How to query the most recent n records from Azure Table Storage?

Question

I am using the following query in c# .net:

TableQuery<MyType> query = new TableQuery<MyType>().Take(50);

This works in grabbing 50 records, but I want to grab the most recent (descending) records from the table. I have looked at other answers, but none were concise or working.

What is the most efficient way to grab n most recent records from an Azure Table Storage entity? Please provide a concise answer with a working code example.

Edit: I'm particularly interested in how Azure Storage Explorer navigates 'cached items'. I can easily order my results (amongst millions of rows) within Azure Storage Explorer by clicking on the column. This will return me what I want, however, I'm not seeing any documentation on how to access these 'cached items'.

score 1 · Answer 1 · answered Nov 14 '21 at 05:17

1

Unfortunately there is no easy way to fetch latest records from Azure Table Storage as it does not allow you to sort the records on attributes. Records in Azure Table Storage are always sorted by PartitionKey and then by RowKey within a partition.

One way to fix this problem is to specify the PartitionKey value as reverse chronological ticks (something like (DateTime.MaxValue.Ticks - DateTime.UtcNow.Ticks).ToString("d20")) so that whenever you add an entity, it will be prepended (i.e. added to the top of the table). Now when you do the query and fetch "x" number of records, you will always the most recent records.

Other option is to fetch all entities and do the sorting on the client side. This is highly inefficient and is generally not recommended. This solution might work if you have very small number of entities (less than 1000 for example) in your table.

answered Nov 14 '21 at 05:17

Gaurav Mantri

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I have read this answer before, but it does not answer my question because it will not work for data that is already in the table. – jamesdlivesinatree Nov 14 '21 at 17:27
In Azure Storage Explorer, I can order by a column we have called 'Timestamp'. This table has millions of rows, but it orders by 'Timestamp' in under a second. There must be a way to replicate this in code? – jamesdlivesinatree Nov 14 '21 at 17:33
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Azure Storage Explorer does the sorting on the data which is fetched (1000 entities max). – Gaurav Mantri Nov 15 '21 at 00:35
How does it grab and sort these so quickly? How would i replicate in code? – jamesdlivesinatree Nov 18 '21 at 03:34

How to query the most recent n records from Azure Table Storage?

1 Answers1