|
|
Browse by Tags
All Tags » internals » Iterators (RSS)
-
A few days ago, Sandra Mueller (twitter | blog) asked a question using twitter’s #sqlhelp hash tag: “Might SQL Server retrieve (out-of-row) LOB data from a table, even if the column isn’t referenced in the query?” Leaving aside trivial cases (like selecting a computed column that does reference the LOB data), one might be tempted to say ...
-
If you look up Table Hints in Books Online, you’ll find the following statement: If a clustered index exists, INDEX(0) forces a clustered index scan and INDEX(1) forces a clustered index scan or seek.
If no clustered index exists, INDEX(0) forces a table scan and INDEX(1) is interpreted as an error. The interesting thing there is ...
-
Iterators SQL Server uses an extensible architecture for query optimisation and execution, using ‘iterators’ as basic building-blocks.
Iterators are probably most familiar in their graphical showplan representation, where each icon represents a single iterator. They also show up in XML query plan output as RelOp nodes.
Each ...
|
|
|
|