syncer(dm): fix different output format for operate-schema get (#5824)

[ti-chi-bot]

This is an automated cherry-pick of #5824

What problem does this PR solve?

Issue Number: close #5688

What is changed and how it works?

• If the checkpoint doesn't exist and the schema is retrieved from the downstream, replace the downstream table name with the requested upstream table name

• Delete all \n in the SQL results for the operate-schema result

Check List

Tests

• Unit test

Questions

Will it cause performance regression or break compatibility? No.

Do you need to update user documentation, design documentation or monitoring documentation? No.

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has not been approved.

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[ForwardStar]

/run-verify

[dsdashun]

I think we don't need to remove the dbconn.GetTableCreateSQL() calling and replace it with SHOW CREATE TABLE calling. But rather:

			result, err2 := dbconn.GetTableCreateSQL(s.tctx.WithContext(ctx), s.downstreamTrackConn, targetTable.String())
			result = strings.Replace(result, fmt.Sprintf("CREATE TABLE %s", quotes.QuoteName(targetTable.Name)), fmt.Sprintf("CREATE TABLE %s", quotes.QuoteName(sourceTable.Name)), 1)
			return utils.CreateTableSQLToOneRow(result), err2

[ForwardStar]

dbconn.GetTableCreateSQL() is not included in the old-version branch. Moreover, the committed logic is not equal to dbconn.GetTableCreateSQL() since conn.QuerySQL() between the versions are of different APIs.

[dsdashun]

OK. Can we reuse (*schema.Tracker).GetCreateTable() ? In my opinion, this PR mainly changes the table name from target table name to source table name, and changes the sql into a single line ( not in this version ). Maybe :

targetTable := s.route(sourceTable)
result, err2 := s.schemaTracker.GetCreateTable(ctx, targetTable)
result = strings.Replace(result, fmt.Sprintf("CREATE TABLE %s", quotes.QuoteName(targetTable.Name)), fmt.Sprintf("CREATE TABLE %s", quotes.QuoteName(sourceTable.Name)), 1)
return result, err2

[ForwardStar]

Actually I am not sure about this. In my opinion, getting the table from schema tracker is an incorrect version. Getting schema can only be operated when task is paused. However, when the task is paused, the schema tracker is down and nothing would return. I have tried to build the original version and observed this phenomenon.

[dsdashun]

OK. Seems PR #5350 fixed this problem. Does that PR also need to be cherry-picked into 5.4 ? @lance6716

[lance6716]

done by #5415

[ForwardStar]

/close

[ti-chi-bot]

@ForwardStar: Closed this PR.

In response to this:

/close

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 kubernetes/test-infra repository.