Table of Contents
How can I speed up my deletion?
5 Answers
- Make sure your log is adequately sized so that growth events don’t slow you down.
- If you are deleting the whole table, use TRUNCATE or DROP / CREATE .
- If you are deleting most of the table, use SELECT INTO to put the data you want to keep into another table, then TRUNCATE , then move the small portion back.
Why delete is slow?
Things that can cause a delete to be slow: deleting a lot of records. many indexes. cascade delete (those ten parent records you are deleting could mean millions of child records getting deleted)
Why does Windows take forever to delete?
Why Windows 10 Deleting Files Takes Long Time Hard disk drive not running well. Conflicts with other programs. Problematic file system. Too many or too large files.
Which is faster delete or truncate?
TRUNCATE is faster than DELETE , as it doesn’t scan every record before removing it. TRUNCATE TABLE locks the whole table to remove data from a table; thus, this command also uses less transaction space than DELETE . Unlike DELETE , TRUNCATE does not return the number of rows deleted from the table.
What is the fastest way to delete large numbers?
Tap on the Windows-key, type cmd.exe and select the result to load the command prompt. Navigate to the folder that you want to delete (with all its files and subfolders). Use cd path, e.g. cd o:\backups\test\ to do so. The command DEL /F/Q/S *.
Is the merge from a temp table slow?
Okay – so basically the MERGE from a temp table is VERY fast, doing it by processing ‘fixed values’ in a SELECT statement, is EXTREMELY slow. So basically do not do a MERGE unless it is from another table (for non trivial data volumes) – Agent96 Jun 10 ’16 at 14:22 Yes, precisely so it is.
Why is merge so slow in Power BI?
The issue we are seeing is this – the “merge” step itself DOESN’T push down to the database…it pulls in the whole table, which on a 15 million row dimension table takes forever. Once the merge step is done and you click on the “expand column” icon to expand out a few columns – that DOES get pushed to the database, so it’s very fast.
Why is delete so slow in SQL Server?
It requires a thorough testing, would be better if you can test for the chunk value in UAT first. delete can be slow if big table has recursive foreign key. if so, find opportune time, disable dependend services, disable recursive foreign key, perform massive delete, then restore foreign key again. this was exactlly my case.
When to use update or merge in SQL Server?
Actually i’ve found out general recommendations for such a queries: Idea to use SQL Merge or Update is a very clever one but it fails when we need to update many records (i.e. 75M) in a big and wide table (i.e. 240M ). Looking at the query plan of the query below we can say that TABLE SCAN of TABLE1 and final MERGE are taking 90% of time.
Okay – so basically the MERGE from a temp table is VERY fast, doing it by processing ‘fixed values’ in a SELECT statement, is EXTREMELY slow. So basically do not do a MERGE unless it is from another table (for non trivial data volumes) – Agent96 Jun 10 ’16 at 14:22 Yes, precisely so it is.
It requires a thorough testing, would be better if you can test for the chunk value in UAT first. delete can be slow if big table has recursive foreign key. if so, find opportune time, disable dependend services, disable recursive foreign key, perform massive delete, then restore foreign key again. this was exactlly my case.
How long does it take to merge rows in SQL?
To give an indication of performance, for 38k rows with a straight INSERT statement, the time is 8 seconds, with a MERGE it is 3 minutes. This time seems to increase exponentially as the number of rows increases (90k rows=23mins).
How to speed up the DELETE statement in SQL?
In either event, make sure you have an index on column [COL] to speed up the table scan. If you’re deleting all the records in the table rather than a select few it may be much faster to just drop and recreate the table.