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53e99f57fc
Fix lots of bad markup, bad English, bad explanations. This commit covers only about half the contrib modules, but I grow weary...
91 lines
2.3 KiB
Plaintext
91 lines
2.3 KiB
Plaintext
<!-- $PostgreSQL: pgsql/doc/src/sgml/test-parser.sgml,v 1.2 2007/12/06 04:12:10 tgl Exp $ -->
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<sect1 id="test-parser">
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<title>test_parser</title>
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<indexterm zone="test-parser">
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<primary>test_parser</primary>
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</indexterm>
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<para>
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<filename>test_parser</> is an example of a custom parser for full-text
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search. It doesn't do anything especially useful, but can serve as
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a starting point for developing your own parser.
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</para>
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<para>
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<filename>test_parser</> recognizes words separated by white space,
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and returns just two token types:
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<programlisting>
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mydb=# SELECT * FROM ts_token_type('testparser');
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tokid | alias | description
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-------+-------+---------------
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3 | word | Word
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12 | blank | Space symbols
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(2 rows)
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</programlisting>
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These token numbers have been chosen to be compatible with the default
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parser's numbering. This allows us to use its <function>headline()</>
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function, thus keeping the example simple.
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</para>
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<sect2>
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<title>Usage</title>
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<para>
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Running the installation script creates a text search parser
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<literal>testparser</>. It has no user-configurable parameters.
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</para>
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<para>
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You can test the parser with, for example,
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<programlisting>
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mydb=# SELECT * FROM ts_parse('testparser', 'That''s my first own parser');
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tokid | token
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-------+--------
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3 | That's
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12 |
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3 | my
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12 |
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3 | first
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12 |
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3 | own
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12 |
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3 | parser
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</programlisting>
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</para>
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<para>
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Real-world use requires setting up a text search configuration
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that uses the parser. For example,
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<programlisting>
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mydb=# CREATE TEXT SEARCH CONFIGURATION testcfg ( PARSER = testparser );
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CREATE TEXT SEARCH CONFIGURATION
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mydb=# ALTER TEXT SEARCH CONFIGURATION testcfg
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mydb-# ADD MAPPING FOR word WITH english_stem;
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ALTER TEXT SEARCH CONFIGURATION
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mydb=# SELECT to_tsvector('testcfg', 'That''s my first own parser');
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to_tsvector
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-------------------------------
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'that':1 'first':3 'parser':5
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(1 row)
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mydb=# SELECT ts_headline('testcfg', 'Supernovae stars are the brightest phenomena in galaxies',
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mydb(# to_tsquery('testcfg', 'star'));
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ts_headline
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-----------------------------------------------------------------
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Supernovae <b>stars</b> are the brightest phenomena in galaxies
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(1 row)
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</programlisting>
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</para>
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</sect2>
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</sect1>
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