What does this do: SELECT /*+ PARALLEL */..... ?

Question

We have a Datawarehouse using Oracle's ODI technology and Sql Server...... A consultant suggested we add the "query hint" (his words, not mine) /*+ PARALLEL */ to the sql query. Doing so improved execution speed by orders of magnitude but I can't find any t-sql references to it. Where is it documented?

TIA,

BD

Answer 1

That is an Oracle only optimizer hint; this does NOTHING in SQL Server -- except confuse people that read it.  This particular optimizer hint is for a PARALLEL query.  You might be able to find some information here.  If you need more, I suggest that you ask your question in an Oracle forum.

Answer 2

As Kent points out, this is just white noise with no effect in SQL Server. If you saw a performance improvement, this could be because you changed the query text, and got a fresh compilation which fitted you current parameters better.

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Erland Sommarskog, SQL Server MVP, [e-mail]