combined UM/PM useful?

2 posts / 0 new
Last post
squalloser's picture
Last seen: 1 month 2 weeks ago
Joined: Apr 22 2014
Junior Boarder

Posts: 6

Stephan Derp
combined UM/PM useful?



Is there any reason to use the combined UM/PM mode? And if I don't use this mode, is one UM enough for 12 PMs? As far as I understand from the documentation the UM doesn't need many resources.

radams's picture
Last seen: 4 days 22 hours ago
Joined: Jan 3 2011

Posts: 492

Robert Adams
combined UM/PM useful?


Your system configuration will need to be determined by your specific usage.


A single UM can be used for any number of PMs. The configuratuion can also be changed (additional UMs can be added), if it is determined that additional resources are required to perform the user module fucntions.



Primary User Module Operations
The User Module performs these core functions for the InfiniDB database:
 Transform MySQL plan into an InfiniDB Job List
 Perform InfiniDB OID (object ID) lookups from the InfiniDB system catalog
 Inspects the Extent Map (described in detail later in this document) to reduce I/O, which is accomplished via the elimination of unnecessary extents
 Issues instructions (sometimes referred to as ‘primitive operations’) to the Performance Modules
 Executes hash joins as needed (depending on size of smaller table in the join). Helps manage distributed hash joins by sending any hash maps needing processing to Performance Modules
 Execute cross-table-scope functions and expressions that happen after a hash join
 Receives data from the Performance Modules and re-transmits back to them if needed
 Executes follow-up steps for all aggregation and distinct processing
 Return data back to the MySQL interface