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| From: | paul | Date: | October 3 2005 3:23pm |
| Subject: | bk commit - mysqldoc@docsrva tree (paul:1.3674) | ||
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Below is the list of changes that have just been committed into a local mysqldoc repository of paul. When paul does a push these changes will be propagated to the main repository and, within 24 hours after the push, to the public repository. For information on how to access the public repository see http://www.mysql.com/doc/I/n/Installing_source_tree.html ChangeSet 1.3674 05/10/03 08:23:37 paul@stripped +4 -0 Point out that other storage engines are more like nulls_equal. Other minor reformatting. refman/mysql-optimization.xml 1.23 05/10/03 08:23:33 paul@stripped +51 -34 Point out that other storage engines are more like nulls_equal. Other minor reformatting. refman-5.1/mysql-optimization.xml 1.22 05/10/03 08:23:33 paul@stripped +51 -34 Sync. refman-5.0/mysql-optimization.xml 1.22 05/10/03 08:23:33 paul@stripped +51 -34 Sync. refman-4.1/mysql-optimization.xml 1.24 05/10/03 08:23:32 paul@stripped +51 -34 Sync. # This is a BitKeeper patch. What follows are the unified diffs for the # set of deltas contained in the patch. The rest of the patch, the part # that BitKeeper cares about, is below these diffs. # User: paul # Host: frost.snake.net # Root: /Users/paul/bk/mysqldoc --- 1.21/refman-5.1/mysql-optimization.xml 2005-09-30 08:05:01 -05:00 +++ 1.22/refman-5.1/mysql-optimization.xml 2005-10-03 08:23:33 -05:00 @@ -7940,43 +7940,53 @@ variable has two possible values, which differ as follows: </para> - <para> - When <literal>myisam_stats_method</literal> is - <literal>nulls_equal</literal>, all <literal>NULL</literal> - values are treated as identical (that is, they all form a single - value group). - </para> + <itemizedlist> - <para> - If the <literal>NULL</literal> value group size is much higher - than the average non-<literal>NULL</literal> value group size, - this method skews the average value group size upward. This - makes index appear to the optimizer to be less useful than it - really is for joins that look for non-<literal>NULL</literal> - values. Consequently, the <literal>nulls_equal</literal> method - may cause the optimizer not to use the index for - <literal>ref</literal> accesses when it should. - </para> + <listitem> + <para> + When <literal>myisam_stats_method</literal> is + <literal>nulls_equal</literal>, all <literal>NULL</literal> + values are treated as identical (that is, they all form a + single value group). + </para> - <para> - When <literal>myisam_stats_method</literal> is - <literal>nulls_unequal</literal>, <literal>NULL</literal> values - are not considered the same. Instead, each - <literal>NULL</literal> value forms a separate value group of - size 1. - </para> + <para> + If the <literal>NULL</literal> value group size is much + higher than the average non-<literal>NULL</literal> value + group size, this method skews the average value group size + upward. This makes index appear to the optimizer to be less + useful than it really is for joins that look for + non-<literal>NULL</literal> values. Consequently, the + <literal>nulls_equal</literal> method may cause the + optimizer not to use the index for <literal>ref</literal> + accesses when it should. + </para> + </listitem> - <para> - If you have many <literal>NULL</literal> values, this method - skews the average value group size downward. If the average - non-<literal>NULL</literal> value group size is large, counting - <literal>NULL</literal> values each as a group of size 1 causes - the optimizer to overestimate the value of the index for joins - that look for non-<literal>NULL</literal> values. Consequently, - the <literal>nulls_unequal</literal> method may cause the - optimizer to use this index for <literal>ref</literal> lookups - when other methods may be better. - </para> + <listitem> + <para> + When <literal>myisam_stats_method</literal> is + <literal>nulls_unequal</literal>, <literal>NULL</literal> + values are not considered the same. Instead, each + <literal>NULL</literal> value forms a separate value group + of size 1. + </para> + + <para> + If you have many <literal>NULL</literal> values, this method + skews the average value group size downward. If the average + non-<literal>NULL</literal> value group size is large, + counting <literal>NULL</literal> values each as a group of + size 1 causes the optimizer to overestimate the value of the + index for joins that look for non-<literal>NULL</literal> + values. Consequently, the <literal>nulls_unequal</literal> + method may cause the optimizer to use this index for + <literal>ref</literal> lookups when other methods may be + better. + </para> + </listitem> + + </itemizedlist> <para> If you tend to use many joins that use @@ -8055,6 +8065,13 @@ <para> There is no way to tell which method was used to generate statistics for a given <literal>MyISAM</literal> table. + </para> + + <para> + <literal>myisam_stats_method</literal> applies only to + <literal>MyISAM</literal> tables. Other storage engines have + only one method for collecting table statistics. Usually it is + closer to the <literal>nulls_equal</literal> method. </para> </section> --- 1.23/refman-4.1/mysql-optimization.xml 2005-09-30 08:05:00 -05:00 +++ 1.24/refman-4.1/mysql-optimization.xml 2005-10-03 08:23:32 -05:00 @@ -6721,43 +6721,53 @@ variable has two possible values, which differ as follows: </para> - <para> - When <literal>myisam_stats_method</literal> is - <literal>nulls_equal</literal>, all <literal>NULL</literal> - values are treated as identical (that is, they all form a single - value group). - </para> + <itemizedlist> - <para> - If the <literal>NULL</literal> value group size is much higher - than the average non-<literal>NULL</literal> value group size, - this method skews the average value group size upward. This - makes index appear to the optimizer to be less useful than it - really is for joins that look for non-<literal>NULL</literal> - values. Consequently, the <literal>nulls_equal</literal> method - may cause the optimizer not to use the index for - <literal>ref</literal> accesses when it should. - </para> + <listitem> + <para> + When <literal>myisam_stats_method</literal> is + <literal>nulls_equal</literal>, all <literal>NULL</literal> + values are treated as identical (that is, they all form a + single value group). + </para> - <para> - When <literal>myisam_stats_method</literal> is - <literal>nulls_unequal</literal>, <literal>NULL</literal> values - are not considered the same. Instead, each - <literal>NULL</literal> value forms a separate value group of - size 1. - </para> + <para> + If the <literal>NULL</literal> value group size is much + higher than the average non-<literal>NULL</literal> value + group size, this method skews the average value group size + upward. This makes index appear to the optimizer to be less + useful than it really is for joins that look for + non-<literal>NULL</literal> values. Consequently, the + <literal>nulls_equal</literal> method may cause the + optimizer not to use the index for <literal>ref</literal> + accesses when it should. + </para> + </listitem> - <para> - If you have many <literal>NULL</literal> values, this method - skews the average value group size downward. If the average - non-<literal>NULL</literal> value group size is large, counting - <literal>NULL</literal> values each as a group of size 1 causes - the optimizer to overestimate the value of the index for joins - that look for non-<literal>NULL</literal> values. Consequently, - the <literal>nulls_unequal</literal> method may cause the - optimizer to use this index for <literal>ref</literal> lookups - when other methods may be better. - </para> + <listitem> + <para> + When <literal>myisam_stats_method</literal> is + <literal>nulls_unequal</literal>, <literal>NULL</literal> + values are not considered the same. Instead, each + <literal>NULL</literal> value forms a separate value group + of size 1. + </para> + + <para> + If you have many <literal>NULL</literal> values, this method + skews the average value group size downward. If the average + non-<literal>NULL</literal> value group size is large, + counting <literal>NULL</literal> values each as a group of + size 1 causes the optimizer to overestimate the value of the + index for joins that look for non-<literal>NULL</literal> + values. Consequently, the <literal>nulls_unequal</literal> + method may cause the optimizer to use this index for + <literal>ref</literal> lookups when other methods may be + better. + </para> + </listitem> + + </itemizedlist> <para> If you tend to use many joins that use @@ -6836,6 +6846,13 @@ <para> There is no way to tell which method was used to generate statistics for a given <literal>MyISAM</literal> table. + </para> + + <para> + <literal>myisam_stats_method</literal> applies only to + <literal>MyISAM</literal> tables. Other storage engines have + only one method for collecting table statistics. Usually it is + closer to the <literal>nulls_equal</literal> method. </para> </section> --- 1.22/refman/mysql-optimization.xml 2005-09-30 08:05:02 -05:00 +++ 1.23/refman/mysql-optimization.xml 2005-10-03 08:23:33 -05:00 @@ -8007,43 +8007,53 @@ variable has two possible values, which differ as follows: </para> - <para> - When <literal>myisam_stats_method</literal> is - <literal>nulls_equal</literal>, all <literal>NULL</literal> - values are treated as identical (that is, they all form a single - value group). - </para> + <itemizedlist> - <para> - If the <literal>NULL</literal> value group size is much higher - than the average non-<literal>NULL</literal> value group size, - this method skews the average value group size upward. This - makes index appear to the optimizer to be less useful than it - really is for joins that look for non-<literal>NULL</literal> - values. Consequently, the <literal>nulls_equal</literal> method - may cause the optimizer not to use the index for - <literal>ref</literal> accesses when it should. - </para> + <listitem> + <para> + When <literal>myisam_stats_method</literal> is + <literal>nulls_equal</literal>, all <literal>NULL</literal> + values are treated as identical (that is, they all form a + single value group). + </para> - <para> - When <literal>myisam_stats_method</literal> is - <literal>nulls_unequal</literal>, <literal>NULL</literal> values - are not considered the same. Instead, each - <literal>NULL</literal> value forms a separate value group of - size 1. - </para> + <para> + If the <literal>NULL</literal> value group size is much + higher than the average non-<literal>NULL</literal> value + group size, this method skews the average value group size + upward. This makes index appear to the optimizer to be less + useful than it really is for joins that look for + non-<literal>NULL</literal> values. Consequently, the + <literal>nulls_equal</literal> method may cause the + optimizer not to use the index for <literal>ref</literal> + accesses when it should. + </para> + </listitem> - <para> - If you have many <literal>NULL</literal> values, this method - skews the average value group size downward. If the average - non-<literal>NULL</literal> value group size is large, counting - <literal>NULL</literal> values each as a group of size 1 causes - the optimizer to overestimate the value of the index for joins - that look for non-<literal>NULL</literal> values. Consequently, - the <literal>nulls_unequal</literal> method may cause the - optimizer to use this index for <literal>ref</literal> lookups - when other methods may be better. - </para> + <listitem> + <para> + When <literal>myisam_stats_method</literal> is + <literal>nulls_unequal</literal>, <literal>NULL</literal> + values are not considered the same. Instead, each + <literal>NULL</literal> value forms a separate value group + of size 1. + </para> + + <para> + If you have many <literal>NULL</literal> values, this method + skews the average value group size downward. If the average + non-<literal>NULL</literal> value group size is large, + counting <literal>NULL</literal> values each as a group of + size 1 causes the optimizer to overestimate the value of the + index for joins that look for non-<literal>NULL</literal> + values. Consequently, the <literal>nulls_unequal</literal> + method may cause the optimizer to use this index for + <literal>ref</literal> lookups when other methods may be + better. + </para> + </listitem> + + </itemizedlist> <para> If you tend to use many joins that use @@ -8122,6 +8132,13 @@ <para> There is no way to tell which method was used to generate statistics for a given <literal>MyISAM</literal> table. + </para> + + <para> + <literal>myisam_stats_method</literal> applies only to + <literal>MyISAM</literal> tables. Other storage engines have + only one method for collecting table statistics. Usually it is + closer to the <literal>nulls_equal</literal> method. </para> </section> --- 1.21/refman-5.0/mysql-optimization.xml 2005-09-30 08:05:01 -05:00 +++ 1.22/refman-5.0/mysql-optimization.xml 2005-10-03 08:23:33 -05:00 @@ -7941,43 +7941,53 @@ variable has two possible values, which differ as follows: </para> - <para> - When <literal>myisam_stats_method</literal> is - <literal>nulls_equal</literal>, all <literal>NULL</literal> - values are treated as identical (that is, they all form a single - value group). - </para> + <itemizedlist> - <para> - If the <literal>NULL</literal> value group size is much higher - than the average non-<literal>NULL</literal> value group size, - this method skews the average value group size upward. This - makes index appear to the optimizer to be less useful than it - really is for joins that look for non-<literal>NULL</literal> - values. Consequently, the <literal>nulls_equal</literal> method - may cause the optimizer not to use the index for - <literal>ref</literal> accesses when it should. - </para> + <listitem> + <para> + When <literal>myisam_stats_method</literal> is + <literal>nulls_equal</literal>, all <literal>NULL</literal> + values are treated as identical (that is, they all form a + single value group). + </para> - <para> - When <literal>myisam_stats_method</literal> is - <literal>nulls_unequal</literal>, <literal>NULL</literal> values - are not considered the same. Instead, each - <literal>NULL</literal> value forms a separate value group of - size 1. - </para> + <para> + If the <literal>NULL</literal> value group size is much + higher than the average non-<literal>NULL</literal> value + group size, this method skews the average value group size + upward. This makes index appear to the optimizer to be less + useful than it really is for joins that look for + non-<literal>NULL</literal> values. Consequently, the + <literal>nulls_equal</literal> method may cause the + optimizer not to use the index for <literal>ref</literal> + accesses when it should. + </para> + </listitem> - <para> - If you have many <literal>NULL</literal> values, this method - skews the average value group size downward. If the average - non-<literal>NULL</literal> value group size is large, counting - <literal>NULL</literal> values each as a group of size 1 causes - the optimizer to overestimate the value of the index for joins - that look for non-<literal>NULL</literal> values. Consequently, - the <literal>nulls_unequal</literal> method may cause the - optimizer to use this index for <literal>ref</literal> lookups - when other methods may be better. - </para> + <listitem> + <para> + When <literal>myisam_stats_method</literal> is + <literal>nulls_unequal</literal>, <literal>NULL</literal> + values are not considered the same. Instead, each + <literal>NULL</literal> value forms a separate value group + of size 1. + </para> + + <para> + If you have many <literal>NULL</literal> values, this method + skews the average value group size downward. If the average + non-<literal>NULL</literal> value group size is large, + counting <literal>NULL</literal> values each as a group of + size 1 causes the optimizer to overestimate the value of the + index for joins that look for non-<literal>NULL</literal> + values. Consequently, the <literal>nulls_unequal</literal> + method may cause the optimizer to use this index for + <literal>ref</literal> lookups when other methods may be + better. + </para> + </listitem> + + </itemizedlist> <para> If you tend to use many joins that use @@ -8056,6 +8066,13 @@ <para> There is no way to tell which method was used to generate statistics for a given <literal>MyISAM</literal> table. + </para> + + <para> + <literal>myisam_stats_method</literal> applies only to + <literal>MyISAM</literal> tables. Other storage engines have + only one method for collecting table statistics. Usually it is + closer to the <literal>nulls_equal</literal> method. </para> </section>
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| • bk commit - mysqldoc@docsrva tree (paul:1.3674) | paul | 3 Oct |
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