sys.dm_fts_index_keywords (Transact-SQL)

Artikkeli
02/28/2023

Applies to: SQL Server

Returns information about the content of a full-text index for the specified table.

sys.dm_fts_index_keywords is a dynamic management function.

Note

To view lower-level full-text index information, use the sys.dm_fts_index_keywords_by_document dynamic management function at the document level.

Syntax

  
sys.dm_fts_index_keywords( DB_ID('database_name'), OBJECT_ID('table_name') )

Arguments

db_id('database_name')
A call to the DB_ID() function. This function accepts a database name and returns the database ID, which sys.dm_fts_index_keywords uses to find the specified database. If database_name is omitted, the current database ID is returned.

object_id('table_name')
A call to the OBJECT_ID() function. This function accepts a table name and returns the table ID of the table containing the full-text index to inspect.

Table Returned

Column name	Data type	Description
keyword	nvarchar(4000)	The hexadecimal representation of the keyword stored inside the full-text index. Note: OxFF represents the special character that indicates the end of a file or dataset.
display_term	nvarchar(4000)	The human-readable format of the keyword. This format is derived from the hexadecimal format. Note: The display_term value for OxFF is "END OF FILE."
column_id	int	ID of the column from which the current keyword was full-text indexed.
document_count	int	Number of documents or rows containing the current term.

Remarks

The information returned by sys.dm_fts_index_keywords is useful for finding out the following, among other things:

Whether a keyword is part of the full-text index.
How many documents or rows contain a given keyword.
The most common keyword in the full-text index:
- document_count of each keyword_value compared to the total document_count, the document count of 0xFF.
- Typically, common keywords are likely to be appropriate to declare as stopwords.

Note

The document_count returned by sys.dm_fts_index_keywords may be less accurate for a specific document than the count returned by sys.dm_fts_index_keywords_by_document or a CONTAINS query. This potential inaccuracy is estimated to be less than 1%. This inaccuracy can occur because a document_id may be counted twice when it continues across more than one row in the index fragment, or when it appears more than once in the same row. To obtain a more accurate count for a specific document, use sys.dm_fts_index_keywords_by_document or a CONTAINS query.

Permissions

Requires membership in the sysadmin fixed server role.

Examples

A. Displaying high-level full-text index content

The following example displays information about the high-level content of the full-text index in the HumanResources.JobCandidate table.

SELECT * FROM sys.dm_fts_index_keywords(db_id('AdventureWorks2022'), object_id('HumanResources.JobCandidate'))  
GO

Jaa