From 9e1b879f5bcbf105d5581c77f8c368b0ef1708f6 Mon Sep 17 00:00:00 2001
From: Binbin <binloveplay1314@qq.com>
Date: Sun, 23 Oct 2022 01:41:17 +0800
Subject: Make PFMERGE source key optional in docs, add tests with one input
 key, add tests on missing source keys (#11205)

The following two cases will create an empty destkey HLL:
1. called with no source keys, like `pfmerge destkey`
2. called with non-existing source keys, like `pfmerge destkey non-existing-source-key`

In the first case, in `PFMERGE`, the dest key is actually one of the source keys too.
So `PFMERGE k1 k2` is equivalent to `SUNIONSTORE k1 k1 k2`,
and `PFMERGE k1` is equivalent to `SUNIONSTORE k1 k1`.
So the first case is reasonable, the source key is actually optional.

And the second case, `PFMERGE` on missing keys should succeed and create an empty dest.
This is consistent with `PFCOUNT`, and also with `SUNIONSTORE`, no need to change.
---
 src/commands.c            | 2 +-
 src/commands/pfmerge.json | 1 +
 src/help.h                | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/commands.c b/src/commands.c
index 5ee012c79..b9b4b915d 100644
--- a/src/commands.c
+++ b/src/commands.c
@@ -2608,7 +2608,7 @@ struct redisCommandArg PFDEBUG_Args[] = {
 /* PFMERGE argument table */
 struct redisCommandArg PFMERGE_Args[] = {
 {"destkey",ARG_TYPE_KEY,0,NULL,NULL,NULL,CMD_ARG_NONE},
-{"sourcekey",ARG_TYPE_KEY,1,NULL,NULL,NULL,CMD_ARG_MULTIPLE},
+{"sourcekey",ARG_TYPE_KEY,1,NULL,NULL,NULL,CMD_ARG_OPTIONAL|CMD_ARG_MULTIPLE},
 {0}
 };
 
diff --git a/src/commands/pfmerge.json b/src/commands/pfmerge.json
index ae18dad1e..648a8b43a 100644
--- a/src/commands/pfmerge.json
+++ b/src/commands/pfmerge.json
@@ -62,6 +62,7 @@
                 "name": "sourcekey",
                 "type": "key",
                 "key_spec_index": 1,
+                "optional": true,
                 "multiple": true
             }
         ]
diff --git a/src/help.h b/src/help.h
index a95da3695..e8a94210e 100644
--- a/src/help.h
+++ b/src/help.h
@@ -1125,7 +1125,7 @@ struct commandHelp {
     11,
     "2.8.9" },
     { "PFMERGE",
-    "destkey sourcekey [sourcekey ...]",
+    "destkey [sourcekey [sourcekey ...]]",
     "Merge N different HyperLogLogs into a single one.",
     11,
     "2.8.9" },
-- 
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