Timestamp query in Azure

Question

I am really stuck in my query filter on Azure table storage. May I know how to query with timestamp please? When I query for partition key to 1005 alone, I am getting the complete table which I don't want. When I added "and" condition with timestamp (tried with lots of formats but it is not returning anything. Code snippet below :

var lowerlimit = DateTime.Today.AddDays(-52).ToString("yyyy-MM-dd");

string dateRangeFilter = TableQuery.CombineFilters(
    TableQuery.GenerateFilterCondition("PartitionKey", QueryComparisons.Equal, "1005"),
    TableOperators.And,
    TableQuery.GenerateFilterCondition("TimeStamp", QueryComparisons.GreaterThanOrEqual, lowerlimit));

Answer 1

I am able to use the Timestamp with Microsoft.WindowsAzure.Storage version 4.0.1.0. Just and example

var query = TableQuery.CombineFilters(
            TableQuery.GenerateFilterCondition("Level", QueryComparisons.Equal, "ERROR"), 
            TableOperators.And, 
            TableQuery.GenerateFilterConditionForDate("Timestamp", QueryComparisons.GreaterThanOrEqual, DateTimeOffset.Now.AddDays(-20).Date));

var query2 = TableQuery.CombineFilters(query,
            TableOperators.And, 
            TableQuery.GenerateFilterConditionForDate("Timestamp", QueryComparisons.LessThanOrEqual, DateTimeOffset.Now));

var exQuery = new TableQuery<LogEntry>().Where(query2);

CloudTableClient tableClient = _storageAccount.CreateCloudTableClient();

CloudTable table = tableClient.GetTableReference(_tableName);
var results = table.ExecuteQuery(exQuery).Select(ent => (T) ent).ToList();

Answer 2

Property names are case-sensitive. It should be Timestamp and not TimeStamp.

Answer 3

Timestamp can be used to query rows in Azure Table Storage.

However, you will need to use TableQuery.GenerateFilterConditionForDate instead of TableQuery.GenerateFilterCondition. For any DateTime column, TableQuery.GenerateFilterConditionForDate must be used.

From your code sample, change GenerateFilterCondition to GenerateFilterConditionForDate for Timestamp filter:

var lowerlimit = DateTime.Today.AddDays(-52).ToString("yyyy-MM-dd");

string dateRangeFilter = TableQuery.CombineFilters(
    TableQuery.GenerateFilterCondition("PartitionKey", QueryComparisons.Equal, "1005"),
    TableOperators.And,
    TableQuery.GenerateFilterConditionForDate("TimeStamp", QueryComparisons.GreaterThanOrEqual, lowerlimit));

Answer 4

If this is a diagnostics table (e.g. WADLogsTable) I suggest you convert your timestamp to a partition key, then query on that. This would avoid a full table scan since it is an indexed column. Conversion is simple, just prepend "0" to the ticks.

var lowerlimitPartitionKey = DateTimeToPartitionKey(lowerlimit);

// Now query PartitionKey >= lowerlimitPartitionKey
...

where

private string DateTimeToPartitionKey(DateTime dt)
{
    return "0" + dt.Ticks;
}