Skip implicit foreign key index covered by a unique constraint - #7476
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lazerg wants to merge 1 commit into
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Skip implicit foreign key index covered by a unique constraint#7476lazerg wants to merge 1 commit into
lazerg wants to merge 1 commit into
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No, nothing critical riding on this one. If #7477 removes the implicit index entirely and covers this case, I'm happy to close in favor of that. Thanks for taking a look. |
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Summary
When a foreign key's referencing columns are already covered by a unique constraint, DBAL still added an implicit backing index for the foreign key. On MySQL and MariaDB the unique constraint's own index already backs the foreign key, so that extra index is redundant and just duplicates it. DBAL already skips the implicit index when a regular index spans the same columns. This applies the same check to unique constraints.