mirror of https://github.com/postgres/postgres
Tom Lane
18 years ago
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<sect1 id="dict-int"> |
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<title>dict_int</title> |
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<indexterm zone="dict-int"> |
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<primary>dict_int</primary> |
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</indexterm> |
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<para> |
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The motivation for this example dictionary is to control the indexing of |
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integers (signed and unsigned), and, consequently, to minimize the number of |
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unique words which greatly affect the performance of searching. |
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</para> |
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|
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<sect2> |
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<title>Configuration</title> |
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<para> |
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The dictionary accepts two options: |
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</para> |
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<itemizedlist> |
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<listitem> |
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<para> |
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The MAXLEN parameter specifies the maximum length (number of digits) |
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allowed in an integer word. The default value is 6. |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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The REJECTLONG parameter specifies if an overlength integer should be |
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truncated or ignored. If REJECTLONG=FALSE (default), the dictionary returns |
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the first MAXLEN digits of the integer. If REJECTLONG=TRUE, the |
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dictionary treats an overlength integer as a stop word, so that it will |
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not be indexed. |
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</para> |
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</listitem> |
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</itemizedlist> |
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</sect2> |
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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 template |
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<literal>intdict_template</> and a dictionary <literal>intdict</> |
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based on it, with the default parameters. You can alter the |
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parameters, for example |
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<programlisting> |
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mydb# ALTER TEXT SEARCH DICTIONARY intdict (MAXLEN = 4, REJECTLONG = true); |
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ALTER TEXT SEARCH DICTIONARY |
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</programlisting> |
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|
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or create new dictionaries based on the template. |
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</para> |
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<para> |
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To test the dictionary, you can try |
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<programlisting> |
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mydb# select ts_lexize('intdict', '12345678'); |
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ts_lexize |
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----------- |
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{123456} |
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</programlisting> |
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|
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but real-world usage will involve including it in a text search |
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configuration as described in <xref linkend="textsearch">. |
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That might look like this: |
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<programlisting> |
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ALTER TEXT SEARCH CONFIGURATION english |
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ALTER MAPPING FOR int, uint WITH intdict; |
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</programlisting> |
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</para> |
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</sect2> |
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|
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</sect1> |
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@ -0,0 +1,78 @@ |
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<sect1 id="dict-xsyn"> |
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<title>dict_xsyn</title> |
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|
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<indexterm zone="dict-xsyn"> |
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<primary>dict_xsyn</primary> |
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</indexterm> |
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<para> |
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The Extended Synonym Dictionary module replaces words with groups of their |
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synonyms, and so makes it possible to search for a word using any of its |
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synonyms. |
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</para> |
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|
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<sect2> |
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<title>Configuration</title> |
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<para> |
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A <literal>dict_xsyn</> dictionary accepts the following options: |
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</para> |
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<itemizedlist> |
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<listitem> |
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<para> |
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KEEPORIG controls whether the original word is included, or only its |
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synonyms. Default is 'true'. |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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RULES is the base name of the file containing the list of synonyms. |
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This file must be in $(prefix)/share/tsearch_data/, and its name must |
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end in ".rules" (which is not included in the RULES parameter). |
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</para> |
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</listitem> |
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</itemizedlist> |
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<para> |
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The rules file has the following format: |
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</para> |
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<itemizedlist> |
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<listitem> |
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<para> |
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Each line represents a group of synonyms for a single word, which is |
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given first on the line. Synonyms are separated by whitespace: |
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</para> |
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<programlisting> |
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word syn1 syn2 syn3 |
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</programlisting> |
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</listitem> |
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<listitem> |
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<para> |
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Sharp ('#') sign is a comment delimiter. It may appear at any position |
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inside the line. The rest of the line will be skipped. |
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</para> |
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</listitem> |
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</itemizedlist> |
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|
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<para> |
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Look at xsyn_sample.rules, which is installed in $(prefix)/share/tsearch_data/, |
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for an example. |
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</para> |
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</sect2> |
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|
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<sect2> |
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<title>Usage</title> |
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<programlisting> |
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mydb=# SELECT ts_lexize('xsyn','word'); |
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ts_lexize |
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---------------- |
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{word,syn1,syn2,syn3) |
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</programlisting> |
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<para> |
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Change dictionary options: |
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</para> |
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<programlisting> |
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mydb# ALTER TEXT SEARCH DICTIONARY xsyn (KEEPORIG=false); |
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ALTER TEXT SEARCH DICTIONARY |
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</programlisting> |
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</sect2> |
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|
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</sect1> |
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