When using the unified highlighter with hl.bs.type=WORD, I am not able to get context to the left of the matches returned; only words to the right of each match are shown. I see this behaviour on both Solr 6.4 and Solr 7.1.
Without context to the left of a match, the highlighted snippets are much less useful for understanding where the match appears in a document.
As an example, using the techproducts data with Solr 7.1, given a search for "apple", highlighting the "features" field:
I see this snippet:
"<em>Apple</em> Lossless, H.264 video"
Note that "Apple" is anchored to the left. Compare with the original highlighter:
And the match has context either side:
", Audible, <em>Apple</em> Lossless, H.264 video"
(To complicate this, in general I am not sure that the unified highlighter is respecting the hl.fragsize parameter, although
SOLR-9935 suggests support was added. I included the hl.fragsize param in the unified URL too, but it's making no difference unless set to 0.)