Comparing schemas

Schema compare shows what differs between two databases — on the same server or on different ones — and can generate the migration that brings one in line with the other.

Opening it

Right-click a database in the schema tree and choose Compare with. Then pick the other side: first a connection, then a database on it.

Choosing Compare with on a single table or view opens the same comparison, filtered to that object.

Which way it goes

The database you right-clicked is the one that will change. The one you picked is the source of truth. The header shows this with an arrow, so check it before applying anything:

• an object only on the source-of-truth side will be created;
• an object only on the side that changes will be dropped;
• an object on both sides that differs will be altered to match.

Reviewing the differences

The left rail lists every object grouped by kind — tables, views, triggers, routines, sequences and more, as the engine has them — with a tally of how many differ, exist on one side only, or are identical. Select an object to see both sides' definitions next to each other. Filter by name narrows the list, and Include identical shows the objects that match as well.

Every difference that can be applied starts ticked. Untick anything you want to leave alone.

Applying

Press Preview migration. The comparison closes and the SQL for the ticked objects opens in the same preview as the table designer: Apply, Copy or Open in editor. Objects you left unticked are listed there too, so it's clear what the migration leaves as it is.

Limits

• Both databases must be on the same kind of engine. MySQL and MariaDB compare with each other; any other mix can't be compared.
• On MySQL and MariaDB, a trigger, routine or event body is shown but can't be ticked: the server has to give its definition again before Schemaic can recreate it safely.
• A few differences are shown but held back from the migration, each with a note saying why — for example a table whose partitioning differs.
• Both databases are read in full every time, so comparing a large server takes a moment.