Fixed up serg's ft manual.

parent 438e8c7c
...@@ -15,3 +15,4 @@ tim@work.mysql.com ...@@ -15,3 +15,4 @@ tim@work.mysql.com
tonu@work.mysql.com tonu@work.mysql.com
monty@donna.mysql.com monty@donna.mysql.com
jcole@tetra.spaceapes.com jcole@tetra.spaceapes.com
jcole@ham.spaceapes.com
...@@ -2893,15 +2893,16 @@ distributions. ...@@ -2893,15 +2893,16 @@ distributions.
@end enumerate @end enumerate
One goal with this is that the SQL client library should be free enough One goal is that the SQL client library should be free enough that it is
so that it is possible to add @strong{MySQL} support in commercial products possible to add @strong{MySQL} support into commercial products
without any license. So in this case we choose the LGPL license. without a license. For this reason, we chose the LGPL license for the
client code.
This means that you can use @strong{MySQL} for free with any program that uses This means that you can use @strong{MySQL} for free with any program that uses
any of the free software licences. @strong{MySQL} is also free for any end any of the free software licenses. @strong{MySQL} is also free for any end
user for his own or company usage. user for his own or company usage.
But if you use @strong{MySQL} for something important to you, you may However, if you use @strong{MySQL} for something important to you, you may
want to help secure its development by purchasing licenses or a support want to help secure its development by purchasing licenses or a support
contract, @ref{Support}. contract, @ref{Support}.
...@@ -2909,7 +2910,7 @@ contract, @ref{Support}. ...@@ -2909,7 +2910,7 @@ contract, @ref{Support}.
@subsection Copyright changes @subsection Copyright changes
The stable versions of @strong{MySQL} are still using a more strict The stable versions of @strong{MySQL} are still using a more strict
license. See the documatation for that version for more information. license. See the documentation for that version for more information.
@node Licensing examples, Cost, Copyright, Licensing and Support @node Licensing examples, Cost, Copyright, Licensing and Support
@section Example licensing situations @section Example licensing situations
...@@ -2922,7 +2923,7 @@ license. See the documatation for that version for more information. ...@@ -2922,7 +2923,7 @@ license. See the documatation for that version for more information.
This section describes some situations illustrating whether or not you This section describes some situations illustrating whether or not you
must license the @strong{MySQL} server. Generally these examples must license the @strong{MySQL} server. Generally these examples
involve providing @strong{MySQL} as a integrated part of a product. involve providing @strong{MySQL} as an integrated part of a product.
Note that a single @strong{MySQL} license covers any number of CPUs and Note that a single @strong{MySQL} license covers any number of CPUs and
@code{mysqld} servers on a machine! There is no artificial limit on the number @code{mysqld} servers on a machine! There is no artificial limit on the number
...@@ -2947,7 +2948,7 @@ designed your application around @strong{MySQL}, then you've really made ...@@ -2947,7 +2948,7 @@ designed your application around @strong{MySQL}, then you've really made
a commercial product that requires the engine, so you need a license. a commercial product that requires the engine, so you need a license.
If your application does not require @strong{MySQL}, you need not obtain If your application does not require @strong{MySQL}, you need not obtain
a license. For example, if @strong{MySQL} just added some new optional a license. For example, if using @strong{MySQL} just adds some new optional
features to your product (such as adding logging to a database if features to your product (such as adding logging to a database if
@strong{MySQL} is used rather than logging to a text file), it should @strong{MySQL} is used rather than logging to a text file), it should
fall within normal use, and a license would not be required. fall within normal use, and a license would not be required.
...@@ -13436,8 +13437,8 @@ For @code{BLOB} and @code{TEXT} columns, you must index a prefix of the ...@@ -13436,8 +13437,8 @@ For @code{BLOB} and @code{TEXT} columns, you must index a prefix of the
column, you cannot index the entire thing. column, you cannot index the entire thing.
In @strong{MySQL} 3.23.23 or later, you can also create special In @strong{MySQL} 3.23.23 or later, you can also create special
@strong{fulltext} indexes. They are used for full-text search. Only @strong{FULLTEXT} indexes. They are used for full-text search. Only the
@code{MyISAM} table type supports fulltext indexes. They can be created @code{MyISAM} table type supports @code{FULLTEXT} indexes. They can be created
only from @code{VARCHAR}, @code{BLOB}, and @code{TEXT} columns. only from @code{VARCHAR}, @code{BLOB}, and @code{TEXT} columns.
Indexing always happens over the entire column, partial indexing is not Indexing always happens over the entire column, partial indexing is not
supported. See @ref{MySQL full-text search} for details of operation. supported. See @ref{MySQL full-text search} for details of operation.
...@@ -14164,7 +14165,7 @@ mysql> select STRCMP('text', 'text'); ...@@ -14164,7 +14165,7 @@ mysql> select STRCMP('text', 'text');
relevance - similarity measure between the text in columns relevance - similarity measure between the text in columns
@code{(col1,col2,...)} and the query @code{expr}. Relevance is a @code{(col1,col2,...)} and the query @code{expr}. Relevance is a
positive floating point number. Zero relevance means no similarity. positive floating point number. Zero relevance means no similarity.
For @code{MATCH ... AGAINST()} to work, a @strong{fulltext index} For @code{MATCH ... AGAINST()} to work, a @strong{FULLTEXT} index
must be created first. @xref{CREATE TABLE, , @code{CREATE TABLE}}. must be created first. @xref{CREATE TABLE, , @code{CREATE TABLE}}.
@code{MATCH ... AGAINST()} is available in @code{MySQL} 3.23.23 or later. @code{MATCH ... AGAINST()} is available in @code{MySQL} 3.23.23 or later.
For details and usage examples see @xref{MySQL full-text search}. For details and usage examples see @xref{MySQL full-text search}.
...@@ -16422,8 +16423,8 @@ When you use @code{ORDER BY} or @code{GROUP BY} with a @code{TEXT} or ...@@ -16422,8 +16423,8 @@ When you use @code{ORDER BY} or @code{GROUP BY} with a @code{TEXT} or
@item @item
In @strong{MySQL} 3.23.23 or later, you can also create special In @strong{MySQL} 3.23.23 or later, you can also create special
@strong{fulltext} indexes. They are used for full-text search. Only @strong{FULLTEXT} indexes. They are used for full-text search. Only the
@code{MyISAM} table type supports fulltext indexes. They can be created @code{MyISAM} table type supports @code{FULLTEXT} indexes. They can be created
only from @code{VARCHAR}, @code{BLOB}, and @code{TEXT} columns. only from @code{VARCHAR}, @code{BLOB}, and @code{TEXT} columns.
Indexing always happens over the entire column, partial indexing is not Indexing always happens over the entire column, partial indexing is not
supported. See @ref{MySQL full-text search} for details of operation. supported. See @ref{MySQL full-text search} for details of operation.
...@@ -19810,9 +19811,10 @@ table type. ...@@ -19810,9 +19811,10 @@ table type.
For more information about how @strong{MySQL} uses indexes, see For more information about how @strong{MySQL} uses indexes, see
@ref{MySQL indexes, , @strong{MySQL} indexes}. @ref{MySQL indexes, , @strong{MySQL} indexes}.
Fulltext indexes can index only @code{VARCHAR}, @code{BLOB}, and @code{FULLTEXT} indexes can index only @code{VARCHAR}, @code{BLOB}, and
@code{TEXT} columns, and only in @code{MyISAM} tables. Fulltext indexes @code{TEXT} columns, and only in @code{MyISAM} tables. @code{FULLTEXT} indexes
are available from @strong{MySQL} 3.23.23. @ref{MySQL full-text search}. are available in @strong{MySQL} 3.23.23 and later.
@ref{MySQL full-text search}.
@findex DROP INDEX @findex DROP INDEX
@node DROP INDEX, Comments, CREATE INDEX, Reference @node DROP INDEX, Comments, CREATE INDEX, Reference
...@@ -34089,14 +34091,16 @@ DELAYED} threads. ...@@ -34089,14 +34091,16 @@ DELAYED} threads.
Since version 3.23.23, @strong{MySQL} has support for full-text indexing Since version 3.23.23, @strong{MySQL} has support for full-text indexing
and searching. Full-text index in @strong{MySQL} is an and searching. Full-text index in @strong{MySQL} is an
index of type @code{FULLTEXT}. Fulltext indexes can be created from index of type @code{FULLTEXT}. @code{FULLTEXT} indexes can be created from
@code{VARCHAR}, @code{TEXT}, and @code{BLOB} columns at @code{VARCHAR}, @code{TEXT}, and @code{BLOB} columns at
@code{CREATE TABLE} time or added later with @code{ALTER TABLE} or @code{CREATE TABLE} time or added later with @code{ALTER TABLE} or
@code{CREATE INDEX}. Full-text search is performed with @code{MATCH} function. @code{CREATE INDEX}. Full-text search is performed with the @code{MATCH}
function.
@example @example
mysql> CREATE TABLE t (a VARCHAR(200), b TEXT, FULLTEXT (a,b)); mysql> CREATE TABLE t (a VARCHAR(200), b TEXT, FULLTEXT (a,b));
Query OK, 0 rows affected (0.00 sec) Query OK, 0 rows affected (0.00 sec)
mysql> INSERT INTO t VALUES mysql> INSERT INTO t VALUES
-> ('MySQL has now support', 'for full-text search'), -> ('MySQL has now support', 'for full-text search'),
-> ('Full-text indexes', 'are called collections'), -> ('Full-text indexes', 'are called collections'),
...@@ -34105,6 +34109,7 @@ mysql> INSERT INTO t VALUES ...@@ -34105,6 +34109,7 @@ mysql> INSERT INTO t VALUES
-> ('Full-text search in MySQL', 'implements vector space model'); -> ('Full-text search in MySQL', 'implements vector space model');
Query OK, 5 rows affected (0.00 sec) Query OK, 5 rows affected (0.00 sec)
Records: 5 Duplicates: 0 Warnings: 0 Records: 5 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM t WHERE MATCH (a,b) AGAINST ('MySQL'); mysql> SELECT * FROM t WHERE MATCH (a,b) AGAINST ('MySQL');
+---------------------------+-------------------------------+ +---------------------------+-------------------------------+
| a | b | | a | b |
...@@ -34113,6 +34118,7 @@ mysql> SELECT * FROM t WHERE MATCH (a,b) AGAINST ('MySQL'); ...@@ -34113,6 +34118,7 @@ mysql> SELECT * FROM t WHERE MATCH (a,b) AGAINST ('MySQL');
| Full-text search in MySQL | implements vector-space-model | | Full-text search in MySQL | implements vector-space-model |
+---------------------------+-------------------------------+ +---------------------------+-------------------------------+
2 rows in set (0.00 sec) 2 rows in set (0.00 sec)
mysql> SELECT *,MATCH a,b AGAINST ('collections support') as x FROM t; mysql> SELECT *,MATCH a,b AGAINST ('collections support') as x FROM t;
+------------------------------+-------------------------------+--------+ +------------------------------+-------------------------------+--------+
| a | b | x | | a | b | x |
...@@ -34126,11 +34132,11 @@ mysql> SELECT *,MATCH a,b AGAINST ('collections support') as x FROM t; ...@@ -34126,11 +34132,11 @@ mysql> SELECT *,MATCH a,b AGAINST ('collections support') as x FROM t;
5 rows in set (0.00 sec) 5 rows in set (0.00 sec)
@end example @end example
Function @code{MATCH} matches a natural language query @code{AGAINST} a The function @code{MATCH} matches a natural language query @code{AGAINST} a
text collection (which is simply the columns that are covered text collection (which is simply the columns that are covered
by fulltext index). For every row in a table it returns relevance - by a @strong{FULLTEXT} index). For every row in a table it returns
similarity measure between the text in that row (in the columns, that relevance - similarity measure between the text in that row (in the columns
are part of the collection) and the query. When it used in a that are part of the collection) and the query. When it is used in a
@code{WHERE} clause (see example above) the rows returned are @code{WHERE} clause (see example above) the rows returned are
automatically sorted with relevance decreasing. Relevance is a non- automatically sorted with relevance decreasing. Relevance is a non-
negative floating point number. Zero relevance means no similarity. negative floating point number. Zero relevance means no similarity.
...@@ -34138,13 +34144,13 @@ Relevance is computed based on number of words in the row and number of ...@@ -34138,13 +34144,13 @@ Relevance is computed based on number of words in the row and number of
unique words in that row, total number of words in the collection, unique words in that row, total number of words in the collection,
number of documents (rows), that contain a particular word, etc. number of documents (rows), that contain a particular word, etc.
MySQL uses very simple parser to split text into words. "Word" is MySQL uses a very simple parser to split text into words. A "word" is
any sequence of letters, numbers, @code{'}, and @code{_}. Any "word" any sequence of letters, numbers, @code{'}, and @code{_}. Any "word"
that is present in stopword list or just too short (3 characters or less) that is present in the stopword list or just too short (3 characters
is ignored. or less) is ignored.
Every correct word in the collection and in the query is weighted, Every correct word in the collection and in the query is weighted,
according to their significance in the query or collection. This way, a according to its significance in the query or collection. This way, a
word that is present in many documents will have lower weight (and may word that is present in many documents will have lower weight (and may
even have a zero weight), because it has lower semantic value in this even have a zero weight), because it has lower semantic value in this
particular collection. Otherwise, if the word is rare, it will receive a particular collection. Otherwise, if the word is rare, it will receive a
...@@ -34152,7 +34158,7 @@ higher weight. Weights of the words are then combined to compute the ...@@ -34152,7 +34158,7 @@ higher weight. Weights of the words are then combined to compute the
relevance. relevance.
Such a technique works best with big collections (in fact, it was Such a technique works best with big collections (in fact, it was
carefully tuned up this way). For very small tables word distribution carefully tuned up this way). For very small tables, word distribution
does not reflect adequately their semantical value, and this model does not reflect adequately their semantical value, and this model
may sometimes produce bizarre results. may sometimes produce bizarre results.
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