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22dfd116a1
This is advance preparation for introducing even more test modules; the easy solution is to add them to contrib, but that's bloated enough that it seems a good time to think of something different. Moved modules are dummy_seclabel, test_shm_mq, test_parser and worker_spi. (test_decoding was also a candidate, but there was too much opposition to moving that one. We can always reconsider later.)
62 lines
1.8 KiB
Plaintext
62 lines
1.8 KiB
Plaintext
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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test_parser recognizes words separated by white space,
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and returns just two token types:
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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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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 headline()
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function, thus keeping the example simple.
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Usage
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=====
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Installing the test_parser extension creates a text search
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parser testparser. It has no user-configurable parameters.
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You can test the parser with, for example,
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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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Real-world use requires setting up a text search configuration
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that uses the parser. For example,
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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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