This topic's title could seems a bit alarming but it's just a pinch of irony I would give, most of all because I struggled for so many weeks on this feature that it was like fighting against the "dark". However, I just want to focus on few things we should think about before to plan the introduction of the delta index when the environment is updated through the data load.

In particular, if we have to introduce the delta index- in place of the full- and the data load is already set up, or we have to plan from scratch the data load process, we should keep in mind that the data load operations, the order they are executed and the delta updates recorded in the temporary delta tables (TI_DELTA_CATENTRY and TI_DELTA_CATGROUP) are strictly connected; we should not consider the data load a black box respect to the SOLR index, when we need to update the system through the delta mode. The SOLR index and the Data Load are unfortunately tied in a way we cannot think to build a loading process without knowing in which way they interact.

Ok, let's leave fancy words! I will report two specific cases: 

1. delete bundles;
2. delete sales categories (second part of this article);