When you perform a wildcard query, you can use the asterisk (*) and question mark (?) wildcard characters in the query to search for data. The asterisk (*) matches a string of any length at, before, or after a search term. The question mark (?) matches a single character in a specific position. The string can start with an asterisk (*) or a question mark (?). For example, if you search for the "table*e" string, "tablestore" can be matched.
If you want to use *word* (equivalent to WHERE field_a LIKE '%word%' in SQL) to query data, you can use fuzzy query for better performance. For more information, see Fuzzy query. If you perform a fuzzy query, the query performance is not compromised when the data volume increases.
If you want to use the NOT LIKE operator, you must use WildcardQuery together with must_not_queries of BoolQuery.
Prerequisites
A TableStoreClient instance is initialized. For more information, see Initialize an OTSClient instance.
A data table is created and data is written to the data table. For more information, see Create a data table and Write data.
A search index is created for the data table. For more information, see Create a search index.
Parameters
Parameter | Description |
query | The type of the query. Set the query parameter to WildcardQuery. |
field_name | The name of the column that you want to query. |
value | The string that contains wildcard characters. The string cannot exceed 32 characters in length. |
table_name | The name of the data table. |
index_name | The name of the search index. |
limit | The maximum number of rows that you want the query to return. |
get_total_count | Specifies whether to return the total number of matched rows. Default value: False. If you set the get_total_count parameter to true, the query performance is compromised. |
ColumnsToGet | Specifies whether to return all columns of rows that meet the query conditions.
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Examples
The following sample code provides examples on how to query rows in which the value of the Col_Keyword column matches the 'tablestor*' pattern.
Tablestore SDK for Python V5.2.1 or later
By default, if you use Tablestore SDK for Python V5.2.1 or later to perform a wildcard query, a SearchResponse object is returned. The following code provides a sample request:
query = WildcardQuery('Col_Keyword', 'tablestor*') search_response = client.search( '<TABLE_NAME>', '<SEARCH_INDEX_NAME>', SearchQuery(query, limit=100, get_total_count=True), ColumnsToGet(return_type=ColumnReturnType.ALL) ) print('request_id : %s' % search_response.request_id) print('is_all_succeed : %s' % search_response.is_all_succeed) print('total_count : %s' % search_response.total_count) print('rows : %s' % search_response.rows) # # If deep pagination is required, we recommend that you use the next_token parameter because this method has no limits on the pagination depth. # all_rows = [] # next_token = None # # first round # search_response = client.search( # '<TABLE_NAME>', '<SEARCH_INDEX_NAME>', # SearchQuery(query, next_token=next_token, limit=100, get_total_count=True), # columns_to_get=ColumnsToGet(return_type=ColumnReturnType.ALL)) # all_rows.extend(search_response.rows) # # # loop # while search_response.next_token: # search_response = client.search( # '<TABLE_NAME>', '<SEARCH_INDEX_NAME>', # SearchQuery(query, next_token=search_response.next_token, limit=100, get_total_count=True), # columns_to_get=ColumnsToGet(return_type=ColumnReturnType.ALL)) # all_rows.extend(search_response.rows) # print('Total rows:%s' % len(all_rows))You can use the following sample request to return results of the Tuple type:
query = WildcardQuery('Col_Keyword', 'tablestor*') rows, next_token, total_count, is_all_succeed, agg_results, group_by_results = client.search( '<TABLE_NAME>', '<SEARCH_INDEX_NAME>', SearchQuery(query, limit=100, get_total_count=True), ColumnsToGet(return_type=ColumnReturnType.ALL) ).v1_response()Tablestore SDK for Python earlier than 5.2.1
If you use a version of Tablestore SDK for Python that is earlier than 5.2.1 to perform a wildcard query, results of the Tuple type are returned by default. The following sample code provides a sample request:
query = WildcardQuery('Col_Keyword', 'tablestor*') rows, next_token, total_count, is_all_succeed = client.search( '<TABLE_NAME>', '<SEARCH_INDEX_NAME>', SearchQuery(query, limit=100, get_total_count=True), ColumnsToGet(return_type=ColumnReturnType.ALL) )
FAQ
References
When you use a search index to query data, you can use the following query methods: term query, terms query, match all query, match query, match phrase query, prefix query, range query, wildcard query, geo query, Boolean query, KNN vector query, nested query, and exists query. You can use the query methods provided by the search index to query data from multiple dimensions based on your business requirements.
You can sort or paginate rows that meet the query conditions by using the sorting and paging features. For more information, see Sorting and paging.
You can use the collapse (distinct) feature to collapse the result set based on a specific column. This way, data of the specified type appears only once in the query results. For more information, see Collapse (distinct).
If you want to analyze data in a data table, you can use the aggregation feature of the Search operation or execute SQL statements. For example, you can obtain the minimum and maximum values, sum, and total number of rows. For more information, see Aggregation and SQL query.
If you want to obtain all rows that meet the query conditions without the need to sort the rows, you can call the ParallelScan and ComputeSplits operations to use the parallel scan feature. For more information, see Parallel scan.