The Rain and The Shade

July 8, 2011

Using Reverse Time Stamp in TableStorage

Filed under: Table Storage,Windows Azure — ovaisakhter @ 11:59 am

When you read about the Azure Table Storage one of the earlier things you come to know is that there are only two (properties) fields in the stored Entities which are indexed. i.e. PartitionKey and RowKey.

All the records inside a partition are indexed by RowKey and are also automatically sorted on the RowKey also. I can say that if you can design your key in such a way that the records are always sorted in a way which is more suitable for most of your data access scenarios then you can save a lot processing and get much better performance.

In a lot cases the records should be sorted by their date of creation, so new records should be shown first. In TableStorage you get a property in every entity called TimeStamp which could be the first choice normally in this case for Ordering(good old SQL days ). When you go on and write your LINQ query with OrderBy the first thing you will get will be an error at the runtime. Because table storage does not supports OrderBy.

In TableStorage you can use a TimeStamp in the beginning your RowKey to get the records sorted by time of creation, and if you want to get the new records first you can reverse the timestamp. Here is an interesting code I have used which can do that for you.

string myRowKey = DateTime.MaxValue – DateTime.UtcNow).Ticks.ToString(“d19”)

//think I saw this code in one of the CloudCover videos by Steve Marx

so you can create your key like Entity.RowKey = myRowKey+whatOtherwiseCouldHavebeenMyRowKey+SomethingElseIfYoureallyWantto and when get your records they will be nicely sorted on the date of creation.

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