Adding upstream version 15.4.upstream/15.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/src/test/modules/test_parser/README b/src/test/modules/test_parser/README
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+test_parser is an example of a custom parser for full-text
+search.  It doesn't do anything especially useful, but can serve as
+a starting point for developing your own parser.
+
+test_parser recognizes words separated by white space,
+and returns just two token types:
+
+mydb=# SELECT * FROM ts_token_type('testparser');
+ tokid | alias |  description
+-------+-------+---------------
+     3 | word  | Word
+    12 | blank | Space symbols
+(2 rows)
+
+These token numbers have been chosen to be compatible with the default
+parser's numbering.  This allows us to use its headline()
+function, thus keeping the example simple.
+
+Usage
+=====
+
+Installing the test_parser extension creates a text search
+parser testparser.  It has no user-configurable parameters.
+
+You can test the parser with, for example,
+
+mydb=# SELECT * FROM ts_parse('testparser', 'That''s my first own parser');
+ tokid | token
+-------+--------
+     3 | That's
+    12 |
+     3 | my
+    12 |
+     3 | first
+    12 |
+     3 | own
+    12 |
+     3 | parser
+
+Real-world use requires setting up a text search configuration
+that uses the parser.  For example,
+
+mydb=# CREATE TEXT SEARCH CONFIGURATION testcfg ( PARSER = testparser );
+CREATE TEXT SEARCH CONFIGURATION
+
+mydb=# ALTER TEXT SEARCH CONFIGURATION testcfg
+mydb-#   ADD MAPPING FOR word WITH english_stem;
+ALTER TEXT SEARCH CONFIGURATION
+
+mydb=#  SELECT to_tsvector('testcfg', 'That''s my first own parser');
+          to_tsvector
+-------------------------------
+ 'that':1 'first':3 'parser':5
+(1 row)
+
+mydb=# SELECT ts_headline('testcfg', 'Supernovae stars are the brightest phenomena in galaxies',
+mydb(#                    to_tsquery('testcfg', 'star'));
+                           ts_headline
+-----------------------------------------------------------------
+ Supernovae <b>stars</b> are the brightest phenomena in galaxies
+(1 row)