Teradata I/O's


Teradata I/O's

Hi All

On what basis is the no of logical I/O's decided when a SQL is executed,and during a product join these I/O's increases........and the Node utilization goes up considerably........can somebody help me understand what exactly happens in this above case....


Re: Teradata I/O's

a logical I/O indicates that one of the table is in the memory . Most imp during a Product join always thersa duplication of either one of the table.
to read the the rows of the table from the memory obviously u will notice logical i/o.
thers something we need to understand about the CPU during the product join. it means that whatever rows are accomodated in the memory thers soem sorting going on due to which CPU cycles are been consumed to do that work. So u always notice HIGH CPU ....
a low CPU and HIGh i/o indicates that indexes might be necessary.. i/o might be logical or physical.