Azure数据工厂仅从Blob存储中检索新的Blob文件

Question

I am currently copying blob files from an Azure Blob storage to an Azure SQL Database. It is scheduled to run every 15 minutes but each time it runs it repeatedly imports all blob files. I would rather like to configure it so that it only imports if any new files have arrived into the Blob storage. One thing to note is that the files do not have a date time stamp. All files are present in a single blob container. New files are added to the same blob container. Do you know how to configure this?

Answer 1

I'd preface this answer with a change in your approach may be warranted...

Given what you've described your fairly limited on options. One approach is to have your scheduled job maintain knowledge of what it has already stored into the SQL db. You loop over all the items within the container and check if it has been processed yet.

The container has a ListBlobs method that would work for this. Reference: https://azure.microsoft.com/en-us/documentation/articles/storage-dotnet-how-to-use-blobs/

foreach (var item in container.ListBlobs(null, true))
{
   // Check if it has already been processed or not
}

Note that the number of blobs in the container may be an issue with this approach. If it is too large consider creating a new container per hour/day/week/etc to hold the blobs, assuming you can control this.

Answer 2

Please use CloudBlobContainer. ListBlobs (null, true, BlobListingDetails .Metadata) and check CloudBlob. Properties . LastModified for each listed blob.

Answer 3

Instead of a copy activity, I would use a custom DotNet activity within Azure Data Factory and use the Blob Storage API (some of the answers here have described the use of this API) and Azure SQL API to perform your copy of only the new files.

However, with time, your blob location will have a lot of files, so, expect that your job will start taking longer and longer (after a point taking longer than 15 minutes) as it would iterate through each file every time.

Can you explain your scenario further? Is there a reason you want to add data to the SQL tables every 15 minutes? Can you increase that to copy data every hour? Also, how is this data getting into Blob Storage? Is another Azure service putting it there or is it an external application? If it is another service, consider moving it straight into Azure SQL and cut out the Blob Storage.

Another suggestion would be to create folders for the 15 minute intervals like hhmm. So, for example, a sample folder would be called '0515'. You could even have a parent folder for the year, month and day. This way you can insert the data into these folders in Blob Storage. Data Factory is capable of reading date and time folders and identifying new files that come into the date/time folders.

I hope this helps! If you can provide some more information about your problem, I'd be happy to help you further.