You can perform a prefix query to query data that matches the specified prefix. If the field used to match the prefix condition is a TEXT field, the field values are tokenized. A row meets the query conditions when at least one token contains the specified prefix.
API operation
You can call the Search or ParallelScan operation and set the query type to PrefixQuery to perform a prefix query.
Parameters
Parameter | Description |
query | The type of the query. Set the query parameter to PrefixQuery. |
fieldName | The name of the column that you want to query. |
prefix | The prefix. If the column used to match the prefix condition is a TEXT column, the column is tokenized. A row meets the query conditions when at least one token contains the specified prefix. |
getTotalCount | Specifies whether to return the total number of rows that meet the query conditions. Default value: false. If you set this parameter to true, the query performance is compromised. |
weight | The weight that you want to assign to the column that you want to query to calculate the BM25-based keyword relevance score. This parameter is used in full-text search scenarios. If you specify a higher weight for the column that you want to query, the BM25-based keyword relevance score is higher for the row. The value of this parameter is a positive floating point number. This parameter does not affect the number of rows that are returned. However, this parameter affects the BM25-based keyword relevance scores of the query results. |
tableName | The name of the data table. |
indexName | The name of the search index. |
columnsToGet | Specifies whether to return all columns of each row that meets the query conditions. You can specify the returnAll and columns fields for this parameter. The default value of the returnAll field is false, which specifies that not all columns are returned. In this case, you can use the columns field to specify the columns that you want to return. If you do not specify the columns that you want to return, only the primary key columns are returned. If you set the returnAll field to true, all columns are returned. |
Methods
You can use the Tablestore console, Tablestore CLI, or Tablestore SDKs to perform a prefix query. Before you perform a prefix query, make sure that the following preparations are made:
You have an Alibaba Cloud account or a RAM user that has permissions to perform operations on Tablestore. For information about how to grant Tablestore operation permissions to a RAM user, see Use a RAM policy to grant permissions to a RAM user.
If you want to use Tablestore SDKs or the Tablestore CLI to perform a query, an AccessKey pair is created for your Alibaba Cloud account or RAM user. For more information, see Create an AccessKey pair.
A data table is created. For more information, see Operations on tables.
A search index is created for the data table. For more information, see Create a search index.
If you want to use Tablestore SDKs to perform a query, an OTSClient instance is initialized. For more information, see Initialize an OTSClient instance.
If you want to use the Tablestore CLI to perform a query, the Tablestore CLI is downloaded and started, and information about the instance that you want to access and the data table are configured. For more information, see Download the Tablestore CLI, Start the Tablestore CLI and configure access information, and Operations on data tables.
Billing rules for
When you use a search index to query data, you are charged for the read throughput that is consumed. For more information, see Billable items of search indexes.
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, fuzzy query, Boolean query, geo query, nested query, KNN vector query, and exists query. You can select query methods based on your business requirements to query data from multiple dimensions.
You can sort or paginate rows that meet the query conditions by using the sorting and paging features. For more information, see Perform 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.