drop partiton vs truncate partition?
I am new to partitioning in oracle and just trying to understand major differences between drop partition and truncate partition?
I do understand differences between local and globasl indexes and the ramifications of global indexes becoming unsable.
So lets say that I have a very large table which is using a range partiton by day and each daily partiton is roughly 100gb.
We would like to only keep 3 months data in the table and we want to archive off the partitons to tape by doing a daily data pump export of the previous days partiton to a .dmp file and then just simply send that off to tape.
Once the oldest partition goes past three months we were planning to drop the oldest parttion. IN the event that we would need to restore that days parttion we would the add the parttion back and datapump the data back in from the .dmp file.
This table uses only local indexes.
Is there any reason why we wouldn't just truncate the older parttions so that in the event we would want to restore some partiton at a later date we wouldn't have to recreate the partitition before using datapump to import the partitons data?
We would want to truncate so that we could also use the sapce that we previously consumed by the partiton.
IN this case is there any performance differences between drop and truncate from a overall system/IO prespective?
Thanks.