Scan vs query with specified rps, filterExp and includeBinData = false

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1

Hi there!

We are using Aerospike 5.2.0.12 and have a task to return all user keys(the expected number is about 2 million) by filter (cityName = London) and then process them using Java code. I can see two ways to do it:

  1. via scan
ScanPolicy scanPolicy = new ScanPolicy(aerospikeClient.getQueryPolicyDefault());
scanPolicy.filterExp = Exp.build(Exp.eq(Exp.stringBin("cityName"), Exp.val("London")));
scanPolicy.includeBinData = false;
scanPolicy.recordsPerSecond = 50000;

aerospikeClient.scanAll(scanPolicy, aerospikeTemplate.getNamespace(), "users-set", (key, record) -> executeSomeLogic(key.userKey));
  1. via query
QueryPolicy queryPolicy = new QueryPolicy(aerospikeClient.getQueryPolicyDefault());
queryPolicy.filterExp = Exp.build(Exp.eq(Exp.stringBin("cityName"), Exp.val("London")));
queryPolicy.includeBinData = false;

Statement statement = new Statement();
statement.setNamespace(aerospikeTemplate.getNamespace());
statement.setSetName("users-set");
statement.setRecordsPerSecond(50000);

RecordSet result = aerospikeClient.query(queryPolicy, statement);

result.forEach(keyRecord -> executeSomeLogic(keyRecord.key.userKey));

Do these two approaches have the same effectiveness and efficiency? Will the entire namespace be scanned in both cases? Is there any difference between them?

2

They should be the same, unless there’s some subtle code difference I’m not seeing or you have a SI. A query without a secondary-index (SI) created just creates a scan. It’s a little misleading isn’t it? For your second question, all records will be reviewed/scanned in that namespace unless you have a set index Set indexes | Aerospike Documentation . A set index would probably only be worth it to have if you need to scan a very small set in a large namespace (Say the set you want is 1K records but the entire namespace holds 1G).

3

Many thanks for your reply! Yes, as you you correctly noticed there is no SI in the query.