only send distanceThreshold conditionally

* abuse a bit in the "allow approximation" integer
* we want to cleanup this in several steps later.

2 files changed, 9 insertions, 2 deletions

diff --git a/searchlib/src/vespa/searchlib/parsequery/stackdumpiterator.cpp b/searchlib/src/vespa/searchlib/parsequery/stackdumpiterator.cpp
index 6feec9bbba2..ce24de02281 100644
--- a/searchlib/src/vespa/searchlib/parsequery/stackdumpiterator.cpp
+++ b/searchlib/src/vespa/searchlib/parsequery/stackdumpiterator.cpp
@@ -273,7 +273,13 @@ SimpleQueryStackDumpIterator::next()
             _extraIntArg1 = readCompressedPositiveInt(p); // targetNumHits
             _extraIntArg2 = readCompressedPositiveInt(p); // allow_approximate
             _extraIntArg3 = readCompressedPositiveInt(p); // explore_additional_hits
-            _extraDoubleArg4 = read_double(p); // distance threshold
+            if ((_extraIntArg2 & 0x40) != 0) {
+                _extraIntArg2 &= ~0x40;
+                // in some later release, do this always:
+                _extraDoubleArg4 = read_double(p); // distance threshold
+            } else {
+                _extraDoubleArg4 = std::numeric_limits<double>::max();
+            }
             _currArity = 0;
         } catch (...) {
             return false;
diff --git a/searchlib/src/vespa/searchlib/query/tree/stackdumpcreator.cpp b/searchlib/src/vespa/searchlib/query/tree/stackdumpcreator.cpp
index a006e66310c..d2ac46157b1 100644
--- a/searchlib/src/vespa/searchlib/query/tree/stackdumpcreator.cpp
+++ b/searchlib/src/vespa/searchlib/query/tree/stackdumpcreator.cpp
@@ -263,7 +263,8 @@ class QueryNodeConverter : public QueryVisitor {
         createTermNode(node, ParseItem::ITEM_NEAREST_NEIGHBOR);
         appendString(node.get_query_tensor_name());
         appendCompressedPositiveNumber(node.get_target_num_hits());
-        appendCompressedPositiveNumber(node.get_allow_approximate() ? 1 : 0);
+        // XXX subtract 0x40 later:
+        appendCompressedPositiveNumber(node.get_allow_approximate() ? 0x41 : 0x40);
         appendCompressedPositiveNumber(node.get_explore_additional_hits());
         appendDouble(node.get_distance_threshold());
     }