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.

learn more… | top users | synonyms

3
votes
1answer
541 views

Fastest key-value store for random disk reads?

I want a key-value store, with records stored on disk. (There are too many for memory.) I want to use a single machine. What key-value store will provide the fastest random reads (off disk)?
9
votes
3answers
13k views

Cache MySQL database in memory

I am having problems with a website with 600MB of MySQL database. The website is way too slow. I noticed the bigger the MySQL database gets, the slower it goes. When it was 5MB, the website was very ...
3
votes
1answer
134 views

Database performance for determining entities assigned to users

I am interested in insight in improving performance in the following instance: I am currently working on an application that has a hierarchical entity structure where, depending on a user’s level ...
16
votes
4answers
15k views

What's better for large changes to a table: DELETE and INSERT every time or UPDATE existing?

I am making a project where I need to change around 36K records in one table daily. I'm wondering what will perform better: delete rows and insert new ones, or update already existing rows For me ...
0
votes
3answers
946 views

How using many tables and JOINS affect performance vs. using limited number of tables and lesser JOINS?

I want to design a db schema concerning a schedule. I. I can use all fields in the same table, for example: id | shop_id | mo (varchar) | tu (varchar) | we | th | fr | sa | su 1 | 1 | ...
2
votes
3answers
2k views

Why would recompile query hint result in different plan for same adhoc statement after freeproccache?

This is on SQL 2005 SP2, but I suspect this is something that applies to all query hints in general. I've got an adhoc sql statement that gets a different query plan solely because of ...
13
votes
3answers
8k views

Does “WHERE 1=1” usually have an impact on query performance?

I recently saw the question "where 1=1 statement"; a SQL construct I have used often in constructing dynamic SQL in an effort to write cleaner code (from the perspective of the host language). ...
1
vote
2answers
815 views

MySQL UPDATE Performance Issue

I'm running out of ideas on a performance bottleneck I'm seeing on one of my projects. The table in question is pretty small, with only 5396 records. However, I'm seeing queries like this show up in ...
2
votes
2answers
4k views

Solving high page load time using SQL Profiler

I'm looking into a performance of a login page taking 10-13 seconds to load. I'm using a DEMO database to test the performance and tweak to see any improvement. I'm using SQL Profiler to capture what ...
3
votes
2answers
1k views

MySQL vs SQLite on Amazon EC2

I have a Java program and PHP website I plan to run on my Amazon EC2 instance with an EBS volume. The program writes to and reads from a database. The website only reads from the same database. On ...
10
votes
4answers
5k views

Help me choose a RAID level combination for a SQL Server 2008 instance

I am going to rebuild one IBM 3400 server from scratch. This server is dedicated to a SQL Server 2008 instance running on Windows 2008 R2. I am going to make new RAID configuration. I have 6 SCSI ...
3
votes
1answer
564 views

Can I choose which CPUs / Cores to be used by MySQL?

I have a Windows VPS (Windows 2008 R2 x64) that runs a couple WordPress blogs and other few ASP.NET things. The VPS runs 2 CPUs (for example). With ASP.NET, in such situation, I usually set the app ...
2
votes
1answer
545 views

Pros and Cons of having additional columns in join table of many to many relationship

I searched but did not find any discussions on this topic. Are there any pros and cons on creating many extra columns on joined table? Does it affect speed of data retrieval because we are joining 3 ...
1
vote
1answer
805 views

How to prevent big performance impact during index creation

I have an existing database that is missing some indexes. When I tried creating some the database server really suffered in CPU usage during index creation interfering with the regular workload. Is ...
4
votes
3answers
119 views

Is it much more expensive to use procedures that get lists and deriving a count in the application vs. a separate stored procedure for the count?

I would like to know if returning a count is much more expensive than returning a dataset in regard to processing performance? I assume there is a bandwidth increase in delivery to the application ...
6
votes
1answer
9k views

How can I monitor the call count per stored procedure per timespan?

In order to diagnose some performance issues I would like to get a better understanding of the number of times certain procedures are called compared to the system performance. Is there a way to get ...
11
votes
2answers
437 views

To maximize DB performance, which commands should be run after loading large amounts of data into SQL Server 2008 via SSIS

I have written an SSIS package to load test data into an empty database. Some of the tables are very large (~700 million rows). Once the SSIS package has completed are there any commands I should run ...
6
votes
1answer
949 views

Password hashes: Fixed-length binary fields or single string field?

I'm currently having am amusing debate with a friend, and we simply can't agree on the best method to store salted passwords in a database. The two options on the table are: Storing the hash and the ...
13
votes
8answers
19k views

Tools to monitor Oracle Database Performance on Standard Edition

Here is what I am looking for: Works on Standard Edition i.e. No Diagnostic Pack. Provides both current and historical performance data. Good visuals for easy spotting of trends and presentation ...
3
votes
1answer
2k views

Why does MySQL use all of memory and goes into swap when doing lots of delayed inserts?

We have a database server running Centos 5.6 64bit 64Gb of RAM. The server is idle most of the time. However, every hour it gets a lot of DELAYED inserts. Up to 3 mil INSERTs per hour into a MyISAM ...
8
votes
1answer
7k views

What is the usage of performance_schema in MySQL 5.5?

I have upgraded to MySQL version 5.5. There, I had observed performance_schema in the schema list. What is the usage of this new schema..? How can we monitor using this schema..? What are the ...
16
votes
3answers
23k views

Efficient INSERT INTO a Table With Clustered Index

I have a SQL statement that inserts rows into a table with a clustered index on the column TRACKING_NUMBER. E.G.: INSERT INTO TABL_NAME (TRACKING_NUMBER, COLB, COLC) SELECT TRACKING_NUMBER, COL_B, ...
4
votes
1answer
1k views

Unicode support of PostgreSQL and its performance

How is the Unicode support of PostgreSQL? If I want to save Unicode data does it have to go through the conversion process while storing and retrieving? If yes then what is the performance of such ...
1
vote
1answer
1k views

Set statistics time showing different elapsed_time than dm_exec_query_stats view

When I exec a SQL statement after setting set statistics time on and running dbcc freeproccache and dbcc dropcleanbuffers I get the following output: DBCC execution completed. If DBCC printed error ...
10
votes
6answers
4k views

What could be causing strange query timeouts between PHP and MySQL?

I am the senior developer on a Software-as-a-Service application used by many different customers. Our software runs on a cluster of Apache / PHP application servers, powered by a MySQL backend. On ...
1
vote
1answer
192 views

Appropriate Windows version for Mysql

I have a HP ProLiant DL380 G5 server and I would like to install mysql on it . My questions are: Which MySQL version should I install from this link for better performance, 32 bit or 64 bit? Which ...
3
votes
3answers
9k views

How to avoid index scans in SQL Server 2005?

I have a table named Cell which has columns like Cell_ID, CellValue and CellRow. Cellrow can have values maximum 1 to 5. There is a clustered index on Cell_ID field. This table contains 100000 rows. ...
15
votes
5answers
13k views

Does restarting SQL Server speed it up?

I have noticed that some DBAs restart SQL Server very frequently, sometimes even nightly. I believe they do it to free up some memory, or perhaps to speed up queries too. I know that after a restart ...
5
votes
2answers
5k views

What are the potential causes for a sudden MySQL slowdown?

A few days ago mysql became suddenly very slow with queries taking more than 10s to complete when they used to complete under 100ms... It lasted about an hour and then the speed was normal again. What ...
4
votes
2answers
1k views

Website is too slow when number of records increases?

I have developed a web application called Referral Program, It it developed by using PHP, MySQL. Users can joining the website and when they introduce new members, he/she gets a commission. The system ...
0
votes
1answer
492 views

How could I handle heavy load and consistency for product inventory in online retailers? [closed]

I have posted that question on Stackoverflow and they suggest me to repost my question here, as it would more likely to get help from a DB community (regarding this issue). Hope you guys don't mind. ...
3
votes
1answer
2k views

Is SQL Server Backup single or multi-threaded?

If you perform a... BACKUP DATABASE [DB_Name] TO DISK=N'c:\backups\db_name.bak' WITH STATS=10 Will that perform a single or multi-threaded write? Our Server support company advised us that if we ...
1
vote
2answers
1k views

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 ...
14
votes
5answers
506 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 ...
13
votes
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 ...
5
votes
1answer
334 views

What units is Page Life Expectancy in?

I'm 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 ...
7
votes
2answers
2k 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 ...
2
votes
2answers
280 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 ...
3
votes
3answers
176 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 ...
2
votes
1answer
1k 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 ...
3
votes
3answers
404 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 ...
1
vote
1answer
261 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 ...
7
votes
4answers
934 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 ...
12
votes
3answers
10k 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?
4
votes
2answers
3k 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, ...
24
votes
2answers
41k 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 ...
4
votes
2answers
326 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 ...
3
votes
2answers
104 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, ...
10
votes
3answers
3k 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 ...
3
votes
3answers
3k 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 ...