Mark Callaghan
This has results for Postgres versions 19 beta1, 18.4 and 17.10 with the Insert Benchmark on a small server using a cached and CPU-bound workload. I also used MySQL 8.4.8 to see where performance was different.Postgres continues to be boring in a good way. It is hard to find performance...
Mark Callaghan
This has results for modern Postgres and MySQL using write-heavy tests from sysbench and a large server. I think there are regressions in Postgres that arrive in some of versions 16, 17, 18 and 19 beta1 but I am far from certain and this blog post is just another step in my journey to figure that...
Mark Callaghan
This has results from sysbench on a small server with MySQL 9.7.0 and 8.4.8. Sysbench is run with low concurrency (1 thread) and a cached database. The purpose is to search for changes in performance, often from new CPU overheads.I tested MySQL 9.7.0 with and without the hypergraph optimizer...
Mark Callaghan
This post provides another way to see the performance regressions in MySQL from versions 5.6 to 9.7. It complements what I shared in a recent post. The workload here is cached by InnoDB and my focus is on regressions from new CPU overheads. The good news is that there are few regressions after...
Mark Callaghan
This has performance results for InnoDB from MySQL 5.6.51, 5.7.44, 8.0.X, 8.4.8 and 9.7.0 on a small server with sysbench microbenchmarks. The workload here is cached by InnoDB and my focus is on regressions from new CPU overheads. In many cases, MySQL 5.6.51 gets about 1.5X more QPS than modern...
Mark Callaghan
This has results for HammerDB tproc-c on a small server using MySQL and Postgres. I am new to HammerDB and still figuring out how to explain and present results so I will keep this simple and just share graphs without explaining the results.The comparison might favor Postgres for the IO-bound...
Ivan
Undo log Undo log in MariaDB/InnoDB is divided into a set of rollback segments (128) which reside in dedicated tablespaces (data files) (undo0XXX) including historically the one number Zero (0) that resides in the system tablespace starting at page 6 (FSP_FIRST_RSEG_PAGE_NO / fsp0types.h) (at...
Ivan
Redo log structure The database log (aka redo log) is used to ensure data integrity in the case of a crash or unexpected shutdown. It records changes made to the database before they are actually written (?) so that they can be replayed during recovery. Redo log is stored in ib_logfileX files....