostgreSQL compare to other
-    <SMALL>DBMS</SMALL>s?</H4>
+    <H3><A name="1.12">1.12</A>) How does PostgreSQL compare to other
+    <SMALL>DBMS</SMALL>s?</H3>
 
     <P>There are several ways of measuring software: features,
     performance, reliability, support, and price.</P>
@@ -339,13 +316,7 @@
 
       <DD>PostgreSQL's performance is comparable 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
-      faster for multiple users, complex queries, and a read/write query
-      load.  MySQL is faster for simple SELECT queries done by a few users.
-      Of course, MySQL does not have most of the features mentioned in the
-      <I>Features</I> section above. We are built for reliability and
-      features, and we continue to improve performance in every
-      release. <BR>
+      others.  Our performance is usually +/-10% compared to other databases.
       <BR>
       </DD>
 
@@ -383,13 +354,24 @@
       </DD>
     </DL>
 
+    <H3><A name="1.13">1.13</A>) Who controls PostgreSQL?<BR>
+
+    <P>If you are looking for a PostgreSQL gatekeeper, central committee,
+    or controlling company, give up --- there isn't one.  We do have a
+    core committee and CVS committers, but these groups are more for
+    administrative purposes than control.  The project is directed by
+    the community of developers and users, which anyone can join.  All
+    you need to do is subscribe to the mailing lists and participate in the
+    discussions.   (See the <a href="http://www.postgresql.org/docs/faqs.FAQ_DEV.html">
+    Developer's FAQ</A> for information on how to get involved in PostgreSQL
+    development.)</P>
 
     <HR>
 
     <H2 align="center">User Client Questions</H2>
 
-    <H4><A name="2.1">2.1</A>) What interfaces are available for
-    PostgreSQL?</H4>
+    <H3><A name="2.1">2.1</A>) What interfaces are available for
+    PostgreSQL?</H3>
 
     <P>The PostgreSQL install includes only the <SMALL>C</SMALL> and embedded
     <SMALL>C</SMALL> interfaces.  All other interfaces are independent projects
@@ -403,8 +385,8 @@
     in the <I>Drivers/Interfaces</I> section and via Internet search.
     </P>
 
-    <H4><A name="2.2">2.2</A>) What tools are available for using
-    PostgreSQL with Web pages?</H4>
+    <H3><A name="2.2">2.2</A>) What tools are available for using
+    PostgreSQL with Web pages?</H3>
 
     <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>
@@ -416,25 +398,11 @@
     <P>For complex cases, many use the Perl and DBD::Pg with CGI.pm or
     mod_perl.</P>
 
-    <H4><A name="2.3">2.3</A>) Does PostgreSQL have a graphical user
-    interface?</H4>
-
-    <P>Yes, there are several graphical interfaces to PostgreSQL
-    available. These include pgAdmin III (<a
-    href="http://www.pgadmin.org">http://www.pgadmin.org</a>, PgAccess
-    <a href="http://www.pgaccess.org"> http://www.pgaccess.org</a>),
-    RHDB Admin (<a
-    href="http://sources.redhat.com/rhdb/">http://sources.redhat.com/rhdb/
-    </a>), TORA (<a href="http://www.globecom.net/tora/">
-    http://www.globecom.net/tora/</a>, partly commercial), and Rekall (<a
-    href="http://www.rekallrevealed.org/">
-    http://www.rekallrevealed.org/</a>). There is also PhpPgAdmin (<a
-    href="http://phppgadmin.sourceforge.net/">
-    http://phppgadmin.sourceforge.net/ </a>), a web-based interface to
-    PostgreSQL.</P>
-
-    <P>See <a href="http://techdocs.postgresql.org/guides/GUITools">
-    http://techdocs.postgresql.org/guides/GUITools</a> for a more 
+    <H3><A name="2.3">2.3</A>) Does PostgreSQL have a graphical user
+    interface?</H3>
+
+    <P>Yes, see <a href="http://techdocs.postgresql.org/guides/GUITools">
+    http://techdocs.postgresql.org/guides/GUITools</a> for a
     detailed list.</P>
 
     <HR>
@@ -442,14 +410,14 @@
 
     <H2 align="center">Administrative Questions</H2>
 
-    <H4><A name="3.1">3.1</A>) How do I install PostgreSQL somewhere
-    other than <I>/usr/local/pgsql</I>?</H4>
+    <H3><A name="3.1">3.1</A>) How do I install PostgreSQL somewhere
+    other than <I>/usr/local/pgsql</I>?</H3>
 
     <P>Specify the <I>--prefix</I> option when running
     <I>configure</I>.</P>
 
-    <H4><A name="3.2">3.2</A>) How do I control connections from other
-    hosts?</H4>
+    <H3><A name="3.2">3.2</A>) How do I control connections from other
+    hosts?</H3>
 
     <P>By default, PostgreSQL only allows connections from the local
     machine using Unix domain sockets or TCP/IP connections. Other
@@ -458,8 +426,8 @@
     host-based authentication by modifying the
     <I>$PGDATA/pg_hba.conf</I> file, and restart the server.</P>
 
-    <H4><A name="3.3">3.3</A>) How do I tune the database engine for
-    better performance?</H4>
+    <H3><A name="3.3">3.3</A>) How do I tune the database engine for
+    better performance?</H3>
 
     <P>There are three major areas for potential performance
     improvement:</P>
@@ -515,57 +483,15 @@
     </DD>
     </DL>
 
-    <H4><A name="3.4">3.4</A>) What debugging features are
-    available?</H4>
+    <H3><A name="3.4">3.4</A>) What debugging features are
+    available?</H3>
 
     <P>There are many <CODE>log_*</CODE> server configuration variables
     that enable printing of query and process statistics which can be
     very useful for debugging and performance measurements.</P>
 
-    <P><B>The following detailed debug instructions are to be used to
-    provide more detailed information for server developers debugging a
-    problem.</B></P>
-
-    <P>It is also possible to debug the server if it isn't operating
-    properly.  First, by running <I>configure</I> with the --enable-cassert
-    option, many <I>assert()</I>s monitor the progress of the backend
-    and halt the program when something unexpected occurs.</P>
-
-    <P>The <I>postmaster</I> has a <I>-d</I> option that allows even more
-    detailed information to be reported. The <I>-d</I> option takes a
-    number that specifies the debug level. Be warned that high debug
-    level values generate large log files.</P>
-
-    <P>If <I>postmaster</I> is not running, you can actually run the
-    <I>postgres</I> backend from the command line, and type your
-    <SMALL>SQL</SMALL> statement directly. This is recommended
-    <B>only</B> 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 <I>postmaster</I>, it is not
-    running in an identical environment and locking/backend interaction
-    problems may not be duplicated.</P>
-
-    <P>If <I>postmaster</I> is running, start <I>psql</I> in one
-    window, then find the <SMALL>PID</SMALL> of the <I>postgres</I>
-    process used by <I>psql</I> using <CODE>SELECT pg_backend_pid()</CODE>.
-    Use a debugger to attach to the <I>postgres</I> <SMALL>PID</SMALL>.
-    You can set breakpoints in the debugger and issue queries from
-
-    <I>psql</I>. If you are debugging <I>postgres</I> startup, you can
-    set PGOPTIONS="-W n", then start <I>psql</I>. This will cause startup
-    to delay for <I>n</I> seconds so you can attach to the process with
-    the debugger, set any breakpoints, and continue through the startup
-    sequence.</P>
-
-    <P>You can also compile with profiling to see what functions are
-    taking execution time. The backend profile files will be deposited
-    in the <I>pgsql/data/base/dbname</I> directory. The client profile
-    file will be put in the client's current directory. Linux requires
-    a compile with <I>-DLINUX_PROFILE</I> for proper profiling.</P>
-
-    <H4><A name="3.5">3.5</A>) Why do I get <I>"Sorry, too many
-    clients"</I> when trying to connect?</H4>
+    <H3><A name="3.5">3.5</A>) Why do I get <I>"Sorry, too many
+    clients"</I> when trying to connect?</H3>
 
     <P>You have reached the default limit is 100 database sessions. You
     need to increase the <I>postmaster</I>'s limit on how many
@@ -573,18 +499,18 @@
     <I>max_connections</I> value in <I>postgresql.conf</I> and
     restarting the <I>postmaster</I>.</P>
 
-    <H4><A name="3.6">3.6</A>) Why do I need to do a dump and restore
-    to upgrade between major PostgreSQL releases?</H4>
+    <H3><A name="3.6">3.6</A>) Why do I need to do a dump and restore
+    to upgrade between major PostgreSQL releases?</H3>
 
     <P>The PostgreSQL team makes only small changes between minor releases,
-    so upgrading from 7.4 to 7.4.1 does not require a dump and restore.
+    so upgrading from 7.4.0 to 7.4.1 does not require a dump and restore.
     However, major releases (e.g. from 7.3 to 7.4) often change the internal
     format of system tables and data files. These changes are often complex,
     so we don't maintain backward compatibility for data files. A dump outputs
     data in a generic format that can then be loaded in using the new internal
     format.</P>
 
-    <H4><A name="3.7">3.7</A>) What computer hardware should I use?</H4>
+    <H3><A name="3.7">3.7</A>) What computer hardware should I use?</H3>
 
     <P>Because PC hardware is mostly compatible, people tend to believe that
     all PC hardware is of equal quality.  It is not.  ECC RAM, SCSI, and
@@ -598,8 +524,8 @@
 
     <H2 align="center">Operational Questions</H2>
 
-    <H4><A name="4.1">4.1</A>) How do I <SMALL>SELECT</SMALL> only the
-    first few rows of a query?  A random row?</H4>
+    <H3><A name="4.1">4.1</A>) How do I <SMALL>SELECT</SMALL> only the
+    first few rows of a query?  A random row?</H3>
 
     <P>To retrieve only a few rows, if you know at the number of rows
     needed at the time of the <SMALL>SELECT</SMALL> use
@@ -617,9 +543,9 @@
     LIMIT 1;
 </PRE>
 
-    <H4><A name="4.2">4.2</A>) How do I find out what tables, indexes,
+    <H3><A name="4.2">4.2</A>) How do I find out what tables, indexes,
     databases, and users are defined?  How do I see the queries used
-    by <I>psql</I> to display them?</H4>
+    by <I>psql</I> to display them?</H3>
 
     <P>Use the \dt command to see tables in <I>psql</I>. For a complete list of
     commands inside psql you can use \?. Alternatively you can read the source 
@@ -640,7 +566,7 @@
     illustrates many of the <SMALL>SELECT</SMALL>s needed to get
     information from the database system tables.</P>
 
-    <H4><A name="4.3">4.3</A>) How do you change a column's data type?</H4>
+    <H3><A name="4.3">4.3</A>) How do you change a column's data type?</H3>
 
     <P>Changing the data type of a column can be done easily in 8.0
     and later with <SMALL>ALTER TABLE ALTER COLUMN TYPE</SMALL>.</P>
@@ -656,12 +582,12 @@
     <P>You might then want to do <I>VACUUM FULL tab</I> to reclaim the
     disk space used by the expired rows.</P>
     
-    <H4><A name="4.4">4.4</A>) What is the maximum size for a row, a
-    table, and a database?</H4>
+    <H3><A name="4.4">4.4</A>) What is the maximum size for a row, a
+    table, and a database?</H3>
 
     <P>These are the limits:</P>
 <BLOCKQUOTE>
-<TABLE >
+<TABLE>
 <TR><TD>Maximum size for a database?</TD><TD>unlimited (32 TB databases
 exist)</TD></TR>
 <TR><TD>Maximum size for a table?</TD><TD>32 TB</TD></TR>
@@ -687,8 +613,8 @@ table?</TD><TD>unlimited</TD></TR>
     <P>The maximum table size and maximum number of columns can be
     quadrupled by increasing the default block size to 32k.</P>
 
-    <H4><A name="4.5">4.5</A>) How much database disk space is required
-    to store data from a typical text file?</H4>
+    <H3><A name="4.5">4.5</A>) How much database disk space is required
+    to store data from a typical text file?</H3>
 
     <P>A PostgreSQL database may require up to five times the disk
     space to store data from a text file.</P>
@@ -724,14 +650,14 @@ table?</TD><TD>unlimited</TD></TR>
     <P><SMALL>NULL</SMALL>s are stored as bitmaps, so they
     use very little space.</P>
     
-    <H4><A name="4.6">4.6</A>) Why are my queries slow?  Why don't they
-    use my indexes?</H4>
+    <H3><A name="4.6">4.6</A>) Why are my queries slow?  Why don't they
+    use my indexes?</H3>
 
-    <P>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. </P>
+    <P>Indexes are not used by every query. Indexes are used only 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. </P>
 
     <P>To determine if an index should be used, PostgreSQL must have
     statistics about the table. These statistics are collected using
@@ -759,7 +685,7 @@ table?</TD><TD>unlimited</TD></TR>
 
     <P>If you believe the optimizer is incorrect in choosing a
     sequential scan, use <CODE>SET enable_seqscan TO 'off'</CODE> and
-    run tests to see if an index scan is indeed faster.</P>
+    run query again to see if an index scan is indeed faster.</P>
 
     <P>When using wild-card operators such as <SMALL>LIKE</SMALL> or
     <I>~</I>, indexes can only be used in certain circumstances:</P>
@@ -788,14 +714,14 @@ table?</TD><TD>unlimited</TD></TR>
     types exactly match the index's column types.  This was particularly
     true of int2, int8, and numeric column indexes.</P>
 
-    <H4><A name="4.7">4.7</A>) How do I see how the query optimizer is
-    evaluating my query?</H4>
+    <H3><A name="4.7">4.7</A>) How do I see how the query optimizer is
+    evaluating my query?</H3>
 
     <P>See the <SMALL>EXPLAIN</SMALL> manual page.</P>
 
-    <H4><A name="4.8">4.8</A>) How do I perform regular expression
+    <H3><A name="4.8">4.8</A>) How do I perform regular expression
     searches and case-insensitive regular expression searches? How do I
-    use an index for case-insensitive searches?</H4>
+    use an index for case-insensitive searches?</H3>
 
     <P>The <I>~</I> operator does regular expression matching, and
     <I>~*</I> does case-insensitive regular expression matching. The
@@ -809,19 +735,18 @@ table?</TD><TD>unlimited</TD></TR>
     FROM tab
     WHERE lower(col) = 'abc';
 </PRE>
-
     This will not use an standard index. However, if you create a
     expresssion index, it will be used: 
 <PRE>
     CREATE INDEX tabindex ON tab (lower(col));
 </PRE>
 
-    <H4><A name="4.9">4.9</A>) In a query, how do I detect if a field
+    <H3><A name="4.9">4.9</A>) In a query, how do I detect if a field
     is <SMALL>NULL</SMALL>?  How can I sort on whether a field is <SMALL>
-    NULL</SMALL> or not?</H4>
+    NULL</SMALL> or not?</H3>
 
     <P>You test the column with <SMALL>IS NULL</SMALL> and <SMALL>IS
-    NOT NULL</SMALL>.</P>
+    NOT NULL</SMALL>, like this:</P>
 
 <PRE>
    SELECT *
@@ -830,7 +755,7 @@ table?</TD><TD>unlimited</TD></TR>
 </PRE>
 
    <P>To sort by the <SMALL>NULL</SMALL> status, use the <SMALL>IS NULL</SMALL>
-   and <SMALL>IS NOT NULL</SMALL> modifiers in your <SMALL>WHERE</SMALL> clause.
+   and <SMALL>IS NOT NULL</SMALL> modifiers in your <SMALL>ORDER BY</SMALL> clause.
    Things that are <I>true</I> will sort higher than things that are <I>false</I>,
    so the following will put NULL entries at the top of the resulting list:</P>
 
@@ -840,10 +765,10 @@ table?</TD><TD>unlimited</TD></TR>
    ORDER BY (col IS NOT NULL)
 </PRE>
 
-    <H4><A name="4.10">4.10</A>) What is the difference between the
-    various character types?</H4>
+    <H3><A name="4.10">4.10</A>) What is the difference between the
+    various character types?</H3>
 <BLOCKQUOTE>
-<TABLE >
+<TABLE>
 <TR><TH>Type</TH><TH>Internal Name</TH><TH>Notes</TH></TR>
 <TR><TD>VARCHAR(n)</TD><TD>varchar</TD><TD>size specifies maximum
 length, no padding</TD></TR>
@@ -863,9 +788,8 @@ length</TD></TR>
     <P>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 <SMALL>TOAST</SMALL>, so the space on disk
-    might also be less than expected.</P>
+    However, long values are also subject to compression, so the space
+    on disk might also be less than expected.</P>
 
     <SMALL>VARCHAR(n)</SMALL> is best when storing variable-length
     strings and it limits how long a string can be. <SMALL>TEXT</SMALL>
@@ -877,12 +801,11 @@ length</TD></TR>
     particularly values that include <SMALL>NULL</SMALL> bytes. All the
     types described here have similar performance characteristics.</P>
 
-    <H4><A name="4.11.1">4.11.1</A>) How do I create a
-    serial/auto-incrementing field?</H4>
+    <H3><A name="4.11.1">4.11.1</A>) How do I create a
+    serial/auto-incrementing field?</H3>
 
     <P>PostgreSQL supports a <SMALL>SERIAL</SMALL> data type. It
-    auto-creates a sequence.  For example,
-    this:</P>
+    auto-creates a sequence.  For example, this:</P>
 <PRE>
     CREATE TABLE person ( 
         id   SERIAL, 
@@ -891,19 +814,20 @@ length</TD></TR>
 </PRE>
 
     is automatically translated into this: 
+
 <PRE>
     CREATE SEQUENCE person_id_seq;
     CREATE TABLE person ( 
         id   INT4 NOT NULL DEFAULT nextval('person_id_seq'),
-        name TEXT 
+        name TEXT
     );
 </PRE>
 
     See the <I>create_sequence</I> manual page for more information
     about sequences.
 
-    <H4><A name="4.11.2">4.11.2</A>) How do I get the value of a
-    <SMALL>SERIAL</SMALL> insert?</H4>
+    <H3><A name="4.11.2">4.11.2</A>) How do I get the value of a
+    <SMALL>SERIAL</SMALL> insert?</H3>
 
     <P>One approach is to retrieve the next <SMALL>SERIAL</SMALL> value
     from the sequence object with the <I>nextval()</I> function
@@ -915,39 +839,39 @@ length</TD></TR>
     execute("INSERT INTO person (id, name) VALUES (new_id, 'Blaise Pascal')");
 </PRE>
 
-    You would then also have the new value stored in
-    <CODE>new_id</CODE> for use in other queries (e.g., as a foreign
-    key to the <CODE>person</CODE> table). Note that the name of the
-    automatically created <SMALL>SEQUENCE</SMALL> object will be named
-    &lt;<I>table</I>&gt;_&lt;<I>serialcolumn</I>&gt;_<I>seq</I>, where
-    <I>table</I> and <I>serialcolumn</I> are the names of your table
-    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>
+    You would then also have the new value stored in <CODE>new_id</CODE>
+    for use in other queries (e.g., as a foreign key to the <CODE>person
+    </CODE> table). Note that the name of the automatically created
+    <SMALL>SEQUENCE</SMALL> object will be named &lt;<I>table</I>&gt;_&lt;<I>
+    serialcolumn</I>&gt;_<I>seq</I>, where <I>table</I> and <I>serialcolumn</I>
+    are the names of your table 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>
     execute("INSERT INTO person (name) VALUES ('Blaise Pascal')");
     new_id = execute("SELECT currval('person_id_seq')");
 </PRE>
     
-    <H4><A name="4.11.3">4.11.3</A>) Doesn't <I>currval()</I>
-    lead to a race condition with other users?</H4>
+    <H3><A name="4.11.3">4.11.3</A>) Doesn't <I>currval()</I>
+    lead to a race condition with other users?</H3>
 
     <P>No. <I>currval()</I> returns the current value assigned by your
     session, not by all sessions.</P>
 
-    <H4><A name="4.11.4">4.11.4</A>) Why aren't my sequence numbers
+    <H3><A name="4.11.4">4.11.4</A>) Why aren't my sequence numbers
     reused on transaction abort? Why are there gaps in the numbering of
-    my sequence/SERIAL column?</H4>
+    my sequence/SERIAL column?</H3>
 
     <P>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.</P>
 
-    <H4><A name="4.12">4.12</A>) What is an <SMALL>OID</SMALL>? What is
-    a <SMALL>TID</SMALL>?</H4>
+    <H3><A name="4.12">4.12</A>) What is an <SMALL>OID</SMALL>? What is
+    a <SMALL>CTID</SMALL>?</H3>
 
     <P>Every row that is created in PostgreSQL gets a unique
     <SMALL>OID</SMALL> unless created <SMALL>WITHOUT OIDS</SMALL>.
@@ -964,13 +888,13 @@ length</TD></TR>
     <SMALL>SERIAL8</SMALL> is available for storing eight-byte sequence
     values.</P>
 
-    <P>T<SMALL>ID</SMALL>s are used to identify specific physical rows
-    with block and offset values. T<SMALL>ID</SMALL>s change after rows
+    <P>C<SMALL>TID</SMALL>s are used to identify specific physical rows
+    with block and offset values. C<SMALL>TID</SMALL>s change after rows
     are modified or reloaded. They are used by index entries to point
     to physical rows.</P>
 
-    <H4><A name="4.13">4.13</A>) Why do I get the error <I>"ERROR:
-    Memory exhausted in AllocSetAlloc()"</I>?</H4>
+    <H3><A name="4.13">4.13</A>) Why do I get the error <I>"ERROR:
+    Memory exhausted in AllocSetAlloc()"</I>?</H3>
 
     <P>You probably have run out of virtual memory on your system,
     or your kernel has a low limit for certain resources. Try this
@@ -988,36 +912,20 @@ length</TD></TR>
     backend is returning too much data, try it before starting the
     client.
 
-    <H4><A name="4.14">4.14</A>) How do I tell what PostgreSQL version
-    I am running?</H4>
+    <H3><A name="4.14">4.14</A>) How do I tell what PostgreSQL version
+    I am running?</H3>
 
     <P>From <I>psql</I>, type <CODE>SELECT version();</CODE></P>
 
-    <H4><A name="4.15">4.15</A>) Why does my large-object operations
-    get <I>"invalid large obj descriptor"</I>?</H4>
-
-    <P>You need to put <CODE>BEGIN WORK</CODE> and <CODE>COMMIT</CODE>
-    around any use of a large object handle, that is, surrounding
-    <CODE>lo_open</CODE> ... <CODE>lo_close.</CODE></P>
-
-    <P>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 <I>invalid large obj descriptor</I>. 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.</P>
-
-    <P>If you are using a client interface like <SMALL>ODBC</SMALL> you
-    may need to set <CODE>auto-commit off.</CODE></P>
-
-    <H4><A name="4.16">4.16</A>) How do I create a column that will
-    default to the current time?</H4>
+    <H3><A name="4.15">4.15</A>) How do I create a column that will
+    default to the current time?</H3>
 
     <P>Use <I>CURRENT_TIMESTAMP</I>:</P>
 <PRE>
     CREATE TABLE test (x int, modtime TIMESTAMP DEFAULT CURRENT_TIMESTAMP );
 </PRE>
 
-    <H4><A name="4.17">4.17</A>) How do I perform an outer join?</H4>
+    <H3><A name="4.16">4.16</A>) How do I perform an outer join?</H3>
 
     <P>PostgreSQL supports outer joins using the SQL standard syntax.
     Here are two examples:</P>
@@ -1040,8 +948,8 @@ length</TD></TR>
     <SMALL>RIGHT</SMALL>, and <SMALL>FULL</SMALL> joins. Ordinary joins
     are called <SMALL>INNER</SMALL> joins.</P>
 
-    <H4><A name="4.18">4.18</A>) How do I perform queries using
-    multiple databases?</H4>
+    <H3><A name="4.17">4.17</A>) How do I perform queries using
+    multiple databases?</H3>
 
     <P>There is no way to query a database other than the current one.
     Because PostgreSQL loads database-specific system catalogs, it is
@@ -1052,16 +960,16 @@ length</TD></TR>
     connections to different databases and merge the results on the
     client side.</P>
 
-    <H4><A name="4.19">4.19</A>) How do I return multiple rows or
-    columns from a function?</H4>
+    <H3><A name="4.18">4.18</A>) How do I return multiple rows or
+    columns from a function?</H3>
 
     <P>It is easy using set-returning functions, 
     <a href="http://techdocs.postgresql.org/guides/SetReturningFunctions">
     http://techdocs.postgresql.org/guides/SetReturningFunctions</a></P>.
 
-    <H4><A name="4.20">4.20</A>) Why do I get "relation with OID #####
+    <H3><A name="4.19">4.19</A>) Why do I get "relation with OID #####
     does not exist" errors when accessing temporary tables in PL/PgSQL
-    functions?</H4>
+    functions?</H3>
 
     <P>PL/PgSQL caches function scripts, and an unfortunate side effect
     is that if a PL/PgSQL function accesses a temporary table, and that
@@ -1071,56 +979,26 @@ length</TD></TR>
     <SMALL>EXECUTE</SMALL> for temporary table access in PL/PgSQL. This
     will cause the query to be reparsed every time.</P>
 
-    <H4><A name="4.21">4.21</A>) What encryption options are available?
-    </H4>
-    <UL>
-    <LI><I>contrib/pgcrypto</I> contains many encryption functions for
-    use in <SMALL>SQL</SMALL> queries.</LI>
-    <LI>To encrypt transmission from the client to the server, the server
-    must have the <I>ssl</I> option set to <I>true</I> in <I>postgresql.conf,
-    </I> and an applicable <I>host</I> or <I>hostssl</I> record must exist in
-    <I>pg_hba.conf</I>, and the client <I>sslmode</I> must not be
-    <I>disable.</I> (Note that it is also possible to use a third-party
-    encrypted transport, such as stunnel or ssh, rather than PostgreSQL's
-    native SSL connections.)</LI>
-    <LI>Database user passwords are automatically encrypted when stored in
-    the system tables.</LI>
-    <LI>The server can run using an encrypted file system.</LI>
-    </UL>
-
-    <HR>
-
-    <H2 align="center">Extending PostgreSQL</H2>
-
-    <H4><A name="5.1">5.1</A>) I wrote a user-defined function. When I
-    run it in <I>psql</I>, why does it dump core?</H4>
-
-    <P>The problem could be a number of things. Try testing your
-    user-defined function in a stand-alone test program first.</P>
-
-    <H4><A name="5.2">5.2</A>) How can I contribute some nifty new
-    types and functions to PostgreSQL?</H4>
-
-    <P>Send your extensions to the <I>pgsql-hackers</I> mailing list,
-    and they will eventually end up in the <I>contrib/</I>
-    subdirectory.</P>
+    <H3><A name="4.20">4.20</A>) What replication solutions are available?
+    </H3>
 
-    <H4><A name="5.3">5.3</A>) How do I write a C function to return a
-    tuple?</H4>
+    <P>Though "replication" is a single term, there are several technologies
+    for doing replication, with advantages and disadvantages for each.</P>
 
-    <P>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
-    <I>contrib/tablefunc</I>.</P>
+    <P>Master/slave replication allows a single master to receive read/write
+    queries, while slaves can only accept read/<SMALL>SELECT</SMALL>
+    queries. The most popular freely available master-slave PostgreSQL
+    replication solution is <A
+    href="http://gborg.postgresql.org/project/slony1/projdisplay.php">
+    Slony-I</A>.</P>
 
-    <H4><A name="5.4">5.4</A>) I have changed a source file. Why does
-    the recompile not see the change?</H4>
+    <P>Multi-master replication allows read/write queries to be sent to
+    multiple replicated computers.  This capability also has a severe impact
+    on performance due to the need to synchronize changes between servers. 
+    <A href="http://pgfoundry.org/projects/pgcluster/">Pgcluster</a> is the
+    most popular such solution freely available for PostgreSQL.</P>
 
-    <P>The <I>Makefiles</I> do not have the proper dependencies for
-    include files. You have to do a <I>make clean</I> and then another
-    <I>make</I>. If you are using <SMALL>GCC</SMALL> you can use the
-    <I>--enable-depend</I> option of <I>configure</I> to have the
-    compiler compute the dependencies automatically.</P>
+    <P>There are also commercial and hardware-based replication solutions
+    available supporting a variety of replication models.</P>
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