AlloyDB: what is the meaning of different columnar cache search modes?

[morpheus]

the only documentation i could find on this is below:

https://cloud.google.com/alloydb/docs/columnar-engine/monitor-tune

and it does not explain difference between various modes.

• Columnar cache search mode can be columnar filter only, native, or row store scan. The planner chooses the search mode automatically based on costing and pushdown evaluation capability.

When the planner chooses the native mode, it pushes down some of the columnar operators to the scan:

• Rows Aggregated by Columnar Scan lists the number of rows that are aggregated.
• Rows Sorted by Columnar Scan lists the number of rows that are sorted.
• Rows Limited by Columnar Scan lists the limited number of rows that were scanned.