Sun Solaris specific

To be read in conjunction with the installation instructions.

============================================================

Last updated: $Date: 2006/10/10 22:19:08 $

Last updated: $Date: 2006/12/02 09:29:51 $

Contents:

8) Can I use DTrace for tracing PostgreSQL?

PostgreSQL 8.2 has implemented DTrace support. You can enable it by

the --enable-dtrace configure switch. If you want to build 64-bit

binaries with DTrace you must specify DTRACEFLAGS='-64', e.g.,

Using GCC compiler:

$ ./configure CC='gcc -m64' --enable-dtrace DTRACEFLAGS='-64' ...

Using Sun compiler:

$ ./configure CC='/opt/SUNWspro/bin/cc -xtarget=native64' --enable-dtrace DTRACEFLAGS='-64'

Yes, see the chapter "Monitoring Database Activity" in the documentation

for further information.

If you see the linking of the postgres executable abort with an error

message like

<!-- $PostgreSQL: pgsql/doc/src/sgml/installation.sgml,v 1.267 2006/12/01 21:17:51tgl Exp $ -->

<!-- $PostgreSQL: pgsql/doc/src/sgml/installation.sgml,v 1.268 2006/12/02 09:29:51petere Exp $ -->

<chapter id="installation">

<title><![%standalone-include[<productname>PostgreSQL</>]]>

specified in the environment variable

<envar>DTRACEFLAGS</envar>.

</para>

<para>

To include DTrace support in a 64-bit binary, specify

<literal>DTRACEFLAGS="-64"</> to configure. For example,

using the GCC compiler:

<screen>

./configure CC='gcc -m64' --enable-dtrace DTRACEFLAGS='-64' ...

</screen>

Using Sun's compiler:

<screen>

./configure CC='/opt/SUNWspro/bin/cc -xtarget=native64' --enable-dtrace DTRACEFLAGS='-64' ...

</screen>

</para>

</listitem>

</varlistentry>

<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.40 2006/12/0200:42:54 tgl Exp $ -->

<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.41 2006/12/0209:29:51 petere Exp $ -->

<chapter id="monitoring">

<title>Monitoring Database Activity</title>

</para>

<sect2 id="compiling-for-trace">

<title>Compiling for DynamicTrace</title>

<title>Compiling for DynamicTracing</title>

<para>

By default, trace points are disabled, so you will need to

explicitly tell the configure script to make the probes available

in <productname>PostgreSQL</productname>. To include DTrace support

in a 32-bit binary, specify <option>--enable-dtrace</> to configure.

For example:

<programlisting>

$ ./configure --enable-dtrace ...

</programlisting>

To include DTrace support in a 64-bit binary, specify

<option>--enable-dtrace</>

and <literal>DTRACEFLAGS="-64"</> to configure. For example,

using the gcc compiler:

<programlisting>

$ ./configure CC='gcc -m64' --enable-dtrace DTRACEFLAGS='-64' ...

</programlisting>

Using Sun's compiler:

<programlisting>

$ ./configure CC='/path_to_sun_compiler/cc -xtarget=native64' --enable-dtrace DTRACEFLAGS='-64' ...

</programlisting>

</para>

specify <option>--enable-dtrace</> to configure. See <xref

linkend="install-procedure"> for further information.

</sect2>

<sect2 id="trace-points">

<para>

A few standard trace points are provided in the source code

(of course, more can be added as needed for a particular problem).

These are:

These are shown in <xref linkend="trace-point-table">.

</para>

<table id="trace-point-table">

Note how the double underline in trace point names needs to

be replaced by a hyphen when using D script.

When executed, the example D script gives output such as:

<programlisting>

<screen>

# ./txn_count.d `pgrep -n postgres`

^C

Start 71

Commit 70

Abort 1

Total time (ns) 2312105013

</programlisting>

</screen>

</para>

<para>

You should remember that trace programs need to be carefully written and

<para>

New trace points can be defined within the code wherever the developer

desires, though this will require are-compile.

desires, though this will require arecompilation.

</para>

<para>

occurrence of an event can be achieved with a single line, using

just the trace point name, e.g.

<programlisting>

PG_TRACE (my__new__trace__point);

PG_TRACE (my__new__trace__point);

</programlisting>

More complex trace points can be provided with one or more variables

for inspection by the dynamic tracing utility by using the

<literal>PG_TRACE</><replaceable>n</> macro that corresponds to the number

of parameters after the trace point name:

<programlisting>

PG_TRACE3 (my__complex__event, varX, varY, varZ);

PG_TRACE3 (my__complex__event, varX, varY, varZ);

</programlisting>

The definition of the transaction__start trace point is shown below:

<programlisting>

</para>

<para>

You should take care that thedatatypes specified for the probe arguments

You should take care that thedata types specified for the probe arguments

match the datatypes of the variables used in the <literal>PG_TRACE</>

macro. This is not checked at compile time. You can check that your newly

added trace point is available by recompiling, then running the new binary,