What is QuantumDB?
Performing schema migrations in SQL databases in any production environments is full of risks. Altering
a table that's subject to any read or write operations can severely impact the performance of your
application. As we know from previous research, (certain) Data Definition Language operations
(red. schema operations) require specific locks on the table they're affecting. These locks in turn prevent
your application from accessing these tables, which can make your application unresponsive for the duration
of the schema operation. QuantumDB is here to address this problem:
QuantumDB is a tool designed execute database schema migrations on SQL databases with zero-downtime.
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Like many other schema migration tools, QuantumDB treats the structure of existing tables and
constraints as immutable. It simply creates new (ghost) tables whenever they're needed, copies data
between tables and keeps the data in sync. This way costly table locks are avoided during the migration
process.
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QuantumDB employs a two step migration. This allows the developers and system administrators to decide
when to switch between database schemas, when (if need be) to roll back to the old database schema,
or when to commit to the new database schema.
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Since QuantumDB exposes all active database schemas concurrently through the database, using
QuantumDB's JDBC driver, your application can elect on which version of the database schema it would
like to operate. This ensures you can run old and new versions of your application side-by-side on the
same database even when they require different database schemas to operate on.
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And lastly, QuantumDB is the only database schema migration tool which fully embraces and supports
foreign key constraints. Where other tools temporarily disable these constraints during migrations,
or simply refuse to work, QuantumDB will plan and execute its migration accordingly, making sure
they're never violated, or disabled.
