precheck(dm): refine error message & instruction

[buchuitoudegou]

What problem does this PR solve?

Issue Number: close #7621

What is changed and how it works?

• refine error message and instruction
• merge instruction for each table in table compatibility check

Check List

Tests

• Unit test

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

`None`.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• D3Hunter
• okJiang

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[buchuitoudegou]

/area dm
/run-dm-integration-test

the message and instruction need to be confirmed by Frank

[buchuitoudegou]

/run-dm-integration-test

[buchuitoudegou]

/cc @okJiang

[buchuitoudegou]

/cc @D3Hunter PTAL

[ti-chi-bot]

@buchuitoudegou: GitHub didn't allow me to request PR reviews from the following users: PTAL.

Note that only pingcap members and repo collaborators can review this PR, and authors cannot review their own PRs.

In response to this:

/cc @D3Hunter PTAL

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[codecov-commenter]

Codecov Report

Merging #7696 (658fafc) into master (bf9e9ad) will increase coverage by 0.0165%.
The diff coverage is 81.3559%.

Additional details and impacted files

Flag	Coverage Δ
cdc	66.3374% <ø> (-0.0100%)	⬇️
dm	52.2171% <81.2500%> (+0.0544%)	⬆️
engine	64.0202% <81.8181%> (-0.0023%)	⬇️

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

@@               Coverage Diff                @@
##             master      #7696        +/-   ##
================================================
+ Coverage   59.9132%   59.9297%   +0.0165%     
================================================
  Files           810        810                
  Lines         93098      93129        +31     
================================================
+ Hits          55778      55812        +34     
+ Misses        32472      32468         -4     
- Partials       4848       4849         +1     

[okJiang]

rest lgtm

[okJiang]

Function and text are LGTM

[buchuitoudegou]

/merge

[ti-chi-bot]

@buchuitoudegou: /merge is only allowed for the committers, you can assign this pull request to the committer in list by filling /assign @committer in the comment to help merge this pull request.

In response to this:

/merge

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[buchuitoudegou]

/run-dm-integration-test

[lance6716]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 9e9e7c0

[buchuitoudegou]

/run-verify

[buchuitoudegou]

cdc unstable test? https://do.pingcap.net/jenkins/blue/organizations/jenkins/pingcap%2Ftiflow%2Fghpr_verify/detail/ghpr_verify/7/pipeline/149

/run-verify

[ti-chi-bot]

@buchuitoudegou: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.