[erlang-questions] what are ets bags sets and duplicate_bags?

Joe Armstrong <>
Tue Feb 13 21:00:52 CET 2007


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>From the ets manual page:

  * set The table is a set table - one key, one object, no order among
objects. This is the default  table type.

* ordered_set  The  table  is a ordered_set table - one key, one
object, ordered in Erlang term order,  which is the order implied by
the < and > operators. Tables of this type have a  somewhat  different
 behavior in some situations than tables of the other types.

* bag  The table is a bag table which can have many objects, but only
one instance of each object,   per key.

 * duplicate_bag The table is a duplicate_bag table which can have
many  objects,  including  multiple copies of the same object, per
key.

    Is this trying to say that:

     {a,1} {b,2} {c,3}   is a set
     {a,1} {a,2} {b,2}  is a bag
     {a,1} {a,1}{a,2} {b,3} is a duplicate_bag

  ?????

/Joe


/Joe



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