arangosh> db.test.ensureIndex({ type: "hash", fields: [ "a" ] });
{
"deduplicate" : true,
"fields" : [
"a"
],
"id" : "test/17903",
"isNewlyCreated" : true,
"selectivityEstimate" : 1,
"sparse" : false,
"type" : "hash",
"unique" : false,
"code" : 201
}
arangosh> db.test.save({ a : 1 });
{
"_id" : "test/17906",
"_key" : "17906",
"_rev" : "_WnWX-Dq--_"
}
arangosh> db.test.save({ a : 1 });
{
"_id" : "test/17910",
"_key" : "17910",
"_rev" : "_WnWX-Dq--B"
}
arangosh> db.test.save({ a : null });
{
"_id" : "test/17913",
"_key" : "17913",
"_rev" : "_WnWX-Dq--D"
}