firstworks SQL Relay - Query Routing and Filtering

Query Routing and Filtering

Query routing sends queries that match one pattern to one set of database servers and queries that match another pattern to another set of servers. A comon use for query routing is to route DML and DDL queries to a master and distribute select queries over a pool of slaves.

Query filtering prevents queries that match a certian pattern from being run at all. There are often certain queries that will bring the entire database to its knees. A common use for query filtering is to identify those queries and prevent them from being run.

For example, select * from hugetable where id=100 might be fine...

...but select * from hugetable without a where clause might crush the database.

SQL Relay can be configured to allow one and reject the other.

The configuration is a bit more complex than suggested by these diagrams, but a complete descripton of query routing and filtering with example configuration files is given here.