From 41d334aeaf7cc850cb9e2cbe83c839d7e8a3b4bc Mon Sep 17 00:00:00 2001
From: Travis <travis@pilosa.com>
Date: Wed, 8 Mar 2017 16:09:56 -0600
Subject: [PATCH] If a top-n query contains BitmapIDs, then treat N as having
 value 0.

---
 executor.go      |  4 ----
 executor_test.go |  4 ++--
 fragment.go      | 18 ++++++++++++------
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/executor.go b/executor.go
index 774e2443f..5862fbe3b 100644
--- a/executor.go
+++ b/executor.go
@@ -189,10 +189,6 @@ func (e *Executor) executeTopN(ctx context.Context, db string, c *pql.Call, slic
 	// Only the original caller should refetch the full counts.
 	other := c.Clone()
 
-	// Double the size of n for other calls in order to...
-	// TODO: travis review
-	other.Args["n"] = len(bitmapIDs) * 2
-
 	ids := Pairs(pairs).Keys()
 	sort.Sort(uint64Slice(ids))
 	other.Args["ids"] = ids
diff --git a/executor_test.go b/executor_test.go
index 1cc0985ac..196c2e815 100644
--- a/executor_test.go
+++ b/executor_test.go
@@ -241,7 +241,7 @@ func TestExecutor_Execute_TopN_fill(t *testing.T) {
 	idx := MustOpenIndex()
 	defer idx.Close()
 
-	// Set bits for bitmaps 0, 10, & 20 across two slices.
+	// Set bits for bitmaps 0 & 1 across two slices.
 	idx.MustCreateFragmentIfNotExists("d", "f", 0).SetBit(0, 0)
 	idx.MustCreateFragmentIfNotExists("d", "f", 0).SetBit(0, 1)
 	idx.MustCreateFragmentIfNotExists("d", "f", 0).SetBit(0, 2)
@@ -601,7 +601,7 @@ func TestExecutor_Execute_Remote_TopN(t *testing.T) {
 				t.Fatalf("unexpected query(0): %s", query.String())
 			}
 		case 1:
-			if query.String() != `TopN(frame="f", ids=[0,10,30], n=0)` {
+			if query.String() != `TopN(frame="f", ids=[0,10,30], n=3)` {
 				t.Fatalf("unexpected query(1): %s", query.String())
 			}
 		default:
diff --git a/fragment.go b/fragment.go
index e70dab80c..82f2e50f2 100644
--- a/fragment.go
+++ b/fragment.go
@@ -476,6 +476,11 @@ func (f *Fragment) Top(opt TopOptions) ([]Pair, error) {
 	// Retrieve pairs. If no bitmap ids specified then return from cache.
 	pairs := f.topBitmapPairs(opt.BitmapIDs)
 
+	// If BitmapIDs are provided, we don't want to truncate the result set
+	if len(opt.BitmapIDs) > 0 {
+		opt.N = 0
+	}
+
 	// Create a fast lookup of filter values.
 	var filters map[interface{}]struct{}
 	if opt.FilterField != "" && len(opt.FilterValues) > 0 {
@@ -489,10 +494,10 @@ func (f *Fragment) Top(opt TopOptions) ([]Pair, error) {
 	//results := make(PairHeap, 0, opt.N)
 	results := &PairHeap{}
 	for _, pair := range pairs {
-		bitmapID, n := pair.ID, pair.Count
+		bitmapID, cnt := pair.ID, pair.Count
 
 		// Ignore empty bitmaps.
-		if n <= 0 {
+		if cnt <= 0 {
 			continue
 		}
 
@@ -513,7 +518,7 @@ func (f *Fragment) Top(opt TopOptions) ([]Pair, error) {
 		// The initial n pairs should simply be added to the results.
 		if opt.N == 0 || results.Len() < opt.N {
 			// Calculate count and append.
-			count := n
+			count := cnt
 			if opt.Src != nil {
 				count = opt.Src.IntersectionCount(f.Bitmap(bitmapID))
 			}
@@ -530,6 +535,7 @@ func (f *Fragment) Top(opt TopOptions) ([]Pair, error) {
 					break
 				}
 			}
+
 			continue
 		}
 
@@ -538,14 +544,13 @@ func (f *Fragment) Top(opt TopOptions) ([]Pair, error) {
 		threshold := results.Pairs[0].Count
 
 		// If the bitmap doesn't have enough bits set before the intersection
-		// then we can assume that any remaing bitmaps also have a count too low.
-		if n < threshold {
+		// then we can assume that any remaining bitmaps also have a count too low.
+		if cnt < threshold {
 			break
 		}
 
 		// Calculate the intersecting bit count and skip if it's below our
 		// last bitmap in our current result set.
-
 		count := opt.Src.IntersectionCount(f.Bitmap(bitmapID))
 		if count < threshold {
 			continue
@@ -569,6 +574,7 @@ func (f *Fragment) topBitmapPairs(bitmapIDs []uint64) []BitmapPair {
 		f.mu.Lock()
 		defer f.mu.Unlock()
 		f.cache.Invalidate()
+		// TODO: make sure this is just returning a reference to the entire cache
 		return f.cache.Top()
 	}