Cost of a query in/dependent of amount of data

Could you please tell me whether the cost of a query is dependent on the amount of data available in the databas开发者_如何学Goe at that time?

means, does the cost varies with the variation in the amount of data?

Thanks, Savitha

The answer is, Yes, the data size will influence the query execution plan, that is why you must test your queries with real amounts of data (and if possible realistic data as the distribution of the data is also important and will influence the query cost).

Any Database management system is different in some respect and what works well for Oracle,MS SQL, PostgreSQL may not work well for MySQL and other way around. Even storage engines have very important differences which can affect performance dramatically.

Of course, mass data will Slow down the process, In fact If u are firing a query, it need to traverse and search into the database. For more data it ll take time, The three main issues you should be concerned if you’re dealing with very large data sets are Buffers, Indexes and Joins..