CREATE TEXT SEARCH CONFIGURATION

Function

CREATE TEXT SEARCH CONFIGURATION creates a text search configuration. A text search configuration specifies a text search parser that can divide a string into tokens, plus dictionaries that can be used to determine which tokens are of interest for searching.

Precautions

• If only the parser is specified, the new text search configuration initially has no mapping from token types to dictionaries, and therefore will ignore all words. Subsequently, ALTER TEXT SEARCH CONFIGURATION must be used to create mapping to make the configuration useful. If COPY is specified, the parser, mapping and parameters of the text search configuration is copied automatically.
• If the schema name is given, the text search configuration will be created in the specified schema. Otherwise, the configuration will be created in the current schema.
• The user who defines a text search configuration becomes its owner.
• PARSER and COPY options are mutually exclusive, because when an existing configuration is copied, its parser selection is copied too.
• If only the parser is specified, the new text search configuration initially has no mapping from token types to dictionaries, and therefore will ignore all words.

Syntax

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CREATE TEXT SEARCH CONFIGURATION name 
    ( PARSER = parser_name | COPY = source_config )
    [ WITH ( {configuration_option = value} [, ...] )];

Parameter Description

• name

  Specifies the name of the text search configuration to be created. The name can be schema-qualified.

• parser_name

  Specifies the name of the text search parser to use for this configuration.

• source_config

  Specifies the name of an existing text search configuration to copy.

• configuration_option

  Specifies parameters for the text search configuration, particularly for the parser executed by parser_name or contained by source_config.

  Value range: The default and ngram parsers are supported. The parser of default type has no corresponding configuration_option. Table 1 lists configuration_option for ngram parsers.

  Table 1 Configuration parameters for ngram parsers

  Parser	Parameter	Description	Value Range
  ngram	gram_size	Length of word segmentation	Integer, 1 to 4 Default value: 2
  	punctuation_ignore	Whether to ignore punctuations	true (default value): Ignore punctuations. false: Do not ignore punctuations.
  	grapsymbol_ignore	Whether to ignore graphical characters	true: Ignore graphical characters. false (default value): Do not ignore graphical characters.

Examples

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-- Create a text search configuration.
openGauss=# CREATE TEXT SEARCH CONFIGURATION ngram2 (parser=ngram) WITH (gram_size = 2, grapsymbol_ignore = false);

-- Create a text search configuration.
openGauss=# CREATE TEXT SEARCH CONFIGURATION ngram3 (copy=ngram2) WITH (gram_size = 2, grapsymbol_ignore = false);

-- Add type mapping.
openGauss=# ALTER TEXT SEARCH CONFIGURATION ngram2 ADD MAPPING FOR multisymbol WITH simple;

-- Create user joe.
openGauss=# CREATE USER joe IDENTIFIED BY 'xxxxxxxxxxx';

-- Change the owner of the text search configuration.
openGauss=# ALTER TEXT SEARCH CONFIGURATION ngram2 OWNER TO joe;

-- Change the schema of the text search configuration.
openGauss=# ALTER TEXT SEARCH CONFIGURATION ngram2 SET SCHEMA joe;

-- Rename the text search configuration.
openGauss=# ALTER TEXT SEARCH CONFIGURATION joe.ngram2 RENAME TO ngram_2;

-- Delete the type mapping.
openGauss=# ALTER TEXT SEARCH CONFIGURATION joe.ngram_2 DROP MAPPING IF EXISTS FOR multisymbol;

-- Delete the text search configuration.
openGauss=# DROP TEXT SEARCH CONFIGURATION joe.ngram_2;
openGauss=# DROP TEXT SEARCH CONFIGURATION ngram3;

-- Delete the schema and user joe.
openGauss=# DROP SCHEMA IF EXISTS joe CASCADE;
openGauss=# DROP ROLE IF EXISTS joe;

Helpful Links

ALTER TEXT SEARCH CONFIGURATION and DROP TEXT SEARCH CONFIGURATION