IFS 10 Upgrade - Rowkey and Java heap issue

Dears,

We are upgrading IFS 10 from IFS 7.5 

we are getting 2 errors while deploying database upgrage

1. Java.lang.outofmemory Java Heap space
2. The installation gets struck on - Database_SYS.List_Rowkeys_To_Enable('&ENABLE_ROWKEY', '&ENABLE_ROWKEY_HOURS');

Please suggest on the both. 

• Can we updade rowkey after or before the upgrade. 
• Can we update rowkey in ifs7.5 itself and then do upgrade
• Please suggest on Java heap also.

Best Regards

Pankaj