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by m3047 999 days ago
The opposite of true. InnoDB updates the memory view and writes a journal; then it writes the disk view; it maintains a highwater mark for the journal somehow, not sure I care. MyISAM just writes the disk view; no journal is written.

So what happens with InnoDB as writes increase is that eventually you get freezes while the disk view catches up, which frees up journal space so it can go on another writing spree. If you try to shut down the database during one of these freezes it hangs. If you force it to restart anyway, it immediately freezes again on restart... until it frees up some journal space. Paradoxically in this case you have to decide how long of a freeze you can tolerate and reduce the size of the journal(s) accordingly.

MyISAM doesn't write the journal, so it doesn't have journal writes. "Half as many writes" is the best case, in practice there are additional writes pertaining to indexes. (You can be even more clever and disable updating indexes or even drop all indexes and re-create them after all table writes are completed. You can even write to some temp table, build the indexes on it, then rename it to the actual table; or fail over to a new node with the refreshed tables.)

Everything I know about tuning InnoDB I learned tuning DEC RDB (based on the KODA engine, Oracle bought RDB to get the KODA engine for its distributed locking implementation), not much has changed in 30+ years.
1 comments
whatwhaaaaat 999 days ago
Ok but row level locking. I love this conversation btw. We could be having this same discussion in 2013 with seemingly very few differences. Shows what shit oracle’s stewardship of MySQL has been.
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m3047 997 days ago
Ok but mtbl. There's a whole culture devoted to immutable (write once) databases at very large scale. There's another whole culture which thinks ACID shouldn't apply to distributed systems and that global context should be avoided.

In the context of cloud, (MariaDB versus MySQL) what both brand options offer is multiple engine support. The cloud tends to offer its own engines, under its own brand(s).

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