AnsweredAssumed Answered

What are segments and spills in MapR-DB?

Question asked by john.humphreys on Jul 17, 2018
Latest reply on Jul 18, 2018 by john.humphreys

Running table/region/pack on my MapR-DB table significantly brings down its # of spills as shown below.


I'm having trouble finding any documentation on what segments and spills actually are though.

  1. What is a segment?
  2. What is a spill?
  3. Why do spills go down so much when you pack a region?
  4. Does having the extra spills have a performance impact?


Before Pack:

"fid": "6158.26926.2555980",
"logicalsize": 8322318336,
"physicalsize": 5481234432,
"copypendingsize": 12943360,
"numberofrows": 247444,
"numberofrowswithdelete": 1833,
"numberofspills": 12185,
"numberofsegments": 4115


After Pack:

"logicalsize": 7504232448,
"physicalsize": 4887347200,
"copypendingsize": 0,
"numberofrows": 188483,
"numberofrowswithdelete": 0,
"numberofspills": 4113,
"numberofsegments": 4113