Clustered Indexes Do Not Guarantee Physical Order

Gail Shaw on how clustered indexes do not guarantee physical order:

Do indexes (clustered or non-clustered) define the physical storage order of the rows?

No, absolutely not.

What indexes do is provide a logical ordering, a collection of pointers, that allow the storage engine to retrieve data from an index ordered by the index key, but that’s logical ordering, it specified nothing regarding the physical ordering.

Read the whole thing.

Related Posts

Adaptive Joins and Index Width

Erik Darling wants to pump your indexes up: Now, there’s an Extended Event that… Used to work. These days it just stares blankly at me. But since I’ve worked with this before, I know the problem. It’s that Key Lookup — I’ll explain more in a minute. Adaptive joins won’t do all the work for you, […]

Read More

Making Non-SARGable Queries SARGable with an Index

Denis Gobo violates Betteridge’s Law of Headlines: This question came up the other day from a co-worker, he said he couldn’t change a query but was there a way of making the same query produce a better plan by doing something else perhaps (magic?) He said his query had a WHERE clause that looked like […]

Read More

Categories

November 2015
MTWTFSS
« Jan Dec »
 1
2345678
9101112131415
16171819202122
23242526272829
30