Locks for smart large objects

Smart large objects have several unique locking behaviors because their columns are typically much larger than other columns in a table.

This section discusses the following unique behaviors:
  • Types of locks on smart large objects
  • Byte-range locking
  • Lock promotion
  • Dirty Read isolation level with smart large objects

Types of locks on smart large objects

The database server uses one of the following granularity levels for locking smart large objects:
  • The sbspace chunk header partition
  • The smart large object
  • A byte range of the smart large object

The default locking granularity is at the level of the smart large object. In other words, when you update a smart large object, by default the database server locks the smart large object that is being updated.

Locks on the sbspace chunk header partition only occur when the database server promotes locks on smart large objects. For more information, see Lock promotion.

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