We're running ES 5.1.1 and are using a custom highlighter, although we've tested and this effects the plain highlighter (and I would imagine any highlighter) as well.
In short, it would appear our highlighter is being called once by HighlightPhase.hitExecute and once by PercolatorHighlightSubFetchPhase(HighlightPhase).hitExecute, even though we're not doing any Percolate queries (nor do we have any registered).
Detail
The PercolatorPlugin registers the percolatorHighlightSubFetchPhase on ES initialization:
PercolatorPlugin.java
@Override
public List<FetchSubPhase> getFetchSubPhases(FetchPhaseConstructionContext context) {
return singletonList(new PercolatorHighlightSubFetchPhase(settings, context.getHighlighters()));
}
I can see this in FetchPhase.fetchSubPhases:
FetchPhase.execute iterates over each fetchSubPhase and calls hitExecute:
for (FetchSubPhase fetchSubPhase : fetchSubPhases) {
fetchSubPhase.hitExecute(context, hitContext);
}
For both HighlightPhase and PercolatorHighlightSubFetchPhase (which does not override HighlightPhase.hitExecute) the highlighter is executed:
@Override
public void hitExecute(SearchContext context, HitContext hitContext) {
if (context.highlight() == null) {
return;
}
...
HighlightField highlightField = highlighter.highlight(highlighterContext);
if (highlightField != null) {
highlightFields.put(highlightField.name(), highlightField);
}
}
}
hitContext.hit().highlightFields(highlightFields);
}
Finally FetchPhase.execute calls hitsExecute on each sub-phase:
for (FetchSubPhase fetchSubPhase : fetchSubPhases) {
fetchSubPhase.hitsExecute(context, hits);
}
PercolatorHighlightSubFetchPhase does override hitsExecute and the first thing it does is verify the query is some sort of percolate query:
PercolatorHighlightSubFetchPhase.java
boolean hitsExecutionNeeded(SearchContext context) { // for testing
return context.highlight() != null && locatePercolatorQuery(context.query()).isEmpty() == false;
}
@Override
public void hitsExecute(SearchContext context, SearchHit[] hits) throws IOException {
if (hitsExecutionNeeded(context) == false) {
return;
}
...
}
static List<PercolateQuery> locatePercolatorQuery(Query query) {
if (query instanceof PercolateQuery) {
return Collections.singletonList((PercolateQuery) query);
} else if (query instanceof BooleanQuery) {
List<PercolateQuery> percolateQueries = new ArrayList<>();
for (BooleanClause clause : ((BooleanQuery) query).clauses()) {
List<PercolateQuery> result = locatePercolatorQuery(clause.getQuery());
if (result.isEmpty() == false) {
percolateQueries.addAll(result);
}
}
return percolateQueries;
} else if (query instanceof DisjunctionMaxQuery) {
List<PercolateQuery> percolateQueries = new ArrayList<>();
for (Query disjunct : ((DisjunctionMaxQuery) query).getDisjuncts()) {
List<PercolateQuery> result = locatePercolatorQuery(disjunct);
if (result.isEmpty() == false) {
percolateQueries.addAll(result);
}
}
return percolateQueries;
} else if (query instanceof ConstantScoreQuery) {
return locatePercolatorQuery(((ConstantScoreQuery) query).getQuery());
} else if (query instanceof BoostQuery) {
return locatePercolatorQuery(((BoostQuery) query).getQuery());
} else if (query instanceof FunctionScoreQuery) {
return locatePercolatorQuery(((FunctionScoreQuery) query).getSubQuery());
}
return Collections.emptyList();
}
Ultimately InternalSearchHit.highlightFields gets overwritten so I don't believe there's any functional impact, but we notice a performance hit.
I'm hoping I'm missing something here or there's a way to turn off PercolatorHighlightSubFetchPhase that we're not seeing.
Edit: Temporary Solution
We've just removed the percolator module (es/modules/percolator) such that the PercolatorPlugin (and subsequently the relevant Fetch-Sub-Phase) is never registered. Temporary in that we can no longer run percolate-queries.
Thanks,
Mike K.
