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System DesignHard· Multilingual Search· Cost Optimization· Search Architecture

Platform wants to consolidate five per-language indexes...

Correct the premise: consolidation does not save storage because the number of documents remains the same. Savings come from reducing the number of model deployments, evaluation suites, and on-call rotations. To adjudicate, measure the dominant language’s recall under both models to test for monolingual regression. If cross-lingual queries are negligible, keep per-language indexes and consolidate only the serving layer. If cross-lingual queries are material, the single space is necessary, and the monolingual loss is the price of the new capability.

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