3,467 reputation
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bio website karwin.com
location California
age 47
visits member for 3 years, 4 months
seen Dec 13 at 0:42

I'm Senior Knowledge Manager at Percona, a services company specializing in the MySQL database.

I've been a software engineer since 1987, and my specialty is as an SQL maven. I also have experience programming in Java, PHP, Perl, C, JavaScript, and I have many other coding skills.

I've written a book, SQL Antipatterns: Avoiding the Pitfalls of Database Programming from Pragmatic Bookshelf, based on the most common SQL problems I've answered on Stack Overflow and other forums, mailing lists, and newsgroups over the past 15 years.


Sep
24
revised Using an index for both asc and desc on a string column
added 148 characters in body
Sep
24
answered Using an index for both asc and desc on a string column
Sep
24
answered WARNING Error checking mysqldump version Error retrieving version from mysqldump.exe: mysqldump: unknown option '--no-beep' (exit 2)
Sep
12
comment Amazon: How to change database name in Amazon RDS MySQL?
Aha, I tried it, and that doesn't work if you have triggers. I get an error: ERROR 1435 (HY000): Trigger in wrong schema
Sep
12
comment Amazon: How to change database name in Amazon RDS MySQL?
Why not just RENAME TABLE tablename TO db2.tablename; for each table? Then there shouldn't be any shipping of data back and forth.
Sep
9
revised Which database technologies to consider for a data search application?
added 2344 characters in body
Sep
7
revised Which database technologies to consider for a data search application?
edited tags
Sep
7
answered Which database technologies to consider for a data search application?
Sep
4
comment MySQL does not start - Ubuntu 14.04 LTS after migration to new disk
At this point I'd try using sudo -u mysql -g mysql and see if you can read and write files under the datadir. It could still be permission problems in the ancestor directories, or it could be AppArmor interfering and giving misleading error messages. Try disabling AppArmor temporarily and see if that makes the errors go away.
Sep
4
revised MySQL does not start - Ubuntu 14.04 LTS after migration to new disk
added 175 characters in body
Sep
4
answered MySQL does not start - Ubuntu 14.04 LTS after migration to new disk
Sep
4
comment Calculating RAM requirements for an in-memory database
Check the total resident memory used by all processes by summing the RSS column from ps. You can also use free to check RAM in use. Also don't forget to leave some spare RAM for filesystem buffers.
Sep
3
answered How much memory will allocated for a mysql view
Sep
1
comment How to generate auto increment values for my duplicate column in my sql?
You just cross-posted this on StackOverflow. Please post to one site.
Aug
29
comment MySQL CPU & Memory Spikes
CPU spikes in MySQL are not uncommon, depending on the version. It could be a variety of causes. To be sure, you'd want to use oprofile or something to find out exactly which functions within the mysqld process account for the most execution time during the CPU spikes. My first guess is the query cache, which has been known to spend time resorting itself internally - try setting query_cache_type=0 and query_cache_size=0 and restart. See if that helps.
Aug
29
answered Row size error with MySQL
Aug
27
comment Proposal: MySQL blob handling revision
@IGotRoot, how would your idea support transaction isolation, transaction rollback, redo logging, or crash recovery? You should learn more about what databases do, that makes a database not the same as a filesystem.
Aug
25
comment How to change rows to columns in mysql?
It's hard to debug an SQL query by staring at the code that generates the query. I suggest you SELECT @sql to return the final query before you try to prepare it. The syntax error may be more clear if you look at the full query.
Aug
20
revised How to make MySQL log to 2 separate remote servers?
added 182 characters in body
Aug
20
answered How to make MySQL log to 2 separate remote servers?