all-amp and group-amp operations in Explain plan

Database
Enthusiast

all-amp and group-amp operations in Explain plan

Can anyone please explain the explain terms all-amp and group-amp operations with examples

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3) We do an all-AMPs RETRIEVE step from a single partition of
work_tbls.samp_tbl with a condition of (
"work_tbls.samp_tbl.dept = 20") with a residual condition of
("work_tbls.samp_tbl.dept = 20") into Spool 1 (all_amps), <<<<<<<<<<<
which is built locally on the AMPs. The size of Spool 1 is
estimated with low confidence to be 189 rows. The estimated time
for this step is 0.01 seconds.

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We do an all-AMPs RETRIEVE step from 2 partitions of
work_tbls.samp_tbl with a condition of (
"(work_tbls.samp_tbl.dept = 10) OR
(work_tbls.samp_tbl.dept = 30)") into Spool 1 (group_amps), <<<<<<<<<<<<<<
which is built locally on the AMPs. The size of Spool 1 is
estimated with no confidence to be 36 rows. The estimated time
for this step is 0.01 seconds.

please explain with example...

Thanks in Advance....
3 REPLIES
Junior Contributor

Re: all-amp and group-amp operations in Explain plan

Check the Database Design manual for details:
Chapter 17: Design Issues for Tactical Queries
Localizing the Work

Dieter
Enthusiast

Re: all-amp and group-amp operations in Explain plan

Thanks Dieter. That was really helpful...

Re: all-amp and group-amp operations in Explain plan

please explain the term all-amps operation