Is it against license to publish Oracle and SQL Server performance test?

I don't think you can license block a valid research paper. That's like Ford saying you can't verify its emissions claims. Gag orders like that on products/services are not generally legal, even if the terms say you agree to it. You could get sued out the ass for slander or libel though if there are flaws in either your experimentation methods or research analysis.

It is REALLY difficult to benchmark to the companies standards in such a way that you won't get sued.

Here's a paper on Oracle technology already. http://www.iisocialcom.org/conference/passat2012/PASSATProceedings/data/4578b119.pdf

"I am not keen on digging through boring license stuff" Well maybe you should be keen if you're afraid of getting sued.

Here's an oracle license from July. Quick glance, i see no restriction. http://docs.oracle.com/cd/E11882_01/license.112/e10594.pdf

Unless you state the specific technology down to the version or link to the license/terms of use, we cannot specifically say.

Here is an interesting read on the "gag" policies, but it's from 2007. http://genellebelmas.com/documents/Belmas-Larson-Clicking%20away.pdf

Notable in the conclusion: First Amendment jurisprudence provides considerable support to the concept of a right to hear. Using the First Amendment to attack gagwrap clauses directly would require that state action be found first. Even without state action, however, the First Amendment provides a significant public policy basis upon which gagwrap clauses might be found to be unenforceable. It remains to be seen how this public policy rationale will work with the Restatement of Contracts framework when evaluating gagwrap clauses.

The standard license you agree to when you download software from the Oracle Technology Network (OTN) does state that you're not allowed to disclose benchmarks.

You may not: 
<<list of things you cannot do>>
- disclose results of any program benchmark tests without our prior consent. 

Microsoft's licenses (such as an older SQL Server 7.0 license) generally have similar terms

Performance or Benchmark Testing. You may not disclose the results of any benchmark test of either the Server Software or Client Software for Microsoft SQL Server, Microsoft Exchange Server, or Microsoft Proxy Server to any third party without Microsoft's prior written approval.

Most other large companies put similar terms in their license agreements. Whether those license terms are actually enforcable as a matter of law in your case (particularly where this is an academic exercise) and whether either company would ever seriously consider suing over the publication of a Masters thesis is something that you would need to discuss with your university's legal department (and/or the legal department of whoever owns the licenses for the software that you're using). As a practical matter, I would think it's extraordinarily unlikely that either company would ever seriously consider suing a masters student with no money over unfavorable benchmark results. Bloggers and conference presenters publish benchmark results all the time in forums that are much more likely to attract (or repel) potential customers and aren't sued.