Developer's Frequently Asked Questions (FAQ) for PostgreSQL

Last updated:Mon Nov 13 23:18:46 EST 2006

Last updated:Tue Dec 19 17:37:24 EST 2006

Current maintainer: Bruce Momjian (bruce@momjian.us)

1.16) Where can I get a copy of the SQL standards?

1.17) Where can I get technical assistance?

1.18) How do I get involved in PostgreSQL web site development?

1.19) What is the timeline for the next major PostgreSQL release?

Technical Questions

pgsql/data directory. The client profile file will be put in the

client's current directory. Linux requires a compile with

-DLINUX_PROFILE for proper profiling.

2.9) What is the timeline for the next major PostgreSQL release?

The development schedule for the 8.3 release is:

March 1, 2006

Initial community review of all major feature patches

April 1, 2006

Feature freeze, all patches must be submitted for review and

application

mid-May, 2006

All patches applied, beta testing begins

July, 2006

Release of 8.3.0

Patches that appear after appropriate dates are typically not applied

but held for the next major release.

<H1>Developer's Frequently Asked Questions (FAQ) for

PostgreSQL</H1>

<P>Last updated:Mon Nov 13 23:18:46 EST 2006</P>

<P>Last updated:Tue Dec 19 17:37:24 EST 2006</P>

<P>Current maintainer: Bruce Momjian (<Ahref=

"mailto:bruce@momjian.us">bruce@momjian.us</A>)<BR>

assistance?<BR>

<Ahref="#item1.18">1.18</A>) How do I get involved in PostgreSQL web

site development?<BR>

<Ahref="#item1.19">1.19</A>) What is the timeline for the next major

PostgreSQL release?<BR>

<H2>Technical Questions</H2>

<H3id="item2.7">2.7) What is CommandCounterIncrement()?</H3>

<P>Normally, transactions can not see the rows they modify. This

allows<CODE>UPDATE foo SET x = x + 1</CODE> to work correctly.</P>

<P>Normally, transactions can not see the rows they modify.

This allows<CODE>UPDATE foo SET x = x + 1</CODE> to work

correctly.</P>

<P>However, there are cases where a transactions needs to see rows

affected in previous parts of the transaction. This is accomplished

using a Command Counter. Incrementing the counter allows

transactions to be broken into pieces so each piece can see rows

modified by previous pieces.<I>CommandCounterIncrement()</I>

<P>However, there are cases where a transactions needs to see

rowsaffected in previous parts of the transaction. This is

accomplishedusing a Command Counter. Incrementing the counter

allowstransactions to be broken into pieces so each piece can

see rowsmodified by previous pieces.<I>CommandCounterIncrement()</I>

increments the Command Counter, creating a new part of the

transaction.</P>

<H3id="item2.8">2.8) What debugging features are

available?</H3>

<H3id="item2.8">2.8) What debugging features are available?</H3>

<P>First, try 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 the<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. 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 might not be duplicated.</P>

<P>If the<I>postmaster</I> is running, start<I>psql</I> in one

window, then find the<SMALL>PID</SMALL> of the<I>postgres</I>

option, many<I>assert()</I>s monitor the progress of the

backendand halt the program when something unexpected occurs.</P>

<P>The<I>postmaster</I> has a<I>-d</I> option that allows

even moredetailed information to be reported. The<I>-d</I>

option takes anumber that specifies the debug level. Be warned

that high debuglevel values generate large log files.</P>

<P>If the<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. If you have compiled with

debuggingsymbols, you can use a debugger to see what is

happening. Becausethe backend was not started from<I>postmaster</I>,

it is notrunning in an identical environment and locking/backend

interactionproblems might not be duplicated.</P>

<P>If the<I>postmaster</I> is running, start<I>psql</I> in

onewindow, 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 the

other. If you are looking to find the location that is generating

an error or log message, set a breakpoint at<I>errfinish</I>.

<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</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>

You can set breakpoints in the debugger and issue queries from

the other. If you are looking to find the location that is

generating an error or log message, set a breakpoint at

<I>errfinish</I>.

<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</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>

<H3id="item2.9">2.9) What is the timeline for the next major

PostgreSQL release?<BR>

<P>The development schedule for the 8.3 release is:</P>

<DD>March 1, 2006</DD>

<DT>Initial community review of all major feature patches</DT>

<DD>April 1, 2006</DD>

<DT>Feature freeze, all patches must be submitted for review and application</DT>

<DD>mid-May, 2006</DD>

<DT>All patches applied, beta testing begins</DT>

<DD>July, 2006</DD>

<DT>Release of 8.3.0</DT>

<P>Patches that appear after appropriate dates are typically

not applied but held for the next major release.</P>