What types of join algorithms can you have?
There are three kinds of JOINS in SQL Server, Nested table, Merge and Hash joins. All of the
above depend upon the resources available, MERGE and HASH consume lots of memory; so, a
system that is low on memory would sparingly resort to the above two join methodologies.
Nested table joins are based on the fact that indexes exist on nested tables in a SELECT query, for
each row in the outer table, a scan is done for the rows available on the inner tables' rows. If a
match is found, that row is retrieved.
There are three kinds of JOINS in SQL Server, Nested table, Merge and Hash joins. All of the
above depend upon the resources available, MERGE and HASH consume lots of memory; so, a
system that is low on memory would sparingly resort to the above two join methodologies.
Nested table joins are based on the fact that indexes exist on nested tables in a SELECT query, for
each row in the outer table, a scan is done for the rows available on the inner tables' rows. If a
match is found, that row is retrieved.
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