PostgreSQL is a popular relational database system, frequently used in applications. While working with PostgreSQL, you may come across the error message, “ERROR: prepared statement ‘S_1’ already exists.” This error occurs when you attempt to prepare a statement with the same name as an existing prepared statement in the current session. One effective solution to prevent this error is to use the preparedStatementCacheQueries configuration setting. In this article, we’ll explore how preparedStatementCacheQueries helps resolve this issue.

Understanding the Error

The error message “ERROR: prepared statement ‘S_1’ already exists” often arises from connection reuse or within complex transaction management scenarios. PostgreSQL retains prepared statements within the session, which can lead to conflicts when the same statement is prepared again with the same name.

Solution:

Modify the connection string

jdbc:postgresql://localhost:5432/postgresDB?preparedStatementCacheQueries=0

you won’t need to manually deallocate prepared statements, as PostgreSQL handles this for you if preparedStatementCacheQueries=0 is used.