It was in a definition with the name "merge-candidate".
Backtracking that to HTML code, I was then able to trace further to find
the Java code in the segment info handler that actually turns the
Based on what I found, I think that pink segments are those segments
which the system thinks are most likely to be chosen for automatic
merging, according to whatever merge policy you have active. Most
likely the merge policy is TieredMergePolicy.
The pink color is not an indication of a problem. Sounds like the admin
UI needs a color legend for the segments display, so that users can
instantly know what they are looking at. It also needs to be mentioned
in the documentation, where I cannot find "pink" mentioned anywhere
other than the page about the classic query parser, which is completely