Some databases require a FROM clause, even if jOOQ users did not supply it. jOOQ will generate a DUAL table, or something equivalent in those cases.

In order to assess whether the FROM keyword is required, jOOQ generated the TableList QueryPart in SelectQueryImpl. This used to be necessary in the past, as the DUAL logic wasn't centralised in the org.jooq.impl.Dual type (long ago).

Since this is no longer needed, we shouldn't accept the overhead created by generating the dummy SQL clause. Removing the duplicate DefaultRenderContext, and the rendering improves performance by another 15% in high throughput benchmarks!

This is a finding from analyses made after a third-party benchmark comparing jOOQ with JDBC, Hibernate, Spring Data:
https://github.com/nithril/sandbox-query-benchmark-jooq-hibernate-jdbc