to solve the issue #2246.
scheme is as following:
add a optional preferred_rowset_type in TabletMeta for V2 format rollup index tablet
add a boolean session variable use_v2_rollup, if set true, the query will v2 storage format rollup index to process the query.
test queries will be sent to online service to verify the correctness of segment-v2 by send the the same queries to fe with use_v2_rollup set or not to check whether the returned results are the same.
The current compaction selection strategy and cumulative point update logic
will cause the cumulative compaction to not work, and all compaction tasks
will be completed only by the base compaction. This can cause a large number
of data versions to pile up.
In the current cumulative point update logic, when a cumulative cannot select
enough number of rowsets, it will directly increase the cumulative point.
Therefore, when the data version generates the same speed as the cumulative
compaction polling, it will cause the cumulative point to continuously increase
without triggering the cumulative compaction.
The new strategy mainly modifies the update logic of cumulative point to ensure
that the above problems do not occur. At the same time, the new strategy also
takes into account the problem that compaction cannot be performed if cumulative
points stagnate for a long time. Cumulative points will be forced to increase
through threshold settings to ensure that compaction has a chance to execute.
Also add a new HTTP API to view the compaction status of specified tablet.
See `compaction-action.md` for details.
1. Calculate cumulative point when loading tablet first time.
2. Simplify pick rowsets logic upon delete predicate.
3. Saving meta and modify rowsets only once after cumulative compaction.
