From e3234116ada02bdaff72a0d1eab91e381b0277b5 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Fri, 28 Mar 2014 14:09:28 +0100
Subject: [PATCH] HyperLogLog: redefine constants using "P".

---
 src/hyperloglog.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/hyperloglog.c b/src/hyperloglog.c
index 455270965..087aa7632 100644
--- a/src/hyperloglog.c
+++ b/src/hyperloglog.c
@@ -51,8 +51,9 @@
  *     analysis of a near-optimal cardinality estimation algorithm.
  */
 
-#define REDIS_HLL_REGISTERS 16384
-#define REDIS_HLL_BITS 6
+#define REDIS_HLL_P 14 /* The greater is P, the smaller the error. */
+#define REDIS_HLL_REGISTERS (1<<REDIS_HLL_P) /* With P=14, 16384 registers. */
+#define REDIS_HLL_BITS 6 /* Enough to count up to 63 leading zeroes. */
 #define REDIS_HLL_REGISTER_MAX ((1<<REDIS_HLL_BITS)-1)
 #define REDIS_HLL_SIZE ((REDIS_HLL_REGISTERS*REDIS_HLL_BITS+7)/8)