Index locking
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Index locking
Index locking blocks all access by other tasks to the entire table in a database. With index locking you may want to lock the index build for a column, not just the data items themselves
The circumstances where it is necessary to index lock include:
- Adding a new level to the root page
- Shrinking the root page
- Splitting or shrinking the immediate child of the root page, causing an update on the root page
Circumstances where it is not necessary to Index lock include where:
- You have small tables with index levels no higher than 3.
- You envision possible modifications to the root page of an index
An example of doing an aggregate function(sum of salary field)
- update happens along the way
- result depends on the order of interleaving
- best to lock the index as well as the record.