docs: RFC for better staleness read syntax.

[sunxiaoguang]

Signed-off-by: Xiaoguang Sun sunxiaoguang@zhihu.com

What problem does this PR solve?

Issue Number: 22505

Problem Summary:
Existing timestamp bound read SQL syntax is over complicate and hard to use

What is changed and how it works?

Propose new syntax to staleness read and deprecates existing timestamp bounds read SQL syntax which is over complicate.

What's Changed:

RFC documents.

Check List

Tests

• No code

Release note

• No release note

[sre-bot]

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[sre-bot]

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[sunxiaoguang]

/rebuild

[siddontang]

I think we can support the simple syntax, meanwhile, we can also support the full syntax. like start transaction read only with timestamp = xxx

[siddontang]

PTAL @morgo

[morgo]

Time travel queries are not part of MySQL, but they are part of MariaDB and the SQL:2011 standard. The syntax is in this FR: #18672

I don't believe either specify syntax that is transaction scoped, but I can see this can be useful.

[sunxiaoguang]

Time travel queries are not part of MySQL, but they are part of MariaDB and the SQL:2011 standard. The syntax is in this FR: #18672

I don't believe either specify syntax that is transaction scoped, but I can see this can be useful.

There are two statements related to staleness read, the last statement is time travel read. A unified syntax for both cases would be nice.

[nolouch]

I think READ ONLY warnings the txn must be a read-only transaction, rather than the user may do write operator in the transaction.

[siddontang]

Refer to #18672

@sunxiaoguang maybe we can use AS OF instead of WITH?

[sunxiaoguang]

Refer to #18672

@sunxiaoguang maybe we can use AS OF instead of WITH?

Refer to #18672

@sunxiaoguang maybe we can use AS OF instead of WITH?

I'm not sure, maybe AS OF usually comes with a particular point of time but not bounds?

[nolouch]

How about discussing more at #22765?

[nolouch]

We have a conclusion: #22765 (comment)
cc @sunxiaoguang

[sunxiaoguang]

We have a conclusion: #22765 (comment)
cc @sunxiaoguang

Great. Since the detail discussion is not here, maybe we should close this issue for now. What do you think @nolouch?

[nolouch]

Yes, I closed #22505, and I will update the RFC document in another PR.

[tisonkun]

Closed as resolved in #22765