There are Three Types of Bugs: Unpublished, Published, and Features

Sometimes the cure is worse than the disease. A newly discovered bug in Oracle Database 12.2.0.1 (October 2018 RU) is causing quite a bit of consternation with my developers and customers:

Bug 26577716 : USE OF BLOOM FILTERS CAUSES ASSERT KGGMSREM1

The companion bug is 26534055 and is documented here, although the bugs themselves are still unpublished:

Oracle Support Document 2437590.1 (Getting ORA-00600 [kggmsRem1] – on a complex query when Bloom Filters are enabled) can be found at: https://support.oracle.com/epmos/faces/DocumentDisplay?id=2437590.1

Usually, “ASSERT” is a nicer way of saying, “ORA-00600”. And there is no way I’m releasing code that might generate an ORA-00600. The fix (tentatively included in Oracle Database 20.1, hopefully an actual patch sooner) is to disable bloom filters:

alter system set “_bloom_filter_enabled”=false;

WHAT? Disable bloom filters? Something I’ve been relying on for years, and even more useful on Exadata?

Exadata, smart scans, and Bloom filters, OH MY!

I’m hoping for that targeted patch soon. In the meantime, I guess I’ll just be using query hints.

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