Create search indexes

Background information

The actual query requirements determine the number of search indexes created for a table.

Assume that you have a table that contains the following fields: id, name, age, city, and sex. To query data by name, age, or city, you can use one of the following methods to create a search index:

• Method 1: Create a search index for each index field
  If you use this method, you must create the following search indexes: name_index, age_index, and city_index.

  • To query students by city, use city_index. To query students by age, use age_index.
  • However, this method does not work if you want to query students who are younger than 12 years old and live in Chengdu.

  The implementation of the method is similar to that of global secondary index. However, this method is not cost-effective. We recommend that you do not use this method to create a search index.

• Method 2: Create one search index for multiple index fields
  If you use this method, the search index named student_index contains the following fields: name, age, and city.

  • To query students by city, use the city field in student_index. To query students by age, use the age field in student_index.
  • To query students who are younger than 12 years old and live in Chengdu, use the age and city fields in student_index.

  This method provides more functions at a lower cost. We recommend that you use this method to create search indexes.

Limits

• Timeliness of index creation

  It takes a few seconds to use a search index after the search index is created. In the creation process, you can write data to the table. However, metadata queries of the search index and data queries by using the search index are affected.

• Limits on the number of resources

  For more information, see Limits.

Operations

You can call the CreateSearchIndex operation to create a search index.

Use Tablestore SDKs

Parameters

Examples

• Example 1
  Create a search index that consists of the Col_Keyword and Col_Long columns. Set the type of data in Col_Keyword to String and Col_Long to Long.

  
  private static void createSearchIndex(SyncClient client) {
      CreateSearchIndexRequest request = new CreateSearchIndexRequest();
      request.setTableName(TABLE_NAME); // Set the name of the table.
      request.setIndexName(INDEX_NAME); // Set the name of the search index.
      IndexSchema indexSchema = new IndexSchema();
      indexSchema.setFieldSchemas(Arrays.asList(
              new FieldSchema("Col_Keyword", FieldType.KEYWORD) // Set the field name and field type.
                      .setIndex(true) // Set the parameter to true to enable the index.
                      .setEnableSortAndAgg(true), // Set the parameter to true to enable sorting and aggregation.
              new FieldSchema("Col_Long", FieldType.LONG)
                      .setIndex(true)
                      .setEnableSortAndAgg(true)));
      request.setIndexSchema(indexSchema);
      client.createSearchIndex(request); // Call client to create the search index.
  }

• Example 2
  Specify IndexSort when you create a search index.

  private static void createSearchIndexWithIndexSort(SyncClient client) {
      CreateSearchIndexRequest request = new CreateSearchIndexRequest();
      request.setTableName(TABLE_NAME);
      request.setIndexName(INDEX_NAME);
      IndexSchema indexSchema = new IndexSchema();
      indexSchema.setFieldSchemas(Arrays.asList(
              new FieldSchema("Col_Keyword", FieldType.KEYWORD).setIndex(true).setEnableSortAndAgg(true),
              new FieldSchema("Col_Long", FieldType.LONG).setIndex(true).setEnableSortAndAgg(true),
              new FieldSchema("Col_Text", FieldType.TEXT).setIndex(true),
              new FieldSchema("Timestamp", FieldType.LONG).setIndex(true).setEnableSortAndAgg(true)));
      // Presort data by the Timestamp column. You must create a search index and enable sorting and aggregation for the Timestamp column.
      indexSchema.setIndexSort(new Sort(
              Arrays. <Sort.Sorter>asList(new FieldSort("Timestamp", SortOrder.ASC))));
      request.setIndexSchema(indexSchema);
      client.createSearchIndex(request);
  }