How data is actually stored.
WHAT A STORAGE ENGINE IS
The component handling storage, indexing and locking for a table.
WHAT THE DEFAULT MODERN ENGINE PROVIDES
Transactions Row-level locking Foreign key enforcement Crash recovery
WHAT THE OLDER ENGINE PROVIDED
Table-level locking No transactions No foreign keys
WHY IT STILL APPEARS
Old applications and old defaults.
WHAT THAT CAUSES
Poor concurrency, and data loss on crash.
WHAT TO DO ABOUT TABLES STILL USING IT
Convert them, after testing.
WHAT TO CHECK BEFORE CONVERTING
Full-text indexes, which behave differently Table size, since conversion takes time and space
WHAT MEMORY ENGINES PROVIDE
Speed, with data lost on restart.
WHERE THAT SUITS
Temporary or cached data only.
WHAT TO CHECK ON ANY SERVER YOU INHERIT
Which engine each table uses.
HOW
Query the table metadata.
WHAT MIXED ENGINES CAUSE
Transactions that partially apply, since one engine ignores them.
WHY THAT IS SERIOUS
A rollback leaves the non-transactional table changed.
WHAT TO STANDARDISE ON
One transactional engine, throughout.
