*: cherry-pick recent PRs for dumpling v5.0.1

[lichunzhu]

What problem does this PR solve?

Some features are not cherry-picked to release-5.0.

What is changed and how it works?

Cherry-pick PRs on the master branch to release-5.0.

BugFix:

• Fix the format problem for connection session variables. Add conn session vars #265
• Fix panic bugs for metrics when used as library export: fix a metric not using labelNames #266, export: fix estimateTotalRowsCounter nil pointer #267
• Fix the problem that pd client's logs are not printed to dumpling's log: replace pingcap global logger when start dumpling binary #270

Feature:

• Add estimate total rows count to metrics for dump table. add estimate total rows count to metrics for dump table #254

Tests:

• Add more tests for sample SQL generator sql: fix table sample sql generator bug #262

Check List

Tests

• Unit test
• Integration test

Release note

• No release note

[lance6716]

Here using ? will let sql driver to check the type of pv, to decide if pv need quotes.

Instead, I prefer always use the input value as-is, that is to say we always use %s and printf to construct a SQL. So user should quote the value if it's a string type variable in SQL.

https://github.com/go-sql-driver/mysql/blob/bcc459a906419e2890a50fc2c99ea6dd927a88f2/connection.go#L68-L78

(I deleted previous misleading comment)

[lance6716]

we might append --param to dsn 😂 otherwise we can't control https://github.com/go-sql-driver/mysql#parameters and have to write a doc about dealing with , in parameter KVs.

[lichunzhu]

Here using ? will let sql driver to check the type of pv, to decide if pv need quotes.

Instead, I prefer always use the input value as-is, that is to say we always use %s and printf to construct a SQL. So user should quote the value if it's a string type variable in SQL.

https://github.com/go-sql-driver/mysql/blob/bcc459a906419e2890a50fc2c99ea6dd927a88f2/connection.go#L68-L78

(I deleted previous misleading comment)

conf.SessionParams is a map[string]interface{}. I think using an original value to construct SQL is in-proper for being used as a library.

[lance6716]

what's the detailed in-proper case?

if user input key=val, successful parsing val as a integer does not mean key is an interger MySQL variable, at that time it will raise an error.

[kennytm]

I think that SET SESSION X = 123 and SET SESSION X = '123' are equivalent for system variables.

[lichunzhu]

@lance6716 @kennytm
Fixed in 1b33d20, and add an integration test in 278a128. PTAL again

[lance6716]

sorry I didn't reply to above comment in time 😂 I didn't found a case for system variables that SET SESSION X = 123 will cause error if X is a string type variable. Will check it now.

[kennytm]

/lgtm

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[lichunzhu]

/merge

[ti-chi-bot]

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

Commit hash: a7c8c08