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

0
votes
0answers
31 views

Fix missing performance counters [duplicate]

Possible Duplicate: How to revive SQL Server 2008R2 performance counters? On one machine, I have an instance of SQL Server 2008R2 Enterprise, Visual Studio 2010 and VS 11 Developer Preview. ...
4
votes
1answer
2k views

Performance difference between SQL Server Linked Server and direct query

A Management Studio query pane connected directly to a remote sql server executes and displays a simple table query of (SELECT * FROM table) in just under 2 seconds. The same Management Studio but ...
1
vote
2answers
855 views

Very slow performance from MySQL

I have the following procedure: drop procedure if exists deletebatches; create procedure deletebatches() BEGIN declare acount int default 0; declare done INT default 0; declare abatchno ...
2
votes
1answer
852 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 ...
18
votes
5answers
6k views

SQL: What is slowing down INSERTs if not CPU or IO?

We have a database for a product that is write-heavy. We just bought a new server machine with a SSD to help. To our surprise, the insertions were not faster than on our old machine with much slower ...
9
votes
2answers
5k views

INSERT performance difference between temporary tables and table variable

I have the following issue in SQL Server 2005: trying to inserts some rows into a table variable takes a lot of time compared to the same insert using a temporary table. This is the code to insert ...
2
votes
2answers
3k 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), ...
4
votes
1answer
479 views

SQL Express 2008 R2 on Amazon EC2 instance: tons of free memory, poor performance

The old SQL Express 2005 was running on a low-end single Xeon CPU Dell server, RAID 5 7200 disks, 2 GB RAM (SBS 2003). I have not done any baseline measurements on the old physical server, but the ...
9
votes
2answers
2k views

Is there a way to force an index to stay in memory with SQL Server 2008?

I've got a table with several millions rows, from which I need to run some queries from time to time. First query will usually be quite slow (around 10s), and subsequent queries are usually way faster ...
2
votes
0answers
82 views

Permon counters on SQL 2005 mirroring (user defined counter log file is empty) [closed]

I've been attempting to gather performance counters for mirroring using perfmon, over a period of time and saving this to a log file. I am able to do this without problem for general SQL Server ...
4
votes
2answers
4k views

oracle distinct doing sort

I'm getting poor performance from DISTINCT. The explain plan indicates that it is doing SORT (GROUP BY) which doesn't sound right. I would expect some kind of HASH aggregation to produce much better ...
2
votes
2answers
425 views

Performance differences between executing via Linked Server vs. SSMS

We've had an issue reported where a stored procedure was behaving badly when called from some .Net code. On the face of it, that sounds similar to this case, which turned out to be due to EDMX, but in ...
6
votes
1answer
187 views

What is the expected performance impact when dropping a large table

I have a 100G+ innodb table that needs to be dropped in a production environment. I am trying to do this without interruption to service. The table is no longer being written to, and needs to be ...
4
votes
1answer
834 views

Ways to speed up IN queries under PostgreSQL

I have a query of the following form: SELECT * FROM twitter_personas WHERE twitter_user_id IN ($1, $2, $3, ..., $25000) The IN query has anywhere from 10 to 25000 values. The query runs for minutes ...
5
votes
2answers
591 views

Unexpected extremely long query time (~5 minutes using nested WHEN-INs)

For the first time, I am running up against a horrifically long execution time of a MySQL query (~5 minutes). The data in the database is highly (and not arbitrarily) normalized. It very efficient ...
8
votes
2answers
560 views

Pros and Cons of Checking if value exist for unique column or let db raise unique error on inserting

While writing a query other day a thought came to me and have stuck in my mind. What is preferable, first checking if a value for a unique column exists and then inserting or insert and let db raise ...
2
votes
2answers
355 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 ...
2
votes
3answers
399 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. ...
1
vote
1answer
203 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
votes
2answers
684 views

How to compare performances of two databases

There are two database servers and I want to compare their performances. Both have Windows operating system and and Oracle (10.2.0.4 and 11.0.2) database. Both are OLAP databases with 15-20 users ...
3
votes
2answers
2k views

How can I optimize performance on a MySQL ndbcluster?

So, this is what I have: A simple table classes__to_students: |class |student| --------------- Math Alice Math Bob Math Peter Math Anne Music Bob Music Chis Music ...
5
votes
2answers
2k views

The order of INNER JOIN's

I would like to know if there are any rules about the order of INNER JOIN's in T-SQL 2000. I had 62x the performance on my query when my INNER JOIN that act like a filter is placed at first instead ...
1
vote
1answer
65 views

Reading and writing the common data

I have a couple tables and application service that intensively inserts, updates its. From the other hand some client application have to read data using those tables. Sometimes client application ...
9
votes
2answers
536 views

How many Sproc Parameters is too many?

I've just started writing a Stored Procedure in SQL Server 2008 and have 30+ parameters. I've never written one with more than ~10 parameters, and that got me thinking... At what point are there too ...
1
vote
2answers
1k views

How to keep one query from slowing down entire database?

Using MySQL 5.0.x, we have a process to generate benchmarks for our business that consolidates a bunch of data, then pull out data based on certain criteria. This process used to take 18 hours, it's ...
3
votes
1answer
4k views

I have lots of free memory. How do I use it to increase performance?

I am running Litespeed (with suExec, PHP SAPI), MySQL, DirectAdmin, named on a VPS with a 16-core Xeon CPU and 2GB RAM. Currently, only 300 MB out of 2048 are used. It might sound a stupid, but how ...
8
votes
3answers
2k views

SQL Server - Multiple running totals

I've got a base table with transactions and I need to create a table with running totals. I need them to be per account and and also have a few running totals for each account (depending on the ...
5
votes
4answers
2k views

T-SQL INNER JOIN Optimisation

Well, I really have read so many articles, used different techniques and done some random things to do this. My problem was that a have big tables (over one million rows) and some small (with few ...
7
votes
1answer
322 views

Could Stack Overflow run on SQL Server Web Edition?

I am starting a new web venture that may need to scale to a high number of users. I am confident with the SPLA licencing for SQL Server Web edition, but want to know if I will need to factor in ...
3
votes
1answer
5k views

Sql. Calculating the size in KB of each row

I'm building now a new sql 2005 database for my company, and we expect this database to be huge with 100's of millions of records. We already know we need to dedicate a separate server with new hard ...
1
vote
1answer
138 views

Is it possible to allow write-through computed columns for legacy code that expects a column to be read/write?

I have this existing table for IP storage: CREATE TABLE [dbo].[IPAddresses]( [ID] [int] IDENTITY(1,1) NOT NULL, [IPv4Address] [varchar](15) NULL, [IPv6Address] [varchar](45) NULL, ...
2
votes
3answers
286 views

What affects the speed of a count(*) besides the number of records

I have a query like SELECT COUNT(*) FROM Foo Where Bar = 1 AND Baz = 2 the table has 12934600 records of which 1000001 match that predicate Looking at the query statistics I see (1 row(s) ...
1
vote
2answers
128 views

Improving MySQL efficiency

I have a table now containing over 43 million records. To execute SELECT, I usually select records with the same field, say A. Will it be more efficient to divide the table into several tables by ...
1
vote
3answers
1k views

SQL Server 2008 Partitioning Evaluation

I'm trying to do a performance comparison of a table with partitioning and the same table without partitioning. So we have Subcriber and SubscriberPartitioned tables. Tables structure is: ...
4
votes
2answers
8k views

Is InnoDB Engine up to speed against Memory Engine?

I am exploring the efficiency of different database engines in MySQL version 5.5.18 to see which is best suited for use with a range query on a dataset of 5 million rows: SELECT P.col1, P.col2, ...
3
votes
1answer
795 views

Can you have a WHERE clause with a greater than operator on a composite key?

I'm a web developer (not DB admin!) having performance problems processing a 1.7m record table on MySQL. Here is that table : CREATE TABLE `bbcmapimp_pc_raw` ( `postcode` char(8) NOT NULL, ...
1
vote
2answers
637 views

All columns of table should be indexed or not mysql database?

I am having one table with 4 columns. I that one is primary key and other three columns are references to columns of other tables. I am using join of these four tables for search filter. These joins ...
10
votes
1answer
7k views

Order by column should have index or not?

I have added indexes to table which are used for searching result. I am showing results by ASC or DESC order. So that column should have index or not? I have 2 more indexes on that table. How ...
5
votes
1answer
894 views

How to calculate cache misses for PostgreSQL

I'm administering a server where a tool using a PostgreSQL runs. The tool takes care of most PostgreSQL configurations by itself, but I'm observing some performance problems. I could confirm at OS ...
2
votes
0answers
111 views

MySQL MEMORY table has high Lock Wait Ratio [duplicate]

Possible Duplicate: Mysql Memory table getting many locks on my site I log every pageview (date,ip,referrer,page,etc) in a simple mysql table. This table gets very little selects (3 per ...
20
votes
4answers
17k views

Pattern matching with LIKE, SIMILAR TO or regular expressions in PostgreSQL

I had to write a simple query where I go looking for people's name that start with a B or a D : SELECT s.name FROM spelers s WHERE s.name LIKE 'B%' OR s.name LIKE 'D%' ORDER BY 1 I was wondering ...
6
votes
3answers
2k views

Why performance degradation with query hint FIRST_ROWS(1000)? [closed]

I have a query with user supplied arguments that can produce a very high amount of rows depending on the user's input. In case the user supplies very unselective arguments, the query takes a lot of ...
3
votes
1answer
5k views

Query performance with subquery and IN clause

I am trying to select a range of data for multiple devices (unique serial numbers) from a historical table and was wondering why there is such a big difference in time for the following queries: ...
1
vote
2answers
139 views

why doesn't time for a simple update scale linearly with the number of records?

I am running some performance tests and I started with a dataset of 900.000 records the update took 10 seconds or about 90000 records per second. Then I increased the number of records to 9.000.000 ...
2
votes
1answer
415 views

Query takes hours

Up until now all queries in my PostgreSQL application were fast. During the last days, sometimes a query takes several hours. Index are healthy, because after dump, restore, vacuum -z, it is still the ...
3
votes
3answers
1k views

Does ORDER BY on a clustered key effect performance?

Say I have a table clustered on PrimaryKey, and in all cases I want my results to be ordered by PrimaryKey so I additionally always ORDER BY PrimaryKey in all queries. Does this ORDER BY affect ...
4
votes
2answers
3k views

MySql - How can I speed up this query

I have the following tables: CREATE TABLE `users` ( `id` int(11) NOT NULL AUTO_INCREMENT, `first_name` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `last_name` varchar(255) COLLATE ...
4
votes
1answer
292 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 ...
17
votes
3answers
9k 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
957 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' ...