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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1answer
416 views

Is there a way to make SQL Server's Database Tuning Advisor use more than one core?

I'm using SQL Server's Database Engine Tuning Advisor to generate recommendations for performance improvements on my database server. For the "consuming workload" step, it appears to use all ...
24
votes
3answers
19k views

Configuring PostgreSQL for write performance

One of my PostgreSQL servers hosts several (1-3) databases which receive a constant stream of data. The data is not particularly structured, it amounts to the current time and a variety of observed ...
5
votes
1answer
1k views

Nested queries or temp (#) tables in SQL Server

I have written a web application which aggregates and presents data from a SQL Server. The data involved is large, and there is a lot of aggregation involved. Currently, under advice from an 'expert' ...
9
votes
5answers
2k 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 ...
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votes
4answers
1k views

Four db servers all identical, one is much slower than the others

The setup We have an application loading a lot of transaction data for later querying. It's sharded on 4 SQL Server 2008R2 Enterprise Edition on Windows Server 2008 64 bits. All servers are ...
3
votes
2answers
6k views

Mysql consumes a lot of memory

Here is my situation. I have an ubuntu server monitored by nagios. recently nagios sends alarms regarding the memory consumption on the server. I logged into the server and executed the top command ...
5
votes
1answer
803 views

Database as a service (DbaaS) over dimensions--performance, scalability, & reliability?

MySql Database as a service: Amazon Xeround Another eg. PostgreSQL Database-as-a-Service. You can get the list of similar products here. Does anyone have details on their performance, ...
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vote
2answers
2k views

Oracle 11. Updating BLOB field. Db file sequential read inappropriately slow?

I've and Oracle (11 Enterprise) schema with a table CREATE TABLE USER.WSP_BUNDLE ( NODE_ID RAW(16) NOT NULL, BUNDLE_DATA BLOB NOT NULL ); CREATE UNIQUE INDEX USER.WSP_BUNDLE_IDX ...
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2answers
2k views

Tuning SQL Server Performance

While profiling my application against SQL Server 2008 running against a JDBC Application most of the time consumed were by following COMMIT TRAN FETCH API_CURSOR & exec sp_cursorfetch I ...
3
votes
2answers
705 views

Performance gain by moving a large table from a database and referencing with a synonym

We have SQL Server 2008 R2 database which is currently about 80Gb. About 10Gb of this is down to one table, and I wondered if there would be a performance gain if I moved this table into it's own ...
3
votes
1answer
2k views

MySQL Config for Large MyISAM tables

I have to do some updates on myisam tables which have around 20 M records. Our server has 24GB of ram and 2 quad core xeon with 24 MB of cache. I want to know how I can change the my.ini file so I get ...
11
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6answers
27k views

Fastest way to check if InnoDB table has changed

My application is very database intensive. Currently, I'm running MySQL 5.5.19 and using MyISAM, but I'm in the process of migrating to InnoDB. The only problem left is checksum performance. My ...
2
votes
3answers
4k views

Improve `Update` performance (rows locking issue)

I am running 30 scripts (PHP CLI) on Linux , each script are updating (loop) the data in the MySQL database. When I typed 'mysqladmin proc' in terminal, I can see a lot of rows has been locked for ...
3
votes
1answer
53 views

Is time to deliver data included in time measured for a Slow Query

I'm looking at some horrible numbers in a SLOW_QUERY_LOG (one example) Count: 2563 Time=23.21s (59498s) Lock=0.00s (1s) Rows=21.4 (54857) This is for a simple SELECT statement that runs for less ...
3
votes
1answer
3k views

How to find the detail cpu high process name which occupying most resource in the SQL Server database?

I'm running into a problem when using the following SQL to identify CPU usage in the production SQL Server 2005 env. DECLARE @ts_now bigint; SELECT @ts_now = cpu_ticks / CONVERT(float, ...
3
votes
1answer
302 views

Possible to add KEEPFIXED PLAN option to reduce the recompile in SqlServer2k5 on Production Env?

I'm not sure if it is good to enable the KEEPFIXED PLAN to reduce the impact of recompilation in the Production Env? I'd know if we may gain performance after that or on the other hand it will be ...
1
vote
1answer
1k views

What are some good methods of structuring a MySQL audit trail to be both immutable, and perform well for usage?

In one application, we have an audit table that uses the ArchiveEngine in conjunction with a few triggers to capture 100% of the changes that occur. The upside to this is that 20+ million rows ...
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vote
4answers
1k 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
138 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 ...
8
votes
2answers
2k 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
306 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
1k 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 ...
3
votes
2answers
13k 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
157 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
1k 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 ...
7
votes
3answers
3k 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
5k 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
435 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
683 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 ...
3
votes
1answer
547 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
14k 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
5answers
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
958 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
816 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
571 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
551 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
826 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
438 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
953 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 ...
14
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 ...