An evaluation of whether a system works well enough to be fit for purpose. Normally performance refers to the speed with which a system completes an operation or set of operations over time.

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How to troubleshoot SQL “The timeout period elapsed prior to completion of the operation or the server is not responding.”

I'm trying to troubleshoot a timeout issue that occurs on one of our SQL 2005 servers. The database responds normally for about a day until we start to see sql timeout errors. After that all ...
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5answers
489 views

Indexing from start or when performance problem arises?

My question is regarding use of indexes. Should I start indexing right from the start or when performance problem arises? We can also create temporary index while executing a query. What are the ...
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3answers
2k views

Slow deletion of records when a trigger is enabled

Thought this was solved with the link below - the work around works - but the patch doesn't. Working with Microsoft support to resolve. http://support.microsoft.com/kb/2606883 Ok so I have an ...
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1answer
208 views

What units is this metric in?

Im currently using the following query to get the Page Life expectancy from sql server: declare @PLE int select @PLE=cntr_value from psql1.master.sys.dm_os_performance_counters where ...
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2answers
1k views

Database locking issues?

I have run into a transaction related issue on a SQL Server 2008 production database. A brief overview is that we have a website that has numerous concurrent users around the state, who do GUI type ...
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2answers
236 views

Improving the performance of a long query

I have a query that i have let run for a few hours. I am forced to kill the query because it is taking up 60% of the CPU. Is there anything i can do to improve its performance? select ...
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3answers
162 views

SQL Server Express acting strange

I'm not an IT pro, but a web developer that happens to have his own blog. The blog is hosted on a private VM on which I have both IIS and SQL Server. Sometime my blog, which is not super busy stops ...
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1answer
950 views

SQL Server Replication causing locks on table

we have three MSSQL 2005 servers (database is set to compatibility level 80 for legacy reasons) which we have just set up Transactional Replication w/ Updateable Subscriptions on. Two which are ...
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3answers
339 views

Same tables with same data, different SQL Server stored procedure performance

I have 2 SQL Server 2008 instances installed on the same server. They have same table structures with same data. I have a stored procedure deployed on both of them. The stored procedure performs ...
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1answer
259 views

MySQL Performance Planning

I am considering moving my existing script which is downloaded to be a hosted script. One of the things it does is to keep track of some stats. My concern is with heavy hitters (100,000 ...
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4answers
772 views

DDL contention on TempDB

I have a SQL Server 2005 Standard x64 that is experiencing issues with TempDB DDL contention for the past few months. The server will experiencing contention on wait resource 2:1:103 (the wait type ...
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3answers
6k views

Best of MyISAM and InnoDB

Is it possible to make InnoDB to use indexes same as MyISAM instead of clustered index due to limitation of RAM while getting benefit of its concurrency performance?
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2answers
2k views

Database design for dynamic Meta fields of an entity that shall be queried intensively

I'm designing a database structure for a system at which an entity can have a dynamic set of user-defined meta attributes. The meta fields (e.g.: popularity, conversion etc.) and skill values (int, ...
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2answers
25k views

Multi cores and MySQL Performance

Importance of RAM is an established fact but far less material is available about the importance of cores and multithreading when it comes to the usage of CPU by MySQL. I am talking about the ...
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2answers
256 views

What is the consensus on using NOT NULL constraints on all text-based fields in a table?

Some of the tables I have come across don't have any NOT NULL constraints, which has yielded to some gotchas when querying. I'm curious what the feelings are with using something like NOT NULL ...
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2answers
99 views

Should fields that aren't needed often be kept in separate tables?

I have a tagging system on my site. I also want to add descriptions to the tags just like on the S.E. sites. The tags are used for a lot of stuff. Its how categories know what products to display, ...
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3answers
1k views

Testing stored procedure scalability

I have an email application that will be called upon to deliver to the UI the number of new messages for a given user on each page load. I have a few variations of things I am testing on the DB level ...
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3answers
2k views

When do hash indexes become reasonable?

MySQL natively doesn't support hash indexes. So, making a pseudo hash column and creating an index on a hash column needs some thinking. And it seems to be widely understood that if the text field is ...
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3answers
1k views

For every insert statement I see sp_executesql in SQL Server Profiler

Working on tuning our database and queries for one of our products, I decided to pop open Profiler in the QA environment and see what it shows. I saw for every insert I called, a call was made to ...
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1answer
622 views

What is com_set_option?

As the title says, I'm wondering what is this command and why am I seeing a large amount of this query on my database? It's currently 13.30% of my total queries. I've tried googling this but there's ...
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2answers
264 views

Differences between development and live database setups

I was wondering if there are any best practice recommendations on setting up databases in a dev environment versus a live environment with regards to configuration. Should they be as similar as ...
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3answers
42k views

Possible to make MySQL use more than one core?

I've been presented with some dedicated MySQL servers that never use more than a single core. I'm more developer then DBA for MySQL so need some help Setup The servers are quite hefty with an ...
3
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1answer
854 views

Replication slows down on massive deletes

First of all, I'm not a DBA, but I'd like to get advice how to deal with the following issue. We have few database servers based on SQL Server 2008 R2 SP1. They have been organized as shown below, so ...
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2answers
4k views

How to know when/if I have too many indexes?

Running Microsoft SQL Server Profiler every now and then, it suggests me with a bunch of new indexes and statistics to create ("...97% estimated improvement..."). From my understanding every added ...
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3answers
5k views

Is nested view a good database design?

I have read somewhere long time ago. The book states that we should not allow to having a nested view in SQL Server. I am not sure the reason why we can't do that or I might remember incorrect ...
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2answers
164 views

How can a key lookup with zero executions and zero actual rows take time?

I have a query that is taking about 10 seconds to run and I am trying to optimize it. All the time is spent in the key lookup which is fine however in this case if I mouse over the key lookup in the ...
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2answers
856 views

SQL 2005- stored procedure performance troubleshooting

I am investigating performance issues for a stored procedure on SQL 2005 server. This is how I intend to do it: Analyze the stored procedure for any bad TSQL practices (like count * etc) Run it ...
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3answers
451 views

Usage of SQL Server 2008 R2 Express. Please Advise

I'd like you all to give me hints and advise on the following scenario: We are considering using Microsoft's SQL Server 2008 R2 Express for a business Web Application. The Web Application won't have ...
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5answers
795 views

Should Query Tuning be Proactive or Reactive?

As a software developer and an aspiring DBA, I try to encorporate best practices when I design my SQL Server databases (99% of the time my software sits on top of SQL Server). I make the best ...
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1answer
103 views

Are there significant performance differences when linking to a simple data view, rather than a data table, in a simple data view?

Sorry for the long question, but let me give you my scenario. I have a DB that houses data exported from another DB. The containing tables are copies from the other (non-SQL) database. Each column ...
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2answers
202 views

Best way(s) to time ad hoc queries and stored procedures

What are the most accepted ways to time your queries, whether they are ad hoc or stored procedures? Is it more accurate to use SQL Profiler than SET STATISTICS TIME ON?
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2answers
734 views

Will creating partitions reduce locking and how do we implement this in sql-server?

A client wants our application to process more data faster so arranged a meeting with their dba to discuss options. This application generates quite a lot of data that is used for reporting. Before ...
2
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2answers
489 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 ...
6
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2answers
257 views

Row padding to get more performance

I have read a document (Designing Highly Scalable OLTP Systems) that describe a trick how to get more performance: Because rows are small (many fit a page) multiple locks may compete for one ...
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3answers
297 views

Things to consider with a bigger table

I have a table that has around 12 billion rows (row size 32 B) which grows each month by 300 million rows. I have setup partitions for each month and each month has 8 data files (since I currently ...
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2answers
3k views

Updating 700 million rows to same value

I've got a data warehouse (oracle) where I need to set a column to the same value for all 700 million rows. I don't have admin access, or access to an admin, so this needs to be accomplished with ...
2
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1answer
678 views

Optimising a Database Shrink (in terms of speed and reducing fragmentation)

We have a large database that has had a lot of older data stripped out, leaving primary datafile (all objects are currently in the primary filegroup) of about 80Gb containing a little less than 20Gb ...
6
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4answers
336 views

What are the performance implications of running multiple smaller DBs instead of a single larger DB on a server?

Our database architecture allows multiple 'customers' to exist in the same database, yet we split them into mulitple database for administrative reasons [patching, backup, etc.] Question 1 What ...
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2answers
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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 ...
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3answers
223 views

When you select from a table on an indexed column and order by that column in the opposite direction of the index, does the index help

Let's say I have a large table of transactions with a date field and an index on that field in ascending order. If I select that field from the table and order by in reverse order is it able to ...
9
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1answer
2k views

Optimising BCP performance for BLOB data

I'm the process of planning the live migration of a 2TB database to partitioned tables. The system is broadly speaking a document store, the majority of the space being allocated to LOBs of between ...
4
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1answer
579 views

Terabyte data set

I have the feeling that most of the database systems originate in the '80s and stereotypically implement tables, ACID transactions and constraints. They were build having in mind the scarcity of ...
2
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1answer
128 views

Does document “depth” affect CouchDB performance?

I have a project where it is very tempting to use a deeply nested collection of data. But how does that affect performance? Are there any reasons why I should avoid doing this? I'm talking about lists ...
9
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3answers
308 views

Query Performance Tuning

When you finish writing a query/stored proc/function, what's the most informative way to quickly get some performance parameters? Do you run the query and view the actual execution plan? If so, what ...
5
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5answers
807 views

Advice with date column SQL Server 2005

I have two datetime columns in SQL Server 2005 that I need to query without the time portion of the datetime. Currently, my query looks something resembling this (just an example): WITH Dates AS ( ...
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2answers
1k views

SQL Server: Has anyone used the large-page allocations tuning option?

Has anyone used the tuning option of using TF834 large page allocations. I was just reading an MS article on it and was wondering if anybody had used it and seen performance gains. Are there any ...
4
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2answers
1k views

SQL Server query result transfer time over VPN (WAN)

I have a mysterious phenomenon on one remote SQL Server 2005 which I manage and query using SQL Server Management Studio. I connect to the server through a VPN tunnel (provided by an ISP, about 8 ...
13
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7answers
303 views

Which of these table designs is better for performance?

I have been asked to create something which tracks the daily cost to collect on accounts, and I am trying to figure out a database table schema that would support this. Here's what I know Company ...
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3answers
3k views

Too Many Connections

I'm using MATLAB to feed the database but after a time I'm getting a too many connections error. I always using opendb and closedb in pair. Is it to fast the feeding? Do I have to wait after I ...
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3answers
3k views

Efficency of stored procedures vs raw queries

I have read much on both sides of this debate: is there a signficant performance gain to be had by using only stored procedures over raw queries? I am specifically interested in SQL Server but would ...