EXPLODE_BITMAP
描述
explode_bitmap 表函数，接受一个位图（bitmap）类型的数据，将位图中的每个 bit（位）映射为单独的行。通常用于处理位图数据，将位图中的每个元素展开成单独的记录。需配合 Lateral View 使用。
explode_bitmap_outer 与 explode_bitmap 类似，但在处理空值或 NULL 时，行为有所不同。它允许空位图或 NULL 位图的记录存在，并在返回结果中将空位图或者 NULL 位图展开为 NULL 行。
语法
EXPLODE_BITMAP(<bitmap>)
EXPLODE_BITMAP_OUTER(<bitmap>)
参数
| 参数 | 说明 |
|---|---|
<bitmap> | bitmap 类型 |
返回值
返回位图中每一位对应的行，其中每一行包含一个位值。
举例
CREATE TABLE example1 (
k1 INT
)DUPLICATE KEY(k1)
DISTRIBUTED BY HASH(k1) BUCKETS AUTO
PROPERTIES (
"replication_allocation" = "tag.location.default: 1");
insert into example1 values(1),(2),(3),(4),(5),(6);
select k1 from example1 order by k1;
+------+
| k1 |
+------+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
+------+
select k1, e1 from example1 lateral view explode_bitmap(bitmap_empty()) tmp1 as e1 order by k1, e1;
Empty set
select k1, e1 from example1 lateral view explode_bitmap(bitmap_from_string("1")) tmp1 as e1 order by k1, e1;
+------+------+
| k1 | e1 |
+------+------+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
+------+------+
select k1, e1 from example1 lateral view explode_bitmap(bitmap_from_string("1,2")) tmp1 as e1 order by k1, e1;
+------+------+
| k1 | e1 |
+------+------+
| 1 | 1 |
| 1 | 2 |
| 2 | 1 |
| 2 | 2 |
| 3 | 1 |
| 3 | 2 |
| 4 | 1 |
| 4 | 2 |
| 5 | 1 |
| 5 | 2 |
| 6 | 1 |
| 6 | 2 |
+------+------+
select k1, e1 from example1 lateral view explode_bitmap(bitmap_from_string("1,1000")) tmp1 as e1 order by k1, e1;
+------+------+
| k1 | e1 |
+------+------+
| 1 | 1 |
| 1 | 1000 |
| 2 | 1 |
| 2 | 1000 |
| 3 | 1 |
| 3 | 1000 |
| 4 | 1 |
| 4 | 1000 |
| 5 | 1 |
| 5 | 1000 |
| 6 | 1 |
| 6 | 1000 |
+------+------+
select k1, e1, e2 from example1
lateral view explode_bitmap(bitmap_from_string("1,1000")) tmp1 as e1
lateral view explode_split("a,b", ",") tmp2 as e2 order by k1, e1, e2;
+------+------+------+
| k1 | e1 | e2 |
+------+------+------+
| 1 | 1 | a |
| 1 | 1 | b |
| 1 | 1000 | a |
| 1 | 1000 | b |
| 2 | 1 | a |
| 2 | 1 | b |
| 2 | 1000 | a |
| 2 | 1000 | b |
| 3 | 1 | a |
| 3 | 1 | b |
| 3 | 1000 | a |
| 3 | 1000 | b |
| 4 | 1 | a |
| 4 | 1 | b |
| 4 | 1000 | a |
| 4 | 1000 | b |
| 5 | 1 | a |
| 5 | 1 | b |
| 5 | 1000 | a |
| 5 | 1000 | b |
| 6 | 1 | a |
| 6 | 1 | b |
| 6 | 1000 | a |
| 6 | 1000 | b |
+------+------+------+
CREATE TABLE example (
k1 INT,
v1 bitmap
)DUPLICATE KEY(k1)
DISTRIBUTED BY HASH(k1) BUCKETS AUTO
PROPERTIES (
"replication_allocation" = "tag.location.default: 1");
insert into example values(1,to_bitmap('10101')),(2,to_bitmap('0')),(3,to_bitmap(NULL));
SELECT id, k, v
FROM example
LATERAL VIEW explode_json_object(value_json) exploded_table AS k , v;
+------+-------+
| k1 | bit |
+------+-------+
| 2 | 0 |
| 1 | 10101 |
+------+-------+
SELECT id, k, v
FROM example
LATERAL VIEW explode_json_object_outer(value_json) exploded_table AS k, v;
+------+-------+
| k1 | bit |
+------+-------+
| 2 | 0 |
| 1 | 10101 |
| 3 | NULL |
+------+-------+
