public IEnumerable <T> Enumerate(params Expression[] conditions) // Scans the entire table
{
// Each scan may return upto 1MB of data
// TODO, consider parellel scans
DynamoExpression filterExpression = null;
if (conditions.Length > 0)
{
filterExpression = DynamoExpression.Conjunction(conditions);
}
var result = new QueryResult();
do
{
var request = new ScanRequest(tableName)
{
Limit = 1000,
ExclusiveStartKey = result.LastEvaluatedKey
};
if (filterExpression != null)
{
request.SetFilterExpression(filterExpression);
}
result = client.Scan(request).Result;
// If LastEvaluatedKey is null, then the "last page" of results has been processed and there is no more data to be retrieved.
// If LastEvaluatedKey is anything other than null, this does not necessarily mean that there is more data in the result set.
// The only way to know when you have reached the end of the result set is when LastEvaluatedKey is null.
foreach (var item in result.Items)
{
yield return(item.As <T>(metadata));
}
}while (result.LastEvaluatedKey != null);
}
public async Task <IList <T> > ScanAsync(IEnumerable <KeyValuePair <string, object> > startKey = null,
Expression[] conditions = null,
int take = 1000)
{
var request = new ScanRequest(tableName)
{
Limit = take
};
if (conditions != null && conditions.Length > 0)
{
request.SetFilterExpression(DynamoExpression.Conjunction(conditions));
}
if (startKey != null)
{
request.ExclusiveStartKey = AttributeCollection.FromJson(startKey.ToJson());
}
var result = await client.Scan(request).ConfigureAwait(false);
return(new QueryResult <T>(result));
}