Prepared Statement Support

The Simba Amazon Redshift JDBC Driver supports prepared statements. You can use prepared statements to improve the performance of parameterized queries that need to be executed multiple times during the same connection.

A prepared statement is a SQL statement that is compiled on the server side but not executed immediately. The compiled statement is stored on the server as a PreparedStatement object until you close the object or the connection. While that object exists, you can execute the prepared statement as many times as needed using different parameter values, without having to compile the statement again. This reduced overhead enables the set of queries to be executed more quickly.

Note:

For more information about prepared statements, see "Using Prepared Statements" in the JDBC Basics tutorial from Oracle: https://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html.

You can prepare a statement that contains multiple queries. For example, the following prepared statement contains two INSERT queries:

PreparedStatement pstmt = conn.prepareStatement("INSERT INTO MyTable VALUES (1, 'abc'); INSERT INTO CompanyTable VALUES (1, 'abc');");

However, be aware that these queries cannot depend on the results of other queries that are specified within the same prepared statement. Because queries are not executed during the prepare step, the results have not been returned yet, and therefore are not available to other queries that are part of the same prepared statement.

For example, the following prepared statement, which creates a table and then inserts values into that newly-created table, is not allowed:

PreparedStatement pstmt = conn.prepareStatement("CREATE TABLE MyTable(col1 int, col2 varchar); INSERT INTO myTable VALUES (1, 'abc');");

If you try to prepare this statement, the server returns an error stating that the destination table (myTable) does not exist yet. The CREATE query must be executed before the INSERT query can be prepared.

Note:

This process for handling multiple queries in a prepared statement is consistent with established standards.