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MySQL 5.7 Reference Manual  /  ...  /  Predicate Locking for Spatial Indexes

15.3.6 Predicate Locking for Spatial Indexes

As of MySQL 5.7.5, InnoDB supports SPATIAL indexing of columns containing spatial columns (see Section 12.5.3.5, “Optimizing Spatial Analysis”).

To handle locking for operations involving SPATIAL indexes, next-key locking does not work well to support REPEATABLE READ or SERIALIZABLE transaction isolation levels. There is no absolute ordering concept in multidimensional data, so it is not clear which is the next key.

To enable support of isolation levels for tables with SPATIAL indexes, InnoDB uses predicate locks. A SPATIAL index contains minimum bounding rectangle (MBR) values, so InnoDB enforces consistent read on the index by setting a predicate lock on the MBR value used for a query. Other transactions cannot insert or modify a row that would match the query condition.


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