I use this following code to extract all of the Keys start with "NAME:" and it return only over 5,000 records (There is over 60,000 keys in my index). Can anyone explain why it is happening or how can I extract all of the keys from Redis Database.
jedis.select(3);
Set<String> names=jedis.keys("NAME:*");
Iterator<String> it = names.iterator();
while (it.hasNext()) {
String s = it.next();
System.out.println(s);
}
Answer
When Redis server store many record, using jedis.keys() command can make it over-processing. Thus, result in it stop when the task is un-done.
Instead of it, you use jedis.hscan() so as to avoid above problem.
ScanParams scanParam = new ScanParams();
String cursor = "0";
int i = 0;
scanParam.match(prefix + "*");
scanParam.count(50000); // 2000 or 30000 depend on your
do {
ScanResult<Map.Entry<String, String>> hscan = jedis.hscan(key, cursor, scanParam);
// any code here
//
//
// check cursor
cursor = hscan.getStringCursor();
} while("0".equals(cursor));
It work well in your case.