mysql

Antijoin in MySQL 8 In MySQL 8.0.17, we made an observation in the well-known TPC-H benchmark for one particular query. The query was executing 20% faster than in MySQL 8.0.16. This improvement is because of the “antijoin” optimization which I implemented. Here is its short mention in the release notes: “The optimizer now transforms a WHERE condition having NOT IN (subquery), NOT EXISTS (subquery), IN (subquery) IS NOT TRUE, or EXISTS (subquery) IS NOT TRUE internally into an antijoin, thus removing the subquery.”… Facebook Twitter LinkedIn Source: Antijoin in MySQL 8

Hash join in MySQL 8 For a long time, the only algorithm for executing a join in MySQL has been variations of the nested loop algorithm. With the release of MySQL 8.0.18, the server can now execute joins using hash join. This blog post will have a look at how it works, when it is used, and how it compares to the old join algorithms in MySQL in terms of performance.… Facebook Twitter LinkedIn Source: Hash join in MySQL 8

InnoDB : Tablespace Space Management A user defined table and its corresponding  index data, in InnoDB, is  stored in files that have an extension .ibd. There are two types of tablespaces, general (or shared) tablespace and file-per-table.  For shared  tablespaces, data from many different  tables and their corresponding indexes may reside in a single .ibd file.… Facebook Twitter LinkedIn Source: InnoDB : Tablespace Space Management