/// <summary>
/// Initiates a Search object to Scan a DynamoDB table, with the
/// specified config.
///
/// No calls are made until the Search object is used.
/// </summary>
/// <param name="config">Configuration to use.</param>
/// <returns>Resultant Search container.</returns>
public Search Scan(ScanOperationConfig config)
{
var currentConfig = config ?? new ScanOperationConfig();
Search ret = new Search(SearchType.Scan);
ret.SourceTable = this;
ret.TableName = TableName;
ret.Limit = currentConfig.Limit;
ret.Filter = currentConfig.Filter;
ret.AttributesToGet = currentConfig.AttributesToGet;
return ret;
}
/// <summary>
/// A utility method for cleaning up expired sessions that IIS failed to delete. The method performs a scan on the table
/// with a condition that the expiration date is in the past and calls delete on all the keys returned. Scans can be costly on performance
/// so use this method sparingly like a nightly or weekly clean job.
/// </summary>
/// <param name="dbClient">The AmazonDynamoDB client used to find a delete expired sessions.</param>
/// <param name="tableName">The table to search.</param>
public static void DeleteExpiredSessions(AmazonDynamoDB dbClient, string tableName)
{
Table table = Table.LoadTable(dbClient, tableName, Table.DynamoDBConsumer.SessionStateProvider);
ScanFilter filter = new ScanFilter();
filter.AddCondition(ATTRIBUTE_EXPIRES, ScanOperator.LessThan, DateTime.Now);
ScanOperationConfig config = new ScanOperationConfig();
config.AttributesToGet = new List<string>();
config.AttributesToGet.Add(ATTRIBUTE_SESSION_ID);
config.Filter = filter;
Search search = table.Scan(config);
do
{
List<Document> page = search.GetNextSet();
foreach (var document in page)
{
table.DeleteItem(document);
}
} while (!search.IsDone);
}
