arangosh> db.test.ensureIndex({ type: "hash", fields: [ "a" ] });
{
"id" : "test/15878",
"type" : "hash",
"fields" : [
"a"
],
"selectivityEstimate" : 1,
"unique" : false,
"sparse" : false,
"isNewlyCreated" : true,
"code" : 201
}
arangosh> db.test.save({ a : 1 });
{
"_id" : "test/15881",
"_key" : "15881",
"_rev" : "15881"
}
arangosh> db.test.save({ a : 1 });
{
"_id" : "test/15885",
"_key" : "15885",
"_rev" : "15885"
}
arangosh> db.test.save({ a : null });
{
"_id" : "test/15888",
"_key" : "15888",
"_rev" : "15888"
}