…data if you don’t need to?). I get up to speed a lot faster and can… 5.6.10 sandbox: description=MySQL driver=com.mysql.jdbc.Driver connectionSpec=jdbc:mysql://127.0.0.1:5610… There are additional tabs: Tables – Names, number of children, parents, count of columns, row counts, and comments — a great…
Post: MySQL Query Patterns, Optimized - Webinar questions followup
June 3, 2013 By 2 Comments
…presentation on “MySQL Query Patterns, Optimized” for Percona MySQL Webinars. If you … matching rows that you’ll get skewed results. For instance, if… no movies, but your random number generator picks values in that … that it requires storing another column, and reinitializing the sequence after …
Post: Percona XtraDB Cluster 5.5.30-23.7.4 for MySQL now available
April 17, 2013 By 2 Comments
…fixed #1080539 (Teemu Ollakka). Standard MySQL port would be used when port number wasn’t explicitly defined… fail in case mixed CHAR and VARCHAR columns would be used in foreign key definitions. …server package, /usr/bin/clustercheck script would get overwritten, and any changes (such as username …
Post: Understanding the maximum number of columns in a MySQL table
April 8, 2013 By 5 Comments
… polls: “What is the maximum number of columns in MySQL?” and “What is the minimum maximum number of columns in MySQL?”. Before you read on, ponder…. However… for those using MySQL, Percona Server, MariaDB or any other of the MySQL branches/forks, you get to have these odd limitations…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
…get to disk. This has no effect on standard MySQL replication from this instance, since MySQL replication is asynchronous. What about semi-sync MySQL…, each autocommit is retried only the number of times specified by this variable…above, how above moving the ‘joined’ column to the users_groups table …
Post: How to recover table structure from InnoDB dictionary
April 22, 2013 By 4 Comments
…NULL properties etc. `LEN` is the maximum number of bytes a field uses to …`PREC` please let me know. mysql> select * from SYS_COLUMNS WHERE TABLE_ID=741; +———-+—–+————-+——-+———+——+——+ | TABLE_ID… know all fields of the table, we can get the type. Is it enough for …
Post: Multi Column indexes vs Index Merge
September 19, 2009 By 31 Comments
… about how MySQL uses the index but not exactly what it gets from the index – typically (unless it is covering index) MySQL gets a… combined index but single index on another column. This is because MySQL is able to estimate number of rows it will find using… it: If we disable index on the second column we get a full table scan: mysql [localhost] {msandbox} (test) > explain select avg(length…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
…number of MySQL 5.0 and 5.1 installations that would upgrade or are in the process of upgrading to MySQL… | 1 | 46.78110075 | ALTER TABLE test add column c char(32) default ‘dummy_text…get piled up waiting for table metadata lock bringing down the MySQL server or causing all the connections to get…
Post: High Rate insertion with MySQL and Innodb
January 7, 2011 By 17 Comments
…directly, still it is nice to see you can get the numbers as high with Innodb too. I will spare… bunch of indexes will see lower numbers. So what’s the deal ? First MySQL 5.5 (frankly I did not… performance by hash partitioning table by one of the columns and I would expect gains can be higher with…
Post: Testing MySQL column stores
August 16, 2010 By 15 Comments
… since I have experience developing such cases for MySQL column-based storage engines in the past. I reported … version. In addition, I was not able to get accurate results for all of the queries on …carsales.sales_fact” when run on InfiniDB returned a number that was higher than it should have been, …
