问答平台（7），Redis高级数据类型

HyperLogLog

- 采用一种基数算法，用于完成独立总数的统计。
- 占据空间小，无论统计多少个数据，只占12K的内存空间。
- 不精确的统计算法，标准误差为0.81%。

应用

统计网站的PV、UV

测试类

• RedisTests: 增加内容

  // 统计20万个重复数据的独立总数
  @Test
  public void testHyperLogLog() {
      String redisKey = "test:hll:01";
  
      for (int i = 1; i <= 100000; i++) {
          redisTemplate.opsForHyperLogLog().add(redisKey, i);
      }
  
      for (int i = 1; i <= 100000; i++) {
          int random = (int) (Math.random() * 100000 + 1);
          redisTemplate.opsForHyperLogLog().add(redisKey, random);
      }
  
      Long size = redisTemplate.opsForHyperLogLog().size(redisKey);
      System.out.println(size);
  }
  
  // 将3组数据合并，再统计合并后的重复数据的独立总数
  @Test
  public void testHyperLogLogUnion() {
      String redisKey2 = "test:hll:02";
      for (int i = 1; i <= 10000; i++) {
          redisTemplate.opsForHyperLogLog().add(redisKey2, i);
      }
  
      String redisKey3 = "test:hll:03";
      for (int i = 5001; i <= 15000; i++) {
          redisTemplate.opsForHyperLogLog().add(redisKey3, i);
      }
  
      String redisKey4 = "test:hll:04";
      for (int i = 10001; i <= 20000; i++) {
          redisTemplate.opsForHyperLogLog().add(redisKey4, i);
      }
  
      String unionKey = "test:hll:union";
      redisTemplate.opsForHyperLogLog().union(unionKey, redisKey2, redisKey3, redisKey4);
  
      long size = redisTemplate.opsForHyperLogLog().size(unionKey);
      System.out.println(size);
  }

结果展示

---

Bitmap

- 不是一种独立的数据结构，实际上就是字符串。
- 支持按位存取数据，可以将其看成是byte数组。
- 适合存储大量的连续的数据的布尔值。

应用

统计用户的签到

测试类

• RedisTests: 增加内容

  public void testBitMap() {
      String redisKey = "test:bm:01";
  
      // 记录
      redisTemplate.opsForValue().setBit(redisKey, 1, true);
      redisTemplate.opsForValue().setBit(redisKey, 4, true);
      redisTemplate.opsForValue().setBit(redisKey, 7, true);
  
      // 查询
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 0));
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 1));
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 2));
  
      // 统计
      Object obj = redisTemplate.execute(new RedisCallback() {
          @Override
          public Object doInRedis(RedisConnection redisConnection) throws DataAccessException {
              return redisConnection.bitCount(redisKey.getBytes());
          }
      });
  
      System.out.println(obj);
  } 
  
  // 统计3组数据的布尔值，并对这3组数据做OR运算
  @Test
  public void testBitMapOperation() {
      String redisKey2 = "test:bm:02";
      redisTemplate.opsForValue().setBit(redisKey2, 0, true);
      redisTemplate.opsForValue().setBit(redisKey2, 1, true);
      redisTemplate.opsForValue().setBit(redisKey2, 2, true);
  
      String redisKey3 = "test:bm:03";
      redisTemplate.opsForValue().setBit(redisKey3, 2, true);
      redisTemplate.opsForValue().setBit(redisKey3, 3, true);
      redisTemplate.opsForValue().setBit(redisKey3, 4, true);
  
      String redisKey4 = "test:bm:04";
      redisTemplate.opsForValue().setBit(redisKey4, 4, true);
      redisTemplate.opsForValue().setBit(redisKey4, 5, true);
      redisTemplate.opsForValue().setBit(redisKey4, 6, true);
  
      String redisKey = "test:bm:or";
      Object obj = redisTemplate.execute(new RedisCallback() {
          @Override
          public Object doInRedis(RedisConnection redisConnection) throws DataAccessException {
              redisConnection.bitOp(RedisStringCommands.BitOperation.OR,
                      redisKey.getBytes(), redisKey2.getBytes(), redisKey3.getBytes(), redisKey4.getBytes());
              return redisConnection.bitCount(redisKey.getBytes());
          }
      });
  
      System.out.println(obj);
  
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 0));
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 1));
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 2));
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 3));
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 4));
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 5));
      System.out.println(redisTemplate.opsForValue().getBit(redisKey, 6));
  }

结果展示

---

参考资料

• https://blog.csdn.net/shang_0122/article/details/106340489