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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2
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1answer
68 views

Single field instead of several fields

There is a relational database with the following Users table User Id Name Age Parents Friends Colleagues ... And there are tables Parents, Friends, Colleauges, etc. Due to specifics of database ...
2
votes
1answer
45 views

What will happen when a forum uses 24 char length as an URL ID?

I found a forum using self made/custom engine still in beta version, previously using vBulletin. Now, their new engine uses very long URL id, 24 char length. ...
2
votes
1answer
399 views

PostgreSQL partitioning query performance inexplicably bad

I find this a bit mysterious. The cost of getting the maximum value out of just the partition parent table (which is empty) is very cheap: evlampts=# explain select max(timestamp) from only mcdata; ...
2
votes
2answers
2k views

Oracle aggregate function performance

Can Oracle be smart about aggregate functions, such as MIN(), MAX(), and (AVG)? My testing shows that it seems to be surprisingly stupid. I have the following query: SELECT COUNT(userId), AVG(age), ...
2
votes
2answers
767 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 ...
2
votes
3answers
788 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 ...
2
votes
1answer
391 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)?
2
votes
1answer
548 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 ...
2
votes
2answers
457 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 ...
2
votes
3answers
504 views

Best database choice for a highly scalable web ticketing system?

Essentially, we are developing using Ruby on Rails and want to make a highly scalable ticketing system. Essentially we will have a small database (containing event details and tickets sold) that will ...
2
votes
2answers
802 views

Is it better to store calculated values or recalculate them on request? [duplicate]

Possible Duplicate: Storing vs calculating aggregate values At an old job, we had this database, it wasn't normalized rigth, some tables wheren't used anymore, it was patch after patch. In ...
2
votes
2answers
47 views

SQL Server 2008 R2 Missing Index

I am performing index maintenance on a database. I have run SQL script that uses DMVs to provides a list of indexes SQL Server believes should be created. I am not creating indexes just because the ...
2
votes
1answer
61 views

How to monitor load on database server

Could anybody please suggest me a way to monitor the load on my database server? What perfmon counters should I monitor on daily basis and confirm that load on the server is increasing day by day [or] ...
2
votes
1answer
73 views

Debugging why postgres is snowballing with system cpu usage

I am having an issue where my postgres database which run on a dedicated machine is getting hammered with kernal level cpu usage. This essentially takes down the web service that run on this database. ...
2
votes
1answer
51 views

Does Windows Server File Compression slow Oracle DB performance?

I'm starting a new a new contract and I get to troubleshoot their Oracle instance... I'm more apps and sql, but I'll be trying to figure out their crashes and slow performance. Go figure. I can ...
2
votes
1answer
49 views

How can I compare the server impact of transaction replication

We are developing a system that must extract data from an existing SQL Server 2008 R2 cluster. One of our design goals is to limit the performance impact on that cluster as much as is practical. ...
2
votes
1answer
60 views

Clustered Index / Index Oriented Table performance in join, worse than nonclustered?

Can a clustered index (or IOT in Oracle) be detrimental, when to be used on a very "broad" table, but only few columns are used? In this case, the "Product" table is used only like a junction table ...
2
votes
2answers
148 views

Improve Performance -Update query with OR in WHERE

How do we improve this Update query Performance as currently it is taking 1 Minute to update 17643 Rows. Query -> Declare @date datetime = '09-Dec-2013' update #tmp_sp_abc set ...
2
votes
1answer
46 views

Should I be concerned about excessive Com_change_db commands?

I installed MONyog recently to check for problems on a MySQL server that I admin. Most of the information was useful and helpful, but there's one warning I am not sure is worth fixing. It reports ...
2
votes
1answer
253 views

Getting the most out of SQL Server with a million rows a day [closed]

I have a windows service that is inserting 1000 rows at 1 minute intervals to a SQL Server 2008 Standard database table that looks like: id, datetime, key_id, value key_id is a foreign key to ...
2
votes
1answer
191 views

MySQL / Fusion IO Configuration Question

I need a little configuration optimization. I think what I have is pretty good but feel like there's still room for improvement. Current Config [mysqld] user=mysql datadir=/var/lib/mysql ...
2
votes
1answer
71 views

Defining a process for troubleshooting performance issues [closed]

The issue of poor database performance is one which presents itself from time to time and there are many techniques which can be employed to examine the root cause of slowness. Does anyone have a ...
2
votes
1answer
105 views

user permission cache in session or check from database?

On each page of my websites 2 or 3 permissions have to be checked and I use role-permission model. Which one is better? to check permissions of each user always through database directly or once ...
2
votes
1answer
166 views

TempInsertStateItemShort procedure on ASPState is taking more than 1 second to execute

I'm working on a .NET website who runs in load balance within more than one server and because of that I need to have my session on SQL Server. In the last 2 weeks I've notice that the procedure ...
2
votes
1answer
113 views

How to avoid large joins when determining which rows a user is authorized for?

Typical wep app situation: you have logged in users querying for resources exposed through an API. As a hypothetical example, company administrators quering for their employees' time sheets: company ...
2
votes
2answers
271 views

Bandwidth comparison between log shipping and transactional replication

Which technique uses more network bandwidth: Log shipping Transactional Replication Can some one share any benchmarks for the same ? What would be the Memory and I/O impact on the Primary server ...
2
votes
1answer
266 views

How to improve INSERT speed in large table that has unique constraint

I have a simple MyISAM table: explain entities; +------------+-------------+------+-----+-------------------+----------------+ | Field | Type | Null | Key | Default | Extra ...
2
votes
1answer
405 views

What causes InnoDB to write 100% more pages while slowing down answering queries?

I have a somewhat big database server: 4 processors, 32 cores, 288GB RAM, 2 ethernet cards bounded together, 2 independent RAID controller cards with 1GB cache each, 24 2.5" disks, being 8 SAS, ...
2
votes
1answer
154 views

Deriving formulas for input/output

I'm currently enrolled in a DBS class and am having problem with an assignment. I've searched around and have been unable to understand what it is I'm meant to be doing with this derivation formula. ...
2
votes
2answers
132 views

MySQL Server Config, Small Timeframe, Extreme Usage-Scenario

I want to configure a MySQL server for the following scenario. A large amount of users will need to sign up for a university course selecting individual "timeslots". The signup page will open at a ...
2
votes
1answer
479 views

Fastest way to copy data from MyISAM to InnoDB

I want to copy all data from a MyISAM table with 16 millions rows to a InnoDB table, that will have a different (optimized) schema. See tables below to see the changes. However, every approach I try ...
2
votes
1answer
2k views

PostgreSQL tree structure and recursive CTE optimization

I'm trying to represent a tree structure in PostgreSQL (8.4) to be able to query the path from the root to a given node or to find all the nodes within a sub-branch. Here is a test table: CREATE ...
2
votes
1answer
1k views

Connection to localhost dramatically slower than to network server

I have an Excel VBA application that connects to a SQL Server 2008 R2 database through ADODB. When I'm on the network at work, the connection is almost instantaneous. When I am at home working with ...
2
votes
1answer
464 views

performance issues when concurrent requests

We are using SQL Server 2008 R2 on a Windows Server 2008 server. We have some main functions which uses some Stored Procedures which has a lot of sub-queries inside of it. I'll take one SP as an ...
2
votes
2answers
854 views

Will an ALTER TABLE ADD COLUMN on a slave break replication?

I need to add a last_modified column to a MyISAM table tbl_items. The crux of this problem is that tbl_items houses several gigabytes of data. Also of note, I am using a master-slave deployment with ...
2
votes
2answers
236 views

Does the number of indexes effect the modification of table?

First of all Good morning ! Today I got one question regarding indexes and tables. Actually I am not facing problem regarding this but due to curiosity I want to post !! Now come to the point, ...
2
votes
1answer
635 views

tempdb on raid1 isolated or raid10 shared with high write db

PROPOSAL 2 8x600gb raid 10 mdf array 4x600gb raid 10 ldf array PROPOSAL 3 8x600gb raid 10 mdf array 2x600gb raid 1 ldf array 2x600gb raid 1 tempdb mdf/ldf array READ/WRITE STATS ON ...
2
votes
1answer
1k 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 ...
2
votes
2answers
7k 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 ...
2
votes
1answer
370 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
559 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 ...
2
votes
1answer
122 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 ...
2
votes
1answer
1k views

Tips for Optimizing Oracle Warehouse Builder 11.1 with Oracle DB 10.2

Are there any tips for improving performance of Control Center and Design Center in Oracle Warehouse Builder? At the client side it is very slow to open and refresh Design center and control center ...
2
votes
1answer
34 views

Will MySQL be effective when selecting a row from a table with billions of records?

Note: this is a hypothetical scenario Lets say that: I'm running MySQL, InnoDB engine, UTF-8 encoding I have a table with 50+ billions of rows The tables primary key is a BIGINT The table also has ...
2
votes
1answer
61 views

In Oracle AWR report how to use “Latch statistics” section in analysis

Latch statistics in AWR report contain following sections 1.Latch Activity 2.Latch Sleep Breakdown 3.Latch Miss Sources 4.Parent Latch Statistics 5.Child Latch Statistics How can I use these ...
2
votes
1answer
61 views

Non-Clustered Index key columns to cover a variable where clause

To whoever reads this, sorry for the long question and thanks so much for your time. I'm needing some help on understanding what columns should be key/non key in the following situation, and what ...
2
votes
0answers
48 views

Identical query & instance but other execution plans & performance [duplicate]

I have 2 identical queries . One is executed with parameters, the other is executed with hardcoded values. Somehow sql server is creating 2 different execution plans for the 2 queries. The first one ...
2
votes
1answer
107 views

Is this amount of disk IO expected with MySQL?

I am running MySQL 5.5.34 on an Amazon EC2 micro instance with EBS (elastic block storage). The instance has been running for around 10 days and according to Amazon I've accumulated around 8.5 ...
2
votes
0answers
49 views

SQL Server 2012 STIntersects

I have one table, T_PIN, with 300,000 pins and another, T_POLYGON, with 36,000 polygons. T_PIN has this index : CREATE SPATIAL INDEX [T_PIN_COORD] ON [dbo].[T_PIN] ( [Coord] )USING GEOGRAPHY_GRID ...
2
votes
0answers
24 views

optimizing a CTE Hierarchy [duplicate]

I have a table of accounts with a typical acct/parent account architecture to represent a hierarchy of accounts (SQL Server 2012). I created a VIEW using a CTE to hash out the hierarchy, and on the ...