title: Orientdb GC overhead limit exceeded/out of memory error and slow performance
body: <p>My orientdb database has around 2.3 million records. I'm trying to query all duplicate records (there are around 750,000 of them) using statement-
  <code>SELECT FROM (select PROP1, PROP2, count(*) as c from vin_data group by PROP1 ) where c &gt; 1</code>. When I set the limit to around 200, It takes around 180s to query (which I believe is slow). But when I set the limit to 750000, it gives me Out of memory error. My ram is 4GB and I have set Xms64m and Xmx3600m. I have set index on PROP1 and PROP1+PROP2(composite). My question is- Is 4GB ram enough for a 2.3 million record database?</p>