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> <channel><title>MySQL Diary</title> <atom:link href="http://www.mysqldiary.com/feed/" rel="self" type="application/rss+xml" /><link>http://www.mysqldiary.com</link> <description>Exploring, Sharing and  Discussing MySQL practice</description> <lastBuildDate>Mon, 18 Jul 2011 20:03:03 +0000</lastBuildDate> <language>en</language> <sy:updatePeriod>hourly</sy:updatePeriod> <sy:updateFrequency>1</sy:updateFrequency> <generator>http://wordpress.org/?v=3.3.1</generator> <item><title>MySQL Left Join</title><link>http://www.mysqldiary.com/mysql-left-join/</link> <comments>http://www.mysqldiary.com/mysql-left-join/#comments</comments> <pubDate>Wed, 06 Jul 2011 09:23:47 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[Cool MySQL Queries]]></category> <category><![CDATA[is null]]></category> <category><![CDATA[left join]]></category> <category><![CDATA[on]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=234</guid> <description><![CDATA[Even if you think you know everything about LEFT JOIN, I bet you will learn something or two in this post! A reminder about &#8220;A LEFT JOIN B ON conditional_expr&#8221; The ON condition (in the expression &#8220;A LEFT JOIN B ON conditional_expr&#8221;) is used to decide how to retrieve rows from table B (Matching-Stage). If [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/mysql-left-join/feed/</wfw:commentRss> <slash:comments>8</slash:comments> </item> <item><title>As restoring a dump table into the MySQL master &#8211; you better get some sleep</title><link>http://www.mysqldiary.com/as-restoring-a-dump-table-into-the-mysql-master-you-better-get-some-sleep/</link> <comments>http://www.mysqldiary.com/as-restoring-a-dump-table-into-the-mysql-master-you-better-get-some-sleep/#comments</comments> <pubDate>Mon, 04 Apr 2011 08:09:45 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[Cool MySQL Queries]]></category> <category><![CDATA[MySQL Script]]></category> <category><![CDATA[mysqldump]]></category> <category><![CDATA[sleep]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=198</guid> <description><![CDATA[Restoring a dump table into the MySQL master server can lead to serious replication delay. The massive inserts commands cause the Master and slaves to use most of their resources for replication. As a result, replication lag may increase dramatically (linear to the table size). To overcome the replication delay, caused by restoring the dump [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/as-restoring-a-dump-table-into-the-mysql-master-you-better-get-some-sleep/feed/</wfw:commentRss> <slash:comments>4</slash:comments> </item> <item><title>If you copy a MyISAM table with PRIMARY key, don’t forget to order the rows first</title><link>http://www.mysqldiary.com/if-you-copy-a-myisam-table-with-primary-key-don%e2%80%99t-forget-to-order-the-rows-first/</link> <comments>http://www.mysqldiary.com/if-you-copy-a-myisam-table-with-primary-key-don%e2%80%99t-forget-to-order-the-rows-first/#comments</comments> <pubDate>Mon, 14 Mar 2011 19:02:23 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[Cool MySQL Queries]]></category> <category><![CDATA[MySQL feature]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=189</guid> <description><![CDATA[In a case that you copy (INSERT INTO .. SELECT ..) a MyISAM table that have a PRIMARY key, it is much faster to insert the new rows in the primary key order: The insertion will be faster: because the primary key cannot disabled, every insertion will also updates the primary key. In a case [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/if-you-copy-a-myisam-table-with-primary-key-don%e2%80%99t-forget-to-order-the-rows-first/feed/</wfw:commentRss> <slash:comments>2</slash:comments> </item> <item><title>You Must Have A Killer In Your System</title><link>http://www.mysqldiary.com/you-must-have-a-killer-in-your-system/</link> <comments>http://www.mysqldiary.com/you-must-have-a-killer-in-your-system/#comments</comments> <pubDate>Tue, 08 Feb 2011 16:10:18 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[MySQL Script]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=181</guid> <description><![CDATA[Every system can have a slow query that randomly seems to emerge from nowhere. The main threat from these slow queries is that it can unexpectedly bring down your site. Even though the query is not called often (less than one percent), it can definitely harm your site performance. For example: Assume a system with [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/you-must-have-a-killer-in-your-system/feed/</wfw:commentRss> <slash:comments>2</slash:comments> </item> <item><title>A many to many relationship table – solving the exclude relation problem</title><link>http://www.mysqldiary.com/a-many-to-many-relationship-table-solving-the-exclude-relation-problem/</link> <comments>http://www.mysqldiary.com/a-many-to-many-relationship-table-solving-the-exclude-relation-problem/#comments</comments> <pubDate>Tue, 18 Jan 2011 12:36:07 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[Cool MySQL Queries]]></category> <category><![CDATA[exclude]]></category> <category><![CDATA[inner query]]></category> <category><![CDATA[many to many]]></category> <category><![CDATA[pivot]]></category> <category><![CDATA[relation]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=138</guid> <description><![CDATA[I will start by defining the MySQL Many to Many relationship (Experts can skip to the next paragraph) What is A MySQL many to many relationship A MySQL many to many relationship is a relationship that is multi-valued in both directions. This type of relationship is helped by the use of a linking table. For [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/a-many-to-many-relationship-table-solving-the-exclude-relation-problem/feed/</wfw:commentRss> <slash:comments>9</slash:comments> </item> <item><title>The battle between FORCE INDEX and the QUERY OPTIMIZER</title><link>http://www.mysqldiary.com/the-battle-between-force-index-and-the-query-optimizer/</link> <comments>http://www.mysqldiary.com/the-battle-between-force-index-and-the-query-optimizer/#comments</comments> <pubDate>Mon, 25 Oct 2010 21:15:41 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[Cool MySQL Queries]]></category> <category><![CDATA[MySQL feature]]></category> <category><![CDATA[analyze table]]></category> <category><![CDATA[Cardinality]]></category> <category><![CDATA[Force Index]]></category> <category><![CDATA[key distributions]]></category> <category><![CDATA[MySQL optimizer]]></category> <category><![CDATA[QUERY OPTIMIZER]]></category> <category><![CDATA[Use Index]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=146</guid> <description><![CDATA[Query Optimizer is a part of the server that takes a parsed SQL query and produces a query execution plan. MySQL Query Optimizer uses (as one of its parameters) the stored key distribution (Cardinality) mechanism to determine the order in which tables should be joined, when you perform a join on something other than a [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/the-battle-between-force-index-and-the-query-optimizer/feed/</wfw:commentRss> <slash:comments>2</slash:comments> </item> <item><title>Optimizing the MySQL IN() Comparison Operations Which Include the Indexed Field</title><link>http://www.mysqldiary.com/optimizing-the-mysql-in-comparison-operations-which-include-the-indexed-field/</link> <comments>http://www.mysqldiary.com/optimizing-the-mysql-in-comparison-operations-which-include-the-indexed-field/#comments</comments> <pubDate>Thu, 07 Oct 2010 12:06:13 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[Cool MySQL Queries]]></category> <category><![CDATA[Comparison operator]]></category> <category><![CDATA[IN]]></category> <category><![CDATA[MySQL IN]]></category> <category><![CDATA[performance]]></category> <category><![CDATA[query]]></category> <category><![CDATA[union all]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=128</guid> <description><![CDATA[The MySQL IN() Comparison Operator is said to be very quick if all the values are constants (the values are then evaluated and sorted first, and the search is done using a binary search). However, what if the field which the IN clause refers to, is part of the index used to execute the query? [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/optimizing-the-mysql-in-comparison-operations-which-include-the-indexed-field/feed/</wfw:commentRss> <slash:comments>5</slash:comments> </item> <item><title>MySQL User Defined Variables</title><link>http://www.mysqldiary.com/user-defined-variables/</link> <comments>http://www.mysqldiary.com/user-defined-variables/#comments</comments> <pubDate>Wed, 02 Jun 2010 21:04:19 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[MySQL feature]]></category> <category><![CDATA[case sensitivity]]></category> <category><![CDATA[mysql features]]></category> <category><![CDATA[mysql query]]></category> <category><![CDATA[procedural logic]]></category> <category><![CDATA[relational logic]]></category> <category><![CDATA[User defined variable]]></category> <category><![CDATA[variables]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=7</guid> <description><![CDATA[When I have discovered MySQL User-defined variables at the first time, I didn&#8217;t pay much attention to them and didn&#8217;t realize their strength. At first, one can think that they are just one of the many unnoticed MySQL features. Well, I was wrong. Here, I will try to summarize their strength, though I think there is [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/user-defined-variables/feed/</wfw:commentRss> <slash:comments>23</slash:comments> </item> <item><title>Limited SELECT count(*)</title><link>http://www.mysqldiary.com/limited-select-count/</link> <comments>http://www.mysqldiary.com/limited-select-count/#comments</comments> <pubDate>Thu, 13 May 2010 21:52:43 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[Cool MySQL Queries]]></category> <category><![CDATA[count(*)]]></category> <category><![CDATA[limit]]></category> <category><![CDATA[limited count]]></category> <category><![CDATA[performance]]></category> <category><![CDATA[select]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=98</guid> <description><![CDATA[A SELECT statement with COUNT returns the number of rows retrieved by the SELECT statement (see mysql select count). For performance reasons, the desired result is to limit that count. Including a LIMIT clause in the SELECT statement will not work since it only restricts the number of rows returned, which is always one. The [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/limited-select-count/feed/</wfw:commentRss> <slash:comments>23</slash:comments> </item> <item><title>Conditional Joins in MySQL</title><link>http://www.mysqldiary.com/conditional-joins-in-mysql/</link> <comments>http://www.mysqldiary.com/conditional-joins-in-mysql/#comments</comments> <pubDate>Sun, 07 Feb 2010 19:43:12 +0000</pubDate> <dc:creator>Hazan Ilan</dc:creator> <category><![CDATA[Cool MySQL Queries]]></category> <category><![CDATA[conditional join]]></category> <category><![CDATA[join in Mysql]]></category> <category><![CDATA[left join]]></category> <category><![CDATA[mysql join]]></category> <guid
isPermaLink="false">http://www.mysqldiary.com/?p=71</guid> <description><![CDATA[One way to do a “Conditional Join” in MySQL is by using a “LEFT JOIN”.  Create a “LEFT JOIN” for each condition and combine the results into one column using an “IF” statement by the “SELECT” expression.  Here’s an example: Suppose you have three tables: questions: a table consisting of question ids, timestamps, and whether [...]]]></description> <wfw:commentRss>http://www.mysqldiary.com/conditional-joins-in-mysql/feed/</wfw:commentRss> <slash:comments>9</slash:comments> </item> </channel> </rss>
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