Restricting Azure TableQuery by Entity type

Question

I have a single table in Azure Table Storage (well, actually in the emulator) which contains multiple entity types, two of which are AzureRuleInfo and AzureCostCodeInfo. I want to pull out a range of AzureRuleInfo and AzureCostCodeInfo entities from the same partition.

I started off with two table queries, one for each type, on the assumption that new TableQuery<T>() would return only entities of type T - but it seems to pull back everything that matches the partition key.

TableQuery<AzureRuleInfo> query = new TableQuery<AzureRuleInfo>()
                .Where(TableQuery.GenerateFilterCondition("PartitionKey", QueryComparisons.Equal, financialPeriodId));


TableQuery<AzureCostCodeInfo> query = new TableQuery<AzureCostCodeInfo>()
                .Where(TableQuery.GenerateFilterCondition("PartitionKey", QueryComparisons.Equal, financialPeriodId));

My question is:

• Does the API offer a way of querying by entity type? (Preferably without having to add a custom entity property like "MyEntityType").
• Or am I better off pulling back everything and filtering the results into two separate collections?

This is for a personal app, my first foray into Azure Table Storage, so I don't have any specific design drivers such as performance.

Answer 1

We do not exposed any specialized field for entity types. It needs to be dealt with a custom manner.

Have you looked at working with the heterogeneous entity type section in the following article https://azure.microsoft.com/en-us/documentation/articles/storage-table-design-guide/#working-with-heterogeneous-entity-types.

You can either prepend the entity type to the RowKey or Use a separate property to store the entity type (I think you do not want to do that).

Thanks,

Aung