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 <Chapter Id="runtime">
  <Title>Runtime Environment</Title>

  <Para>
   This chapter outlines the interaction between <Productname>Postgres</Productname> and
   the operating system.
  </para>

  <sect1>
   <title>Using <Productname>Postgres</Productname> from Unix</title>

   <para>
    All <Productname>Postgres</Productname> commands that are executed 
    directly from a Unix shell are
    found in the directory <quote>.../bin</quote>.  Including this directory in
    your search path will make executing the commands easier.
   </para>

   <para>
    A collection of system catalogs exist at each site.  These include a
    class (<literal>pg_user</literal>) that contains an instance for each valid
    <Productname>Postgres</Productname> user.  The instance specifies a set of
    <Productname>Postgres</Productname> privileges, such as
    the ability to act as <Productname>Postgres</Productname> super-user,
    the ability to create/destroy
    databases, and the ability to update the system catalogs.  A Unix
    user cannot do anything with <Productname>Postgres</Productname> 
    until an appropriate instance is
    installed in this class.  Further information on the system catalogs
    is available by running queries on the appropriate classes.
   </para>
  </sect1>

  <sect1 Id="postmaster">
   <Title>Starting <Application>postmaster</Application></Title>

   <Para>
    Nothing can happen to a database unless the
    <Application>postmaster</Application>
    process  is  running.  As the site administrator, there
    are a number  of  things  you  should  remember  before
    starting  the  <Application>postmaster</Application>.   
    These are discussed in the installation and configuration sections
    of this manual.
    However, if <ProductName>Postgres</ProductName> has been installed by following 
    the installation instructions exactly  as  written,  the  
    following  simple  command is all you should
    need to start the <Application>postmaster</Application>:

    <ProgramListing>
% postmaster
    </ProgramListing>
   </para>

   <para>
    The <Application>postmaster</Application> occasionally prints out  
    messages  which
    are  often helpful during troubleshooting.  If you wish
    to view debugging messages from the <Application>postmaster</Application>, 
    you can
    start  it with the -d option and redirect the output to
    the log file:

    <ProgramListing>
% postmaster -d > pm.log 2>&1 &
    </ProgramListing>

    If you do not wish to see these messages, you can type
    <ProgramListing>
% postmaster -S
    </ProgramListing>
    and the <Application>postmaster</Application> will be "S"ilent.  
    No ampersand ("&amp") is required in this case, since the postmaster
    automatically detaches from the terminal when -S is specified.
   </Para>
  </sect1>

  <sect1 Id="pg-options">
   <Title id="pg-options-title">Using pg_options</Title>

   <Para>
    <Note>
     <Para>
      Contributed by <ULink url="mailto:dz@cs.unitn.it">Massimo Dal Zotto</ULink>
     </Para>
    </Note>
   </para>
   <Para>
    The optional file <filename>data/pg_options</filename> contains runtime
    options used by the backend to control trace messages and other backend
    tunable parameters.
    The file is re-read by a backend
    when it receives a SIGHUP signal, making thus possible to change run-time
    options on the fly without needing to restart 
    <productname>Postgres</productname>.
    The options specified in this file may be debugging flags used by the trace
    package (<filename>backend/utils/misc/trace.c</filename>) or numeric
    parameters which can be used by the backend to control its behaviour.
   </para>

   <para>
    All pg_options are initialized to zero at backend startup.
    New or modified options will be read by all new backends when they are started.
    To make effective any changes for all running backends we need to send a
    SIGHUP to the postmaster. The signal will be automatically sent to all the
    backends. We can also activate the changes only for a specific backend by
    sending the SIGHUP directly to it.
   </para>
   <para>
    pg_options can also be specified with the <option>-T</option> switch of 
    <productname>Postgres</productname>:

    <programlisting>
postgres <replaceable>options</replaceable> -T "verbose=2,query,hostlookup-"
    </programlisting>
   </para>

   <Para>
    The functions used for printing errors and debug messages can now make use
    of the <citetitle>syslog(2)</citetitle> facility. Message printed to stdout
    or stderr are prefixed by a timestamp containing also the backend pid:

    <programlisting>
#timestamp          #pid    #message
980127.17:52:14.173 [29271] StartTransactionCommand
980127.17:52:14.174 [29271] ProcessUtility: drop table t;
980127.17:52:14.186 [29271] SIIncNumEntries: table is 70% full
980127.17:52:14.186 [29286] Async_NotifyHandler
980127.17:52:14.186 [29286] Waking up sleeping backend process
980127.19:52:14.292 [29286] Async_NotifyFrontEnd
980127.19:52:14.413 [29286] Async_NotifyFrontEnd done
980127.19:52:14.466 [29286] Async_NotifyHandler done
    </programlisting>
   </para>
   <para>
    This format improves readability of the logs and allows people to understand
    exactly which backend is doing what and at which time. It also makes
    easier to write simple awk or perl scripts which monitor the log to
    detect database errors or problem, or to compute transaction time statistics.
   </para>
   <para>
    Messages printed to syslog use the log facility LOG_LOCAL0.
    The use of syslog can be controlled with the syslog pg_option.
    Unfortunately many functions call directly <function>printf()</function>
    to print their messages to stdout or stderr and this output can't be
    redirected to syslog or have timestamps in it. 
    It would be advisable that all calls to printf would be replaced with the
    PRINTF macro and output to stderr be changed to use EPRINTF instead so that
    we can control all output in a uniform way.
   </Para>

   <para>
    The format of the <filename>pg_options</filename> file is as follows:

    <programlisting>
# <replaceable>comment</replaceable>
<replaceable>option</replaceable>=<replaceable class="parameter">integer_value</replaceable>  # set value for <replaceable>option</replaceable>
<replaceable>option</replaceable>                # set <replaceable>option</replaceable> = 1
<replaceable>option</replaceable>+               # set <replaceable>option</replaceable> = 1
<replaceable>option</replaceable>-               # set <replaceable>option</replaceable> = 0
    </programlisting>

    Note that <replaceable class="parameter">keyword</replaceable> can also be
    an abbreviation of the option name defined in
    <filename>backend/utils/misc/trace.c</filename>.

    <example>
     <title>pg_options File</title>

     <para>
      For example my pg_options file contains the following values:

      <programlisting>
verbose=2
query
hostlookup
showportnumber
      </programlisting>
     </para>
    </example>
   </para>

   <sect2>
    <title>Recognized Options</title>

    <Para>
     The options currently defined are:

     <variablelist>
      <varlistentry>
       <term>
	all
       </term>
       <listitem>
	<para>
	 Global trace flag. Allowed values are:
	</para>

       <variablelist>
	<varlistentry>
	 <term>
	  0
	 </term>
	 <listitem>
	  <para>
	   Trace messages enabled individually
	  </para>
	 </listitem>
	</varlistentry>

	<varlistentry>
	 <term>
	  1
	 </term>
	 <listitem>
	  <para>
	   Enable all trace messages
	  </para>
	 </listitem>
	</varlistentry>
	
	<varlistentry>
	 <term>
	  -1
	 </term>
	 <listitem>
	  <para>
	   Disable all trace messages
	  </para>
	 </listitem>
	</varlistentry>

       </variablelist>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       verbose
      </term>
      <listitem>
       <para>
	Verbosity flag. Allowed values are:
       </para>

       <variablelist>
	<varlistentry>
	 <term>
	  0
	 </term>
	 <listitem>
	  <para>
	   No messages. This is the default.
	  </para>
	 </listitem>
	</varlistentry>

	<varlistentry>
	 <term>
	  1
	 </term>
	 <listitem>
	  <para>
	   Print information messages.
	  </para>
	 </listitem>
	</varlistentry>

	<varlistentry>
	 <term>
	  2
	 </term>
	 <listitem>
	  <para>
	   Print more information messages.
	  </para>
	 </listitem>
	</varlistentry>

       </variablelist>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       query
      </term>
      <listitem>
       <para>
	Query trace flag. Allowed values are:
       </para>

       <variablelist>
	<varlistentry>
	 <term>
	  0
	 </term>
	 <listitem>
	  <para>
	   Don't print query.
	  </para>
	 </listitem>
	</varlistentry>

	<varlistentry>
	 <term>
	  1
	 </term>
	 <listitem>
	  <para>
	   Print a condensed query in one line.
	  </para>
	 </listitem>
	</varlistentry>

	<varlistentry>
	 <term>
	  4
	 </term>
	 <listitem>
	  <para>
	   Print the full query.
	  </para>
	 </listitem>
	</varlistentry>

       </variablelist>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       plan
      </term>
      <listitem>
       <para>
	Print query plan.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       parse
      </term>
      <listitem>
       <para>
	Print parser output.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       rewritten
      </term>
      <listitem>
       <para>
	Print rewritten query.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       parserstats
      </term>
      <listitem>
       <para>
	Print parser statistics.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       plannerstats
      </term>
      <listitem>
       <para>
	Print planner statistics.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       executorstats
      </term>
      <listitem>
       <para>
	Print executor statistics.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       shortlocks
      </term>
      <listitem>
       <para>
	Currently unused but needed to enable features in the future.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       locks
      </term>
      <listitem>
       <para>
	Trace locks.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       userlocks
      </term>
      <listitem>
       <para>
	Trace user locks.
       </para>
      </listitem>
     </varlistentry>
     
     <varlistentry>
      <term>
       spinlocks
      </term>
      <listitem>
       <para>
	Trace spin locks.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       notify
      </term>
      <listitem>
       <para>
	Trace notify functions.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       malloc
      </term>
      <listitem>
       <para>
	Currently unused.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       palloc
      </term>
      <listitem>
       <para>
	Currently unused.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       lock_debug_oidmin
      </term>
      <listitem>
       <para>
	Minimum relation oid traced by locks.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       lock_debug_relid
      </term>
      <listitem>
       <para>
	oid, if not zero, of relation traced by locks.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       lock_read_priority
      </term>
      <listitem>
       <para>
	Currently unused.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       deadlock_timeout
      </term>
      <listitem>
       <para>
	Deadlock check timer.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       syslog
      </term>
      <listitem>
       <para>
	syslog flag. Allowed values are:
       </para>

       <variablelist>
	<varlistentry>
	 <term>
	  0
	 </term>
	 <listitem>
	  <para>
	   Messages to stdout/stderr.
	  </para>
	 </listitem>
	</varlistentry>

	<varlistentry>
	 <term>
	  1
	 </term>
	 <listitem>
	  <para>
	   Messages to stdout/stderr and syslog.
	  </para>
	 </listitem>
	</varlistentry>

	<varlistentry>
	 <term>
	  2
	 </term>
	 <listitem>
	  <para>
	   Messages only to syslog.
	  </para>
	 </listitem>
	</varlistentry>

       </variablelist>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       hostlookup
      </term>
      <listitem>
       <para>
	Enable hostname lookup in ps_status.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       showportnumber
      </term>
      <listitem>
       <para>
	Show port number in ps_status.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       notifyunlock
      </term>
      <listitem>
       <para>
	Unlock of pg_listener after notify.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term>
       notifyhack
      </term>
      <listitem>
       <para>
	Remove duplicate tuples from pg_listener.
       </para>
      </listitem>
     </varlistentry>

    </variablelist>
    </para>
   </sect2>
  </sect1>

</Chapter>

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