The relative priority for requests. Note that priority is not
The priority acts as a hint to the Cloud Spanner scheduler and does
not guarantee priority or order of execution. For example:
Some parts of a write operation always execute at
PRIORITY_HIGH, regardless of the specified priority. This may
cause you to see an increase in high priority workload even when
executing a low priority request. This can also potentially cause
a priority inversion where a lower priority request will be
fulfilled ahead of a higher priority request.
If a transaction contains multiple operations with different
priorities, Cloud Spanner does not guarantee to process the
higher priority operations first. There may be other constraints
to satisfy, such as order of operations.