UPSERT EDGE

UPSERT EDGE语句结合UPDATE和INSERT，如果边存在，会更新边的属性；如果边不存在，会插入新的边。

UPSERT EDGE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。

Danger

禁止在高并发写操作的情况下使用UPSERT语句，请使用UPDATE或INSERT代替。

语法

  1. UPSERT EDGE ON <edge_type>
  2. <src_vid> -> <dst_vid> [@rank]
  3. SET <update_prop>
  4. [WHEN <condition>]
  5. [YIELD <properties>]
参数是否必须说明示例
ON <edge_type>是指定Edge type。要修改的属性必须在这个Edge type内。ON serve
<src_vid>是指定边的起始点ID。“player100”
<dst_vid>是指定边的目的点ID。“team204”
<rank>否指定边的rank值。10
SET <update_prop>是指定如何修改属性值。SET start_year = start_year +1
WHEN <condition>否指定过滤条件。WHEN end_year < 2010
YIELD <output>否指定语句的输出格式。YIELD start_year AS Start_Year

插入不存在的边

如果边不存在，无论WHEN子句的条件是否满足，都会插入边，同时执行SET子句，因此新插入的边的属性值取决于：

  • SET子句。

  • 属性是否有默认值。

例如：

  • 要插入的边包含基于Edge typeserve的属性start_year和end_year。

  • SET子句指定end_year = 2021。

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start_year属性值end_year属性值
是是默认值2021
是否NULL2021
否是默认值2021
否否NULL2021

示例如下：

  1. // 查看如下三个点是否有serve类型的出边，结果“Empty set”表示没有serve类型的出边。
  2. nebula> GO FROM "player666", "player667", "player668" \
  3.         OVER serve \
  4.         YIELD serve.start_year, serve.end_year;
  5. Empty set
  7. nebula> UPSERT EDGE on serve \
  8.         "player666" -> "team200"@0 \
  9.         SET end_year = 2021 \
  10.         WHEN end_year == 2010 \
  11.         YIELD start_year, end_year;
  12. +------------+----------+
  13. | start_year | end_year |
  14. +------------+----------+
  15. | __NULL__   | 2021     |
  16. +------------+----------+
  18. nebula> UPSERT EDGE on serve \
  19.         "player666" -> "team200"@0 \
  20.         SET end_year = 2022 \
  21.         WHEN end_year == 2010 \
  22.         YIELD start_year, end_year;
  23. +------------+----------+
  24. | start_year | end_year |
  25. +------------+----------+
  26. | __NULL__   | 2021     |
  27. +------------+----------+
  29. nebula> UPSERT EDGE on serve \
  30.         "player667" -> "team200"@0 \
  31.         SET end_year = 2022 \
  32.         YIELD start_year, end_year;
  33. +------------+----------+
  34. | start_year | end_year |
  35. +------------+----------+
  36. | __NULL__   | 2022     |
  37. +------------+----------+
  39. nebula> UPSERT EDGE on serve \
  40.         "player668" -> "team200"@0 \
  41.         SET start_year = 2000, end_year = end_year + 1 \
  42.         YIELD start_year, end_year;
  43. +------------+----------+
  44. | start_year | end_year |
  45. +------------+----------+
  46. | 2000       | __NULL__ |
  47. +------------+----------+

上面最后一个示例中，因为end_year没有默认值，插入边时，end_year默认值为NULL，执行end_year = end_year + 1后仍为NULL。如果end_year有默认值，则end_year = end_year + 1可以正常执行，例如：

  1. nebula> CREATE EDGE serve_with_default(start_year int, end_year int DEFAULT 2010);
  2. Execution succeeded
  4. nebula> UPSERT EDGE on serve_with_default \
  5.         "player668" -> "team200" \
  6.         SET end_year = end_year + 1 \
  7.         YIELD start_year, end_year;
  8. +------------+----------+
  9. | start_year | end_year |
  10. +------------+----------+
  11. | __NULL__   | 2011     |
  12. +------------+----------+

修改存在的边

如果边存在，且满足WHEN子句的条件，就会修改边的属性值。

  1. nebula> MATCH (v:player{name:"Ben Simmons"})-[e:serve]-(v2) \
  2.         RETURN e;
  3. +-----------------------------------------------------------------------+
  4. | e                                                                     |
  5. +-----------------------------------------------------------------------+
  6. | [:serve "player149"->"team219" @0 {end_year: 2019, start_year: 2016}] |
  7. +-----------------------------------------------------------------------+
  9. nebula> UPSERT EDGE on serve \
  10.         "player149" -> "team219" \
  11.         SET end_year = end_year + 1 \
  12.         WHEN start_year == 2016 \
  13.         YIELD start_year, end_year;
  14. +------------+----------+
  15. | start_year | end_year |
  16. +------------+----------+
  17. | 2016       | 2020     |
  18. +------------+----------+

如果边存在，但是不满足WHEN子句的条件，修改不会生效。

  1. nebula> MATCH (v:player{name:"Ben Simmons"})-[e:serve]-(v2) \
  2.         RETURN e;
  3. +-----------------------------------------------------------------------+
  4. | e                                                                     |
  5. +-----------------------------------------------------------------------+
  6. | [:serve "player149"->"team219" @0 {end_year: 2020, start_year: 2016}] |
  7. +-----------------------------------------------------------------------+
  10. nebula> UPSERT EDGE on serve \
  11.         "player149" -> "team219" \
  12.         SET end_year = end_year + 1 \
  13.         WHEN start_year != 2016 \
  14.         YIELD start_year, end_year;
  15. +------------+----------+
  16. | start_year | end_year |
  17. +------------+----------+
  18. | 2016       | 2020     |
  19. +------------+----------+

最后更新: August 19, 2021