… article_comment values(4300000002,1); Query OK, 1 row affected, 1 warning (0.00 sec) mysql> select * from article_comment; +————+————+ | article_id | comment_id… number of comments but a as a all articles outside of allowed range have it: mysql> explain select count(*) from article_comment where article…
Post: How fast can MySQL Process Data
April 9, 2008 By 3 Comments
… CHARSET=latin1 mysql> select count(*) from m; +———-+ | count(*) | +———-+ | 1047684 | +———-+ 1 row in set (0.00 sec) mysql> select count(*) from m where i>0; +———-+ | count(*) | +———-+ | 349229… Checksum: NULL Create_options: Comment: 1 row in set (0.00 sec) mysql> select count(*) from m4 where c>”a”; +———-+ | count(*) | +———-+ | 0 | +———-+ 1 row…
Post: A common problem when optimizing COUNT()
September 20, 2008 By 19 Comments
… with COUNT(). This is database-agnostic, not related to MySQL. The problem is when the COUNT() contains a column name, like this: select count… the same thing. COUNT(*) always counts the number of rows in the result. If you write COUNT(col1) it counts the number of times… errors unless some magic comment is embedded in the code next to them: select count(col1) from table; — COUNT_COL_OK Alas, there…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…20 nodes? Peter asked this question in comments to to my previous Shard-Query benchmark… speaks SQL, but right now only MySQL storage nodes are supported. Amdahl’s …`origin_airport_id`=VALUES(`origin_airport_id`), `count(*)`=`count(*)` + VALUES(`count(*)`), `sum(AirTime)`=`sum(AirTime)` + VALUES(`sum(…
Post: SQL Injection Questions Followup
July 26, 2012 By 2 Comments
…sql-antipatterns Jonathan C. also commented: Q: My preferred variable parameter format: bug_id IN (?” . str_repeat(‘, ?’, count($params) – 1) . “) Good suggestion…moves too much computation load onto their database server. Their MySQL server became CPU-bound, while their multiple PHP application …
Post: Figuring out what limits MySQL Replication
March 7, 2007 By Leave a Comment
… knowing count was enough for me so I turned my attention to mysqlsla which I remembered parses all kinds of MySQL Logs. Too bad MySQL Binary log is the only one which it… provides what we’re looking for, if you strip out comments, USE statements and SET statements, which was done by running…
Post: MySQL performance on EC2/EBS versus RDS
August 4, 2011 By 11 Comments
…’t need high concurrency from your MySQL database. When you do, the limitations on the core counts and effective CPU speeds can… plug into this post’s comments. I haven’t evaluated their technology, so I can’t comment on it. I’m sure… good. Do you have experience running MySQL in the Amazon cloud to share with other readers? I welcome your comments, as always.
Post: The two even more fundamental performance metrics
May 5, 2011 By 6 Comments
… some people can post their favorite techniques in the comments. I’ll show you one technique that is interesting…, maybe a bit longer. This is common in MySQL servers I work with when they’re running … between seconds will be small. So if we count the arrivals and completions in each second, and …
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… revenue, c_acctbal, n_name, c_address, c_phone, c_comment from customer, orders, lineitem, nation where c_custkey = o_custkey…_name, c_acctbal, c_phone, n_name, c_address, c_comment order by revenue desc LIMIT 20; In-memory workload Now… in MySQL 5.6 code? As MRR was used in both MySQL 5.6 and MariaDB 5.5. Handler_mrr_rowid_refills counts…
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
… called “Query Cache” which is quite helpful for MySQL Performance optimization tasks but there are number of… preform select to retrieve data from table. Avoid comment (and space) in the start of the query -… you know do not need to be cached. Counting query cache efficiency There are few ways you…
