This could also be considered when using workarounds like the one from above. CTAS operations writing to clustered columnstore index tables perform better using a higher resource class.See this post by Stephan Köppen for details. Remember to wrap the delete and the insert into a single transaction. row_number() modulo something) into #DupKeyStore and to use this key for splitting into batches. Since delete top(nnn) is not supported on PDW, SET ROWCOUNT does not work either here and you also don’t have a a good approach is add “cluster-column” (e.g. For a larger amount of rows, these statements should be split to batches having one transaction for a bunch of keys. The delete/insert operations require tempdb space.If there are too many duplicates (I would say more than 5% of the total rows) consider the CTAS operation instead of the delete/insert operation. You can get it on my This is a small 18 x 6 subset of this dataset orders table as you can see below. Before deleting any data You can’t undo data deletions, so make sure your database is ready before you try to delete duplicate records: Make sure that the file is not read-only. Note: The methods described in this article do not apply to Access web apps. Check the number of duplicates first (table #DupKeyStore). The first step is to Find duplicate records with a query in your database.And having more compute nodes would result in a much shorter query time for this task.īefore extending this solution to even more rows, consider the following topics: Compared to the 1 hour 15 minutes using the first approach, this is a huge performance boost. The insert was quite fast, only taking 30 seconds.Īt a total of 4 minutes the 2.5 billion rows were cleaned from duplicates.
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