The afternoon at Percona Live 2017 is slipping by quickly, and people are still actively looking for sessions to attend – like the session I just sat in on histograms in MySQL and MariaDB.
Histograms are a type of column statistic that provides more detailed information about data distributions in table columns. A histogram sorts values into buckets.
MariaDB Server has had histograms since MariaDB 10.0. Now, MySQL 8.0 will have them too. This session presented an overview of histogram implementations in MariaDB, MySQL 8.0, and looked at PostgreSQL for comparison. The session covered everything about histograms:
- Why do query optimizers need histograms
- What are the costs of collecting and maintaining a histogram in each database
- How the query optimizers use histogram data
- What are the strong and weak points of histogram implementation in each database
At the end, Sergei talked a bit about a related development in MariaDB Server: the optimizer will have the capability of using constraints.
Sergei was kind enough to speak briefly with me after his talk on histograms in MySQL and MariaDB. Check it out below:
Don’t miss any of tomorrow’s talks! You can find Thursday’s (4/27) session schedule here.