restore: support restoring SQL wrapping with TiDB special comments

tangenta commented 3 years ago

What problem does this PR solve?

TiDB Binlog and Lightning use regex to substitute the TiDB-specific keyword with special comments:

FeatureIDAutoRandom:   regexp.MustCompile(`(?P<REPLACE>(?i)AUTO_RANDOM\b\s*(\s*\(\s*\d+\s*\)\s*)?)`),
...
FeatureIDForceAutoInc: regexp.MustCompile(`(?P<REPLACE>(?i)FORCE)\b\s*AUTO_INCREMENT\s*`),

The regex is fragile because it is easy to get things wrong when the table names or column names contain these keywords, for example:

CREATE TABLE AUTO_RANDOM (id int);

is incorrectly rewritten to

CREATE TABLE `/*T![auto_rand] AUTO_RANDOM AUTO_RANDOM */ ` (id int);

Comparing with pattern matching, using ast.Restore to wrap special comments is not prone to error.

What is changed and how it works?

Collect TiDB-specific features into tidb/features.go as the single source of truth.
Add a restore flag: RestoreTiDBSpecialComment, support wrapping with TiDB special comment.
Remove SpecialCommentsController.

Check List

Tests

Unit test
Integration test

Code changes

Has exported function/method change
Has interface methods change

Side effects

NA

Related changes

Need to cherry-pick to the release branch

ti-chi-bot commented 3 years ago

[REVIEW NOTIFICATION]

This pull request has been approved by:

kennytm
tiancaiamao

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kennytm commented 3 years ago

what is the reason removing SpecialCommentsController and exposing the SpecialComments map directly 🤔

(i mean i don't really like to keep SpecialCommentsController, but allowing anyone to modify the global SpecialComments sounds prone to abuse)

lance6716 commented 3 years ago

Thanks. TODO: DM needs to revert https://github.com/pingcap/dm/pull/1823 after update parser dependency

kennytm commented 3 years ago

/merge

ti-chi-bot commented 3 years ago

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kennytm commented 3 years ago

/merge cancel

kennytm commented 3 years ago

/merge

ti-chi-bot commented 3 years ago

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

Commit hash: d0b457fbbb0321dfe3a4fd228630ff03e2bea216

pingcap / parser