Description

quarkus.datasource.reactive.cache-prepared-statement defaults to false, because it's only supported for some databases.

This creates a performance disadvantage for reactive compared to JDBC for databases that do support caching prepared statement; e.g. the PostgreSQL JDBC driver caches prepared statements by default (preparedStatementCacheQueries defaults to 256), and @franz1981 tells us this has a sizeable impact on benchmarks.

We should:

• Make cachePreparedStatements an Optional<Boolean>.
• Remove @WithDefault from that field.
• Add @ConfigDocDefault to explain what the default is: true if supported (PostgreSQL/MySQL/MariaDB/DB2), false otherwise.
• Handle the default with a Optional#orElse in relevant places, i.e. where the DB-specific code forwards the setting.
• Test, at least manually, that the default is effective.

Implementation ideas

No response