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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10
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2answers
2k views

Postgresql 8.3: Limit resource consumption per query

I'm using PostgreSQL 8.3+PostGIS 1.3 to store geospatial data on Ubuntu 8.04 Hardy. This particular version of PostGIS has a bug when calculating a buffer() on very complex segments, which causes ...
2
votes
2answers
20k views

Where all can the /*+ PARALLEL */ hint be used?

It works with SELECT and UPDATE statements. Are there some more statements with which it works? I was able to use it with create, but am not sure if the hint was actually considered. SQL> create ...
4
votes
1answer
657 views

What can be done, if anything, to tune a SharePoint database?

SharePoint uses a single table (i.e. dbo.AllUserData) with columns like nvarchar1, nvarchar2, ..., nvarchar64 or int1, int2, ..., int16 (193 columns altogether) to store all items from all lists in ...
5
votes
3answers
1k views

Is the ADO.NET Entity Framework known for generating poorly performing queries?

This question is inspired by the comment posted to the latest ServerFault blog post: Are you guys still using LINQ to SQL? I know I can use SQL Server Profiler and/or the ToTraceString method to ...
4
votes
3answers
262 views

Does separating VARCHAR values based on size have a performance gain?

I am working with a team that is trying to implement an EAV system. They have decided to split the attribute-value tables out by type and they are debating using different tables for different size ...
6
votes
4answers
5k views

MySQL: Index when joining to tables not being used (Performance optimizing question)

I need to optimize the following query: SELECT /* [things omitted] */ articles.blogpost_id, articles.id AS articleid FROM blogposts JOIN articles ON articles.blogpost_id = blogposts.id WHERE ...
5
votes
5answers
2k views

What is the best use of memory in MySQL?

I have a MySql server with 2Gb of memory. What's the best configuration to use then with best results? How can I "distribute" this memory fine to MySql server?
6
votes
3answers
2k views

Building Dynamic SQL-Server Where Clause

Let us review this dba.exchange Oracle question for SQL-Server. This is SaUce's code, after a little formatting: CREATE PROCEDURE GetCustomer @FirstN nvarchar(20) = NULL, @LastN ...
19
votes
3answers
11k views

Is it a good idea/approach to index a VARCHAR column?

We're using PostgreSQL v8.2.3. There are tables involved: EMPLOYEE and EMAILLIST. Table 1: EMPLOYEE (column1, column2, email1, email2, column5, column6) Table 2: EMAILLIST (email) 2 tables are ...
6
votes
4answers
5k views

Why does this Entity Framework query perform so bad in MySQL?

Let me give you a little setup. We have a InnoDB table on MySQL 5.1 with close to 20 million records, no foreign keys, and proper indexes for queries we do. We are using the latest 6.3.5 MySQL ...
6
votes
1answer
190 views

Is my function nondeterministic one

I have two functions: fn_Without_Param and fn_With_Param CREATE FUNCTION [dbo].[fn_Without_Param] ( ) ... INNER JOIN .. ON .. AND SubmitDate = CONVERT( varchar(10), GETUTCDATE(), 101 ) and /* ...
5
votes
1answer
114 views

Data transformation implementation

My company's database, I am working with, makes available a data to a lot of external applications. So I need to transform the same data to a lot of dynamic views. I can see that a former database ...
6
votes
1answer
340 views

How can I benchmark the performance of UDFs to figure out which one is faster?

Basically I have two scalar UDFs that output the same data, one that uses a cursor and one that uses a recursive CTE. I want to determine which one should be used and discard the other; I'd prefer to ...
11
votes
2answers
6k views

SQL Server 2008 - Cross database performance on same physical machine and server instance

Is there any performance hit when doing a select across another DB on the same physical machine? So I have 2 databases on the same physical machine running within the same SQL 2008 instance. For ...
17
votes
4answers
2k views

SSDs with Oracle

We've been looking into using SSDs with Oracle to speed up our test migration runs. It currently takes 12-18 hours to complete a migration run, depnding on the volume of data (we're obviously doing ...
5
votes
1answer
336 views

MySQL and Solid State Disks on EMC

Since all writes and sequential reads are cached by the EMC storage system, the best use for solid state disk is to store data that has a random READ pattern. On Oracle, that is the temp tablespace ...
10
votes
3answers
12k views

How do you clear out all old query plans from within Microsoft SQL Server?

We have an off the shelf application that uses a Microsoft SQL database. Within this application we pick and choose various selection criteria for each report. This application then runs these ...
3
votes
1answer
615 views

MySQL CREATE statement are really slow (Mac OS X / Macport install) [closed]

I recently noticed that recreating the database for the web application I am working on is taking a lot of time. I had just reinstalled Mysql from Macport... I am getting really lousy performances, ...
19
votes
5answers
3k views

How far should you go with normalization?

I have a decent amount of data in a database. I have well formed tables and good relationships between them with some redundancy in my data. But how far should I go with normalization? Are there ...
18
votes
4answers
978 views

When using an ORM, what are some things to watch out for in your database design

What are some database design gotchas to watch out for when you know the database will be accessed using a Object Relational Mapper (ORM) Wikipedia? Also see Entity Framework NHibernate or LLBLGenPro. ...
3
votes
2answers
4k views

MS SQL Server 2008: How to improve performance after deleting transaction log file

Due to the size of transaction log file (it grew up to 200 GB) I had to delete it because the disk was running out of space. I know this is not a good practice but anyway after that the performance is ...
3
votes
2answers
2k 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 ...
58
votes
5answers
21k views

Guid vs INT - Which is better as a primary key?

I've being reading around reasons to use or not Guid and int. int is smaller, faster, easy to remember, keeps a chronological sequence. And as for Guid, the only advantage I found is that it is ...
21
votes
3answers
2k views

Which collation should I choose for a muiti-language website?

Does a collation have any influence over a query speed? Does the size of a table change depending of the collation? If I want to build a website that must support all possible languages (lets take ...
8
votes
3answers
199 views

Is there a performance gain by handling data with stored procedures versus feeding it into functions after retrieval?

Title sums it up. I'm reasonably well off with PHP, and comfortable getting it to do what I need it to with values pulled from MySQL, however in the interest of expanding my knowledge I've been ...
33
votes
5answers
48k views

How do you tune MySQL for a heavy InnoDB workload?

Assuming a production OLTP system with predominantly InnoDB tables What are the common symptoms of a mistuned/misconfigured system? What configuration parameters do you most commonly change from ...
7
votes
4answers
3k views

For a MySQL query, how do you determine physical and logical I/O?

I'm used to having a showplan in Microsoft SQL and have gotten lazy with using tools to tune MySQL queries. How can I determine physical/logical I/O for a query in MySQL? (EXPLAIN shows the index ...
17
votes
2answers
599 views

Get and Put performance testing on Google BigTables (and other integrated DBs)

What are some effective ways to perform programmatic performance testing on database operations, especially in environments where the databases themselves do not offer dedicated tools? For example, ...
77
votes
6answers
54k views

How to determine if an Index is required or necessary

I've been running an auto-index tool on our MS SQL database (I modified a script originating from Microsoft that looks at the index statistics tables - Automated Auto Indexing). From the stats, I now ...
8
votes
2answers
2k views

In Google App Engine, what is the most effective many-to-many join model?

The BigTable design rejects many of the philosophies of standard relational models, explicitly preferring denormalization to a big host of tiny tables. One of the larger areas where this is a problem ...
12
votes
1answer
238 views

What are the performance implications of polymodels versus normal BigTable models in google app engine?

What produces the best performance in regular google app engine use, a polymodel or a normal "BigTable" model? The polymodel, effectively, creates a column in the parent table called "class" which ...
105
votes
7answers
107k views

How can I optimize a mysqldump of a large database?

I have a symfony application with an InnoDB database that is ~2GB with 57 tables. The majority of the size of the database resides in a single table (~1.2GB). I am currently using mysqldump to ...
3
votes
1answer
3k views

To 'DBCC SHRINKDATABASE' or Not To 'DBCC SHRINKDATABASE': That's the question

We're freeing lots of space in a SQL Server 2008 R2 database -a Loooot! enough to care about- (we're dropping lots of unnecessary data). but the database file conserves its file size. we want to ...
1
vote
3answers
1k views

SSIS 2008 painfully slow to import CSV

I am using SSIS to import a 25,000 row CSV to an empty table. The table has a primary key that is populated as the data is inserted. I am using an ADO.Net destination. What reasons are there why ...
1
vote
2answers
314 views

What is wrong in debunking myths about clustered indexes?

What is wrong in code. or its results, illustrating that clustered index is evil [1]? and how to de-debunk, i.e. to return to customary myths and best practices? [1] Debunking myths about ...
4
votes
2answers
280 views

SQL Filegroup degrading performance

On our dev boxes, our database resides entirely in the PRIMARY filegroup, and everything works fine. On one of our production servers, recently upgraded from 2005 to 2008, we noticed it was ...
12
votes
3answers
6k views

SQL Server - Temporary vs. Physical Tables

A movement is afoot in my place of employ to move away from using #temp tables and instead to use permanent physical tables with SPIDs. Whenever one would have previously INSERTed INTO a #temp table, ...
8
votes
3answers
8k views

Performance Hit using CAST() in TSQL (SQL Server)?

We have a SQL generator that emits SQL conditional statements generically for specified fields (which for the sake of discussion: we will label as myField). So, if myField is of type NVARCHAR, we ...
7
votes
1answer
130 views

Is there a performance hit by breaking out tables into different schemas in SQL Server?

Is there any kind of performance hit when querying by placing tables in different schemas in SQL Server. For instance if I had 2 tables, Table1 and Table2, and put Table1 into the test schema and ...
2
votes
3answers
312 views

Is there an equivalent of “OPTION(RECOMPILE)” or “WITH RECOMPILE” for an entire connection?

I'm curious. Is there any way to prevent SQL query execution plans from being cached for an entire connection's duration? Can I run a command that basically says, "use OPTION(RECOMPILE) for all ...
2
votes
2answers
86 views

query plan caching (sql server)

Is there a measure of time frame as to which the execution plan of inline queries will cached?
2
votes
4answers
491 views

Help understanding SQL Server 2005 execution plan

One of my stored procedure has long execution time (average around 4 to 7 minutes). Now I trying to tweak it an make it run faster. I am looking at execution plan and two things I see that using ...