Add chunk skipping GUC

[antekresic]

Add the ability to enable/disable new chunk skipping functionality completely.

[codecov]

Codecov Report

Attention: Patch coverage is 81.25000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 82.57%. Comparing base (59f50f2) to head (d791330).
Report is 1009 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ts_catalog/chunk_column_stats.c	25.00%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7360      +/-   ##
==========================================
+ Coverage   80.06%   82.57%   +2.51%     
==========================================
  Files         190      229      +39     
  Lines       37181    42678    +5497     
  Branches     9450    10723    +1273     
==========================================
+ Hits        29770    35243    +5473     
- Misses       2997     3160     +163     
+ Partials     4414     4275     -139     

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[timescale-automation]

Automated backport to 2.17.x not done: cherry-pick failed.

Git status

HEAD detached at origin/2.17.x
You are currently cherry-picking commit 8767565e3.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   .unreleased/pr_7360
	modified:   src/guc.h
	modified:   src/hypertable.c
	modified:   src/hypertable_restrict_info.c
	modified:   src/nodes/chunk_append/exec.c
	modified:   src/ts_catalog/chunk_column_stats.c
	modified:   tsl/test/expected/chunk_column_stats-14.out
	modified:   tsl/test/expected/chunk_column_stats-15.out
	modified:   tsl/test/expected/chunk_column_stats-16.out
	modified:   tsl/test/expected/chunk_column_stats-17.out
	modified:   tsl/test/sql/chunk_column_stats.sql.in

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   src/guc.c

Job log

[jflambert]

Sorry @fabriziomello and @svenklemm but I have a few questions

Why is it desirable to disable skipping chunks in v2.17.1? Are there downsides I should be aware of?

[fabriziomello]

Sorry @fabriziomello and @svenklemm but I have a few questions

Why is it desirable to disable skipping chunks in v2.17.1? Are there downsides I should be aware of?

We noticed some CPU spikes in our fleet due to extra catalog lookups at planning time introduced by this feature. Usually such kind of feature is added behing a feature flag to control the usage but we missed it when the feature was developed. As the actual fix isn't something trivial and obvious we decided to add the feature flag for now and then have time to rework it and fix it.