[KYLIN-3138] cuboids on-demand build

• Type: New Feature
• Status: Open
• Priority: Critical
• Resolution: Unresolved
• Affects Version/s: v2.2.0, v2.3.0
• Component/s: Job Engine, Query Engine, Spark Engine
• Assignee: Shao Feng Shi
• Reporter: Ruslan Dautkhanov
• Created: 28/Dec/17 19:18
• Updated: 02/Feb/18 19:58

Description

We just started using Kylin and quite like it so far.

Although some of the datasets we have are quite wide to even consider for OLAP cubing.
Unless those cuboids will be built on-demand.
I know some commercial non-open source products do this successfully.

This idea is to build a cuboid only when a user actually needs it.
So for example, our BI dashboards does a certain rollup, so then a SQL
query hits Kylin backend. Kylin realizes it hasn't built that particular cuboid just yet,
so immediately starts building it. Users has to wait a bit longer first time
it request that combination of dimensions. But all other requests or requests
of other users will be fast from that point on.

Kylin (or any other OLAP solution) wouldn't be feasible to use on very wide datasets
unless this on-demand functionality is implemented. For example, some datasets we have have 100-200 dimensions. And we don't know up front rollups users would want to do.

Suggesting to have a new dimension build rule "lazy / on-demand". All previous rules apply. This new rule type would mean, a cuboid for a particular set of dimensions wouldn't be built up-front if it's marked as "lazy / on-demand".

Thoughts / ideas?

Issue Links

• is related to: KYLIN-2727 Introduce cube planner able to select cost-effective cuboids to be built by cost-based algorithms