Tagged Questions
4
votes
1answer
407 views
SQL Server 2008 query planner failing after index drop & recreate
Recently we ran a script to our production DB that would dynamically drop and recreate hundreds of indexes as filtered indexes. While this script had run perfectly in all other previous tests, now ...
10
votes
2answers
738 views
Parameter Sniffing vs VARIABLES vs Recompile vs OPTIMIZE FOR UNKNOWN
So we had a long running proc causing problems this morning (30 sec + run time). We decided to check to see if parameter sniffing was to blame. So, we rewrote the proc and set the incoming ...
9
votes
1answer
196 views
Does SQL Server 2008 store the creation date of execution plans?
We recently upgraded an application we use, which involved modifying the schema for the database. These changes could have forced cached execution plans to be discarded. If SQL Server was forced to ...
1
vote
1answer
106 views
SQl code performance
What measurement do you know if this sql code is efficient based on execution plans?
How do you know if this sql code is efficient based on execution plans?
SELECT [CustomerID], ...
10
votes
1answer
473 views
Why does SQL Server “Compute Scalar” when I SELECT a persisted computed column?
The three SELECT statements in this code
USE [tempdb];
GO
SET NOCOUNT ON;
CREATE TABLE dbo.persist_test (
id INT NOT NULL
, id5 AS (id * 5)
, id5p AS (id ...
4
votes
1answer
110 views
Filtered indices: Why include the filtered-on field?
This just drives me mad.
Consider a simple table with irrelevant columns removed:
create table boxes (
row_id int not null identity(1,1) primary key,
location varchar(15) null,
dismantled bit ...
4
votes
1answer
677 views
Why does it take so long to calculate an Execution Plan?
One of our customers has just upgraded to a new server.
For a particular stored procedure the first time you execute it, is taking over three minutes to run. Subsequent runs are less than 1 second.
...
8
votes
1answer
1k views
Are there any risks to granting users SQL Server SHOWPLAN permission?
I'm doing some performance tuning on a large SQL server 2008 database, and the IT group is unwilling to give SHOWPLAN permission. In the past, "Show Execution Plan" has been the most effective way to ...
2
votes
2answers
403 views
Clustered monotonically increased index insert performance
I have a table with field Id (bigint, IDENTITY) as primary key and clustered index on it.
I inserted 400 rows and saw execution plan. I got: the relative query cost for this insertion 36% and for this ...
2
votes
1answer
486 views
View SQL 2008 sp_cursorexecute Underlying Query and Execution Plan
I'm performance tuning a Dynamics AX application and see in a SQL trace a long-running, high-I/O query of the form exec sp_cursorexecute 1073742882 ... When I try and run that query in a new SQL ...
4
votes
1answer
291 views
how to improve performance by using or not using table variables
I have a table variable:
DECLARE @to_process TABLE
(
[Id] [bigint] NOT NULL,
[SequenceId] [bigint] NOT NULL,
...
)
INSERT INTO @to_process
( Id
, SequenceId
...
)
SELECT
...
