Hello, On Fri, Jun 30, 2017 at 08:58:08AM -0700, MARK CALLAGHAN wrote: > This started as a question on a MyRocks list. MyRocks comes from MariaDB in > this case and the code that determines whether the truncate table fast path > is used looks different in MariaDB than in FB MySQL. By "fast path" for > truncate I mean the use of drop/recreate for truncate. The slow path is > delete one row at a time. In this case, truncate is doing delete one row at > a time for MyRocks in MariaDB but drop/recreate in FB MySQL. > > https://groups.google.com/forum/#!topic/myrocks-dev/dhweTwN-9xg
I didn't try to measure speed, but when I debugged TRUNCATE statements in MariaDB and MySQL, I see they both call ha_rocksdb::create(), which re-creates the table. MariaDB 10.2: https://gist.github.com/spetrunia/35738308469e27381056c6e90a5e2ce6 FB/MySQL-5.6: https://gist.github.com/spetrunia/18096aa8ec965dc37a502496217c0bb0 MariaDB also prints these statements into stderr 2017-07-08 2:53:10 140737294370560 [Note] RocksDB: Begin filtering dropped index (0,261) 2017-07-08 2:53:10 140736961083136 [Note] RocksDB: Finished filtering dropped index (0,261) which is another indication that there is no row-by-row deletion. I was using current github trees of both FB/mysql-5.6 and MariaDB-10.2. Maybe that is the reason... I'll do more checks. BR Sergei -- Sergei Petrunia, Software Developer MariaDB Corporation | Skype: sergefp | Blog: http://s.petrunia.net/blog _______________________________________________ Mailing list: https://launchpad.net/~maria-discuss Post to : maria-discuss@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-discuss More help : https://help.launchpad.net/ListHelp
