UPSERT VERTEX¶
UPSERT VERTEX
语句结合UPDATE
和INSERT
,如果点存在,会修改点的属性值;如果点不存在,会插入新的点。
Note
UPSERT VERTEX
一次只能修改一个 Tag。
UPSERT VERTEX
性能远低于INSERT
,因为UPSERT
是一组分片级别的读取、修改、写入操作。
Caution
并发UPSERT
同一个 TAG 或 EDGE TYPE 会报错。
语法¶
UPSERT VERTEX ON <tag> <vid>
SET <update_prop>
[WHEN <condition>]
[YIELD <output>]
参数 | 是否必须 | 说明 | 示例 |
---|---|---|---|
ON <tag> |
是 | 指定点的 Tag。要修改的属性必须在这个 Tag 内。 | ON player |
<vid> |
是 | 指定要修改或插入的点 ID。 | "player100" |
SET <update_prop> |
是 | 指定如何修改属性值。 | SET age = age +1 |
WHEN <condition> |
否 | 指定过滤条件。 | WHEN name == "Tim" |
YIELD <output> |
否 | 指定语句的输出格式。 | YIELD name AS Name |
插入不存在的点¶
如果点不存在,无论WHEN
子句的条件是否满足,都会插入点,同时执行SET
子句,因此新插入的点的属性值取决于:
SET
子句。
- 属性是否有默认值。
例如:
- 要插入的点包含基于 Tag
player
的属性name
和age
。
SET
子句指定age=30
。
不同情况下的属性值如下表。
是否满足WHEN 子句条件 |
属性是否有默认值 | name 属性值 |
age 属性值 |
---|---|---|---|
是 | 是 | 默认值 | 30 |
是 | 否 | NULL |
30 |
否 | 是 | 默认值 | 30 |
否 | 否 | NULL |
30 |
示例如下:
// 查看三个点是否存在,结果 “Empty set” 表示顶点不存在。
nebula> FETCH PROP ON * "player666", "player667", "player668" YIELD properties(vertex);
+--------------------+
| properties(VERTEX) |
+--------------------+
+--------------------+
Empty set
nebula> UPSERT VERTEX ON player "player666" \
SET age = 30 \
WHEN name == "Joe" \
YIELD name AS Name, age AS Age;
+----------+----------+
| Name | Age |
+----------+----------+
| __NULL__ | 30 |
+----------+----------+
nebula> UPSERT VERTEX ON player "player666" \
SET age = 31 \
WHEN name == "Joe" \
YIELD name AS Name, age AS Age;
+----------+-----+
| Name | Age |
+----------+-----+
| __NULL__ | 30 |
+----------+-----+
nebula> UPSERT VERTEX ON player "player667" \
SET age = 31 \
YIELD name AS Name, age AS Age;
+----------+-----+
| Name | Age |
+----------+-----+
| __NULL__ | 31 |
+----------+-----+
nebula> UPSERT VERTEX ON player "player668" \
SET name = "Amber", age = age + 1 \
YIELD name AS Name, age AS Age;
+---------+----------+
| Name | Age |
+---------+----------+
| "Amber" | __NULL__ |
+---------+----------+
上面最后一个示例中,因为age
没有默认值,插入点时,age
默认值为NULL
,执行age = age + 1
后仍为NULL
。如果age
有默认值,则age = age + 1
可以正常执行,例如:
nebula> CREATE TAG IF NOT EXISTS player_with_default(name string, age int DEFAULT 20);
Execution succeeded
nebula> UPSERT VERTEX ON player_with_default "player101" \
SET age = age + 1 \
YIELD name AS Name, age AS Age;
+----------+-----+
| Name | Age |
+----------+-----+
| __NULL__ | 21 |
+----------+-----+
修改存在的点¶
如果点存在,且满足WHEN
子句的条件,就会修改点的属性值。
nebula> FETCH PROP ON player "player101" YIELD properties(vertex);
+--------------------------------+
| properties(VERTEX) |
+--------------------------------+
| {age: 36, name: "Tony Parker"} |
+--------------------------------+
nebula> UPSERT VERTEX ON player "player101" \
SET age = age + 2 \
WHEN name == "Tony Parker" \
YIELD name AS Name, age AS Age;
+---------------+-----+
| Name | Age |
+---------------+-----+
| "Tony Parker" | 38 |
+---------------+-----+
如果点存在,但是不满足WHEN
子句的条件,修改不会生效。
nebula> FETCH PROP ON player "player101" YIELD properties(vertex);
+--------------------------------+
| properties(VERTEX) |
+--------------------------------+
| {age: 38, name: "Tony Parker"} |
+--------------------------------+
nebula> UPSERT VERTEX ON player "player101" \
SET age = age + 2 \
WHEN name == "Someone else" \
YIELD name AS Name, age AS Age;
+---------------+-----+
| Name | Age |
+---------------+-----+
| "Tony Parker" | 38 |
+---------------+-----+
最后更新:
September 4, 2023