Tablestore:Configure a filter

Prerequisites

• An OTSClient 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.

Usage notes

When you call the GetRow, BatchGetRow, or GetRange operation to query data, you can use a filter to return only the rows that match the filter conditions.

The available filters are SingleColumnValueFilter, SingleColumnValueRegexFilter, and CompositeColumnValueFilter.

• SingleColumnValueFilter determines whether to filter a row based on the value of a reference column.

• SingleColumnValueRegexFilter uses regular expressions to match column values of the String type and extract matched substrings. Then, this filter converts the data type of the extracted substrings to String, Integer, or Double and filters the values after conversion.

• CompositeColumnValueFilter determines whether to filter a row based on a logical combination of the matching results for the values of multiple reference columns.

Precautions

• Filter conditions support relational operators of =, !=, >, >=, <, and <= and logical operators of NOT, AND, and OR. A filter condition can include up to 10 subconditions.

• The reference columns that are used by a filter must be included in the query results. If the specified columns from which data is read do not include reference columns, the filter cannot query the values of reference columns.

• When you use the GetRange operation, up to 5,000 rows or 4 MB of data can be scanned at a time.

  If no data matches the filter conditions in the range of the scan, the returned rows are empty. However, NextStartPrimaryKey may not be empty. If NextStartPrimaryKey is not empty, use the parameter value to continue scanning until the return value of NextStartPrimaryKey is empty.

Parameters

Examples

private static void getRow(SyncClient client, String pkValue) {
    // Construct the primary key. 
    PrimaryKeyBuilder primaryKeyBuilder = PrimaryKeyBuilder.createPrimaryKeyBuilder();
    primaryKeyBuilder.addPrimaryKeyColumn("pk", PrimaryKeyValue.fromString(pkValue));
    PrimaryKey primaryKey = primaryKeyBuilder.build();

    // Specify the table name and primary key to read a row of data. 
    SingleRowQueryCriteria criteria = new SingleRowQueryCriteria("<TABLE_NAME>", primaryKey);
    // Set the MaxVersions parameter to 1 to read the latest version of data. 
    criteria.setMaxVersions(1);

    // Configure a filter to return a row in which the value of the Col0 column is 0. 
    SingleColumnValueFilter singleColumnValueFilter = new SingleColumnValueFilter("Col0",
            SingleColumnValueFilter.CompareOperator.EQUAL, ColumnValue.fromLong(0));
    // If the Col0 column does not exist, the row is not returned. 
    singleColumnValueFilter.setPassIfMissing(false);
    criteria.setFilter(singleColumnValueFilter);

    GetRowResponse getRowResponse = client.getRow(new GetRowRequest(criteria));
    Row row = getRowResponse.getRow();

    System.out.println("Read complete. Result:");
    System.out.println(row);
}

private static void getRange(SyncClient client) {
    // Specify the name of the data table. 
    RangeRowQueryCriteria criteria = new RangeRowQueryCriteria("<TABLE_NAME>");
 
    // Specify ["pk:2020-01-01.log", "pk:2021-01-01.log") as the range of the primary key of the data that you want to read. The range is a left-closed and right-open interval. 
    PrimaryKey pk0 = PrimaryKeyBuilder.createPrimaryKeyBuilder()
        .addPrimaryKeyColumn("pk", PrimaryKeyValue.fromString("2020-01-01.log"))
        .build();
    PrimaryKey pk1 = PrimaryKeyBuilder.createPrimaryKeyBuilder()
        .addPrimaryKeyColumn("pk", PrimaryKeyValue.fromString("2021-01-01.log"))
        .build();
    criteria.setInclusiveStartPrimaryKey(pk0);
    criteria.setExclusiveEndPrimaryKey(pk1);
 
    // Set the MaxVersions parameter to 1 to read the latest version of data. 
    criteria.setMaxVersions(1);
 
    // Configure a filter. A row is returned when cast<int>(regex(Col1)) is greater than 100. 
    RegexRule regexRule = new RegexRule("t1:([0-9]+),", RegexRule.CastType.VT_INTEGER);
    SingleColumnValueRegexFilter filter =  new SingleColumnValueRegexFilter("Col1",
        regexRule,SingleColumnValueRegexFilter.CompareOperator.GREATER_THAN,ColumnValue.fromLong(100));
    criteria.setFilter(filter);

    while (true) {
        GetRangeResponse resp = client.getRange(new GetRangeRequest(criteria));
        for (Row row : resp.getRows()) {
            // do something
            System.out.println(row);
        }
        if (resp.getNextStartPrimaryKey() != null) {
            criteria.setInclusiveStartPrimaryKey(resp.getNextStartPrimaryKey());
        } else {
            break;
        }
   }
}

private static void getRange(SyncClient client) {
    // Specify the name of the data table. 
    RangeRowQueryCriteria criteria = new RangeRowQueryCriteria("<TABLE_NAME>");

    // Specify the primary key range. The primary key range is a left-closed and right-open interval. 
    PrimaryKey pk0 = PrimaryKeyBuilder.createPrimaryKeyBuilder()
            .addPrimaryKeyColumn("pk", PrimaryKeyValue.fromString("a"))
            .build();
    PrimaryKey pk1 = PrimaryKeyBuilder.createPrimaryKeyBuilder()
            .addPrimaryKeyColumn("pk", PrimaryKeyValue.fromString("h"))
            .build();
    criteria.setInclusiveStartPrimaryKey(pk0);
    criteria.setExclusiveEndPrimaryKey(pk1);

    // Set the maxVersions parameter to 1 to read the latest version of data. 
    criteria.setMaxVersions(1);

    // Set the composite1 condition to (Col0 == 0) AND (Col1 > 100). 
    CompositeColumnValueFilter composite1 = new CompositeColumnValueFilter(CompositeColumnValueFilter.LogicOperator.AND);
    SingleColumnValueFilter single1 = new SingleColumnValueFilter("Col0",
            SingleColumnValueFilter.CompareOperator.EQUAL, ColumnValue.fromLong(0));
    SingleColumnValueFilter single2 = new SingleColumnValueFilter("Col1",
            SingleColumnValueFilter.CompareOperator.GREATER_THAN, ColumnValue.fromLong(100));
    composite1.addFilter(single1);
    composite1.addFilter(single2);

    // Set the composite2 condition to ( (Col0 == 0) AND (Col1 > 100) ) OR (Col2 <= 10). 
    CompositeColumnValueFilter composite2 = new CompositeColumnValueFilter(CompositeColumnValueFilter.LogicOperator.OR);
    SingleColumnValueFilter single3 = new SingleColumnValueFilter("Col2",
            SingleColumnValueFilter.CompareOperator.LESS_EQUAL, ColumnValue.fromLong(10));
    composite2.addFilter(composite1);
    composite2.addFilter(single3);
    criteria.setFilter(composite2);

    while (true) {
        GetRangeResponse resp = client.getRange(new GetRangeRequest(criteria));
        for (Row row : resp.getRows()) {
            // do something
            System.out.println(row);
        }
        if (resp.getNextStartPrimaryKey() != null) {
            criteria.setInclusiveStartPrimaryKey(resp.getNextStartPrimaryKey());
        } else {
            break;
        }
    }
}

References

• If an application needs to use different attribute columns as query conditions to query data, you can specify the attribute columns as the primary key columns of a secondary index. This way, you can use the secondary index to query data based on the attribute columns. This accelerates data queries. For more information, see Secondary index.

• If your business requires multi-dimensional queries and data analysis, you can create a search index and specify the required attribute columns as the fields of the search index. Then, you can query and analyze data by using the search index. For example, you can use a search index to perform queries based on non-primary key columns, Boolean queries, and fuzzy queries. You can also use a search index to obtain the maximum and minimum values, collect statistics about the number of rows, and group query results. For more information, see Search index.

• You can use the SQL query feature to query and analyze data in a table. For more information, see Query data.