PFADD(3valkey)

💖 PFADD — bestie, it's giving HyperLogLog glow-up ✨

okay so this is PFADD from the Valkey Command Manual (that's the 3valkey manual section, bestie, iykyk) — and it's literally the cutest little command for stuffing elements into a HyperLogLog key. Let's get into it 🫶

---

✨ NAME ✨

pfadd — adds elements to a HyperLogLog key. and like, it creates the key if it doesn't exist too, because it's generous like that 💅

---

🌸 SYNOPSIS 🌸

PFADD key element [element...]

---

🦋 DESCRIPTION 🦋

So basically? It adds all the element arguments to the HyperLogLog data structure that's stored at the variable name you passed as the first argument. all of them. every single one. no cap 🎀

and as a little side effect of this command, the HyperLogLog internals may get updated to reflect a different estimation of the number of unique items added so far — that's the cardinality of the set, for those of you keeping score at home ✨

Here's the vibe check on the return value: if the approximated cardinality estimated by the HyperLogLog changed after running the command, PFADD returns 1. Otherwise it returns 0. periodt 💅

and if the key you specified doesn't exist? It automatically creates an empty HyperLogLog structure for you — that's, like, a String of a specified length and with a given encoding. it just shows up. main character energy 👑

You can also call the command with no elements at all, just the variable name — that's totally valid! And it will result in:

• no operation performed if the variable already exists, or
• just the creation of the data structure if the key does not exist (and in that latter case, 1 is returned 🌈)

wanna actually understand what a HyperLogLog is, bestie? go check the valkey-pfcount(7) PFCOUNT command page, it's got the whole introduction 🧚

---

💜 REPLY 💜

One of the following, bestie:

• valkey-protocol(7) Integer reply: 1 if at least one HyperLogLog internal register was altered. slay 💖
• valkey-protocol(7) Integer reply: 0 if no HyperLogLog internal registers were altered. nothing moved. it's giving stillness 🍓

---

🔥 COMPLEXITY 🔥

O(1) to add every element. yeah. constant time. we love efficiency in this house ✨

---

👑 ACL CATEGORIES 👑

@fast @hyperloglog @write

---

🌈 HISTORY 🌈

• Available since: 2.8.9 — an icon from the very beginning 💅

---

⭐ EXAMPLES ⭐

127.0.0.1:6379> PFADD hll a b c d e f g
(integer) 1
127.0.0.1:6379> PFCOUNT hll
(integer) 7

look at that. seven elements in, seven counted out. we ate that fr fr 🍽️✨

---

🎀 SEE ALSO 🎀

pfcount(3valkey), pfdebug(3valkey), pfmerge(3valkey), pfselftest(3valkey)

---

and that's the whole page, bestie 🫶 this was written for Valkey 9.0.0, dated 2025-10-21, and it lives at PFADD(3valkey). go forth and add elements. you're gonna do amazing 💖🌸🦋