Skip to main content

How we can remove millions of entities from a Windows Azure Table (part 2)

In one of my latest post I tacked about how we can remove a lot of entities from Windows Azure – deleting the table.
This solution works but we will have to face up with an odd problem. When we are deleting a table, we only mark it for deletion, our client will not be able to access the table and in background Windows Azure will start deleting the table. If we have a table with millions of entities will face up with a big problem. Until Windows Azure will finish deletion of the table will not be able to create a new table with the same time.
This can be a blocker. We don’t want to wait 4 hours, until our table is deleted to be able to recreate another one.
And here is a big BUT. We can be smart and use ListTables. Basically we can create another table that have the name something like [MyTableName]+[Guid] and using ListTable method to retrieve the name of our table only using [MyTableName].
Using this solution, we can add mark our old table for delegation and create a new table with a similar name where we can store our entities. In this way we will be able to remove items from a table in only a few seconds.  Even if this “virtual” clean it works great and can speed up our applications.
The following code can be used to delete a table:
CloudTableClient tableStorage = new CloudTableClient([tableUri],[credential]);
string tableName = [MyTableName];
tableName = tableStorage.ListTables(tableName).FirstOrDefault();
if (tableName != null)
{
  tableStorage.DeleteTableIfExist(tableName);
}
The following code can be used to retrieve the name of our table and recreate a new table of don’t exist:
string tableName = tableStorage.ListTables([MyTableName]).FirstOrDefault();
if (tableName == null)
{
  tableName = [MyTableName] + Guid.NewGuid();
  tableStorage.CreateTableIfNotExist(tableName);
}

The only downside of this solution is that there are some seconds when we will not have a table where clients can access it. If we can leave with this solution and we can manage this problem on the client side than we can use it without any kind of problem.

Comments

  1. The question is: why/when would you need to do something like this is a real application? :)
    (sure, for testing/debugging scenarios it might be useful, but other than that..)

    ReplyDelete
    Replies
    1. There are times when you need to clean a table very fast. For example a table that store the assignment between updates and system where this update is available.

      Delete

Post a Comment

Popular posts from this blog

Windows Docker Containers can make WIN32 API calls, use COM and ASP.NET WebForms

After the last post , I received two interesting questions related to Docker and Windows. People were interested if we do Win32 API calls from a Docker container and if there is support for COM. WIN32 Support To test calls to WIN32 API, let’s try to populate SYSTEM_INFO class. [StructLayout(LayoutKind.Sequential)] public struct SYSTEM_INFO { public uint dwOemId; public uint dwPageSize; public uint lpMinimumApplicationAddress; public uint lpMaximumApplicationAddress; public uint dwActiveProcessorMask; public uint dwNumberOfProcessors; public uint dwProcessorType; public uint dwAllocationGranularity; public uint dwProcessorLevel; public uint dwProcessorRevision; } ... [DllImport("kernel32")] static extern void GetSystemInfo(ref SYSTEM_INFO pSI); ... SYSTEM_INFO pSI = new SYSTEM_INFO(

Azure AD and AWS Cognito side-by-side

In the last few weeks, I was involved in multiple opportunities on Microsoft Azure and Amazon, where we had to analyse AWS Cognito, Azure AD and other solutions that are available on the market. I decided to consolidate in one post all features and differences that I identified for both of them that we should need to take into account. Take into account that Azure AD is an identity and access management services well integrated with Microsoft stack. In comparison, AWS Cognito is just a user sign-up, sign-in and access control and nothing more. The focus is not on the main features, is more on small things that can make a difference when you want to decide where we want to store and manage our users.  This information might be useful in the future when we need to decide where we want to keep and manage our users.  Feature Azure AD (B2C, B2C) AWS Cognito Access token lifetime Default 1h – the value is configurable 1h – cannot be modified

What to do when you hit the throughput limits of Azure Storage (Blobs)

In this post we will talk about how we can detect when we hit a throughput limit of Azure Storage and what we can do in that moment. Context If we take a look on Scalability Targets of Azure Storage ( https://azure.microsoft.com/en-us/documentation/articles/storage-scalability-targets/ ) we will observe that the limits are prety high. But, based on our business logic we can end up at this limits. If you create a system that is hitted by a high number of device, you can hit easily the total number of requests rate that can be done on a Storage Account. This limits on Azure is 20.000 IOPS (entities or messages per second) where (and this is very important) the size of the request is 1KB. Normally, if you make a load tests where 20.000 clients will hit different blobs storages from the same Azure Storage Account, this limits can be reached. How we can detect this problem? From client, we can detect that this limits was reached based on the HTTP error code that is returned by HTTP