arangosh> db.test.ensureHashIndex("a");
{
"id" : "test/1112922567",
"type" : "hash",
"fields" : [
"a"
],
"selectivityEstimate" : 1,
"unique" : false,
"sparse" : false,
"isNewlyCreated" : true,
"code" : 201
}
arangosh> db.test.save({ a : 1 });
{
"_id" : "test/1113184711",
"_rev" : "1113184711",
"_key" : "1113184711"
}
arangosh> db.test.save({ a : 1 });
{
"_id" : "test/1113381319",
"_rev" : "1113381319",
"_key" : "1113381319"
}
arangosh> db.test.save({ a : null });
{
"_id" : "test/1113643463",
"_rev" : "1113643463",
"_key" : "1113643463"
}