Author: jstephens
Date: 2005-11-05 15:48:51 +0100 (Sat, 05 Nov 2005)
New Revision: 269
Log:
M trunk/refman-5.0/introduction.xml - Fixed the markup I managed to break in my last commit.
Modified:
trunk/refman-5.0/introduction.xml
Modified: trunk/refman-5.0/introduction.xml
===================================================================
--- trunk/refman-5.0/introduction.xml 2005-11-05 07:54:15 UTC (rev 268)
+++ trunk/refman-5.0/introduction.xml 2005-11-05 14:48:51 UTC (rev 269)
@@ -505,7 +505,7 @@
</para>
</listitem>
- <listitem>
+ <listitem>
<para>
<emphasis role="bold">Performance enhancements</emphasis>: A
number of improvements were made in MySQL 5.0 to improve the
@@ -513,7 +513,7 @@
certain types. These include:
</para>
- <itemizedlist>
+ <itemizedlist>
<listitem>
<remark role="todo">
[js] Consider adding Greedy Optimiser section to
@@ -690,154 +690,11 @@
(See <xref linkend="ndbcluster"/>.)
</para>
</listitem>
-
- <listitem>
- <para>
- <literal>COUNT(DISTINCT)</literal> is made faster in
- cases not involving <literal>BLOB</literal> columns
- through the use of a temporary file rather than a
- temporary table.
- </para>
-
- <para>
- <literal>MIN()</literal> and <literal>MAX()</literal>
- with <literal>GROUP BY</literal> are also now better
- optimized. See <xref linkend="loose-index-scan"/>.
- </para>
- </listitem>
-
- <listitem>
- <para>
- The performance of the MySQL client library is increased
- through the use of a receive buffer that greatly reduces
- the number of system calls which the library needs to
- make. This can speed up the retrieval of large result
- sets by a factor of 2.
- </para>
- </listitem>
-
- <listitem>
- <para>
- Null keys can be <quote>pre-eliminated</quote> in many
- cases, speeding up <literal>COUNT(*)</literal> queries.
- An example of such a query might be
- </para>
-
-<programlisting>
-SELECT COUNT(*) FROM t1,t2 WHERE t2.c=t1.a;
-</programlisting>
- <para>
- where <literal>c</literal> is an indexed column allowing
- <literal>NULL</literal> values.
- </para>
- </listitem>
-
- <listitem>
- <para>
- Single-table <literal>UPDATE</literal> or
- <literal>DELETE</literal> queries containing an
- <literal>ORDER BY ... LIMIT
- <replaceable>N</replaceable></literal> clause (but not
- having any <literal>WHERE</literal> clause) can now take
- advantage of an index to read only the first
- <replaceable>N</replaceable> records, as opposed to
- scanning the entire table.
- </para>
- </listitem>
-
</itemizedlist>
- </listitem>
-
- </itemizedlist>
-
- <listitem>
- <para>
- Faster handling of queries that use
- <literal>IN</literal> and
- <literal>BETWEEN</literal>.
- </para>
+
</listitem>
+ </itemizedlist>
- <listitem>
- <para>
- <emphasis role="bold">Condition pushdown</emphasis>:
- In cases involving the comparison of an unindexed
- column with a constant, this condition is
- <quote>pushed down</quote> to the cluster where it
- is evaluated in all partitions simultaneously,
- eliminating the need to send non-matching records
- over the network. This can make such queries 10 to
- 100 times faster than in MySQL 4.1 Cluster.
- </para>
- </listitem>
-
- </itemizedlist>
-
- <para>
- (See <xref linkend="ndbcluster"/>.)
- </para>
- </listitem>
-
- <listitem>
- <para>
- <literal>COUNT(DISTINCT)</literal> is made faster in
- cases not involving <literal>BLOB</literal> columns
- through the use of a temporary file rather than a
- temporary table.
- </para>
-
- <para>
- <literal>MIN()</literal> and <literal>MAX()</literal>
- with <literal>GROUP BY</literal> are also now better
- optimized. See <xref linkend="loose-index-scan"/>.
- </para>
- </listitem>
-
- <listitem>
- <para>
- The performance of the MySQL client library is increased
- through the use of a receive buffer that greatly reduces
- the number of system calls which the library needs to
- make. This can speed up the retrieval of large result
- sets by a factor of 2.
- </para>
- </listitem>
-
- <listitem>
- <para>
- Null keys can be <quote>pre-eliminated</quote> in many
- cases, speeding up <literal>COUNT(*)</literal> queries.
- An example of such a query might be
- </para>
-
-<programlisting>
-SELECT COUNT(*) FROM t1,t2 WHERE t2.c=t1.a;
-</programlisting>
-
- <para>
- where <literal>c</literal> is an indexed column allowing
- <literal>NULL</literal> values.
- </para>
- </listitem>
-
- <listitem>
- <para>
- Single-table <literal>UPDATE</literal> or
- <literal>DELETE</literal> queries containing an
- <literal>ORDER BY ... LIMIT
- <replaceable>N</replaceable></literal> clause (but not
- having any <literal>WHERE</literal> clause) can now take
- advantage of an index to read only the first
- <replaceable>N</replaceable> records, as opposed to
- scanning the entire table.
- </para>
- </listitem>
-
- </itemizedlist>
- </listitem>
-
- </itemizedlist>
-
<para>
For those wishing to take a look at the bleeding edge of MySQL
development, we make our BitKeeper repository for MySQL publicly
| Thread |
|---|
| • svn commit - mysqldoc@docsrva: r269 - trunk/refman-5.0 | jstephens | 5 Nov |
