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If you don’t care about any records in the table, as mentioned TRUNCATE TABLE foo will work. If the table has a lot of indices and foreign keys, that might slow things down.
If it’s heavily used, you may not be able to get locks to delete, or once you do get a lock block other stuff.
The index update and Sort operation together take 64% of the execution cost. Removing index on the column to be updated The same query takes 14-18 seconds when there isn’t any index on col1.
The decreased result was similar to earlier Vertica releases before optimized MERGE was available.One thing I’ve found useful in stuff like this one of the few times doing a loop can be effective.Depending on how many rows you really need to delete and how much of an issue blocking (and log size) may be you can try something like this: This will limit the amount of locking that happens and you can monitor things.So, the starting point is that we do not have all of the fields.Updating only two fields does not fulfill the optimized MERGE query plan conditions.
The fastest way to speed up the update query is to replace it with a bulk-insert operation.