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Merge zgreant@work.mysql.com:/home/bk/mysql-4.0
into mysql.com:/home/zak/Work/bk/mysql-4.0 Docs/manual.texi: Auto merged
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commit
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2 changed files with 19 additions and 15 deletions
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@ -69,3 +69,4 @@ zak@balfor.local
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zak@linux.local
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zak@linux.local
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salle@geopard.(none)
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salle@geopard.(none)
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walrus@mysql.com
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walrus@mysql.com
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zgreant@mysql.com
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@ -30674,12 +30674,12 @@ mysql> SELECT INTERVAL(22, 23, 30, 44, 200);
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@end example
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@end example
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@end table
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@end table
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If you are comparing case-sensitive string with any of the standard
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If you are comparing case-insensitive strings with any of the standard
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operators (@code{=}, @code{<>}..., but not @code{LIKE}) end space will
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operators (@code{=}, @code{<>}..., but not @code{LIKE}) trailing whitespace
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be ignored.
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(spaces, tabs and newlines) will be ignored.
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@example
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@example
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mysql> SELECT "a" ="A ";
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mysql> SELECT "a" ="A \n";
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-> 1
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-> 1
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@end example
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@end example
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@ -36874,28 +36874,26 @@ parameters to @code{FULLTEXT} in @code{CREATE/ALTER TABLE}).
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From version 4.0.1, @code{MySQL server} features a @code{Query Cache}.
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From version 4.0.1, @code{MySQL server} features a @code{Query Cache}.
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When in use, the query cache stores the text of a @code{SELECT} query
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When in use, the query cache stores the text of a @code{SELECT} query
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together with the corresponding result that is sent to a client.
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together with the corresponding result that was sent to the client.
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If another identical query is received, the server can then retrieve
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If an identical query is later received, the server will retrieve
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the results from the query cache rather than parsing and executing the
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the results from the query cache rather than parsing and executing the
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same query again.
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same query again.
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@strong{NOTE:} The query cache does not return stale data. When data
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is modified, any relevant entries in the query cache are flushed.
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The query cache is extremely useful in an environment where (some)
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The query cache is extremely useful in an environment where (some)
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tables don't change very often and you have a lot of identical queries.
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tables don't change very often and you have a lot of identical queries.
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This is a typical situation for many web servers that use a lot of
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This is a typical situation for many web servers that use a lot of
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dynamic content.
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dynamic content.
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Following are some performance data for the query cache
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Below is some performance data for the query cache. (These results were
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(We got these by running the MySQL benchmark suite on a Linux Alpha
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generated by running the MySQL benchmark suite on a Linux Alpha
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2x500 MHz with 2GB RAM and a 64MB query cache):
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2 x 500 MHz with 2GB RAM and a 64MB query cache):
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@itemize @bullet
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@itemize @bullet
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@item
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@item
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If you want to disable the query cache code set @code{query_cache_size=0}.
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If all of the queries you're performing are simple (such as selecting a
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By disabling the query cache code there is no noticeable overhead.
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(query cache can be excluded from code with help of configure option
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@code{--without-query-cache})
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@item
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If all of the queries you're preforming are simple (such as selecting a
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row from a table with one row); but still differ so that the queries can
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row from a table with one row); but still differ so that the queries can
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not be cached, the overhead for having the query cache active is 13%.
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not be cached, the overhead for having the query cache active is 13%.
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This could be regarded as the worst case scenario. However, in real life,
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This could be regarded as the worst case scenario. However, in real life,
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@ -36905,6 +36903,11 @@ is normally significantly lower.
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Searches after one row in a one row table is 238% faster.
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Searches after one row in a one row table is 238% faster.
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This can be regarded as close to the minimum speedup to be expected for
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This can be regarded as close to the minimum speedup to be expected for
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a query that is cached.
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a query that is cached.
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@item
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If you want to disable the query cache code set @code{query_cache_size=0}.
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By disabling the query cache code there is no noticeable overhead.
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(query cache can be excluded from code with help of configure option
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@code{--without-query-cache})
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@end itemize
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@end itemize
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@menu
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@menu
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