RowContainer's columns' HasNulls info

[zsmj2017]

Description

#11558
and
#10775

Both of these PRs add column-based statistics to RowContainer (the former includes column length information and nullcnt, while the latter only includes nullcnt).

Can we consider merging these two statistics?
From the current perspective, the changes in PR 10775 can be fully covered by PR 11558 (But PR 10775 is always enabled, while PR 11558 provides an option to decide whether to enable it).

I simply think that the statistical information should come from the same data source as much as possible. Dispersed data sources may lead to certain changes missing part of the logic, which could result in APIs that are supposed to have consistent semantics failing to return the same results.

[xiaoxmeng]

@zsmj2017 good point. We can consider to support this. cc @tanjialiang @zation99

[zation99]

@xiaoxmeng @tanjialiang one decision we need to make is, after we merge these two places to add the stats, do we want to enable it by default as what #10775 does, or make it disabled by default as what #11558 does?
Another choice is that we only make this stats nullcnt enabled by default but others disabled by default. Not sure if the effort worths it though.
The problem is if we keep all of the stats disabled as in #11558 after the merge, there will be performance regression in #10775 cases.
What do you think?

[zation99]

nvm @tanjialiang pointed me to the recent PR that enabled col stats by default: #11731