sql server - What is the difference between Index Scan, Table Scan, and an Index Seek? -
can 1 briefly explain what's difference between these 3 index scan, table scan, , index seek?
index scan
index scan scans each , every record in index.
table scan
table processed row row beginning end. if index clustered index index scan table scan. since scan touches every row in table whether or not qualifies, cost proportional total number of rows in table. hence, scan efficient strategy if table small.
index seek
since seek touches rows qualify , pages contain these qualifying rows, cost proportional number of qualifying rows , pages rather total number of rows in table.
Comments
Post a Comment