spring-data-redis hscan操作解密 |

9月 4, 2023 | Nix.Huang

	String pattern = "test:1023*";
	List<Object> listOfObjects = new ArrayList<>();
	Cursor<Map.Entry<Object, Object>> cursorMap = redisTemplate.boundHashOps("test_hash")
			.scan(ScanOptions.scanOptions().match(pattern).count(100).build());

	while (cursorMap.hasNext()) {
		listOfObjects.add(cursorMap.next().getKey());
	}
	cursorMap.close();

String pattern = "test:1023*";

List<Object> listOfObjects = new ArrayList<>();

Cursor<Map.Entry<Object, Object>> cursorMap = redisTemplate.boundHashOps("test_hash")

.scan(ScanOptions.scanOptions().match(pattern).count(100).build());

while (cursorMap.hasNext()) {

listOfObjects.add(cursorMap.next().getKey());

}

cursorMap.close();

第一次hscan 传入cursor=0，返回新的cursor和结果集列表，第二次传入返回的cursor值，直到hscan返回cursor=0
100万数据集居然耗时5s, spring-data-redis 返回的cursor迭代时，先迭代hscan返回的数据，如果迭代完成会再次发起hscan,直到hscan返回的cursor=0为止。当前场景很容易错误以为只查询一次数据库,如果匹配的结果集很稀疏，那么将count设置大些能减少应用和数据库之间的往返时间。

reference:
Hscan in Redis with 1,000,000 records is taking longer than usual

Posted in: redis

知行合一，止于至善

spring-data-redis hscan操作解密

站内搜索