Query index information for a mapping table

Prerequisites

Install the Tablestore SDK for Java and initialize a client.
Use Tablestore SDK for Java 5.13.0 or later.

Description

Call the sqlQuery method to execute a SHOW INDEX statement and query the index information for a mapping table.

SQLQueryResponse sqlQuery(SQLQueryRequest request)

Note

For a data table mapping, the result contains the primary key and the fields of the secondary and search indexes that are created for the data table. For a search index mapping, the result contains only the primary key and the fields of the specified search index.

The following example queries the index information for the example_search_index_mapping search index mapping and reads commonly used fields from the response.

SQLQueryRequest request =
        new SQLQueryRequest("SHOW INDEX IN example_search_index_mapping");
SQLQueryResponse response = client.sqlQuery(request);

SQLResultSet resultSet = response.getSQLResultSet();
while (resultSet.hasNext()) {
    SQLRow row = resultSet.next();
    System.out.println(
            row.getString("Table") + ", "
                    + row.getString("Key_name") + ", "
                    + row.getString("Column_name") + ", "
                    + row.getString("Index_type"));
}

Parameters

SQLQueryRequest contains the following parameter.

Name	Type	Description
query (required)	String	The `SHOW INDEX IN <mapping_table_name>` statement to execute. `mapping_table_name` specifies the mapping table name.

Response

SQLQueryResponse contains the following fields related to mapping table indexes.

Field	Type	Description
`type`	SQLStatementType	The SQL statement type, which is obtained by calling `getSQLStatementType()`. For a `SHOW INDEX` statement, the value is `SQL_SELECT`.
`rows`	ByteString	The serialized index information. Call `getSQLResultSet()` to obtain the parsed `SQLResultSet`.

Result set fields

Each row in the SQLResultSet represents a primary key, secondary index, or search index field and contains the following columns.

Field	Type	Description
`Table`	String	The mapping table name.
`Non_unique`	Long	Whether duplicate values are allowed. `0` indicates no and `1` indicates yes.
`Key_name`	String	The index name. The primary key is returned as `PRIMARY`.
`Seq_in_index`	Long	The one-based position of the field in the index.
`Column_name`	String	The index field name.
`Is_defined_column`	String	Whether the field is a predefined column of the data table.
`Search_type`	String	The query type of the search index field.
`Collation`	String	The sort order of the field in the index.
`Cardinality`	Long	The estimated number of distinct values in the index.
`Sub_part`	Long	The index prefix length of the field.
`Packed`	String	The index compression method.
`Null`	String	Whether the field can be null.
`Index_type`	String	The index type. A global secondary index is returned as `GlobalIndex`, a local secondary index is returned as `LocalIndex`, and a search index is returned as `SearchIndex`.
`Comment`	String	The index remarks.
`Index_comment`	String	The index comment.
`Visible`	String	Whether the index is visible.
`Expression`	String	The index expression.