MySQL
Report table sizes
Replace $DB_NAME with appropriate value.
SELECT
table_name AS `Table`,
round(((data_length + index_length) / 1024 / 1024), 2) `Size in MiB`
FROM information_schema.TABLES
WHERE table_schema = "$DB_NAME"
ORDER BY (data_length + index_length) DESC;Find columns
Replace $DB_NAME, $COLUMN_NAMEi with appropriate values.
SELECT DISTINCT TABLE_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME IN ('$COLUMN_NAME1', '$COLUMN_NAME2')
AND TABLE_SCHEMA='$DB_NAME';Performance IN vs EXISTS
Change
outer_expr IN (SELECT inner_expr FROM ... WHERE subquery_where)into
EXISTS (SELECT 1 FROM ... WHERE subquery_where AND outer_expr=inner_expr)See https://dev.mysql.com/doc/refman/8.0/en/subquery-optimization-with-exists.html