[enhancement](load) make default load mem limit configurable

[Henry2SS]

Proposed changes

Issue Number: close #xxx

Problem summary

Describe your changes.

Checklist(Required)

1. Does it affect the original behavior:
   • Yes
   • No
   • I don't know
2. Has unit tests been added:
   • Yes
   • No
   • No Need
3. Has document been added or modified:
   • Yes
   • No
   • No Need
4. Does it need to update dependencies:
   • Yes
   • No
5. Are there any changes that cannot be rolled back:
   • Yes (If Yes, please explain WHY)
   • No

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[caiconghui]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.

[morningman]

We already had a load_mem_limit session variable for this purpose.
I think we should use that instead of adding a new config.

[Henry2SS]

We already had a load_mem_limit session variable for this purpose. I think we should use that instead of adding a new config.

the defaut value of load_mem_limit is 0. And it means there is no limit. And it is mainly for INSERT INTO operations.
it is okay to set it to 2G by default?

[xinyiZzz]

runtime_state.cpp the code below should be removed and replaced with _query_options.load_mem_limit.

int64_t RuntimeState::get_load_mem_limit() {
    if (_query_options.__isset.load_mem_limit && _query_options.load_mem_limit > 0) {
        return _query_options.load_mem_limit;
    } else {
        return _query_mem_tracker->limit();
    }
}

[xinyiZzz]

runtime_state.cpp the code below should be removed and replaced with _query_options.load_mem_limit.

int64_t RuntimeState::get_load_mem_limit() {
    if (_query_options.__isset.load_mem_limit && _query_options.load_mem_limit > 0) {
        return _query_options.load_mem_limit;
    } else {
        return _query_mem_tracker->limit();
    }
}

To ensure compatibility during the upgrade process, cannot be removed now
Consider recording a TODO in runtime_state.cpp, the code is abandoned, it can be deleted after v1.3

[Henry2SS]

runtime_state.cpp the code below should be removed and replaced with _query_options.load_mem_limit.

int64_t RuntimeState::get_load_mem_limit() {
    if (_query_options.__isset.load_mem_limit && _query_options.load_mem_limit > 0) {
        return _query_options.load_mem_limit;
    } else {
        return _query_mem_tracker->limit();
    }
}

To ensure compatibility during the upgrade process, cannot be removed now Consider recording a TODO in runtime_state.cpp, the code is abandoned, it can be deleted after v1.3

OK. Thx for your advice.

[xinyiZzz]

LGTM

[caiconghui]

LGTM

[caiconghui]

LGTM

[morningman]

LGTM, but please add some document for this config

[Henry2SS]

LGTM, but please add some document for this config

Done.

[morningman]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.