Prefetch is currently being testing in test/format. Once made available at the connection level, sessions may enable prefetch too. However, there is one option that is not tested which is prefetch.default at the connection level. We should test this configuration option too to increase our testing coverage.

To tackle this work, the following should help to get started:

• Inside test/format/config.sh, add a new config item prefetch.default with a 5% probability (5% could be changed)
  • Execute test/format/config.sh to generate the new field
• Inside configure_prefetch, we should now update the value associated with default depending on whether GV(PREFETCH_DEFAULT) is set or not.
• Inside enable_session_prefetch, when enabling prefetch at the session level, if it's enabled by default at the connection level, we should leave it on, otherwise, we should keep the current logic.

Definition of done:

• Test/format now tests the prefetch.default config that can be set at the connection level
• Whenever prefetch.default is set to true, sessions created in test/format use the prefetch feature