Patent warning about the Greenplum source code

Some of you might have seen that the Greenplum database source code has
been published:
https://adtmag.com/articles/2015/10/28/greenplum-open-sourced.aspx

under the Apache 2.0 license:
http://www.apache.org/licenses/LICENSE-2.0

The source code has known patents owned by Pivotal/Greenplum.  The
license has a patent grant clause:
3. Grant of Patent License. Subject to the terms and conditions of thisLicense, each Contributor hereby grants to You a
perpetual,worldwide,non-exclusive, no-charge, royalty-free, irrevocable (except as stated inthis section) patent
licenseto make, have made, use, offer to sell,sell, import, and otherwise transfer the Work, where such licenseapplies
onlyto those patent claims licensable by such Contributor thatare necessarily infringed by their Contribution(s) alone
orbycombination of their Contribution(s) with the Work to which suchContribution(s) was submitted. If You institute
patentlitigationagainst any entity (including a cross-claim or counterclaim in alawsuit) alleging that the Work or a
Contributionincorporated withinthe Work constitutes direct or contributory patent infringement, thenany patent licenses
grantedto You under this License for that Workshall terminate as of the date such litigation is filed.
 

However, while the license defines and uses "Derivative Works", it does
not mention that in the patent grant clause.  I assume this means that
patent grants do not apply to derived works, meaning if code or ideas
were moved from Greenplum to Postgres (which is not Apache 2.0
licensed), it would not have a patent grant. I talked to Greenplum staff
about this a few months ago and they did not dispute my analysis.

Therefore, I caution people from viewing the Greenplum source code as
you might see patented ideas that could be later implemented in
Postgres, opening Postgres up to increased patent violation problems.  I
am also concerned about existing community members who work for
Pivotal/Greenplum and therefore are required to view the patented source
code.  The license issue might eventually be improved by
Pivotal/Greenplum, but, for now, I think caution is necessary.

Of course, never mention known-patented ideas in any community forum,
including this email list.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com

+ As you are, so once was I. As I am, so you will be. +
+ Roman grave inscription                             +