SERVER-18921 Index points to finest level

6 files changed, 51 insertions, 14 deletions

diff --git a/src/mongo/db/exec/geo_near.cpp b/src/mongo/db/exec/geo_near.cpp
index cf1de9618e9..83f14aa887a 100644
--- a/src/mongo/db/exec/geo_near.cpp
+++ b/src/mongo/db/exec/geo_near.cpp
@@ -824,20 +824,33 @@ S2Region* buildS2Region(const R2Annulus& sphereBounds) {
 
     vector<S2Region*> regions;
 
-    S2Cap innerCap = S2Cap::FromAxisAngle(
-        latLng.ToPoint(), S1Angle::Radians(sphereBounds.getInner() / kRadiusOfEarthInMeters));
-    innerCap = innerCap.Complement();
-    regions.push_back(new S2Cap(innerCap));
+    const double inner = sphereBounds.getInner();
+    const double outer = sphereBounds.getOuter();
+
+    if (inner > 0) {
+        // TODO: Currently a workaround to fix occasional floating point errors
+        // in S2, where sometimes points near the axis will not be returned
+        // if inner == 0
+        S2Cap innerCap = S2Cap::FromAxisAngle(latLng.ToPoint(),
+                                              S1Angle::Radians(inner / kRadiusOfEarthInMeters));
+        innerCap = innerCap.Complement();
+        regions.push_back(new S2Cap(innerCap));
+    }
 
     // We only need to max bound if this is not a full search of the Earth
     // Using the constant here is important since we use the min of kMaxEarthDistance
     // and the actual bounds passed in to set up the search area.
-    if (sphereBounds.getOuter() < kMaxEarthDistanceInMeters) {
-        S2Cap outerCap = S2Cap::FromAxisAngle(
-            latLng.ToPoint(), S1Angle::Radians(sphereBounds.getOuter() / kRadiusOfEarthInMeters));
+    if (outer < kMaxEarthDistanceInMeters) {
+        S2Cap outerCap = S2Cap::FromAxisAngle(latLng.ToPoint(),
+                                              S1Angle::Radians(outer / kRadiusOfEarthInMeters));
         regions.push_back(new S2Cap(outerCap));
     }
 
+    // if annulus is entire world, return a full cap
+    if (regions.empty()) {
+        regions.push_back(new S2Cap(S2Cap::Full()));
+    }
+
     // Takes ownership of caps
     return new S2RegionIntersection(&regions);
 }
diff --git a/src/mongo/db/geo/geometry_container.cpp b/src/mongo/db/geo/geometry_container.cpp
index c74918e40c2..f3bfca36cfb 100644
--- a/src/mongo/db/geo/geometry_container.cpp
+++ b/src/mongo/db/geo/geometry_container.cpp
@@ -42,6 +42,10 @@ bool GeometryContainer::isSimpleContainer() const {
     return NULL != _point || NULL != _line || NULL != _polygon;
 }
 
+bool GeometryContainer::isPoint() const {
+    return nullptr != _point;
+}
+
 bool GeometryContainer::supportsContains() const {
     return NULL != _polygon || NULL != _box || NULL != _cap || NULL != _multiPolygon ||
         (NULL != _geometryCollection && (_geometryCollection->polygons.vector().size() > 0 ||
diff --git a/src/mongo/db/geo/geometry_container.h b/src/mongo/db/geo/geometry_container.h
index 95dc8525440..0d7cea0e7c4 100644
--- a/src/mongo/db/geo/geometry_container.h
+++ b/src/mongo/db/geo/geometry_container.h
@@ -61,6 +61,11 @@ public:
     bool isSimpleContainer() const;
 
     /**
+     * Whether this geometry is a point
+     */
+    bool isPoint() const;
+
+    /**
      * Reports the CRS of the contained geometry.
      * TODO: Rework once we have collections of multiple CRSes
      */
diff --git a/src/mongo/db/index/expression_keys_private.cpp b/src/mongo/db/index/expression_keys_private.cpp
index 7e549a8e2bc..82c4b8d5400 100644
--- a/src/mongo/db/index/expression_keys_private.cpp
+++ b/src/mongo/db/index/expression_keys_private.cpp
@@ -95,7 +95,7 @@ Status S2GetKeysForElement(const BSONElement& element,
         return status;
 
     S2RegionCoverer coverer;
-    params.configureCoverer(&coverer);
+    params.configureCoverer(geoContainer, &coverer);
 
     // Don't index big polygon
     if (geoContainer.getNativeCRS() == STRICT_SPHERE) {
diff --git a/src/mongo/db/index/s2_indexing_params.cpp b/src/mongo/db/index/s2_indexing_params.cpp
index 8217f16fa7e..a7579617564 100644
--- a/src/mongo/db/index/s2_indexing_params.cpp
+++ b/src/mongo/db/index/s2_indexing_params.cpp
@@ -30,8 +30,13 @@
 
 #include "third_party/s2/s2regioncoverer.h"
 
+#include "mongo/db/geo/geometry_container.h"
+
 namespace mongo {
 
+// Points will only be indexed at this level
+const int kPointIndexedLevel = S2::kMaxCellLevel;
+
 std::string S2IndexingParams::toString() const {
     std::stringstream ss;
     ss << "maxKeysPerInsert: " << maxKeysPerInsert << std::endl;
@@ -42,9 +47,17 @@ std::string S2IndexingParams::toString() const {
     return ss.str();
 }
 
-void S2IndexingParams::configureCoverer(S2RegionCoverer* coverer) const {
-    coverer->set_min_level(coarsestIndexedLevel);
-    coverer->set_max_level(finestIndexedLevel);
+void S2IndexingParams::configureCoverer(const GeometryContainer& geoContainer,
+                                        S2RegionCoverer* coverer) const {
+    // Points indexed to the finest level was introduced in version 3
+    // For backwards compatibility, only do this if the version is > 2
+    if (indexVersion >= S2_INDEX_VERSION_3 && geoContainer.isPoint()) {
+        coverer->set_min_level(kPointIndexedLevel);
+        coverer->set_max_level(kPointIndexedLevel);
+    } else {
+        coverer->set_min_level(coarsestIndexedLevel);
+        coverer->set_max_level(finestIndexedLevel);
+    }
 
     // This is advisory; the two above are strict.
     coverer->set_max_cells(maxCellsInCovering);
diff --git a/src/mongo/db/index/s2_indexing_params.h b/src/mongo/db/index/s2_indexing_params.h
index dc5123c1423..8c3e3a87323 100644
--- a/src/mongo/db/index/s2_indexing_params.h
+++ b/src/mongo/db/index/s2_indexing_params.h
@@ -34,6 +34,8 @@ class S2RegionCoverer;
 
 namespace mongo {
 
+class GeometryContainer;
+
 // An enum describing the version of an S2 index.
 enum S2IndexVersion {
     // The first version of the S2 index, introduced in MongoDB 2.4.0.  Compatible with MongoDB
@@ -57,9 +59,9 @@ struct S2IndexingParams {
     // This is really an advisory parameter that we pass to the cover generator.  The
     // finest/coarsest index level determine the required # of cells.
     int maxCellsInCovering;
-    // What's the finest grained level that we'll index?
+    // What's the finest grained level that we'll index for non-points?
     int finestIndexedLevel;
-    // And, what's the coarsest?  When we search in larger coverings
+    // And, what's the coarsest for non-points?  When we search in larger coverings
     // we know we can stop here -- we index nothing coarser than this.
     int coarsestIndexedLevel;
     // Version of this index (specific to the index type).
@@ -69,7 +71,7 @@ struct S2IndexingParams {
 
     std::string toString() const;
 
-    void configureCoverer(S2RegionCoverer* coverer) const;
+    void configureCoverer(const GeometryContainer& geoContainer, S2RegionCoverer* coverer) const;
 };
 
 }  // namespace mongo