BtreePlus indexes were introduced in v3.4, and are used by default in new repositories; that is, GsIndexOptions default returns:
GsIndexOptions btreePlusIndex + GsIndexOptions optimizedComparison
Upgraded repositories, however, defaulted to btreePlusIndex; GsIndexOptions default returns GsIndexOptions legacyIndex
This behavior on upgrade was lost due to code reorganization in v3.6; upgrading from pre-3.4 to 3.6 or later would result in the default for GsIndexOptions to include GsIndexOptions btreePlusIndex + GsIndexOptions optimizedComparison, rather than GsIndexOptions legacyIndex.
After upgrade, as SystemUser, set the default using:
GsIndexOptions default: GsIndexOptions legacyIndex
Last updated: 7/25/23