Informix 5 and 7

Something between Informix 5 and 7 I would like to discuss here. If you use Informix 5 and you want to upgrade to 7 or further version now. You may discover that the same statements executed in Informix 5 would show the sqexplain.out as shown: Estimated cost : 1 Estimated # of rows returned: 4 However, the sqexplain.out will be display as follows in Informix 7: Estimated cost : 128000 Estimated # of rows returned: 60000 Also, the first one is better than in my experience. The difference between them is so large that the performance will be greatly affected if your tuning is not suited. We should try many many times before you want to upgrade. Daniel