diff options
Diffstat (limited to 'doc/src/sgml/ref/set.sgml')
| -rw-r--r-- | doc/src/sgml/ref/set.sgml | 33 |
1 files changed, 15 insertions, 18 deletions
diff --git a/doc/src/sgml/ref/set.sgml b/doc/src/sgml/ref/set.sgml index e44e4c273a4..3014bbda502 100644 --- a/doc/src/sgml/ref/set.sgml +++ b/doc/src/sgml/ref/set.sgml @@ -20,7 +20,7 @@ <synopsis> SET <replaceable class="PARAMETER">variable</replaceable> { TO | = } { '<replaceable class="PARAMETER">value</replaceable>' | DEFAULT } SET TIME ZONE { '<replaceable class="PARAMETER">timezone</replaceable>' | LOCAL | DEFAULT }; -SET TRANSACTION ISOLATION LEVEL { READ COMMITTED | SERIALIZED | DEFAULT } +SET TRANSACTION ISOLATION LEVEL { READ COMMITTED | SERIALIZED } </synopsis> <refsect2 id="R2-SQL-SET-1"> @@ -350,36 +350,33 @@ SET TRANSACTION ISOLATION LEVEL { READ COMMITTED | SERIALIZED | DEFAULT } </term> <listitem> <para> - The current transaction reads only - committed rows. READ COMMITTED is the default. + The current transaction queries read only rows committed + before a query began. READ COMMITTED is the default. </para> - </listitem> - </varlistentry> - - <varlistentry> - <term> - SERIALIZABLE - </term> - <listitem> + + <note> <para> - The current transaction will place a - lock on every row read, so later reads in that transaction - see the rows unmodified by other transactions. + <acronym>SQL92</acronym> standard requires + SERIALIZABLE to be the default isolation level. </para> + </note> </listitem> </varlistentry> <varlistentry> <term> - DEFAULT + SERIALIZABLE </term> <listitem> <para> - Sets the isolation level for the current transaction to - <option>READ COMMITTED</option>. + The current transaction queries read only rows committed + before first DML statement + (<command>SELECT/INSERT/DELETE/UPDATE/FETCH/COPY_TO</command>) + was executed in this transaction. </para> </listitem> </varlistentry> + </variablelist> </para> </listitem> @@ -789,7 +786,7 @@ SET TRANSACTION ISOLATION LEVEL { READ COMMITTED | SERIALIZED | DEFAULT } <para> There is no <command>SET <replaceable class="parameter">variable</replaceable></command> - in <acronym>SQL92</acronym>. + in <acronym>SQL92</acronym> (except for SET TRANSACTION ISOLATION LEVEL). The <acronym>SQL92</acronym> syntax for <command>SET TIME ZONE</command> is slightly different, |