Method GetQueryAsyncEnumerable

GetQueryAsyncEnumerable(String, QueryOptions, CancellationToken)

Returns IAsyncEnumerable<T> to query a table based on the query statement.
Declaration
public IAsyncEnumerable<QueryResult<RecordValue>> GetQueryAsyncEnumerable(string statement, QueryOptions options = null, CancellationToken cancellationToken = null)
Parameters
Type Name Description
String statement Query SQL statement.
QueryOptions options (Optional) Options for the Query operation. If not specified or null, appropriate defaults will be used. See QueryOptions.
CancellationToken cancellationToken (Optional) Cancellation token.
Returns
Type Description
IAsyncEnumerable<QueryResult<RecordValue>> Async enumerable to iterate over QueryResult<TRow> objects.
Remarks

This API facilitates iteration over the query results and is equivalent to executing QueryAsync(String, QueryOptions, CancellationToken) in a loop with the continuation key. The iteration over query results is necessary because of the limitations on the amount of data read during each query request as described in QueryAsync(String, QueryOptions, CancellationToken).

Use this API with await foreach construct to iterate over the resulting IAsyncEnumerable<T>. Each iteration of the loop produces QueryResult<TRow> which in turn may contain multiple result records, so a nested loop would be needed to iterate over each result record as shown in the example.

Note that this method itself may only throw ArgumentException. Other exceptions listed can only be thrown during the iteration process as per deferred execution semantics of enumerables.

Examples
Asynchronously iterating over GetQueryAsyncEnumerable. 
await foreach(var result in client.GetQueryAsyncEnumerable(
    "SELECT * FROM myTable"))
{
    foreach(var row in result.Rows)
    {
        // row is an instance of RecordValue
        Console.WriteLine($"Id: {row["id"]}, Name: {row["name"]}");
    }
}
Exceptions
Type Condition
ArgumentException If statement is null or invalid or options contains invalid values.
TimeoutException Operation has timed out.
InvalidOperationException The table or the service is not in a valid state to perform this operation.
NoSQLException NoSQLException or one of its subclasses is thrown if operation cannot be performed for any other reason. See documentation for corresponding subclass of NoSQLException.
See Also

GetQueryAsyncEnumerable(PreparedStatement, QueryOptions, CancellationToken)

Returns IAsyncEnumerable<T> to query a table based on the prepared query statement.
Declaration
public IAsyncEnumerable<QueryResult<RecordValue>> GetQueryAsyncEnumerable(PreparedStatement preparedStatement, QueryOptions options = null, CancellationToken cancellationToken = null)
Parameters
Type Name Description
PreparedStatement preparedStatement Prepared query statement.
QueryOptions options (Optional) Options for the Query operation. If not specified or null, appropriate defaults will be used. See QueryOptions.
CancellationToken cancellationToken (Optional) Cancellation token.
Returns
Type Description
IAsyncEnumerable<QueryResult<RecordValue>> Async enumerable to iterate over QueryResult<TRow> objects.
Remarks
This method is similar to GetQueryAsyncEnumerable(String, QueryOptions, CancellationToken) but it executes a query that has been prepared as PreparedStatement via PrepareAsync(String, PrepareOptions, CancellationToken).
Exceptions
Type Condition
ArgumentException If preparedStatement is null or invalid or options contains invalid values or if the statement uses external variables and there is a variable that was not bound or if a variable was bound that is not present in the query.
TimeoutException Operation has timed out.
InvalidOperationException The table or the service is not in a valid state to perform this operation.
NoSQLException NoSQLException or one of its subclasses is thrown if operation cannot be performed for any other reason. See documentation for corresponding subclass of NoSQLException.
See Also