Add missing file; new docs for start_transaction.

doc/src/sgml/ref/start_transaction.sgml

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+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/start_transaction.sgml,v 1.1 2002/08/04 05:14:06 momjian Exp $ -->
+<refentry id="SQL-START-TRANSACTION">
+ <docinfo>
+  <date>2002-07-26</date>
+ </docinfo>
+
+ <refmeta>
+  <refentrytitle id="SQL-START-TRANSACTION-TITLE">START TRANSACTION</refentrytitle>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>START TRANSACTION</refname>
+  <refpurpose>start a transaction block</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+  <synopsis>
+START TRANSACTION [ ISOLATION LEVEL { READ COMMITTED | SERIALIZABLE } ]
+  </synopsis>
+
+  <refsect2 id="R2-SQL-START-TRANSACTION-1">
+   <refsect2info>
+    <date>1998-09-27</date>
+   </refsect2info>
+   <title>
+    Inputs
+   </title>
+
+   <para>
+    None.
+   </para>
+  </refsect2>
+
+  <refsect2 id="R2-SQL-START-TRANSACTION-2">
+   <refsect2info>
+    <date>1998-09-27</date>
+   </refsect2info>
+   <title>
+    Outputs
+   </title>
+
+   <para>
+
+    <variablelist>
+     <varlistentry>
+      <term><computeroutput>
+START TRANSACTION
+       </computeroutput></term>
+      <listitem>
+       <para>
+    Message returned if successful.
+       </para>
+      </listitem>
+     </varlistentry>
+     <varlistentry>
+      <term><computeroutput>
+WARNING:  BEGIN: already a transaction in progress
+       </computeroutput></term>
+      <listitem>
+       <para>
+    If there is already a transaction in progress when the
+    command is issued.
+       </para>
+      </listitem>
+     </varlistentry>
+    </variablelist>
+   </para>
+  </refsect2>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   This command begins a new transaction. If the isolation level is
+   specified, the new transaction has that isolation level. In all other
+   respects, the behavior of this command is identical to the
+   <command>BEGIN</command>.
+  </para>
+
+ </refsect1>
+
+ <refsect1>
+  <title>Notes</title>
+
+  <para>
+   The isolation level of a transaction can also be set with the <xref
+   linkend="sql-set-transaction" endterm="sql-set-transaction-title">.
+   If no isolation level is specified, the level defaults to
+   <option>READ COMMITTED</option>.
+  </para>
+ </refsect1>
+
+ <refsect1 id="R1-SQL-START-TRANSACTION-3">
+  <title>Compatibility</title>
+
+  <refsect2 id="R2-SQL-START-TRANSACTION-4">
+   <title>SQL99</title>
+
+   <para>
+    <option>SERIALIZABLE</option> is the default level in
+    <acronym>SQL</acronym>. <productname>PostgreSQL</productname>
+    does not provide the isolation levels <option>READ UNCOMMITTED</option>
+    and <option>REPEATABLE READ</option>. Because of multiversion
+    concurrency control, the <option>SERIALIZABLE</option> level is
+    not truly serializable. See the <citetitle>User's Guide</citetitle>
+    for details.
+   </para>
+
+   <para>
+    In <acronym>SQL99</acronym> this statement can specify two other
+    properties of the new transaction: whether the transaction is
+    read-only and the size of the diagnostics area. Neither of these
+    concepts are currently supported in
+    <productname>PostgreSQL</productname>.
+   </para>
+  </refsect2>
+ </refsect1>
+</refentry>
+
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