Re: [Robert.Hufsky@ser.at: autocommit in ecpg] - Mailing list pgsql-hackers

OK, I have added this information to the ecpg and ref/ecpg manual pages
as appropriate.  Let me know if I should add anything else.  I also
removed a comment from the bottom of ref/sgml that didn't make any sense.

---------------------------------------------------------------------------

Michael Meskes wrote:
> I just got this explanation for the autocommit setting. Maybe we should add
> thsi to the docs.
>
> ----- Forwarded message from Robert Hufsky <Robert.Hufsky@ser.at> -----
>
> From: "Robert Hufsky" <Robert.Hufsky@ser.at>
> To: "Michael Meskes" <meskes@debian.org>
> Subject: autocommit in ecpg
> Date: Fri, 18 Jan 2002 08:21:17 +0100
>
> [...]
>
> Transaction Control and Autocommit
> An application can be operating in "autocommit on" or "autocommit off" mode.
> The mode can be selected by issuing
>
> exec sql set autocommit to on; or
> exec sql set autocommit to off;
>
> Autocommit Off
>
> In this mode, no sql statement is ever committed unless explicitly stated by
>
> exec sql commit;
>
> >From the beginning of a database session an implicit transaction is open.
> Each SQL statement that is issued is part of the transaction. The
> transaction is closed and work is committed by exec sql commit;.
>
> Immediately after the exec sql commit; statement a new transaction is opened
> and the same rules apply.
>
> Note that an exec sql begin; statement is not applicable in "autocommit off"
> mode.
>
> Autocommit On
>
> In this mode, each statement is automatically committed. This can be
> convinient but it also can lead to performance problems as each implicit
> commit may cause a disk write operation.
>
> Even in "autocommit on" mode, multi-statememt transactions can be achieved
> by placing multiple SQL statements between
>
> exec sql begin;
>   and
> exec sql commit;
>
> [...]
> ----- End forwarded message -----
>
> Michael
> --
> Michael Meskes
> Michael@Fam-Meskes.De
> Go SF 49ers! Go Rhein Fire!
> Use Debian GNU/Linux! Use PostgreSQL!
>
> ---------------------------(end of broadcast)---------------------------
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>
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>

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
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Index: doc/src/sgml/ecpg.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/ecpg.sgml,v
retrieving revision 1.33
diff -c -r1.33 ecpg.sgml
*** doc/src/sgml/ecpg.sgml    2002/01/07 02:29:11    1.33
--- doc/src/sgml/ecpg.sgml    2002/01/18 20:30:13
***************
*** 1053,1066 ****
      </para>

      <para>
!      All <acronym>SQL</acronym> statements are performed in one
!      transaction unless you issue a commit transaction. To accomplish
!      this auto-transaction behavior, the first statement and the first
!      statement after a commit or rollback always begins a new transaction. To
!      disable this feature, use the <option>-t</option> command-line
!      option.
      </para>
-
     </sect2>
    </sect1>
   </chapter>
--- 1053,1068 ----
      </para>

      <para>
!      In the default mode, queries are committed only when <command>exec
!      sql commit</command> is issued. <application>Ecpg</application>
!      also supports auto-commit of transactions via the
!      <option>-t</option> command-line option or via the <literal>exec
!      sql set autocommit to on</literal> statement. In
!      <literal>autocommit<literal> mode, each query is automatically
!      committed unless it is inside an explicit transaction block. This
!      mode can be explicitly turned off using <literal>exec sql set
!      autocommit to off</literal>.
      </para>
     </sect2>
    </sect1>
   </chapter>
Index: doc/src/sgml/libpq.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v
retrieving revision 1.85
diff -c -r1.85 libpq.sgml
*** doc/src/sgml/libpq.sgml    2002/01/07 02:29:12    1.85
--- doc/src/sgml/libpq.sgml    2002/01/18 20:30:19
***************
*** 2109,2118 ****
  <para>
  <filename>libpq</filename> is thread-safe as of
  <productname>PostgreSQL</productname> 7.0, so long as no two threads
! attempt to manipulate the same <structname>PGconn</> object at the same time.  In particular,
! you cannot issue concurrent queries from different threads through the same
! connection object.  (If you need to run concurrent queries, start up multiple
! connections.)
  </para>

  <para>
--- 2109,2125 ----
  <para>
  <filename>libpq</filename> is thread-safe as of
  <productname>PostgreSQL</productname> 7.0, so long as no two threads
! attempt to manipulate the same <structname>PGconn</> object at the same
! time. In particular, you cannot issue concurrent queries from different
! threads through the same connection object. (If you need to run
! concurrent queries, start up multiple connections.)
! </para>
! <para>
! However, <filename>libpq</filename> clients using the
! <literal>crypt</literal> encryption method rely on the
! <literal>crypt()</literal> operating system function, which often is not
! thread-safe. It is better to use <literal>MD5</literal> encryption,
! which is guarantted to be thread-safe on all platforms.
  </para>

  <para>
Index: doc/src/sgml/ref/ecpg-ref.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/ref/ecpg-ref.sgml,v
retrieving revision 1.16
diff -c -r1.16 ecpg-ref.sgml
*** doc/src/sgml/ref/ecpg-ref.sgml    2002/01/06 18:12:00    1.16
--- doc/src/sgml/ref/ecpg-ref.sgml    2002/01/18 20:30:20
***************
*** 57,63 ****
        <term>-t</term>
        <listitem>
         <para>
!     Turn on auto-commit of transactions.
         </para>
        </listitem>
       </varlistentry>
--- 57,66 ----
        <term>-t</term>
        <listitem>
         <para>
!     Turn on auto-commit of transactions. In this mode, each query is
!     automatically committed unless it is inside an explicit
!     transaction block. In the default mode, queries are committed
!     only when <command>exec sql commit</command> is issued.
         </para>
        </listitem>
       </varlistentry>
***************
*** 403,434 ****
     See the <filename>TODO</filename> file in the source for some more
     missing features.
    </para>
-
- <!--
- .SH FILES
- .PD 0
- .TP
- .B /usr/src/pgsql/postgresql-${ver}/src/interfaces...
-  ./ecpg/include.......source for \fIecpg\fP header files.
-  ./ecpg/lib...........source for \fIecpg\fP libraries.
-  ./ecpg/preproc.......source for \fIecpg\fP header files.
-  ./ecpg/test..........source for \fIecpg\fP libraries.
-  (test contains examples of syntax for ecpg SQL-C.)
- .PD
- .TP
- .B /usr/local/pgsql/bin
- \fIPostgreSQL\fP binaries including \fIecpg\fP.
- .PD
- .TP
- .B /usr/local/pgsql/include
- \fIPostgreSQL\fP headers including \fIecpglib.h\fP \fIecpgtype.h\fP
- and \fIsqlca.h\fP.
- .PD
- .TP
- .B /usr/local/pgsql/lib
- \fIPostgreSQL\fP libraries including \fIlibecpg.a\fP and
- \fIlibecpg.so\fP.
- -->

   </refsect1>
  </refentry>
--- 406,411 ----