mirror/mariadb - May the force be without you: git.fucktheforce.de

mirror/mariadb

mirror of https://github.com/MariaDB/server.git synced 2025-01-29 02:05:57 +01:00

2 lines

172 B

Text

Raw Normal View History

MDEV-34190: r_engine_stats.pages_read_count is unrealistically low The symptoms were: take a server with no activity and a table that's not in the buffer pool. Run a query that reads the whole table and observe that r_engine_stats.pages_read_count shows about 2% of the table was read. Who reads the rest? The cause was that page prefetching done inside InnoDB was not counted. This counts page prefetch requests made in buf_read_ahead_random() and buf_read_ahead_linear() and makes them visible in: - ANALYZE: r_engine_stats.pages_prefetch_read_count - Slow Query Log: Pages_prefetched: This patch intentionally doesn't attempt to count the time to read the prefetched pages: * there's no obvious place where one can do it * prefetch reads may be done in parallel (right?), it is not clear how to count the time in this case.

2024-05-27 17:00:12 +03:00

--innodb-buffer-pool-size=32M --innodb_buffer_pool_dump_at_shutdown=off --innodb_buffer_pool_load_at_startup=off --innodb-stats-persistent=1 --innodb-stats-auto-recalc=off