All imports/exports talked about here are using datapump, the 10.1.5 system is running on Windows Server 2003 and the 11.2 system is running on Linux.
I have an 11gig datapump dumpfile from a 10.1.5 database that I need to import into a 11.2.0 database and it's taking about 6 hours - much longer than I would expect. Once the data is imported, further exports/imports of the same schema on 11.2 run much faster - typically in about 25 minutes.
The import takes about between 5h30m and 6h30m hours on a reasonably high powered server. We've tried on a few different machines running Centos and Oracle Linux, with raided disks and with SSD's and nothing seems to have much impact on the time. (I've also tried various datapump options like parallel, or direct path with no impact). The logs look normal with no errors presented - it's just extremely slow.
The slowness occurs during the actual table data loading, rather than the index or constraint creation at the end.
Once I have the data imported, I can export it in about 25 minutes, and import it back in about the same and the file sizes produced by these exports are about the same size as the original but just load 5 times quicker.
The most likely explanation I can think of for this is that the datapump format has changed between 10 and 11 and there's some sort of conversion going on when I'm doing the initial import.
Does anyone have any ideas on what's going on? Or how I can further investigate what's happening to cause this?
impdp xxxx/yyyy@zzz directory=backups dumpfile=PROD_AUG2015.DMP EXCLUDE=TRIGGER,CONSTRAINT,GRANT
(Mostly irrelevant background info - this is for a time sensitive upgrade for a client on a remote island with fairly crappy internet. The data is coming from a system we have restricted access to and going into our own database. Due to the restricted access to their current production system it is a major exercise to make changes in the source database so trying to avoid that if possible)