At times we see delete vectors for a table when we have only run drop partition not delete . My understanding was drop partition should not create delete vector . Please confirm
Yes, it doesn't create delete vectors. Please provide a way to reproduce this and I can look at it but on paper this should never happen but I'm guessing that if you saw those they were unrelated.
As Flavien said, drop partition DOES NO create delete vectors. Drop partition for vertica is almost the same to do rm of the file. Delete vectors are created with deletes and updates. Vertica never update a file so when you delete and update, vertica will create a separated file with the epoch and position of the record that you are deleting. Those are the delete vectors. Delete vectors are associated with one ros container and a ros container can have many delete vectors. those delete vectors eventually merge with the ros container. In the way that are merges is vertica create a new file that will have the ros data minus the rows marked to be deleted in the delete vectors. Once that new file is created vertica removes the old ros and the delete vector. When you drop a parition, you are telling vertica removes all the files that make that partition. If it is an inacative partition, it may be just one file ( as vertica always try to merge roses from inactive partition). If it is active partition, it will remove all the roses that belong to that partition.
Comments
Please provide a way to reproduce this and I can look at it but on paper this should never happen but I'm guessing that if you saw those they were unrelated.
As Flavien said, drop partition DOES NO create delete vectors. Drop partition for vertica is almost the same to do rm of the file. Delete vectors are created with deletes and updates. Vertica never update a file so when you delete and update, vertica will create a separated file with the epoch and position of the record that you are deleting. Those are the delete vectors. Delete vectors are associated with one ros container and a ros container can have many delete vectors. those delete vectors eventually merge with the ros container. In the way that are merges is vertica create a new file that will have the ros data minus the rows marked to be deleted in the delete vectors. Once that new file is created vertica removes the old ros and the delete vector. When you drop a parition, you are telling vertica removes all the files that make that partition. If it is an inacative partition, it may be just one file ( as vertica always try to merge roses from inactive partition). If it is active partition, it will remove all the roses that belong to that partition.
Hope this clarify better how the drop work.
Thanks,
Eugenia