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。

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。

语法

  1. UPSERT VERTEX ON <tag> <vid>
  2. SET <update_prop>
  3. [WHEN <condition>]
  4. [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Tagplayer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NULL30
否是默认值30
否否NULL30

示例如下：

  1. // 查看三个点是否存在，结果“Empty set”表示顶点不存在。
  2. nebula> FETCH PROP ON * "player666", "player667", "player668";
  3. Empty set
  5. nebula> UPSERT VERTEX ON player "player666" \
  6.         SET age = 30 \
  7.         WHEN name == "Joe" \
  8.         YIELD name AS Name, age AS Age;
  9. +----------+----------+
  10. | Name     | Age      |
  11. +----------+----------+
  12. | __NULL__ | 30       |
  13. +----------+----------+
  15. nebula> UPSERT VERTEX ON player "player666" SET age = 31 WHEN name == "Joe" YIELD name AS Name, age AS Age;
  16. +----------+-----+
  17. | Name     | Age |
  18. +----------+-----+
  19. | __NULL__ | 30  |
  20. +----------+-----+
  22. nebula> UPSERT VERTEX ON player "player667" \
  23.         SET age = 31 \
  24.         YIELD name AS Name, age AS Age;
  25. +----------+-----+
  26. | Name     | Age |
  27. +----------+-----+
  28. | __NULL__ | 31  |
  29. +----------+-----+
  31. nebula> UPSERT VERTEX ON player "player668" \
  32.         SET name = "Amber", age = age + 1 \
  33.         YIELD name AS Name, age AS Age;
  34. +---------+----------+
  35. | Name    | Age      |
  36. +---------+----------+
  37. | "Amber" | __NULL__ |
  38. +---------+----------+

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：

  1. nebula> CREATE TAG player_with_default(name string, age int DEFAULT 20);
  2. Execution succeeded
  4. nebula> UPSERT VERTEX ON player_with_default "player101" \
  5.         SET age = age + 1 \
  6.         YIELD name AS Name, age AS Age;
  8. +----------+-----+
  9. | Name     | Age |
  10. +----------+-----+
  11. | __NULL__ | 21  |
  12. +----------+-----+

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。

  1. nebula> FETCH PROP ON player "player101";
  2. +-----------------------------------------------------+
  3. | vertices_                                           |
  4. +-----------------------------------------------------+
  5. | ("player101" :player{age: 42, name: "Tony Parker"}) |
  6. +-----------------------------------------------------+
  8. nebula> UPSERT VERTEX ON player "player101" \
  9.         SET age = age + 2 \
  10.         WHEN name == "Tony Parker" \
  11.         YIELD name AS Name, age AS Age;
  12. +---------------+-----+
  13. | Name          | Age |
  14. +---------------+-----+
  15. | "Tony Parker" | 44  |
  16. +---------------+-----+

如果点存在，但是不满足WHEN子句的条件，修改不会生效。

  1. nebula> FETCH PROP ON player "player101";
  2. +-----------------------------------------------------+
  3. | vertices_                                           |
  4. +-----------------------------------------------------+
  5. | ("player101" :player{age: 44, name: "Tony Parker"}) |
  6. +-----------------------------------------------------+
  8. nebula> UPSERT VERTEX ON player "player101" \
  9.         SET age = age + 2 \
  10.         WHEN name == "Someone else" \
  11.         YIELD name AS Name, age AS Age;
  12. +---------------+-----+
  13. | Name          | Age |
  14. +---------------+-----+
  15. | "Tony Parker" | 44  |
  16. +---------------+-----+