feat(frontend): support alter source pause/resume

[lyang24]

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What's changed and what's your intention?

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Please explain IN DETAIL what the changes are in this PR and why they are needed:

• Summarize your change (mandatory)
  Support alter source pause or resume syntax sugar by setting the rate limit to 0 on pause or to cancel rate limit on resume. Please not PAUSE/ RESUME only works when the source haven't configure the rate limit.
• How does this PR work? Need a brief introduction for the changed logic (optional)
• Describe clearly one logical change and avoid lazy messages (optional)
• Describe any limitations of the current code (optional)
• Refer to a related PR or issue link (optional)
  feat: alter source pause/resume #19181

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
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Documentation

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Release note

Public Preview: Do note that the structure and format of ALTER SOURCE PAUSE/ RESUME is considered unstable, and may change overtime.

After this PR, two new alter source syntax will be supported.

ALTER SOURCE <name> PAUSE; to pause processing stream from source.
ALTER SOURCE <name> RESUME; to continue processing stream from source.

[kwannoel]

We should use ALTER SOURCE RESUME instead of "Unpause"

[lyang24]

yep fixed it everywhere

[tabVersion]

Hi @lyang24 , thanks for your contribution.

ALTER SOURCE PAUSE; to pause processing stream from source.
ALTER SOURCE RESUME; to continue processing stream from source.

I have a question about the semantics here, please consider the following use case.

create source s .... ;

alter s set streaming_rate_limit to 100;
alter s pause; -- source stopped
alter s resume; -- source rate_limit set to unlimited rather than 100

Setting rate_limit here may abuse the pause/resume semantic.

cc @fuyufjh, what do you think of the proposed syntax?

[kwannoel]

Hi @lyang24 , thanks for your contribution.

ALTER SOURCE PAUSE; to pause processing stream from source.
ALTER SOURCE RESUME; to continue processing stream from source.

I have a question about the semantics here, please consider the following use case.

create source s .... ;

alter s set streaming_rate_limit to 100;
alter s pause; -- source stopped
alter s resume; -- source rate_limit set to unlimited rather than 100

Setting rate_limit here may abuse the pause/resume semantic.

cc @fuyufjh, what do you think of the proposed syntax?

We can ban alter source pause if source already has rate limit set. Likewise, alter source resume can be banned, unless rate limit is 0.

[lyang24]

Hi @lyang24 , thanks for your contribution.

ALTER SOURCE PAUSE; to pause processing stream from source.
ALTER SOURCE RESUME; to continue processing stream from source.

I have a question about the semantics here, please consider the following use case.

create source s .... ;

alter s set streaming_rate_limit to 100;
alter s pause; -- source stopped
alter s resume; -- source rate_limit set to unlimited rather than 100

Setting rate_limit here may abuse the pause/resume semantic.
cc @fuyufjh, what do you think of the proposed syntax?

We can ban alter source pause if source already has rate limit set. Likewise, alter source resume can be banned, unless rate limit is 0.

The challenge is - The sql parser doesn't know the current rate limit nor can it distinguish from pause or set source_rate_limit to 0. To achieve this we probably need to modify SetSourceRateLimit { rate_limit: i32 }, to something like SetSourceRateLimit { rate_limit: i32 , paused: bool}, and handle in the handle_alter_streaming_rate_limit. let me know if there are better approaches.

[tabVersion]

@kwannoel We can ban alter source pause if source already has rate limit set. Likewise, alter source resume can be banned, unless rate limit is 0.

I am up for this idea.

[kwannoel]

Rest LGTM, thanks for your work!

[fuyufjh]

"PAUSE or RESUME is invalid when the stream has pre configured ratelimit. Just use SET source_rate_limit = 0"