[9.2] Fix ArrayIndexOutOfBoundsException in fetch phase with partial results (#144385)#145003
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elasticsearchmachine merged 1 commit intoelastic:9.2from Mar 26, 2026
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elastic#144385) When a search fetch phase times out on a shard with allow_partial_search_results: true, the coordinating node can hit an ArrayIndexOutOfBoundsException in SearchPhaseController.getHits() or SearchPhaseController.mergeSuggest(). This is caused by: FetchPhaseDocsIterator.iterate() — on timeout, used System.arraycopy(searchHits, 0, partial, 0, i) to build the partial result. Because docs are iterated in doc-id order but placed at their original (score-sorted) positions, this copy produced a corrupted array. It included nulls at unfilled positions and dropped valid hits stored beyond index i. Fixed by replacing the arraycopy with a stripNulls method that returns a compact array of only the successfully fetched hits. SearchPhaseController.getHits() / mergeSuggest() — the query phase promises N docs from a shard, but the fetch phase may return fewer after a timeout. The merge loop used a counter to index into the fetch result array without checking bounds, causing ArrayIndexOutOfBoundsException. Fixed by adding a bounds check that skips entries when the counter exceeds the available hits.
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:Search Foundations/Search
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Backports the following commits to 9.2: