1BSON_OID(3)                         Libbson                        BSON_OID(3)
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NAME

6       bson_oid - ObjectIDs
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8       Libbson  provides a simple way to generate ObjectIDs. It can be used in
9       a single-threaded or multi-threaded manner depending on  your  require‐
10       ments.
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12       The  bson_oid_t  structure  represents  an ObjectID in MongoDB. It is a
13       96-bit identifier that includes various information  about  the  system
14       generating the OID.
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COMPOSITION

17       · 4 bytes : The UNIX timestamp in big-endian format.
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19       · 3 bytes : A hash of the hostname.
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21       · 2 bytes : The pid_t of the current process. Alternatively the task-id
22         if configured.
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24       · 3 bytes : A 24-bit monotonic  counter  incrementing  from  rand()  in
25         big-endian.
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SORTING OBJECTIDS

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

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

38       To generate a bson_oid_t, you may use the following.
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40          bson_oid_t oid;
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42          bson_oid_init (&oid, NULL);
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PARSING OBJECTID STRINGS

45       You  can  also parse a string containing a bson_oid_t. The input string
46       MUST be 24 characters or more in length.
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48          bson_oid_t oid;
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50          bson_oid_init_from_string (&oid, "123456789012345678901234");
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52       If you need to parse may bson_oid_t in a tight loop and  can  guarantee
53       the  data is safe, you might consider using the inline variant. It will
54       be inlined into your code and reduce the need for  a  foreign  function
55       call.
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57          bson_oid_t oid;
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59          bson_oid_init_from_string_unsafe (&oid, "123456789012345678901234");
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HASHING OBJECTIDS

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

71       You  can  easily  fetch  the time that a bson_oid_t was generated using
72       bson_oid_get_time_t().
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74          time_t t;
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76          t = bson_oid_get_time_t (oid);
77          printf ("The OID was generated at %u\n", (unsigned) t);
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AUTHOR

80       MongoDB, Inc
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83       2017-present, MongoDB, Inc
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881.13.1                           Jan 24, 2019                      BSON_OID(3)
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