Help Center/ GaussDB(DWS)/ SQL Syntax Reference/ SQL Syntax Reference (9.1.0.x)/ DDL Syntax/ CREATE TEXT SEARCH DICTIONARY

Updated on 2025-07-22 GMT+08:00

View PDF

CREATE TEXT SEARCH DICTIONARY

Function

CREATE TEXT SEARCH DICTIONARY creates a full-text retrieval dictionary. A full-text search dictionary is used to identify and process particular words during full-text retrieval.

Dictionaries are created by using predefined templates (defined in the PG_TS_TEMPLATE system catalog). Five types of dictionaries can be created, Simple, Ispell, Synonym, Thesaurus, and Snowball. Each type of dictionaries is used to handle different tasks.

Precautions

A user with the SYSADMIN permission can create a dictionary. Then, the user automatically becomes the owner of the dictionary.
A dictionary cannot be created in pg_temp mode.
After a dictionary is created or modified, any modification to the user-defined dictionary definition file will not affect the dictionary in the database. To make such modifications take effect in the dictionary in the database, run the ALTER statement to update the definition file of the dictionary.
The TEMPLATE parameter in a dictionary cannot be modified.
To specify a dictionary, specify both the dictionary definition file path (FILEPATH) and the file name (the parameter varies based on dictionary types).
The name of a dictionary definition file can contain only lowercase letters, digits, and underscores (_).

The predefined dictionary file is stored in the $GAUSSHOME/share/postgresql/tsearch_data directory.

Syntax

     
          CREATE TEXT SEARCH DICTIONARY name (
    TEMPLATE = template
    [, option = value [, ... ]]
);

Parameter Description

**Table 1** CREATE TEXT SEARCH DICTIONARY parameters
Parameter	Description	Value Range
name	Specifies the name (optionally schema-qualified) of the full-text search dictionary to be created.	A string, which must comply with the naming convention.
template	Specifies a template name.	Templates (Simple, Synonym, Thesaurus, Ispell, and Snowball) defined in the PG_TS_TEMPLATE system catalog
option	Specifies the parameter name of a specific option for a full-text search dictionary. Each type of dictionaries has a template containing their custom parameters. Parameters function in a way irrelevant to their setting sequence.	For details, see Table 2.
value	Specifies a parameter value. If the value is not an identifier or a number, enclose it with single quotation marks (''). You can also enclose identifiers and numbers with single quotation marks.	-

Table 2 Option parameters of Simple, Ispell, Synonym, Thesaurus, and Snowball

option

Name of the option

Description

Parameters for a Simple dictionary

STOPWORDS

Specifies the name of a file listing stop words. The default file name extension is .stop. For example, if the value of STOPWORDS is french, the actual file name is french.stop. In the file, each line defines a stop word. Dictionaries will ignore blank lines and spaces in the file and convert stop-word phrases into lowercase.

Specifies whether to accept a non-stop word as recognized. The default value is true.

If ACCEPT=true is set for a Simple dictionary, no token will be passed to subsequent dictionaries. In this case, you are advised to place the Simple dictionary at the end of the dictionary list. If ACCEPT=false is set, you are advised to place the Simple dictionary before at least one dictionary in the list.

FILEPATH

Specifies the directory for storing the stop word file. The stop word file can be stored locally or on the OBS server. If the file is stored locally, the directory format is 'file://absolute_path'. If the file is stored on the OBS server, the directory format is 'obs://bucket/path accesskey=ak secretkey=sk region=region_name'. The directory must be enclosed in single quotation marks ('). The default value is the directory where predefined dictionary files are located. Both the FILEPATH and STOPWORDS parameters need to be specified.

To create a dictionary using the stop word file on the OBS server, perform the following steps:

Upload the stop word file to the OBS server. For example, upload the french.stop file to the gaussdb bucket on the OBS server obsv3.sa-fb-1.externaldemo.com. The URL is https://gaussdb.obsv3.sa-fb-1.externaldemo.com/french.stop. For details about how to upload the file and query the URL, see the OBS User Manual.
Add "region_name": "obs domain" to the $GAUSSHOME/etc/region_map file. region_name can be a string consisting of uppercase letters, lowercase letters, digits, slashes (/), or underscores (_). obs domain indicates the domain name of the OBS server.
For example, if region_name is set to rg, region_map is as follows: "rg": "obsv3.sa-fb-1.externaldemo.com".

NOTICE:

region_name and obs domain are enclosed in double quotation marks. There is no space on the left of the colon and one space on the right of the colon.

Run the CREATE TEXT SEARCH DICTIONARY command to create a dictionary. The command is as follows:

            
                 CREATE TEXT SEARCH DICTIONARY french_dict ( TEMPLATE = pg_catalog.simple, STOPWORDS = french, FILEPATH = 'obs://gaussdb accesskey=xxx secretkey=yyy region=rg' );

The french.stop file is stored in the root directory of the gaussdb bucket. Therefore, the path is empty.

Parameters for a Synonym dictionary

SYNONYM

Specifies the name of the definition file for a Synonym dictionary. The default file name extension is .syn.

The file is a list of synonyms. Each line is in the format of token synonym, that is, token and its synonym separated by a space.

CASESENSITIVE

Specifies whether tokens and their synonyms are case sensitive. The default value is false, indicating that tokens and synonyms in dictionary files will be converted into lowercase. If this parameter is set to true, they will not be converted into lowercase.

FILEPATH

Specifies the directory for storing Synonym dictionary files. The directory can be a local directory or an OBS directory. The default value is the directory where predefined dictionary files are located. The directory format and the process of creating a Synonym dictionary using a file on the OBS server are the same as those of the Simple dictionary.

Parameters for a Thesaurus dictionary

DICTFILE

Specifies the name of a dictionary definition file. The default file name extension is .ths.

The file is a list of synonyms. Each line is in the format of sample words : indexed words. The colon (:) is used as a separator between a phrase and its substitute word. If multiple sample words are matched, the TZ selects the longest one.

DICTIONARY

Specifies the name of a subdictionary used for word normalization. This parameter is mandatory and only one subdictionary name can be specified. The specified subdictionary must exist. It is used to identify and normalize input text before phrase matching.

If an input word cannot be recognized by the subdictionary, an error will be reported. In this case, remove the word or update the subdictionary to make the word recognizable. In addition, an asterisk (*) can be placed at the beginning of an indexed word to skip the application of a subdictionary on it, but all sample words must be recognizable by the subdictionary.

If the sample words defined in the dictionary file contain stop words defined in the subdictionary, use question marks (?) to replace them. Assume that a and the are stop words defined in the subdictionary.

? one ? two : swsw

a one the two and the one a two will be matched and output as swsw.

FILEPATH

Specifies the directory for storing dictionary definition files. The directory can be a local directory or an OBS directory. The default value is the directory where predefined dictionary files are located. The directory format and the process of creating a Synonym dictionary using a file on the OBS server are the same as those of the Simple dictionary.

Parameters for an Ispell dictionary

DICTFILE

Specifies the name of a dictionary definition file. The default file name extension is .dict.

AFFFILE

Specifies the name of an affix file. The default file name extension is .affix.

STOPWORDS

Specifies the name of a file listing stop words. The default file name extension is .stop. The file content format is the same as that of the file for a Simple dictionary.

FILEPATH

Specifies the directory for storing dictionary files. The directory can be a local directory or an OBS directory. The default value is the directory where predefined dictionary files are located. The directory format and the process of creating a Synonym dictionary using a file on the OBS server are the same as those of the Simple dictionary.

Parameters for a Snowball dictionary

LANGUAGE

Specifies the name of a language whose stemming algorithm will be used. According to spelling rules in the language, the algorithm normalizes the variants of an input word into a basic word or a stem.

STOPWORDS

Specifies the name of a file listing stop words. The default file name extension is .stop. The file content format is the same as that of the file for a Simple dictionary.

FILEPATH

Specifies the directory for storing dictionary definition files. The directory can be a local directory or an OBS directory. The default value is the directory where predefined dictionary files are located. Both the FILEPATH and STOPWORDS parameters need to be specified. The directory format and the process of creating a Snowball dictionary using a file on the OBS server are the same as those of the Simple dictionary.

Examples

Create an Ispell dictionary english_ispell (the dictionary definition file is from the open source dictionary).

      
           CREATE TEXT SEARCH DICTIONARY english_ispell (
    TEMPLATE = ispell,
    DictFile = english,
    AffFile = english,
    StopWords = english,
    FilePath = 'obs://bucket_name/path accesskey=ak secretkey=sk region=rg' 
);

See examples in Configuration Examples.

Helpful Links

ALTER TEXT SEARCH DICTIONARY, CREATE TEXT SEARCH DICTIONARY

Parent Topic: DDL Syntax

Previous topic: CREATE TEXT SEARCH CONFIGURATION

Next topic: CREATE TRIGGER

Feedback

Was this page helpful?

Helpful Not helpful

Provide feedback

Thank you very much for your feedback. We will continue working to improve the documentation.See the reply and handling status in My Cloud VOC.

The system is busy. Please try again later.

Which of the following issues have you encountered?

Content is inconsistent with the product UI

Unclear descriptions

Lack of examples or code

Incorrect steps

Can't find what I need

Lack of best practices

Feedback (optional)

0/500

Select at least one type of issue, and enter your comments or suggestions.

Enter a maximum of 500 characters.

Submit Cancel

For any further questions, feel free to contact us through the chatbot.

Chatbot