DATETIME类型。 mysql> CREATE TABLE testTable1 (k1 bigint, k2 varchar(100), v decimal SUM) DISTRIBUTED BY RANDOM BUCKETS 8; mysql> CREATE TABLE testTable1 (k1 bigint, k2 varchar(100), v decimal SUM) DISTRIBUTED -+ +-------+----------------+------+-------+---------+-------+ | k1 | bigint(20) | Yes | true | N/A | | | k1 | bigint(20) | Yes | true | N/A | | | k2 | varchar(100) in set (0.01 sec) CREATE TABLE testTable2 (k1 bigint, k2 varchar(100), v decimal(8,5) SUM) DISTRIBUTED BY RANDOM BUCKETS 8; CREATE TABLE testTable2 (k1 bigint, k2 varchar(100), v decimal(8,5) SUM) DISTRIBUTED

所以 MSETNX 将放弃对键 k1 、 k2 、 k3 和 k4 进⾏设置操作： redis> MGET k1 k2 k3 k4 1) (nil) -- 键 k1 、 k2 和 k3 都不存在 2) (nil) 3) (nil) 4) "hello world" -- 键 k4 已存在 redis> MSETNX k1 "one" k2 "two" k3 未能执⾏设置操作 redis> MGET k1 k2 k3 k4 -- 各个键的值没有变化 1) (nil) 2) (nil) 3) (nil) 4) "hello world" 但是如果我们只对不存在的键 k1 、 k2 和 k3 进⾏设置， 那么 MSETNX 可以正常地完成设置操作： redis> MSETNX k1 "one" k2 "two" k3 "three" "three" (integer) 1 -- 所有给定键都不存在，成功执⾏设置操作 redis> MGET k1 k2 k3 k4 1) "one" -- 刚刚使⽤ MSETNX 设置的三个值 2) "two" 3) "three" 4) "hello world" -- 之前已经存在的键 k4 的值没有改变 2.8.1 其他信息 属性 值 复杂度 O(N)，其中

Placement Driver Transaction � kv ����� k1 � k2 �� k1 ����� 10 � k2 ����� 20 � � k1 � k2 ���� 1 � Transaction � kv ����� �� step 4 �� k1 � k3 � 10 �������� step 3 � k2 ��������

collection 分步查询使用延迟加载 4.7.8 扩展: 分步查询多列值的传递 1) 如果分步查询时，需要传递给调用的查询中多个参数，则需要将多个参数封装成 Map 来进行传递，语法如下: {k1=v1, k2=v2....} 2) 在所调用的查询方，取值时就要参考 Map 的取值方式，需要严格的按照封装 map 时所用的 key 来取值. 4.7.9 扩展: association 或

latest MVCC versions for each of the two rows. • When TiKV processes a scan request with a range of [k1, k2] and a start timestamp of 8: • Without the in-memory engine (left), it needs to process 11 MVCC reducing request latency and CPU consumption. • When TiKV processes a scan request with a range of [k1, k2] and a start timestamp of 7: • Because the required historical versions are missing in the in-memory j2 JSON, a INT, INDEX k1((CAST(j1->'$.path' AS �→ SIGNED ARRAY))), INDEX k2((CAST(j2->'$.path' AS SIGNED ARRAY))), 2069 �→ INDEX ka(a)); EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3

行记录最新的 2 个 MVCC 版本。 • 当 TiKV 处理一个范围为 [k1, k2]，开始时间戳为 8 的扫描请求时： – 左侧未开启内存引擎时需要处理 11 个 MVCC 版本。 – 右侧开启内存引擎时只需处理 4 个 MVCC 版本，因此减少了请求延时和 CPU 消耗。 • 当 TiKV 处理一个范围为 [k1, k2]，开始时间戳为 7 的扫描请求时： – 由于右侧缺少需要读取的 JSON, j2 JSON, a INT, INDEX k1((CAST(j1->'$.path' AS SIGNED ARRAY))), INDEX k2 �→ ((CAST(j2->'$.path' AS SIGNED ARRAY))), INDEX ka(a)); EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE 1 member of (j1->'$.path') �→ AND 2 member of (j2->'$.path') AND (a = 3); > EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE

j2 JSON, a INT, INDEX k1((CAST(j1->'$.path' AS �→ SIGNED ARRAY))), INDEX k2((CAST(j2->'$.path' AS SIGNED ARRAY))), 1596 �→ INDEX ka(a)); EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE 1 �→ member of (j1->'$.path') AND 2 member of (j2->'$.path') AND (a = 3); > EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE root | �→ | �→ type: union | | ￿─ IndexRangeScan_5(Build) | 10.00 | cop[tikv] | table:t3, index:k1(cast( �→ json_extract(`j1`, _utf8'$.path') as signed array)) | range:[1,1], �→ keep order:false, stats:pseudo

j2 JSON, a INT, INDEX k1((CAST(j1->'$.path' AS �→ SIGNED ARRAY))), INDEX k2((CAST(j2->'$.path' AS SIGNED ARRAY))), 1623 �→ INDEX ka(a)); EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE 1 �→ member of (j1->'$.path') AND 2 member of (j2->'$.path') AND (a = 3); > EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE root | �→ | �→ type: union | | ￿─ IndexRangeScan_5(Build) | 10.00 | cop[tikv] | table:t3, index:k1(cast( �→ json_extract(`j1`, _utf8'$.path') as signed array)) | range:[1,1], �→ keep order:false, stats:pseudo

j2 JSON, a INT, INDEX k1((CAST(j1->'$.path' AS �→ SIGNED ARRAY))), INDEX k2((CAST(j2->'$.path' AS SIGNED ARRAY))), 1645 �→ INDEX ka(a)); EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE 1 �→ member of (j1->'$.path') AND 2 member of (j2->'$.path') AND (a = 3); > EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE root | �→ | �→ type: union | | ￿─ IndexRangeScan_5(Build) | 10.00 | cop[tikv] | table:t3, index:k1(cast( �→ json_extract(`j1`, _utf8'$.path') as signed array)) | range:[1,1], �→ keep order:false, stats:pseudo

j2 JSON, a INT, INDEX k1((CAST(j1->'$.path' AS �→ SIGNED ARRAY))), INDEX k2((CAST(j2->'$.path' AS SIGNED ARRAY))), 1653 �→ INDEX ka(a)); EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE 1 �→ member of (j1->'$.path') AND 2 member of (j2->'$.path') AND (a = 3); > EXPLAIN SELECT /*+ use_index_merge(t3, k1, k2, ka) */ * FROM t3 WHERE root | �→ | �→ type: union | | ￿─ IndexRangeScan_5(Build) | 10.00 | cop[tikv] | table:t3, index:k1(cast( �→ json_extract(`j1`, _utf8'$.path') as signed array)) | range:[1,1], �→ keep order:false, stats:pseudo