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The motivation for this example dictionary is to control the indexing of integers (signed and unsigned), and, consequently, to minimize the number of unique words which greatly affect the performance of searching.
The dictionary accepts two options:
The MAXLEN parameter specifies the maximum length (number of digits) allowed in an integer word. The default value is 6.
The REJECTLONG parameter specifies if an overlength integer should be truncated or ignored. If REJECTLONG=FALSE (default), the dictionary returns the first MAXLEN digits of the integer. If REJECTLONG=TRUE, the dictionary treats an overlength integer as a stop word, so that it will not be indexed.
Running the installation script creates a text search template intdict_template and a dictionary intdict based on it, with the default parameters. You can alter the parameters, for example
mydb# ALTER TEXT SEARCH DICTIONARY intdict (MAXLEN = 4, REJECTLONG = true); ALTER TEXT SEARCH DICTIONARY
or create new dictionaries based on the template.
To test the dictionary, you can try
mydb# select ts_lexize('intdict', '12345678'); ts_lexize ----------- {123456}
but real-world usage will involve including it in a text search configuration as described in Chapter 12. That might look like this:
ALTER TEXT SEARCH CONFIGURATION english ALTER MAPPING FOR int, uint WITH intdict;