Default CONTEXT Index Example

The following statement creates a default CONTEXT index called myindex on the text column in the docs table:

CREATE INDEX myindex ON docs(text) INDEXTYPE IS CTXSYS.CONTEXT;

When you use CREATE INDEX without explicitly specifying parameters, the system does the following actions by default for all languages:

• Assumes that the text to be indexed is stored directly in a text column. The text column can be of type CLOB, BLOB, BFILE, VARCHAR2, or CHAR.

• Detects the column type and uses filtering for the binary column types of BLOB and BFILE. Most document formats are supported for filtering. If your column is plain text, the system does not use filtering.

  Note:

  For document filtering to work correctly in your system, you must ensure that your environment is set up correctly to support the AUTO_FILTER filter.

  To learn more about configuring your environment to use the AUTO_FILTER filter, see the Oracle Text Reference.

• Assumes the language of text to index is the language you specify in your database setup.

• Uses the default stoplist for the language you specify in your database setup. Stoplists identify the words that the system ignores during indexing.

• Enables fuzzy and stemming queries for your language, if this feature is available for your language.

You can always change the default indexing behavior by creating your own preferences and specifying these custom preferences in the parameter string of CREATE INDEX.