Tagged Questions

8
votes
1answer
290 views

DELETE vs TRUNCATE

I am trying to get a greater understanding on the differences between the DELETE and TRUNCATE commands. My understanding of the internals goes something along the lines of: DELETE -> the database ...
5
votes
2answers
194 views

Why disabling a clustered index makes the table inaccessible?

When an index is disabled, the definition remains in the system catalog but is no longer used. SQL Server does not maintain the index (as data in the table changes), and the index cannot be used to ...
0
votes
0answers
91 views

SQL Server Internal Memory Pressure

I am trying to identify the cause of internal memory pressure. From what I have learned, Resource Monitor Ring Buffer returns an indicator for internal pressure. For example by using this query, ...
1
vote
1answer
46 views

How SQL Server detects a record internally?

I am following this SO post where the author (stack programmer) states SQL server uses the identity column as the key value to refer to a particular row. So only a single identity column can be ...
4
votes
2answers
209 views

What are the differences between leaf and non-leaf pages?

I've been running some index usage reports, and I'm trying to get a definition of Leaf and Non-leaf. There seem to be both Leaf and Non-leaf Inserts, Updates, Deletes, Page Merges, and Page ...
13
votes
2answers
650 views

Optimising plans with XML readers

Executing the query from here to pull the deadlock events out of the default extended events session SELECT CAST ( REPLACE ( REPLACE ( XEventData.XEvent.value ...
2
votes
1answer
228 views

Index with multiple leaf levels

I have a three-column (int, smallint, smallint) composite clustered index with three leaf levels. My question is how and when does SQL Server create multiple leaf levels (index_level 0) for the same ...
12
votes
1answer
443 views

Where are Statistics physically stored in SQL Server?

Where are the Statistics used by the Query Optimizer physically stored inside a SQL Server database file and the Buffer Pool? More specifically, is there a way to figure out the pages used by ...
3
votes
1answer
90 views

Directly acessing the NULL bitmap of a row in SQL Server

I was reading the question Checking a wide table for nulls and I'm wondering if it's possible to somehow directly access the NULL bitmap of a row to fast check if a row contains NULL values. Would ...
2
votes
1answer
145 views

What is a parse tree object?

I have looked into sys.syscachedobjects table. I found some records have an object type of parsetree. Can anyone tell me in detail what a parsetree is? Is this a data structure used by SQL Server, ...
-1
votes
2answers
113 views

Which SQL Server system database is more important: master or resource? [closed]

Which SQL Server system database is more important: master or resource? If the resource database is damaged, can the database engine work? Can the system work with only the master database? If not, ...