New unified internal table names format, part 1: identifying and accepting new format tables

[shlomi-noach]

Description

See story in #14582

We introduce a new unified internal table name format, which is consistent 56 characters long, and includes a human readable UUID, human readable timestamp, and a table purpose hint. Example name:

_vt_hld_6ace8bcef73211ea87e9f875a4d24e90_20200915120410_

The name still has room to spare to add default MySQL constraint names, such as _ibfk_12 (totaling 64 characters as in _vt_hld_6ace8bcef73211ea87e9f875a4d24e90_20200915120410__ibfk_12).

In this PR Vitess recognizes tables in the new format alongside the old format. Table lifecycle is the single sensitive consumer of table names, because the name of a table indicates its GC state, and the transition and timing of the transition into the next state. Table lifecycle now identifies both formats, e.g. both:

• _vt_DROP_6ace8bcef73211ea87e9f875a4d24e90_20200915120410
• _vt_drp_6ace8bcef73211ea87e9f875a4d24e90_20200915120410_

...indicate the exact same table state and are interpreted in an identical manner.

Online DDL, vreplication, etc., all implicitly become aware of the new format.

However, nothing outside tests actually generates tables in the new format. For backwards compatibility purposes that can only take place in v20, while this PR is expected to be included in v19.

For the next two Vitess versions, there will be some duality. e.g. these two functions:

• schema.GenerateRenameStatement(...)
• schema.GenerateRenameStatementNewFormat(...)

and others, work almost exactly the same name, but using old/new formats.

In v20 and v21 we can remove the duality, and eventually get rid of old format related code.

Related Issue(s)

• Task: unify internal vitess table name formats #14582
• OnlineDDL: standard vitess artifact table name leaves no room for default _ibfk_... suffix #14570

Checklist

• "Backport to:" labels have been added if this change should be back-ported
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on the CI
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

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[shlomi-noach]

Since this PR does not actually introduce table names, it does not require doc changes. We might want to add a preliminary comment in our docs about the expected new format, is all. Keeping the NeedsWebsiteDocsUpdate label for now.

[shlomi-noach]

Documentation PR: vitessio/website#1661