Vector index functions

GoogleSQL for BigQuery supports the following vector index functions.

Function list

VECTOR_INDEX.STATISTICS

  VECTOR_INDEX 
 . 
 STATISTICS 
 ( 
  
 TABLE 
  
 table_name 
 ) 
 

Description

The VECTOR_INDEX.STATISTICS function calculates how much an indexed table's data has drifted between when a vector index was trained and the present. Use this function to determine if table data has changed enough to require a vector index rebuild. If necessary, you can use the ALTER VECTOR INDEX REBUILD statement to rebuild the vector index.

To alter vector indexes, you must have the BigQuery Data Editor ( roles/bigquery.dataEditor ) or BigQuery Data Owner ( roles/bigquery.dataOwner ) IAM role on the table that contains the vector index.

Definitions

• table_name : The name of the table that contains the vector index, in the format dataset_name.table_name .

  If there is no active vector index on the table, the function returns empty results. If there is an active vector index on the table, but the index training isn't complete, the function returns a NULL drift score.

Output

A FLOAT64 value in the range [0,1) . A lower value indicates less drift. Typically, a change of 0.3 or greater is considered significant.

Example

This example returns the drift for the table mytable .

  SELECT 
  
 * 
  
 FROM 
  
 VECTOR_INDEX 
 . 
 STATISTICS 
 ( 
 TABLE 
  
 mydataset 
 . 
 mytable 
 );