I want to understand how the max value is calculated in Teradata.
Eg: My query is
select max(price) from item;
My understanding is Parsing Engine will ask all AMPS to share the maximum value of price column they have for table item. Each AMP will returned it max value into a SPOOL. So say if there are 20 AMPS which store portion of item table. Then all 20 AMPs will return max value they have in their vdisk. Now in SPOOL we will have 20 values , one from each AMP.
If this understanding is correct I wish to know who will pick the MAX value out of these 20 values in SPOOL. Is it the PARSING ENGINE or it will ask one of the AMP to pick the MAX value from these 20 values and return the result ?
Kindly confirm my understanding.
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