arangosh> db.test.ensureIndex({ type: "hash", fields: [ "a" ] });
{
"id" : "test/15989",
"type" : "hash",
"fields" : [
"a"
],
"selectivityEstimate" : 1,
"unique" : false,
"sparse" : false,
"isNewlyCreated" : true,
"code" : 201
}
arangosh> db.test.save({ a : 1 });
{
"_id" : "test/15992",
"_key" : "15992",
"_rev" : "15992"
}
arangosh> db.test.save({ a : 1 });
{
"_id" : "test/15996",
"_key" : "15996",
"_rev" : "15996"
}
arangosh> db.test.save({ a : null });
{
"_id" : "test/15999",
"_key" : "15999",
"_rev" : "15999"
}