View Merging

Here is an odd little bug that was discussed a couple of weeks ago on the OTN forums.

It's about queries on join views by ROWID that fail with "ORA-01410: invalid ROWID" under certain circumstances. The bug can only be reproduced when using the 11.2 code base. In fact the same setup will cause an internal error in 11.1, but 10.2 will return correct results.

It's probably not a very common scenario but it is an interesting example of how features that work fine by themselves can cause problems when used together.

First of all (hopefully) some of you may ask: How is it possible to query from a join view by ROWID, since the view is based on multiple objects and hence doesn't have a simple one-to-one mapping to a ROWID of a single table?