1BSON_OID(3)                         libbson                        BSON_OID(3)
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5Libbson  provides a simple way to generate ObjectIDs. It can be used in a sin‐
6gle-threaded or multi-threaded manner depending on your requirements.
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8The bson_oid_t structure represents an ObjectID in MongoDB.  It  is  a  96-bit
9identifier.
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COMPOSITION

12       • 4 bytes : The UNIX timestamp in big-endian format.
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14       • 5 bytes : A random number.
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16       • 3  bytes  :  A  24-bit  monotonic counter incrementing from rand() in
17         big-endian.
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SORTING OBJECTIDS

20       The typical way to sort in C is using qsort(). Therefore, Libbson  pro‐
21       vides  a qsort() compatible callback function named bson_oid_compare().
22       It returns less than 1, greater than 1, or 0 depending on the  equality
23       of two bson_oid_t structures.
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COMPARING OBJECT IDS

26       If  you  simply want to compare two bson_oid_t structures for equality,
27       use bson_oid_equal().
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GENERATING

30       To generate a bson_oid_t, you may use the following.
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32          bson_oid_t oid;
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34          bson_oid_init (&oid, NULL);
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PARSING OBJECTID STRINGS

37       You can also parse a string containing a bson_oid_t. The  input  string
38       MUST be 24 characters or more in length.
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40          bson_oid_t oid;
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42          bson_oid_init_from_string (&oid, "123456789012345678901234");
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44          bson_oid_t oid;
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46          bson_oid_init_from_string_unsafe (&oid, "123456789012345678901234");
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HASHING OBJECTIDS

49       If  you  need  to  store  items in a hashtable, you may want to use the
50       bson_oid_t as the key. Libbson provides a hash function for  just  this
51       purpose. It is based on DJB hash.
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53          unsigned hash;
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55          hash = bson_oid_hash (oid);
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FETCHING OBJECTID CREATION TIME

58       You  can  easily  fetch  the time that a bson_oid_t was generated using
59       bson_oid_get_time_t().
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61          time_t t;
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63          t = bson_oid_get_time_t (oid);
64          printf ("The OID was generated at %u\n", (unsigned) t);
65

AUTHOR

67       MongoDB, Inc
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70       2017-present, MongoDB, Inc
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751.25.1                           Nov 08, 2023                      BSON_OID(3)
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