What a big database is and why there isn’t anything like that.

Yea, simple question. Usually I hear something like this: “Help me, my database is so slow because it is so big…. about 1,000 records’”. That usually makes me laugh. Adding some indexes and convincing programmers not to get all records with every select usually helps and suddenly the database is not so big.

OK, when someone says that there are over 1M records that doesn’t mean that this database is big. Lets define the big database some other way. The number of records shouldn’t be considered when classifying a database to be big. In databases we’ve got tables used for logging some data (so that those tables can be really big but are not used for complicated queries) and we’ve got tables with much less data but many indexes that are used for many much more complicated queries.

Main problems with databases are all about the speed of getting data. All about speeding up selects. There is no such problem as ‘The Big Database’ problem is always names ‘The Slow Database’. So what is a slow database? Database can be slow because there is too much data, then usually we use indexes and speed all up to some extent. But sometimes we’ve got to replace the server with something better and faster, more ram and faster drives, more CPUs and so on. And then the problem with Slow (also called the Big) Database doesn’t exists. So… there is not a problem called The Big Database. Database is a problem if it is slow, not big. Big doesn’t mean slow and slow doesn’t mean big.

When a database is slow there are many ways to improve that… to some extent. After that I can say that the database is Big if it is still slow. But that simply means that the database and all database operations don’t fit the server.

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