1
vote
3answers
97 views

MySQL: How to avoid case sensitivity in SQL queries when migrate from Windows to Linux?

I have migrated my Database from Windows to Linux server. In many places, query has been written without focusing their cases (uppercase / lowercase). So, these queries are not getting executed and ...
1
vote
1answer
667 views

decreased performance of stored procedure when migrated from mysql server 5.0 to 5.5

i recently testing the move of our db from one server to another. as part of this process i copied all the data to the new db and started testing it. as a comparison i run a store procedure whose ...
2
votes
1answer
966 views

Are many NULL columns harmful in mysql InnoDB?

As I explored the clustered B-tree index system of InnoDB, I think that the presence of many NULL (or small) columns has no significant effect on InnoDB performance. Does the presence of excess ...
4
votes
1answer
917 views

PostgreSQL versus MySQL for EAV structures storage

Is there any practical difference or what are the advantages of using Postgres 9.x versus MySQL 5.x for storing EAV (Entity-Attribute-Value) structures, especially in terms of read performance?
4
votes
2answers
4k views

Performance settings for MyISAM tables - keep everything in memory

I have a 8-core MySQL server with 32 GB of RAM, holding 40 MyISAM tables (total: ~4GB of data). Since the databases size is several times smaller than the available memory, how can I make full usage ...
3
votes
1answer
49 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 ...
2
votes
1answer
415 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 ...
14
votes
5answers
6k views

In MySQL, does the order of the columns in a WHERE clause affect query performance?

I am having performance issues on certain database queries that have large possible result sets. The query in question, I have three ANDs in the WHERE clause Does the order of the clauses matter? ...
5
votes
1answer
3k views

MySQL INNODB SELECT query hanging on copying to tmp table

I have a query that is hanging (seemingly) randomly on a specific query. Most of my website users do not have a problem when this query runs but a few users are having timeout issues on the website ...
65
votes
6answers
50k 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 ...