MEMCACHED_APPEND(3)

💖 memcached_append(3) — bestie edition 💖

okay so this is the page for memcached_append(3) from libmemcached-awesome, and it's all about appending to and prepending data on your memcached server. literally the glow-up-your-stored-data function. let's get into it ✨

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🌸 NAME 🌸

memcached_append — Appending to or Prepending Data

like, you take a thing that's already on the server and you either slap stuff on the end or stick stuff at the front. iconic behaviour tbh 💅

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✨ SYNOPSIS ✨

#include <libmemcached-1.0/memcached.h>
       Compile and link with -lmemcached

memcached_return_t memcached_prepend(memcached_st *ptr, const char *key,
size_t key_length, const char *value, size_t value_length, time_t
expiration, uint32_t flags)

memcached_return_t memcached_append(memcached_st *ptr, const char *key,
size_t key_length, const char *value, size_t value_length, time_t
expiration, uint32_t flags)

memcached_return_t memcached_prepend_by_key(memcached_st *ptr, const
char *group_key, size_t group_key_length, const char *key, size_t
key_length, const char *value, size_t value_length, time_t expiration,
uint32_t flags)

memcached_return_t memcached_append_by_key(memcached_st *ptr, const char
*group_key, size_t group_key_length, const char *key, size_t key_length,
const char *value, size_t value_length, time_t expiration, uint32_t
flags)

🫶 Parameters

• ptr — pointer to an initialized memcached_st struct
• group_key — key namespace
• group_key_length — length of the key namespace without any terminating zero
• key — the key
• key_length — length of the key without any terminating zero
• value — the value to append/prepend
• value_length — the length of the value without any terminating zero
• expiration — expiration as a unix timestamp or as relative expiration time in seconds
• flags — 16 bit flags

⭐ Returns

memcached_return_t indicating success

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🦋 DESCRIPTION 🦋

memcached_prepend() and memcached_append are used to modify information on a server. All methods take a key, and key_length to store the object. Keys are currently limited to 250 characters when using either a version of memcached which is 1.4 or below, or when using the text protocol. You must supply both a value and a length. Optionally you may set an expiration time for the object and a 16 bit value (it is meant to be used as a bitmap). flags is a 4 byte space that is stored along the main value. Many sub libraries make use of this field, so in most cases users should avoid making use of it.

bestie pls note: that flags field is shared real estate. other libs are living in there. unless you know what you're doing, leave it alone 🙈

memcached_prepend() places a segment of data before the last piece of data stored. Currently expiration and key are not used in the server.

memcached_append() places a segment of data at the end of the last piece of data stored. Currently expiration and key are not used in the server.

memcached_prepend_by_key() and memcached_append_by_key() methods both behave in a similar manner as the non key methods. The difference is that they use their group_key parameter to map objects to particular servers.

If you are looking for performance, memcached_set() with non-blocking IO is the fastest way to store data on the server.

All of the above functions are tested with the MEMCACHED_BEHAVIOR_USE_UDP behavior enabled. However, when using these operations with this behavior on, there are limits to the size of the payload being sent to the server. The reason for these limits is that the Memcached Server does not allow multi-datagram requests and the current server implementation sets a datagram size to 1400 bytes. Due to protocol overhead, the actual limit of the user supplied data is less than 1400 bytes and depends on the protocol in use as, well as, the operation being executed. When running with the binary protocol, MEMCACHED_BEHAVIOR_BINARY_PROTOCOL, the size of the key,value, flags and expiry combined may not exceed 1368 bytes. When running with the ASCII protocol, the exact limit fluctuates depending on which function is being executed and whether the function is a cas operation or not. For non-cas ASCII set operations, there are at least 1335 bytes available to split among the key, key_prefix, and value; for cas ASCII operations there are at least 1318 bytes available to split among the key, key_prefix and value. If the total size of the command, including overhead, exceeds 1400 bytes, a MEMCACHED_WRITE_FAILURE will be returned.

🚨 math check bestie: 1400 bytes is the datagram, but overhead eats into it, so the real numbers are 1368 (binary protocol, key + value + flags + expiry combined), 1335 (non-cas ASCII, split across key, key_prefix, value), and 1318 (cas ASCII, same split). go over 1400 total including overhead and you get MEMCACHED_WRITE_FAILURE. periodt 💀

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👑 RETURN VALUE 👑

All methods return a value of type memcached_return_t. On success the value will be MEMCACHED_SUCCESS.

Use memcached_strerror() to translate this value to a printable string.

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💜 SEE ALSO 💜

memcached(1) libmemcached(3) memcached_strerror(3) memcached_set(3) ‐ memcached_add(3) memcached_cas(3) memcached_replace(3)

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and that's the whole page, bestie!! 🌈 this one came out of libmemcached-awesome version 1.1, dated Jul 24, 2025. go forth and append slayfully ✨🎀🦋