ddl: Fix snap after dropping database (#8560)

[ti-chi-bot]

This is an automated cherry-pick of #8560

What problem does this PR solve?

Issue Number: close #8506

Problem Summary:

Introduced by #8536. In that PR, we don't check whether the DatabaseInfo exist when creating a Storage instance.

However, if the DDL "create database" and decoding raftlog or snapshot comes after TiDB executed "drop database". Then applyCreateStorageInstance can not handle it because the IDatabase instance is not created in TiFlash.

What is changed and how it works?

In order to resolve the DatabaseInfo can not be fetched from TiKV, we will construct a "fake" DatabaseInfo and create the IDatabase instance in TiFlash. Because

• If the database is not FLASHBACK, then we don't care its display name in TiFlash, we just need it for storing the raft log / snapshot data
• If the database is FLASHBACK later, then the DatabaseInfo will be overwritten

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[JaySon-Huang]

/run-all-tests

[JaySon-Huang]

/run-all-tests

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JaySon-Huang, Lloyd-Pottiger

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• OWNERS [JaySon-Huang,Lloyd-Pottiger]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-12-23 04:38:06.046001483 +0000 UTC m=+1281377.083228407: ☑️ agreed by JaySon-Huang.
• 2023-12-27 01:54:04.867285277 +0000 UTC m=+1617135.904512203: ☑️ agreed by Lloyd-Pottiger.