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

1
vote
4answers
653 views

Top 2 rows per partition from an absolute value date difference

I have a database of security camera footage in a denormalized database. I have Locations which have multiple Cameras which take multiple images. Location + Camera + image capture_date is the ...
5
votes
3answers
128 views

Dynamic temporary index creation

In my undergrad databases course, my professor mentioned that some DBMS software is so advanced that it can detect when a long-running query would benefit from an index. The DBMS can then create that ...
7
votes
2answers
1k views

PostgreSQL: reuse of complex intermediate result in same query

Using PostgreSQL (8.4), I'm creating a view that summarizes various results from a few tables (e.g creating columns a, b, c in the view), and then I need to combine some of these results together in ...
6
votes
3answers
302 views

Query performance

Why SELECT Barraportfolioname FROM portfolio WHERE id IN (SELECT DISTINCT i1.portfolioid FROM Import i1 LEFT OUTER JOIN Import i2 ON ...
0
votes
2answers
802 views

How to find out the activity which increasing the response time of the Sql Server?

We are using SQL Server 2008 as our database server. Recently we came to know, by using a 3rd party tool, that the response time of our database server is increasing at a specific time for example at ...
4
votes
2answers
1k views

SSAS queries time out when Windows File System Cache drops

We have a SQL 2008 Analysis Services instance on Windows 2003 that is experiencing near-daily performance issues (query timeouts) during peak activity. A second identical instance queried from the ...
2
votes
2answers
9k views

Improve BLOB Writing Performance in Oracle 11g

I have an application that writes a lot of rows into a table that contains a blob column. The average size of the blob is 3k bytes. Is there any buffer that i can resize to improve inserts into this ...
1
vote
2answers
144 views

Restore backup in order to write datafile sequentially in disk

I have just come to a new company and we have one database which was created with standard initial size and autogrowth parameters for data and log files (1 MB autogrowth for data / 10% for log). The ...
2
votes
3answers
998 views

Loading a FACT table per day

I have a database with 13 billion rows, per day I have around 20-30 mio rows. On top of this I have one cube, one of its dimensions is DateTime that goes down to milliseconds. To load the fact table I ...
6
votes
3answers
2k views

Performance issue with xpath in SQL Server 2008

I have a table with lots of large xml-documents. When I run xpath expressions to select data from those documents I run into a peculiar performance issue. My query is SELECT p.n.value('.', 'int') ...
5
votes
2answers
2k views

Compare Microsoft SQL server performance between virtual and dedicated server

I have a dedicated windows 2008 r2 server at the moment and I am thinking about migrating to a virtual server because of the costs. Now I know that SQL should be on a dedicated server, but the ...
5
votes
3answers
4k views

MySQL general query log performance effects

One of our customers who has a somewhat problematic web application would like us to log all the queries for a period of 24 hours. I wouldn't know how much data it will actually write. The amount ...
2
votes
2answers
387 views

Slow SSD on Dell 710

We recently upgraded our Dell T110 server to a Dell T710 with a 100GB SSD drive. We were hoping that we would see a tremendous improvement in mysql select performance, but unfortunately the new ...
3
votes
1answer
488 views

MySQL query 'going away' on executing INSERT ON DUPLICATE UPDATE statement with a 12524 character blob

I have a mysql insert on update query like so insert into table (col1, col2, col3) values (1,2,'huge blob with 12524 chars') on duplicate key update col3 = 'huge blob with 12524 chars'; col1, col2 ...
2
votes
1answer
466 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)?
3
votes
1answer
119 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 ...
10
votes
3answers
5k 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
633 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 | ...
1
vote
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 ...
11
votes
3answers
5k 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
767 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
2k 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
875 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 ...
9
votes
4answers
3k 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 ...
2
votes
1answer
452 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
410 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
497 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
114 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 ...
4
votes
1answer
4k 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
403 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
826 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 ...
11
votes
8answers
9k 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
4k 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 ...
15
votes
3answers
11k 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, ...
2
votes
1answer
736 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
856 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 ...
8
votes
6answers
3k 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
177 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
6k 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. ...
13
votes
5answers
7k 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
3k 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 ...
3
votes
2answers
802 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
352 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 ...
13
votes
5answers
490 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 ...
12
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 ...
4
votes
1answer
220 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 ...
6
votes
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 ...