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Message Posted: Wed, 09 Feb 2005 @ 20:06:26 GMT
When you say:
Are you saying that you believe all of the rows selected on all the AMPs are redistributed to a single AMP and sorted in SPOOL1? I do not see that in the EXPLAIN.
Do you realize that SPOOL1 will exist on an AMP that has at least one row (group_amps) from the select? This is the same as PERM space where it resides on each and every AMP.
For the following EXPLAIN SELECT there is no redistribution mentioned in the EXPLAIN, therefore each AMP is sorting the rows in its own SPOOL1. Once the rows are sorted by each AMP having at one row, they are sent back to the user and that is where the merge takes place on the BYNET as I mentioned previously:
EXPLAIN sel * from employee_table where salary > 30000 order by salary;
Also notice that the END TRANSACTION is sent to all AMPs involved - are you saying this is always one AMP?
Please explain your EXPLAIN.
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