SQLSACT (9/13/2012)
GilaMonster (9/13/2012)
SQLSACT (9/13/2012)
When SQL Server brings pages into Memory, the pages sit in memory in the same way as they were sitting on disk?Meaning?
When the query is submitted for the second time, even though the pages are in memory, are there still reads happening on the disk? Because of the Clustered Index Seek?
Is this right?
Only if some pages are needed that aren't in memory
Meaning?
In the same order as they were on disk
No.
Only if some pages are needed that aren't in memory
Ok this makes sense
What I'm struggling to grasp is why does SQL Server still worry with the Index if all the pages that it needs is already in memory.
Thanks
How else will it find what page a row is on? Indexes are about locating rows. If it didn't bother with an index, it'd have to do a full table scan to find rows needed for the query. Not exactly efficient.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability