Wildcard queries in Tablestore SDK for Node.js use the * and ? characters to construct matching patterns and query data that matches the patterns in Keyword, Text, or FuzzyKeyword fields.
If the query pattern is *word* (equivalent to WHERE field_a LIKE '%word%' in SQL), you can use the token-based wildcard queries feature for better performance. The performance does not degrade as the data size increases.
To perform a NOT LIKE search, use a WildcardQuery with the mustNotQueries parameter of a BoolQuery.
Prerequisites
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An OTSClient instance is initialized. For more information, see Initialize an OTSClient instance.
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A data table is created and data is written to the data table. For more information, see Create data tables and Write data.
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A search index is created for the data table. For more information, see Create a search index.
Parameters
|
Parameter |
Description |
|
tableName |
The name of the data table. |
|
indexName |
The name of the search index. |
|
offset |
The position from which the current query starts. |
|
limit |
The maximum number of rows that you want the current query to return. |
|
queryType |
The query type. Set this parameter to TableStore.QueryType.WILDCARD_QUERY. |
|
fieldName |
The name of the column that you want to query. |
|
value |
The string that contains wildcard characters. The string can be up to 32 characters in length. |
|
getTotalCount |
Specifies whether to return the total number of rows that match the query conditions. By default, the value of this parameter is false, which indicates that the total number of rows that meet the query conditions is not returned. If you set the getTotalCount parameter to true, the query performance is compromised. |
|
columnToGet |
Specifies whether to return all columns of each row that meets the query conditions. You can configure returnType and returnNames for this parameter.
|
Examples
The following sample code searches for rows in which the value of Col_Keyword matches the "table*e" string.
/**
* Search the table for rows in which the value of Col_Keyword matches "table*e".
*/
client.search({
tableName: TABLE_NAME,
indexName: INDEX_NAME,
searchQuery: {
offset: 0,
limit: 10, // To query only the number of rows that meet the query conditions without returning specific data, you can set limit to 0. This way, Tablestore returns the number of rows that meet the query conditions without specific data from the table.
query: { // Set the query type to TableStore.QueryType.WILDCARD_QUERY.
queryType: TableStore.QueryType.WILDCARD_QUERY,
query: {
fieldName: "Col_Keyword",
value: "table*e" // Specify a string that contains one or more wildcard characters in a wildcard query.
}
},
getTotalCount: true // Specify whether to return the total number of rows that meet the query conditions. The default value of this parameter is false, which indicates that the total number of rows that meet the query conditions is not returned.
},
columnToGet: { // Specify the columns that you want to return. You can set the parameter to RETURN_SPECIFIED to return specified columns, RETURN_ALL to return all columns, RETURN_ALL_FROM_INDEX to return all columns in the search index, or RETURN_NONE to return only the primary key columns.
returnType: TableStore.ColumnReturnType.RETURN_ALL
}
}, function (err, data) {
if (err) {
console.log('error:', err);
return;
}
console.log('success:', JSON.stringify(data, null, 2));
});
FAQ
References
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The following query types are supported by search indexes: term query, terms query, match all query, match query, match phrase query, prefix query, range query, wildcard query, Boolean query, geo query, nested query, vector query, and exists query. You can select a query type to query data based on your business requirements.
If you want to sort or paginate the rows that meet the query conditions, you can use the sorting and paging feature. For more information, see Sorting and paging.
If you want to collapse the result set based on a specific column, you can use the collapse (distinct) feature. This way, data of the specified type appears only once in the query results. For more information, see Collapse (distinct).
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If you want to analyze data in a data table, such as obtaining the extreme values, sum, and total number of rows, you can perform aggregation operations or execute SQL statements. For more information, see Aggregation and SQL query.
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If you want to quickly 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.