don't return error when vector index is empty

[aunjgr]

User description

What type of PR is this?

• API-change
• BUG
• Improvement
• Documentation
• Feature
• Test and CI
• Code Refactoring

Which issue(s) this PR fixes:

issue #22508

What this PR does / why we need it:

empty index should return empty result

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PR Type

Bug fix

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Description

• Return empty result instead of error when vector index is empty

• Support multiple batches in search results processing

• Update test expectations to reflect new behavior

• Add integration test case for empty index queries

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Diagram Walkthrough

flowchart LR
  A["Search Query"] --> B["Execute SQL"]
  B --> C{"Batches Empty?"}
  C -->|Old| D["Return Error"]
  C -->|New| E["Return Empty Result"]
  B --> F["Process Batches"]
  F --> G["Return Results"]

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File Walkthrough

	Relevant files
Bug fix	search.go Handle empty batches gracefully in search                                pkg/vectorindex/ivfflat/search.go Removed error return when result batches are empty Changed to return empty slices instead of error Modified loop to iterate over all batches instead of just first batch Moved empty check after batch processing initialization +12/-10
Tests	search_test.go Update tests for empty index behavior                                        pkg/vectorindex/ivfflat/search_test.go Renamed mock function from mock_runSql_streaming to mock_runSql Renamed mock error function from mock_runSql_streaming_parser_error to mock_runSql_parser_error Updated test expectation from require.NotNil to require.Nil for empty index case Updated function references in test cases +5/-5      vector_ivf.sql Add integration test for empty index query                              test/distributed/cases/vector/vector_ivf.sql Added SELECT query test case for empty vector index search Query searches on empty table with L2_distance filter Tests vector search with status filter returning no results Demonstrates expected empty result behavior +13/-0    vector_ivf.result Add expected test results for empty query                                test/distributed/cases/vector/vector_ivf.result Added expected result output for empty vector index query test Shows empty result set with column headers Corresponds to new SQL test case for empty searches +13/-0

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[qodo-merge-pro]

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[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Prevent resource leak with defer Use a defer statement to ensure res.Close() is always called after runSql returns a result, preventing a potential resource leak on early returns. pkg/vectorindex/ivfflat/search.go [193-213] + res, err := runSql(proc, sql) + if err != nil { + return + } + defer res.Close() + + if len(rt.BackgroundQueries) > 0 { + rt.BackgroundQueries[0] = res.LogicalPlan + } + distances = make([]float64, 0, rt.Limit) resid := make([]any, 0, rt.Limit) if len(res.Batches) == 0 { return resid, distances, nil } for _, bat := range res.Batches { for i := 0; i < bat.RowCount(); i++ { pk := vector.GetAny(bat.Vecs[0], i, true) resid = append(resid, pk) dist := vector.GetFixedAtNoTypeCheck[float64](bat.Vecs[1], i) dist = metric.DistanceTransformIvfflat(dist, idxcfg.OpType, metric.MetricType(idxcfg.Ivfflat.Metric)) distances = append(distances, dist) } } - res.Close() - return resid, distances, nil Apply / Chat Suggestion importance[1-10]: 8 __ Why: The suggestion correctly identifies a resource leak introduced in the PR due to an early return path where res.Close() is not called, and it proposes the idiomatic Go solution using defer.	Medium
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