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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Splitting a large table to improve performance

This is a follow-up to an earlier question. I have a SQL Server 2008 R2 Standard server, that holds a single database, which itself has almost nothing except a large table. The table is 100+ million ...
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4answers
856 views

When do I use another type index than integer? (eg string) [integer vs string index]

I was reading about relational databases like sqlite and I always see the schema for user storage like: UserID (index) | Username | Password but wouldn't it be actually much faster to use Username ...
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3answers
12k views

which mysql version to use - 5.1 or 5.5?

I am designing a new database. There are going to be around 1000 write queries per second. There may be as much as 10000 read per second. Which MySQL version is recommended? I came across a post on ...
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2answers
597 views

Is it a good idea to move high-volume and highly-accessed tables to a separate database?

Ours is a web-based application (built on multi-tenant architecture) running PostgreSQL v9.1.3. There are about 450 tables in our application, out of which 2-3 tables, specific to a module in the ...
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1answer
105 views

SQL Server - Data and Log Separation

We have a SQL Server 2008 R2 which has, among others, a 12K RPM HDD and a 7.2K RPM HDD. The original intention was to store the data files on the 12K drive and the log files on the 7.2K drive, as is ...
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3answers
179 views

How to make stored procedures more readable without harming performance

I come from OOP background, and I need to write and maintain huge stored procedures. Naturally, the sprocs become quite unreadable very quickly, no matter how much I try formatting, giving readable ...
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2answers
574 views

Optimize simple query using ORDER BY date and text

I have a query to a table in Postgres with an order based on a date field and a number field, this table has 1000000 records The data types of the table are: fcv_id = serial fcv_fecha_comprobante = ...
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3answers
4k views

When to periodically RESTART SQL SERVER 2008 R2? [closed]

So I've read that it's really a bad practice to restart SQL Server on a production environment.. Does restarting SQL Server speed it up? Automatically restart SQL Server 2008 Why are periodic ...
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2answers
1k views

MongoDB - Should I separate the journal and the data to different drives?

I have seen and heard from multiple sources that it can be a good idea, performance-wise, to write your db journal and your data files to separate disks. What's the recommended way to do this (e.g. ...
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1answer
268 views

How do you figure out what planner cost constants to use in Postgres?

I'm using Postgres 8.4 right now. Performance has started to become an issue as our tables have grown in size and our queries in complexity, so I've started to look into some performance tuning, but I ...
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2answers
3k views

Will altering order of columns in GROUP BY affect performance?

I have a SQL query like this: SELECT A, B, (CASE WHEN C=0 THEN 0 ELSE 1 END), COUNT(D) FROM SomeTable GROUP BY A, B, (CASE WHEN C=0 THEN 0 ELSE 1 END) On a huge dataset the actual execution plan ...
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2answers
1k views

Does it ever make sense to use RAM Disk to force RAM allocation for tempdb with SQL Server 2008

If I give all RAM to SQL Server, it will use it's own pattern to determine what RAM to allocate for what. If I allocate portion of RAM as RAM Disk and put tempdb into that disk it will force RAM ...
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2answers
1k views

Trying to optimize query for performance (MySQL)

So I have this table that has a lot of foreign keys but when I will a record, I need to join all on those tables because I generally need those fields for the record to make any sense. The basic ...
2
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1answer
557 views

Maintenance Plan Takes Too Long - Locks Tables - Indexing To Blame

System: I have a Maintenance Plan that Rebuilds Indexes for Several Tables (10 tables, 50M records total). Issue: During the Index Rebuild (~20 minutes), we fail to insert data into the DB ...
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2answers
377 views

How to quantify TEMPDB usage in relation to other databases hosted on same hardware?

Working on a project to decide if configuration 1 or 2 is the best way to organise disks for my SAN: Config1 (sql 2008): 8 disks @ raid 10 data 2 disks @ raid 1 logs 2 disks @ raid 1 tempdb 2 disks ...
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3answers
423 views

Express union which is dependent on other results

I would like to make a union of two tables that are actually in a hierarchical constellation. How would I write that in relational algebra? Say table A is the parent of B in a 1:n relationship. ...
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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 ...
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1answer
2k views

SQL Server PerfMon: Compilations/sec > Batch Requests/sec

I've been looking at various PerfMon metrics on one of our client's SQL Server instances trying to get a good gauge of where our database (or server) could use improvements. One measure that has me ...
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4answers
1k views

Sql server full text search performance with additional conditions

We have a performance problem with SQL Server (2008 R2) Full text search. When we have additional where conditions to full-text search condition, it gets too slow. Here is my simplified query: ...
2
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1answer
610 views

Will certain Database Compatibility cause performance degradation?

I'm running a variety of SQL Servers from 2005 to 2012 across several machines. I have many of these databases running in SQL Server 2000 compatibility mode. Will using an older compatibility in a ...
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2answers
285 views

Performance effect of indexing foreign keys

My database is for an HR application with performance reviews and I am interested in whether I should index my foreign key. There are two tables involved. The first is a ratings table with 2 columns: ...
2
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1answer
176 views

excessive CPU utilization by SQL server

I have an issue with SQL server 2000. Its CPU utilization is high from 9.00 AM to 5.00 PM. Three applications use this server through three different instances but when the CPU utilization is high one ...
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1answer
258 views

Log all than queries taking more than X seconds

I have a database Microsoft SQL Server 2008r2. I have some applications in different programming languages. I would like to log all the queries that take more than X seconds. I guess that the I ...
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3answers
285 views

How can I identify and fix bottlenecks in an Oracle11gR2 import

I've recently been tasked with moving our Oracle 11g database from a linux CentOS desktop to a windows 2008 server. Given I've not done much behind the scenes stuff with oracle before I'm a bit out of ...
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2answers
839 views

Closed loops in database model, does it affect the performance?

I have heard that having loops in the database relational model should be avoided. From what I can think of, it is not a good practice, because there will be more than one different pathes to get the ...
2
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1answer
2k views

Why Is oracle ignoring my index?

This query is not too complex: select trunc(created_date, 'MONTH') as created_date, al.op_name, al.region, al.alarm_type, COUNT(1) as total_new, SUM( (SELECT ...
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2answers
2k views

Querying a database efficiently for a huge chunk of data

Here is my query SELECT * FROM ( SELECT a.*, rownum rnum FROM ( SELECT id, data FROM t ORDER BY id ) a ...
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1answer
2k views

Prevent a single query from hogging all resources

I have a production database server running SQL Server 2008 R2. How can I keep a user query on one database from hogging all the system resources and bogging down all the databases on the server? The ...
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1answer
1k views

Performance Inserting and Updating Millions of rows into a table

We have a CSV the user imports into the Application. After inspecting the CSV, validating and applying some business logic, we got Inserts and Updates operations we should perform into a ...
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1answer
1k views

Postgres multiple joins slow query, how to store default child record

Ive got a small database in Postgres, about 10,000 records storing company customers. I have a "slow" performing query (about half a second) which is performed very frequently, and my boss wants me to ...
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1answer
206 views

SQL from/where or join?

I was wondering performance wise what would be faster a join or a from and where query. I am trying merge and update query but performance is terrible?
2
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1answer
470 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 ...
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2answers
256 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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2answers
1k 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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2answers
526 views

Degrading PostgreSQL 8.4 write performance

Load testing of postgresql 8.4 for OLTP application suitability resulted in unpleasant situation when throughput of the database significantly degraded over time from thousands of write transactions ...
2
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2answers
729 views

SQL datatype choice for flagging a read/ unread message?

I have a table where I want to track Boolean type operations. in addition, a business requirement is that I know the date of the action and not just the Boolean value. for example if a message is ...
2
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1answer
130 views

Optimise huge Postgres table for fast read

I'm about to create a Postgres table with 1.5 billion rows. The table will just have a single TEXT column. The table is effectively a blacklist. When a user of my software saves certain data, this ...
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2answers
141 views

Is it possible for increasing the SQL Server max memory limit to degrade performance?

As far as I can tell, raising the SQL Server max memory limit has no drawbacks, provided that sufficient memory is left for the OS and other applications. Assuming this is the case, can there be any ...
2
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1answer
241 views

Can you put a SQL DB on a NAS? [closed]

Can you put a SQL DB on a NAS drive? For example can I put the PostgreSQL DB "files" on a Sinology NAS or am I better to leave everything on a "real" PC? (like, say, a regular PC server running Linux) ...
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2answers
165 views

Overhead of decomposing complex query into multiple simple queries?

What kind of overhead should I expect when replacing a single complex query with multiple simple queries? My goal is to improve the readability and portability of all SQL code so I will be favoring ...
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2answers
179 views

Should I drop a foreign key if I use a soft delete?

"ON UPDATE" scenario never happens in my application. As soft delete is used, "ON DELETE" cascade and restrict scenario never happen as well now. Then, should I just drop foreign key because I have ...
2
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2answers
1k views

Ideal values for wait time in SQL server

This is related to my own post here The SQL server starts everyday at 8:30 AM and stops around 9:30 PM.( So wait times will reset everyday) SQL server will be used by around 60 users ...
2
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1answer
440 views

MySQL with high CPU and memory usage

here we have a VPS with 3.2GHz quadcore processor with 2GB of RAM and 4GB of SWAP which need to work with a high intensive legacy system (read: bad coded). The main problem is that the CPU (~80 - ...
2
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1answer
762 views

Performance issue with TOP (1) on a nullable column

I need help to identify the reason for a performance issue. Actually following query sits in a scalar-valued-function but that is not the reason for the issue since it needs the same time as query: ...
2
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1answer
66 views

Can SQL Server WebAdmin degrade the performance of my site?

Once upon a time a had to use the Parallels WebAdmin interface. After contacting the support team that hosts my website and informing them that I must use the Webadmin, they informed me that: MS ...
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2answers
1k views

Does using LIMIT improve the performance and is it noticeable?

I want to understand the following. Assume that I have a complicated query with let's say a join of 5 tables a group by summations and order by. Letting aside any optimizations to the query itself ...
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1answer
4k views

Why is my Amazon RDS instance so slow?

I currently run a Windows Server with SQL Server Express. I'd like follow best practice and separate the application from the database, so I've created an RDS instance and exported my database. ...
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1answer
681 views

SQL Server manage indexes

Is it possible to automate the managing of indexes on my database? I'm looking to see if there are any scripts or programs that can automate this process. Would it be possible to use stats generated ...
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2answers
5k views

Why does MySQL (InnoDB) table get faster after OPTIMIZE TABLE, but then don't work?

I have a Django web application that stores data in a MySQL InnoDB database. There is a particular page that is accessed a lot on the django admin, and the query is taking a long time (~20 seconds). ...
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1answer
2k views

MySQL / InnoDB: Does daily optimization improve performance?

Would performing daily optimizations of tables increase performance for MySQL and InnoDB? I have never did this before, but I have seen this module for Drupal http://drupal.org/project/db_maintenance, ...