which is faster? Statement or PreparedStatement

Question

Often, in the network can be found code like this:

private static final String SQL = "SELECT * FROM table_name";
....

and for this SQL query is used PreparedStatement. Why?
As i know, PreparedStatement spend time to precompile SQL statement. It turns out so that the Statement is faster than a PreparedStatement. Or I'm mistaken?

Answer 1

Prepared statements are much faster when you have to run the same statement multiple times, with different data. Thats because SQL will validate the query only once, whereas if you just use a statement it will validate the query each time.

The other benefit of using PreparedStatements is to avoid causing a SQL injection vulnerability - though in your case your query is so simple you haven't encountered that.

For your query, the difference between running a prepared statement vs a statement is probably negligible.

EDIT: In response to your comment below, you will need to look closely at the DAO class to see what it is doing. If for example, each time the method is called it re-creates the prepared statement then you will lose any benefit of using prepared statements.

What you want to achieve, is the encapsulation of your persistence layer so that their is no specific call to MySQL or Postgres or whatever you are using, and at the same time take advantage of the performance and security benefits of things like prepared statements. To do this you need to rely on Java's own objects such as PreparedStatement,.

I personally would build my own DAO class for doing CRUD operations, using Hibernate underneath and the Java Persistence API to encapsulate it all, and that should use prepared statements for the security benefits. If you have a specific use-case for doing repeated operations, then I would be inclined to wrap that within its own object.

Hibernate can be configured to use whatever database vendor you are using via an XML file, and thus it provides really neat encapsulation of your persistence layer. However, it is quite a complicated product to get right!

Answer 2

Most of the time queries are not as simple as your example. If there is any variation to the query, i.e. any parameters that are not known at compile time, you must use PreparedStatement to avoid SQL injection vulnerabilities. This trumps any performance concerns. If there is any difference between PreparedStatement and Statement, it would be highly dependent on the particular JDBC driver in question and most of the time the penalty will be negligible compare to the cost of going to the database, executing actual query and fetching results back.