MONGOC_SESSION...AL_CONSISTENCY(3)

bestie, welcome to the libmongoc page for mongoc_session_opts_set_causal_consistency — the header abbreviates it as MONGOC_SESSION...AL_CONSISTENCY(3) because apparently we're doing dramatic ellipses now 💅.

✨ SYNOPSIS ✨

void
mongoc_session_opts_set_causal_consistency (mongoc_session_opt_t *opts,
                                            bool causal_consistency);

💖 DESCRIPTION 💖

okay so mongoc_session_opts_set_causal_consistency configures causal consistency in a session. If it's true (and yes bestie, that's the default ✨), each operation in the session will be causally ordered after the previous read or write operation. Set it to false to disable causal consistency. There's a whole MongoDB Manual Entry for Causal Consistency if you wanna go deeper.

big important caveat: causal consistency and snapshot reads are mutually exclusive 🫶. Attempting to set both to true will result in an error. See mongoc_session_opts_set_snapshot().

also, unacknowledged writes are not causally consistent. If you execute a write operation with a mongoc_write_concern_t on which you have called mongoc_write_concern_set_w() with a value of 0, the write does not participate in causal consistency. periodt.

🎀 PARAMETERS 🎀

• opts — A mongoc_session_opt_t.
• causal_consistency — True or false.

🧚 EXAMPLE 🧚

here's the whole example, untouched and slaying:

mongoc_client_t *client;
mongoc_session_opt_t *session_opts;
mongoc_client_session_t *client_session;
mongoc_collection_t *collection;
bson_t insert_opts = BSON_INITIALIZER;
bson_t *doc;
bson_error_t error;
bool r;

client = mongoc_client_new ("mongodb://example/?appname=session-opts-example");
mongoc_client_set_error_api (client, 2);

session_opts = mongoc_session_opts_new ();
mongoc_session_opts_set_causal_consistency (session_opts, false);
client_session = mongoc_client_start_session (client, session_opts, &error);
mongoc_session_opts_destroy (session_opts);

if (!client_session) {
   fprintf (stderr, "Failed to start session: %s\n", error.message);
   abort ();
}

collection = mongoc_client_get_collection (client, "test", "collection");
doc = BCON_NEW ("_id", BCON_INT32 (1));
r = mongoc_client_session_append (client_session, &insert_opts, NULL);
if (!r) {
   fprintf (stderr, "mongoc_client_session_append failed: %s\n", error.message);
   abort ();
}

r = mongoc_collection_insert_one (
   collection, doc, &insert_opts, NULL /* reply */, &error);

if (!r) {
   fprintf (stderr, "Insert failed: %s\n", error.message);
   abort ();
}

👑 AUTHOR 👑

MongoDB, Inc

🌈 COPYRIGHT 🌈

2009-present, MongoDB, Inc.

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okay bye bestie 🫶 — this page is from libmongoc 2.5.6, dated Oct 09, 202, and the footer has MONGOC_SESSION...AL_CONSISTENCY(3) smushed right after it, iconically chaotic 💀.