Tablestore:Use a secondary index to read data

Parameters

When you call the GetRow operation to read data from an index table, take note of the following items:

• You must set the table_name parameter to the name of the index table.

• Tablestore automatically adds the primary key columns of the data table that are not specified as index columns to an index table as the primary key columns of the index table. Therefore, when you specify the primary key columns of a row in an index table, you must specify the index columns based on which you create the index table and the primary key columns of the data table.

Examples

The following sample code provides an example on how to read a row of data in an index table based on the primary key of the row:

$request = [
 'table_name' => '<INDEX_NAME>', // Specify the name of the index table. 
 'primary_key' => [ // Specify the primary key of the row based on which you want to read data. If you want to read data from a local secondary index, the first primary key column of the index table must be the same as the first primary key column of the data table. 
 ['PK0', 123],
 ['Col1', "abc"],
 ['PK1', 'abc']
 ],
 'max_versions' => 1, // Specify that the latest version of data is read. 
 'columns_to_get' => ['Col1'] // Specify the attribute columns that you want to return. 
];
$response = $otsClient->getRow($request); 

Parameters

When you call the GetRange operation to read data from an index table, take note of the following items:

• You must set the table_name parameter to the name of the index table.

• Tablestore automatically adds the primary key columns of the data table that are not specified as index columns to an index table as the primary key columns of the index table. Therefore, when you specify the start primary key and end primary key of the range that you want to query, you must specify the index columns based on which you create the index table and the primary key columns of the data table.

Examples

The following sample code provides an example on how to read data whose primary key values are within a specific range from an index table:

// Query the rows in which the value of the PK0 column is in the range of [1, 4). 
// You must specify values for all primary key columns when you specify a range. If the range does not involve the values of a column, set the value of the column to an infinitely great value (INF_MAX) or an infinitely small value (INF_MIN). 
// If you want to read data from a local secondary index, the first primary key column of the index table must be the same as the first primary key column of the data table. 
$startPK = [
 ['Col1', "abc"], 
 ['PK0', null, PrimaryKeyTypeConst::CONST_INF_MIN] // INF_MIN indicates the minimum value. 
 ['PK1', null, PrimaryKeyTypeConst::CONST_INF_MIN] // INF_MIN indicates the minimum value. 
];
// You must specify values for all primary key columns when you specify a range. If the range does not involve the values of a column, set the value of the column to an infinitely great value (INF_MAX) or an infinitely small value (INF_MIN). 
$endPK = [
 ['Col1', "abc"],
 ['PK0', null, PrimaryKeyTypeConst::CONST_INF_MAX] // INF_MAX indicates the maximum value. 
 ['PK1', null, PrimaryKeyTypeConst::CONST_INF_MAX] // INF_MAX indicates the maximum value. 
];
$request = [
 'table_name' => '<INDEX_NAME>', // Specify the name of the index table. 
 'max_versions' => 1, // Specify that the latest version of data is read. 
 'direction' => DirectionConst::CONST_FORWARD, // Query data in the forward direction. 
 'inclusive_start_primary_key' => $startPK, // Specify the start primary key. 
 'exclusive_end_primary_key' => $endPK, // Specify the end primary key. 
 'limit' => 10 // Specify that up to 10 rows of data can be returned. 
];
$response = $otsClient->getRange ($request);
print "Read CU Consumed: {$response['consumed']['capacity_unit']['read']}\n";

foreach ($response['rows'] as $rowData) {
 // Process each row of data. 
}