Can anybody please tell me whether there are any disadvantage of SQL 
joins in terms of space and time and how postgres has implemented SQL 
joins? I am in the impression that SQL join takes more time for 
execution as well as space because database internally builds Cartesian 
product and then evaluates for condition. Recently I normalized by DB 
and changed my application Data model which resulted in writing lots of 
inner join queries. Later I found that DB server is consuming more 
memory. And once my Database also crashed. I am assuming that because of 
normalization and inner joins, my DB crashed.
Can anybody please give a thought into my assumption?
- R