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It's hard to define what a "fair" columnar store scan is. We use a technique that is called "segment elimination", which allows to skip over compressed segments
by nikita 12y ago
It's hard to define what a "fair" columnar store scan is. We use a technique that is called "segment elimination", which allows to skip over compressed segments of data as you scan. However every solid columnar database uses such techniques. It just happens that Oracle 12c doesn't have the ability to sort columnar indexes, and neither does it have the ability to store columnar indexes on flash or disk, which bloats the overall cost.
- mbesto 12y agoHow does your tech differ from SAP HANA's columnar DB?
- jma24 12y agoThe much bigger problem with Oracle In-Memory is that a lot of operations like joins and sorts often happen in the SGA, in row form. So you end up needing a truckload of SGA for temporary calculations. And when the SGA runs out, which it invariably does, you end up using TEMPDB. And everything comes to a crawl.