Moving data in and out.
WHAT FORMATS ARE COMMON
Statement dumps Delimited text Structured text formats
WHAT BULK LOADING TOOLS PROVIDE
Far faster import than individual statements.
WHY
They bypass per-statement overhead.
WHAT TO DISABLE DURING A LARGE IMPORT
Index updates, rebuilding them afterwards Foreign key checks, where safe Autocommit, wrapping in a transaction
WHY THAT ORDER OF MAGNITUDE MATTERS
An import taking hours can take minutes.
WHAT TO RE-ENABLE AFTERWARDS
All of it, and verify.
WHAT TO SPECIFY EXPLICITLY
The character set.
WHY
It is the commonest cause of corrupted imports.
WHAT TO CHECK IN DELIMITED FILES
The delimiter How quotes and escapes are handled Line endings Whether a header row exists
WHY LINE ENDINGS MATTER
Windows endings leave stray characters on the last column of every row.
WHAT TO DO WITH LARGE FILES
Split them, and import in pieces.
WHY
It bounds the damage of a failure partway.
WHAT TO VERIFY AFTER ANY IMPORT
Row counts A sample of records, particularly with special characters Totals of numeric columns against the source
WHAT TO NEVER DO
Import into production without testing elsewhere first.
