impl(bigquery): expose query metadata on complete query handle

[alvarowolfx]

Towards #5844

[gemini-code-assist]

Code Review

This pull request implements caching of rows, schema, page tokens, and query metadata in CompleteQuery, resolving a pending TODO, and refactors the Schema struct. The review feedback suggests several optimizations to avoid expensive clones of potentially large response data by utilizing std::mem::take and .as_ref(), as well as simplifying the Schema::new constructor to directly store the schema instead of manually reconstructing it.

[gemini-code-assist]

The res parameter is passed by value, meaning we own it. Instead of cloning res.rows (which can be very large and expensive to clone), we can move it into cached_rows using std::mem::take. By converting res to metadata first, we can also avoid cloning schema and page_token multiple times.

    pub(crate) fn from_get_query_results_response(q: &Query, mut res: GetQueryResultsResponse) -> Self {
        let cached_rows = VecDeque::from(std::mem::take(&mut res.rows));
        let metadata = QueryMetadata::from(res);
        let schema = metadata
            .schema
            .clone()
            .expect("complete query should have schema");
        let schema = Arc::new(Schema::new(schema));
        let page_token = if metadata.page_token.is_empty() {
            None
        } else {
            Some(metadata.page_token.clone())
        };
        Self {
            job_service: q.job_service.clone(),
            job_ref: q.job_ref.clone(),
            cached_rows,
            page_token,
            schema,
            metadata,
        }
    }

References

1. Scrutinize expensive uses of clone(). Is it necessary to copy the data? Can we move the data instead? ^(link)

[gemini-code-assist]

Since res is a reference, we must clone it. However, by cloning res once up front, we can move res.rows into cached_rows using std::mem::take and move the rest of res into metadata. This avoids cloning the potentially large rows vector twice.

    pub(crate) fn from_query_response(q: &Query, res: &QueryResponse) -> Self {
        let mut res = res.clone();
        let cached_rows = VecDeque::from(std::mem::take(&mut res.rows));
        let metadata = QueryMetadata::from(res);
        let schema = metadata
            .schema
            .clone()
            .expect("complete query should have schema");
        let schema = Arc::new(Schema::new(schema));
        let page_token = if metadata.page_token.is_empty() {
            None
        } else {
            Some(metadata.page_token.clone())
        };
        Self {
            job_service: q.job_service.clone(),
            job_ref: q.job_ref.clone(),
            cached_rows,
            page_token,
            schema,
            metadata,
        }
    }

References

1. Scrutinize expensive uses of clone(). Is it necessary to copy the data? Can we move the data instead? ^(link)

[gemini-code-assist]

Use .as_ref() instead of .clone() to inspect the Option without moving or cloning. This is more idiomatic and consistent with the other test at line 306.

Suggested change

	assert_eq!(completed.job_ref.clone().unwrap().job_id, "some_job_id");
	assert_eq!(completed.job_ref.as_ref().unwrap().job_id, "some_job_id");

References

1. Scrutinize expensive uses of clone(). Is it necessary to copy the data? Can we move the data instead? ^(link)

[codecov]

Codecov Report

❌ Patch coverage is 89.69072% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.88%. Comparing base (75c4db2) to head (73c4e6c).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/bigquery/src/query/query_handle.rs	89.36%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5925      +/-   ##
==========================================
- Coverage   97.90%   97.88%   -0.02%     
==========================================
  Files         234      235       +1     
  Lines       59940    60019      +79     
==========================================
+ Hits        58683    58752      +69     
- Misses       1257     1267      +10     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.