SYNC(3valkey)

💖 SYNC(3valkey) — the Valkey Command Manual, but make it make sense 💖

okay bestie, so this is a page from the Valkey Command Manual (yes, the 3valkey one) and it's about a little command called SYNC. she's old, she's iconic, she's basically retired but still showing up to the group chat. let's get into it 🦋

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✨ NAME ✨

sync — an internal command used in replication. that's it, that's the whole name section, she's mysterious 💅

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✨ SYNOPSIS ✨

SYNC

no args, no flags, no nothing. just vibes. literally just say her name and she answers 😭

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✨ DESCRIPTION ✨

so. SYNC kicks off a replication stream from the primary. that's the whole job description fr fr.

the tea is that the SYNC command gets called by Valkey replicas to start up a replication stream from the primary. that's her whole purpose, that's her main character energy.

BUT — and this is the part you need to know — she's been replaced in newer versions of Valkey by valkey-psync(7) PSYNC. so she's lowkey legacy. still valid, still around, but the new girl is doing the work now 🙈

ngl, if you're reading this in 2025 wondering whether to use her: the manpage is telling you PSYNC is the upgrade. no cap.

and if you want the full lore on how replication works in Valkey, the page says to go check out the replication page. that's where the deep dive lives, bestie 🫶

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✨ REPLY ✨

this is the fun part — she does not return a normal answer. it's a non-standard return value: a bulk transfer of the data, followed by PING and write requests from the primary.

so like... she doesn't reply with a cute little status code. she just starts dumping data at you and then the primary keeps pinging and writing. it's giving "no small talk, straight to business" 💀

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✨ ACL CATEGORIES ✨

• @admin
• @dangerous
• @slow

all three. at once. she's a lot, and honestly? slay 👑

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✨ HISTORY ✨

• Available since: 1.0.0

she's been here since the very beginning, an OG. respect the elders 🎀

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✨ SEE ALSO ✨

okay this is the big one, the link dump, the "you may also like" of it all. every single one of these, exactly as written:

• acl(3valkey), acl-cat(3valkey), acl-deluser(3valkey), acl-dryrun(3valkey), acl-genpass(3valkey), acl-getuser(3valkey), acl-help(3valkey), acl-list(3valkey), acl-load(3valkey), acl-log(3valkey), acl-save(3valkey), acl-setuser(3valkey), acl-users(3valkey), acl-whoami(3valkey)
• bgrewriteaof(3valkey), bgsave(3valkey)
• command(3valkey), command-count(3valkey), command-docs(3valkey), command-getkeys(3valkey), command-getkeysandflags(3valkey), command-help(3valkey), command-info(3valkey), command-list(3valkey), commandlog(3valkey), commandlog-get(3valkey), commandlog-help(3valkey), commandlog-len(3valkey), commandlog-reset(3valkey)
• config(3valkey), config-get(3valkey), config-help(3valkey), config-resetstat(3valkey), config-rewrite(3valkey), config-set(3valkey)
• dbsize(3valkey), debug(3valkey), failover(3valkey), flushall(3valkey), flushdb(3valkey), info(3valkey), lastsave(3valkey)
• latency(3valkey), latency-doctor(3valkey), latency-graph(3valkey), latency-help(3valkey), latency-histogram(3valkey), latency-history(3valkey), latency-latest(3valkey), latency-reset(3valkey)
• lolwut(3valkey) 💀
• memory(3valkey), memory-doctor(3valkey), memory-help(3valkey), memory-malloc-stats(3valkey), memory-purge(3valkey), memory-stats(3valkey), memory-usage(3valkey)
• module(3valkey), module-help(3valkey), module-list(3valkey), module-load(3valkey), module-loadex(3valkey), module-unload(3valkey), monitor(3valkey)
• psync(3valkey), replconf(3valkey), replicaof(3valkey), restore-asking(3valkey), role(3valkey)
• save(3valkey), shutdown(3valkey), slowlog(3valkey), slowlog-get(3valkey), slowlog-help(3valkey), slowlog-len(3valkey), slowlog-reset(3valkey), swapdb(3valkey), time(3valkey)

iykyk 🌈

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and that's the whole page, bestie!! this version of the manpage is from Valkey 9.0.0, dated 2025-10-21 — so go forth, replicate responsibly, and remember: SYNC is the old queen, PSYNC is the heir to the throne. periodt 💖✨🦋