Microsoft's SQL Server is a relational database management system (RDBMS) that runs as a server providing multi-user access to a number of databases. It originated from the Sybase SQL Server codebase, which is why both products use the extension of SQL called Transact-SQL (T-SQL).

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16
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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 ...
13
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5answers
2k views

Handling concurrent access to a key table without deadlocks in SQL Server

I have a table that is used by a legacy application as a substitute for IDENTITY fields in various other tables. Each row in the table stores the last used ID LastID for the field named in IDName. ...
12
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2answers
1k 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 ...
8
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3answers
434 views

sql server database sharding - what to do with common data / non sharded data

We have a very large scale enterprise level database. As part of our business model all web users hit our web servers at the same time each month which in turn hammer our sql box. The traffic is very ...
7
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2answers
2k views

SQL Server Join/where processing order

After reading Slow SQL query, not sure how to optimize, it got me thinking about the general performance of queries. Surely, we need the results of the first table (when other tables are joined) to be ...
5
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3answers
2k views

SQL Server Primary key / clustered index design decision

Looking for some advice regarding a table / index design decision I've got to make on some tables that I've got to port into SQL server from an existing 4GL based database. I've got a product history ...
4
votes
4answers
2k views

SQL Server - Separating data, log, and TempDB files on a SAN

I have a SQL Server connected to a SAN. Our new storage vendor recommends that all LUNs span the entire disk array, which is RAID5. I would normally request 3 separate LUNs (data, log, and TempDB) ...
13
votes
3answers
6k 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 ...
10
votes
1answer
425 views

Behavior of data in indexes based on fill factor

Let's say you have a database where the default fill factor is 20. Whenever data is inserted, does it only create pages filled up to 20%? From my understanding, when the data is inserted there ...
10
votes
3answers
2k views

Is there a reason to update statistics manually?

In SQL Server, statistics are updated automatically when Auto Update Statistics in True (which is the default). Is there a reason to update statistics manually and in what circumstances?
10
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4answers
1k views

What tools are there to generate test data for SQL Server?

As you can see from another question of mine, generating test data is my theme right now. At this point, I'm still generating my test data by hand. However, this process always generates small ...
8
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3answers
208 views

Nonclustered Index Insert

Say I have a table like this: create table SomeTable ( id int identity(1, 1) not null primary key clustered, SomeString1 varchar(50) not null, SomeString2 varchar(50) not null ) go ...
7
votes
5answers
828 views

Inclusion of ORDER BY on query that returns no rows drastically affects performance

Given a simple three table join, query performance changes drastically when ORDER BY is included even with no rows returned. Actual problem scenario take 30 seconds to return zero rows but is instant ...
6
votes
1answer
3k views

SQL Server Deadlock Graph - Table, Page or Row Lock?

Is there any way to decipher if a lock in a deadlock graph is Table, Page or Row level? I have all the information I need from the graph, including the Isolation Level, (2) but I really want to know ...
0
votes
2answers
1k views

help in multi-language medical database?

My project is to design a medical database for many countries. This database contains many parts: medicines, medical centers, patients, etc. for every country with its own language. I started my ...
32
votes
5answers
6k views

Why does ALTER COLUMN to NOT NULL cause massive log file growth?

I have a table with 64m rows taking 4.3 GB on disk for its data. Each row is about 30 bytes of integer columns, plus a variable NVARCHAR(255) column for text. I added a a NULLABLE column with ...
17
votes
4answers
1k views

What are the consequences of setting varchar(8000)?

Since varchar takes disk space proportional to the size of the field, is there any reason why we shouldn't always define varchar as the maximum, e.g. varchar(8000) on SQL Server? On create table, if ...
10
votes
2answers
307 views

Setting READ UNCOMMITTED when reading DMVs

I've seen several people call SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED before reading system DMVs. Is there ever any reason to do this, assuming you aren't mixing calls to DMVs and tables in ...
10
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6answers
2k views

Suddenly Slow Execution Plan for Stored Proc

I'm trying to understand an issue we're having with SQL Server 2000. We are a moderately transactional website and we have a stored proc called sp_GetCurrentTransactions which accepts a customerID, ...
9
votes
3answers
254 views

Optimizing a CTE hierarchy

Update below I have a table of accounts with a typical acct/parent account architecture to represent a hierarchy of accounts (SQL Server 2012). I created a VIEW using a CTE to hash out the hierarchy, ...
9
votes
2answers
404 views

Hard limitation for merge replication article count?

A bit of background. We developed an app that uses merge replication. Right now, we are currently publishing about 212 articles, and everything is fine, as it appears to fall into the 256 article ...
8
votes
2answers
3k 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 ...
8
votes
2answers
2k views

SQL Server VARCHAR Column Width

Searching around the web, I have found conflicting advice on whether there is a performance impact when specifying overly-wide VARCHAR columns, e.g. VARCHAR(255) when VARCHAR(30) will probably do. I ...
8
votes
2answers
5k views

Difference Between Row Level and Page Level Locking and Consequences

When attempting to run my Maintenance Plan, I receive the following error: Executing the query "" failed with the following error: "The index "" (partition 1) on table "" cannot be reorganized ...
8
votes
1answer
528 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 ...
8
votes
2answers
660 views

What is the meaning of DOP in the context of SQL Server?

What is the meaning of DOP in the context of sql server?
7
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2answers
438 views

SQL Server database design for “archived but available” data

We have this large database (>1TB) that we intend to "shrink". The database revolves around one main entity, let's call it "Visit". For discussion, let's say it is a database for a medical practice. ...
7
votes
2answers
1k views

Difference between SQL batch, statement and RPC?

What is the difference between SQL batch, T-SQL statement and Remote Procedure Call? How can I tell if part of the T-SQL code is a batch or statement?
7
votes
2answers
2k views

How To Profile Stored Procedures

I am using SQL Server 2012 and was wondering how to profile stored procedures For instance can profiler capture each individual SQL statement in a stored procedure, what it is, and how long it takes ...
7
votes
2answers
394 views

Can Availability Groups replace transactional replication?

I've been looking at the new features of SQL Server 2012, and how it can help my current situation. Currently we're on SQL Server 2008 R2, and replicate two OLTP servers' databases to a single ...
7
votes
2answers
411 views

Code creates different plan when ran ad-hoc vs. in a stored procedure

I have a delete statement that is using a bad plan when run inside a stored procedure, but is choosing a much better plan when run ad-hoc. I have rebuilt all the indexes for the tables used by the ...
7
votes
4answers
980 views

SQL Server: what should be done when a process is blocking another process?

I'm an accidental DBA and still learning. When I see from DMV:s or Activity Monitor that some process is blocking another process, what should be done? Should I simply kill those processes or is ...
6
votes
1answer
834 views

Transaction Log maintenance on Mirror database

SQL Server Version: 2008 R2 Enterprise SP2 I am trying to get a handle on our SQL Server maintenance and I came across something I think is incorrect. We have a single production instance with 3 ...
6
votes
3answers
2k views

Pivot rows into multiple columns

I have a SQL Server instance that has a linked server to an Oracle server. There is a table on the Oracle server called PersonOptions which contains the following data: ╔══════════╦══════════╗ ║ ...
6
votes
1answer
229 views

How to Optimise Query

I have a database structure similar to this, CREATE TABLE [dbo].[Dispatch]( [DispatchId] [int] NOT NULL, [ContractId] [int] NOT NULL, [DispatchDescription] [nvarchar](50) NOT NULL, ...
6
votes
3answers
1k views

Passing in the table into a stored procedure

Is it possible to pass in the name of a table into a stored procedure? For example, suppose you have several views of the same table. They all have the exact same structure. You want a store ...
6
votes
1answer
617 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 ...
6
votes
3answers
4k 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 ...
5
votes
1answer
2k views

How and when does SQL Agent update next_run_date/next_run_time values?

I've been working on code in T-SQL to add new schedules to a SQL Agent job using the sp_add_jobschedule proc in the msdb database. When I add a new schedule (typically a run-once at a specific ...
5
votes
5answers
4k views

Pros/Cons Using multiple databases vs using single database

Working on a new project which has the requirement to use 7 databases. Arguing performance, stability, optimization is easier implemented. While I don't agree I'm having trouble collecting good ...
5
votes
2answers
2k views

SQL Server - Tempdb data/log file placement

Currently we got TEMPDB Data (number of data files:2) and LOG file on same drive. On monitoring we have found I/O issues on TempDB. We got an extra drive available - should we move the TempDB Log ...
4
votes
2answers
6k 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 ...
4
votes
3answers
2k views

Test if any fields are NULL

I'm trying to figure out an easy query I can do to test if a large table has a list of entries that has at least ONE blank (NULL / empty) value in ANY column. I need something like SELECT * FROM ...
4
votes
6answers
2k views

Recommendations for MS SQL Server monitoring software or service? [closed]

I have a client with MS SQL Server instances (2000, 2005) scattered across 20-30 servers. I've been engaged to get things organized and will be periodically reviewing the state of the database ...
4
votes
1answer
765 views

SQL Server: How to create a table that fills one 8 KB page?

Is there a way to calculate the amount of data that fills one 8 KB page in SQL Server and create a table that fills one page entirely? This kind of table is presented in in this blog post.
3
votes
2answers
147 views

Server permissions of an activation stored procedure of a Server Broker queue

I have a stored procedure that queries the sys.dm_exec_requests view. In the stored procedure the view only returns one row, while the stored procedure needs to see all of them. The MSDN article on ...
3
votes
0answers
104 views

How to Audit for Access with Cross Database Ownership Chaining

I've just joined the data team of a new company and we have a large SQL Server environment (100+ instances) and cross database ownership chaining is on by what I gather is a necessity. I'm looking for ...
3
votes
1answer
121 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 ...
3
votes
2answers
2k views

Problem Reaching VM SQL Server Instance

Here's what I'm working with right now. I have a host OS which includes a SQL Server 2008 Enterprise instance. I have a virtual machine running on this host which has a SQL Server 2008 R2 Express ...
2
votes
2answers
2k views

After moving database (backup, restore), I have to re-add user

I occasionally move a database (SQL Express 2012) from a development machine to a server, or vice versa, using database backup and restore in SQL Server Management Studio. Whenever I do this, the ...