All versions of Microsoft SQL Server (not MySQL). Please also add a version-specific tag like sql-server-2016 if that is relevant to the question.

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19
votes
1answer
14k views

How do I read Query Cost, and is it always a percentage?

I'm currently studying for SQL 70-433 (the Microsoft Certification exam), and I'm getting very confused about the "query cost" performance metric. According to any documentation I could find via ...
14
votes
3answers
3k views

Is there any benefit to defragmenting SQL indexes in a SAN environment?

Our SQL server lives on a SAN. It contains dozens of OLTP databases, some with several tables containing over 1m records. We have been running Ola Hallengren's index maintenance scripts weekly, and ...
14
votes
3answers
12k views

How does shrinking a SQL Server log file affect performance?

I have a SQL Server 2008 database that has a data file of some 2GB in size, but the log file is over 8GB. With pre-2008 databases I could use the 'Backup log' and the TRUNCATE_ONLY option but this is ...
12
votes
2answers
6k views

SQL Server 2008 - Partitioning and Clustered Indexes

So let me preface by saying I do not have total control over my db design, so a lot of the aspects of the current system cannot be changed for the purposes of this scenario. Comments about how we ...
11
votes
2answers
10k views

What is blocking and how does it happen?

I tried to find some information about blocking in SQL Server, but I could not find a concise explanation for what it is and how it happens. Could you please enlighten me?
5
votes
5answers
20k views

Cannot start SqlLocalDB instance with my Windows account

I'm the administrator and simply run the command: sqllocaldb start v11.0 Result: Start of LocalDB instance "v11.0" failed because of the following error: Error occurred during LocalDB instance ...
18
votes
2answers
3k views

Why do wildcards in GROUP BY statements not work?

I am trying to make the following SQL statement work, but I get a syntax error: SELECT A.*, COUNT(B.foo) FROM TABLE1 A LEFT JOIN TABLE2 B ON A.PKey = B.FKey GROUP BY A.* Here, A is a wide table ...
15
votes
3answers
7k views

Find out what queries are causing the biggest amount of network traffic

On a production SQL server I am seeing intermittent enormous spikes in data traffic. Up to 200Mbit/s which is causing NETWORK IO waits which in turn cause query timeouts. How can I find out what ...
9
votes
4answers
776 views

Is a join optimized to a where clause at runtime?

When I write a query like this... select * from table1 t1 join table2 t2 on t1.id = t2.id Does the SQL optimizer, not sure if that is the correct term, translate that to... select * from table1 ...
8
votes
2answers
1k views

How to schedule jobs in Sql server 2008 for less than 10 sec?

I want to run a job every 3 seconds, however in SQL Server 2008 we cannot define an interval of less than 10 seconds. The job is used to insert/update visitor information, and segmentation ...
7
votes
3answers
256 views

sql server: updating fields on huge table in small chunks: how to get progress/status?

We have a very large (100million row) table, and we need to update a couple of fields on it. For log shipping, etc, we also, obviously, want to keep it to bite-size transactions. Will the below do ...
7
votes
1answer
653 views

What is the correct way to ensure unique entries in a temporal database design?

I'm having trouble with the design of a temporal database. I need to know how to make sure I have only one active record for any given timeframe for a store. I have read this answer, but I'm afraid I ...
10
votes
3answers
2k views

PostgreSQL Initial Database Size

There are 2 parts to my question. Is there a way of specifying the initial size of a database in PostgreSQL? If there isn't, how do you deal with fragmentation when the database grows over time? ...
9
votes
2answers
34k views

What is the easiest way to move data from Oracle to SQL Server?

One of our products supports both Oracle and SQL Server as database backend. We have a customer who wishes to switch from an Oracle backend to Microsoft SQL Server, which isn't a typical transition ...
7
votes
1answer
674 views

Query is slow in SQL Server 2014, fast in SQL Server 2012

During the migration of one of our databases from SQL Server 2012 (SP1, CU2) to SQL Server 2014 (SP1), we have experienced some strange issues. One of the queries that completes within seconds on SQL ...
7
votes
3answers
22k views

How to view an encrypted view or stored procedure

I am working on a third party database. When I try to view the definition of a view by right clicking, CREATE TO and then to NEW QUERY EDIT WINDOW, I am getting an error: This property may not ...
7
votes
1answer
14k views

When is a Dynamic Port “dynamic”?

I was having a discussion today about Dynamic Ports with one of my co-workers and could use some help clarifying how they work. First question: If the IPALL TCP Dynmaic Ports setting is a specific ...
7
votes
3answers
4k views

SQL Server - what isolation level for non-blocking select statements?

I have a long running transaction (called, say, T1) that performs some deletes, updates and inserts on a table in SQL Server 2008 R2. At the same time, another process periodically runs select ...
6
votes
3answers
12k views

Why is a .bak so much smaller than the database it's a backup of?

I just took a backup of a SQL Server database. The MDF and LDF files together total around 29 GB, but the .bak file was only 23 GB, about 20% smaller. My first guess when one version of a set of ...
4
votes
2answers
959 views

SSRS Blocking Processes

We have a busy SSRS Reporting server (SQL Server 2008 R2) on which we see frequent blocking between the below processes: [dbo].[CheckSessionLock] [dbo].[WriteLockSession] We are aware that some ...
4
votes
1answer
2k views

Restore All Databases Script

I am migrating SQL Server DBs to a new instance. I have been told that it is possible to dynamically build a RESTORE script from available backups in the system catalog. Does anyone know of a sample ...
4
votes
2answers
4k views

SQL Server how to detect unused views and/or get usage stats

Is there a way to determine in SQL Server if a view is no longer being used? (without removing it) Ideally i would like to know usage for SQL Server 2000 as well as 2012 if that is possible. I am ...
3
votes
3answers
1k views

Restore a large number of transaction logs

I'm using SQL Server 2008 R2, and I need to restore 36 .trn logs to a database. I have restored the first 4 using the restore transaction log functionality in SSMS (right-click database > tasks > ...
3
votes
2answers
2k views

Missing Transaction log in chain, Possible to skip

We have had one of our clients SQL Servers crash and need to restore it to the most recent possible time. We have a full backup from Monday and transaction logs that run every hour up until this ...
14
votes
3answers
15k views

Common Table Expression (CTE) benefits?

From msdn : Unlike a derived table, a CTE can be self-referencing and can be referenced multiple times in the same query. I'm using CTEs quite a lot, but I've never thought deeply about the ...
12
votes
5answers
14k views

.bak file not visible in any directory in SSMS

I have a .bak file created today by someone else, manually created through SSMS 2008 R2. I'm trying to manually restore the database, unfortunately the file isn't appearing when I go to browse it. I ...
11
votes
3answers
27k views

Reset IDENTITY value

I have a table with an IDENTITY column. While developing I delete the rows from time to time and add them again. But the IDENTITY values always kept increasing and didn't start from 1 when I added ...
10
votes
1answer
942 views

Is there a reliable way to determine when you should run DBCC CLEANTABLE to reclaim space?

Lately, instead of just growing files when they near 80% file utilization, I've been more proactive at reclaiming space via the usual tricks like defragmenting heaps, adding & dropping clustered ...
9
votes
3answers
753 views

Would it be considered as a bad practice to have multiple nullable FKs on a table in SQL Server

On my database structure in SQL Server, I have 3 types of products which requires different information about the order. So, I created one Customers table and three different orders tables: ...
7
votes
2answers
352 views

Automation of backups of Large Number of Database

In a multi-tenant web application where a database is set up for each tenant, the database can be backed up and restored manually through a fairly conventional approach. I am considering this type of ...
6
votes
4answers
5k views

SQL Server script to delete accounts no longer in Active Directory

We have a SQL Server 2000 that will shortly be migrated to SQL Server 2005. It has years of Windows Authentication accounts created that no longer exist in Active Directory, which prevent the Copy ...
6
votes
2answers
3k views

'Conversion failed' error with ORDER BY CASE expression

I have the following Stored Procedure that works great EXCEPT when I set the 'OrderBy' to 'OrderNumber'. I get the following error: Conversion failed when converting the nvarchar value 'SK11270' to ...
6
votes
1answer
812 views

Guarantee SQL Server Identity Columns that two consecutive values differ by constant increments?

I posed a question about Denali sequences here and another question about emulation of identity columns in Oracle Global Tables here. I always thought that I could trust that identity values ...
4
votes
6answers
15k views

SQL Server log shrinking Issue [duplicate]

Possible Duplicate: Why Does the Transaction Log Keep Growing or Run Out of Space? I have a 300 GB database log in our SQL Server. I want to shrink all the logs but it is not allowing me to ...
4
votes
3answers
6k views

How to move data from big table

There is a big table (5-6 million records). I have to move 90% of old records to other database(table). Solution?
3
votes
1answer
155 views

Analysing A Query Plan

Why is the following query slow? select count(*) from [dbo].[mt_dispatch_link] , [dbo].[_mt_dispatch] [_mt_dispatch] where (mt_dispatch_link.contract_id_1 = _mt_dispatch.contract_id ...
2
votes
3answers
38k views

SQL Server 2008 R2 High memory usage

I have SQL Server 2008 R2 that runs multiple jobs over night, the problem is SQL Server will eat up all RAM and CPU, then it will not release the RAM resources after the job finishes, as a workaround ...
8
votes
2answers
2k views

How to backup/restore SQL Server database from command line similar to mysql

I need to automate the migration for some databases from an older server. I know that script a tool using C# for example can be a possibility but I need a simple, fast and effective solution in order ...
8
votes
2answers
559 views

Mirroring the Distributor

Has anyone had success with mirroring the distribution database? We have a dedicated server as a Distributor. It handles all our push replication from prod to reporting. We'd like to build an ...
7
votes
1answer
249 views

Query optimizer recommends adding index instead of using existing index

I am trying to determine why the query optimizer in SQL Server is recommending creating a new index instead of using an existing index that appears to be sufficient for the query. First the table. ...
6
votes
2answers
6k views

When to make changes to the cost threshold for parallelism

While examining a performance issue , I have seen an influx on CXPACKETS suggesting I might need to look at the cost threshold for parallelism and perhaps the MAXDOP. Before making any drastic ...
4
votes
2answers
22k views

Copy a large data from sql query result

In my sql server 2008, after running the query the data return is very huge say in millions. I tried copying but it gives an exception sql memory error. Can you let us know how can i copy the entire ...
4
votes
2answers
1k views

How can I find databases with a large number of virtual log files?

I have several databases on a production server that are in the hundreds of gigabytes, and have many thousands of transactions running through them on a daily basis. Almost all these databases are ...
4
votes
1answer
2k views

Running queries with SQLCMD vs. Running queries with SSMS

I've noticed something which i'm not sure about. can it be that running queries directly with SSMS is much faster than running queries with SQLCMD? I've noticed that the results of queries that ran ...
4
votes
3answers
4k views

NULLs in a composite primary key - SQL Server

I'm trying to work out the best way of creating SQL Server primary keys, foreign keys and constraints to accurately represent my data model in LINQ / Entity Data Objects. Let's assume - for the ...
3
votes
2answers
113 views

Unable to restore database backup because it is accessed by other connection

--first command use master Go -- second command ALTER DATABASE MyDB SET SINGLE_USER WITH ROLLBACK IMMEDIATE Go -- Third command RESTORE DATABASE [MyDB] FROM DISK = ...
3
votes
1answer
158 views

MS SQL Server CPU load goes up dramatically when turning on 2014 features by setting compatibility level

I'm running some Microsoft SQL Server 2014 load testing on a decently spec'ed machine. I'm certainly not an expert on the SQL Server tuning specifics, but with the bits an pieces I've gathered from ...
3
votes
3answers
4k views

Not able to create SSISDB catalog

Getting the error below while trying to create a catalog in sql server 2014 integration services. Any idea what I missed in installation or anywhere else? The catalog backup file 'C:\Program ...
3
votes
1answer
2k views

How to get server cpu, memory, network usage from SQL Server

For reporting purposes, I want to get SQL Server box CPU, memory, network (not SQL Server process alone) and show it in report. Do you have any idea how to pull this? My initial thoughts are run wmi ...
3
votes
3answers
3k views

Query to find GUID's “not in” null containing subquery returns no results

When I have a query that checks if a column of type uniqueidentifer does not exist in a table that has a null value then I get no results back. If the subquery does not return a null it works fine and ...