pkg/lightning : remove get_regions call in physical backend

[mittalrishabh]

What problem does this PR solve?

Problem Summary:
When lightning runs in physical import mode, it runs this sql query

SELECT REGION_ID, APPROXIMATE_SIZE FROM information_schema.TIKV_REGION_STATUS WHERE TABLE_ID = ?

This call is made by each lightning process in parallel import mode and by multiple worker threads in a lightning process. It can potentially overload the PD if number of regions are too many. However, it appears that this call may be unnecessary since its purpose is to display a warning message and increment a counter in the SplitAndScatterRegionByRanges() function. Considering that lightning physical import always operates on a new table, splitting the new region should not pose any harm.

Issue Number: close #45507

What is changed and how it works?

Remove the getRegions call from lightning

Check List

Tests

• Manual test (add detailed scripts or steps below)

1. Run lightning in parallel import mode
2. Check get_Regions call in PD dashboard. It should be 0
3. Lightning should run successfully

Release note

We saw this issue in 6.5.0

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[sre-bot]

All committers have signed the CLA.

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[ti-chi-bot]

Hi @mittalrishabh. Thanks for your PR.

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[wuhuizuo]

/ok-to-test

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@mittalrishabh Thanks for your contribution, please sign the CAL.

[codecov]

Codecov Report

Merging #46202 (a846dec) into master (1bf82bb) will increase coverage by 0.6183%.
Report is 175 commits behind head on master.
The diff coverage is 0.0000%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #46202        +/-   ##
================================================
+ Coverage   73.3396%   73.9580%   +0.6183%     
================================================
  Files          1271       1310        +39     
  Lines        392943     413014     +20071     
================================================
+ Hits         288183     305457     +17274     
- Misses        86386      89224      +2838     
+ Partials      18374      18333        -41     

Flag	Coverage Δ
integration	26.8774% <0.0000%> (?)
unit	74.7094% <0.0000%> (+1.3698%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	54.0444% <ø> (ø)
parser	85.2182% <ø> (+0.1823%)	⬆️
br	48.0807% <0.0000%> (-3.8813%)	⬇️

[mittalrishabh]

/retest

[mittalrishabh]

retest

[lance6716]

Hi I copied the error message from "idc-jenkins-ci-tidb/build" CI.

br/pkg/lightning/backend/local/localhelper_test.go:480:62: too many arguments in call to local.SplitAndScatterRegionByRanges
	have ("context".Context, []Range, nil, bool, number)
	want ("context".Context, []Range, bool)
br/pkg/lightning/backend/local/localhelper_test.go:570:62: too many arguments in call to local.SplitAndScatterRegionByRanges
	have ("context".Context, []Range, nil, bool, number)
	want ("context".Context, []Range, bool)
br/pkg/lightning/backend/local/localhelper_test.go:829:63: too many arguments in call to local.SplitAndScatterRegionByRanges
	have ("context".Context, []Range, nil, bool, number)
	want ("context".Context, []Range, bool)

[mittalrishabh]

@D3Hunter can you review this PR

[mittalrishabh]

can i get approval of this PR

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: D3Hunter, lance6716

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-08-18 07:15:06.960986116 +0000 UTC m=+874471.510002088: ☑️ agreed by lance6716.
• 2023-08-23 02:22:26.397104802 +0000 UTC m=+1288910.946120787: ☑️ agreed by D3Hunter.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-5.3: #46332.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-5.4: #46334.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.1: #46335.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #46336.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #46337.

[Benjamin2037]

Already in 7.5 @mittalrishabh