全文搜索

全文搜索是基于全文索引对值为字符串类型的属性进行前缀搜索、通配符搜索、正则表达式搜索和模糊搜索。

在LOOKUP语句中，使用WHERE子句指定字符串的搜索条件。

前提条件

请确保已经部署全文索引。详情请参见部署全文索引和部署listener。

注意事项

使用全文索引前，请确认已经了解全文索引的使用限制。

自然语言全文搜索

自然语言搜索将搜索的字符串解释为自然人类语言中的短语。搜索不区分大小写，且默认是对字符串的每个子字符串（以空格分隔）单独判断搜索。例如，有三个点属于标签player，标签player含有属性name，这三个点的name分别为Kevin Durant、Tim Duncan和David Beckham。现在已经建立好有关player.name的全文索引，在用全文索引前缀搜索语句LOOKUP ON player WHERE PREFIX(player.name,"d");查询时，这三个点都会被查询到。

语法

创建全文索引

  1. CREATE {TAG | EDGE} INDEX <index_name> ON {<tag_name> | <edge_name>} ([<prop_name_list>]);

显示全文索引

  1. SHOW FULLTEXT INDEXES;

重建全文索引

  1. REBUILD FULLTEXT INDEX;

删除全文索引

  1. DROP FULLTEXT INDEX <index_name>;

使用查询选项

  1. LOOKUP ON {<tag> | <edge_type>} WHERE <expression> [YIELD <return_list>];
  3. <expression> ::=
  4.     PREFIX | WILDCARD | REGEXP | FUZZY
  6. <return_list>
  7.     <prop_name> [AS <prop_alias>] [, <prop_name> [AS <prop_alias>] ...]

  • PREFIX(schema_name.prop_name, prefix_string, row_limit, timeout)

  • WILDCARD(schema_name.prop_name, wildcard_string, row_limit, timeout)

  • REGEXP(schema_name.prop_name, regexp_string, row_limit, timeout)

  • FUZZY(schema_name.prop_name, fuzzy_string, fuzziness, operator, row_limit, timeout)

    • fuzziness：可选项。允许匹配的最大编辑距离。默认值为AUTO。查看其他可选值和更多信息，请参见Elasticsearch官方文档。

    • operator：可选项。解释文本的布尔逻辑。可选值为OR(默认)和and。

  • row_limit：可选项。指定要返回的行数。默认值为100。

  • timeout：可选项。指定超时时间。单位：毫秒（ms）。默认值为200。

示例

  1. //创建图空间。
  2. nebula> CREATE SPACE basketballplayer (partition_num=3,replica_factor=1, vid_type=fixed_string(30));
  4. //登录文本搜索客户端。
  5. nebula> SIGN IN TEXT SERVICE (127.0.0.1:9200);
  7. //切换图空间。
  8. nebula> USE basketballplayer;
  10. //添加listener到Nebula Graph集群。
  11. nebula> ADD LISTENER ELASTICSEARCH 192.168.8.5:9789;
  13. //创建Tag。
  14. nebula> CREATE TAG player(name string, age int);
  16. //创建原生索引。
  17. nebula> CREATE TAG INDEX name ON player(name(20));
  19. //重建原生索引。
  20. nebula> REBUILD TAG INDEX;
  22. //创建全文索引，索引名称需要以nebula开头。
  23. nebula> CREATE FULLTEXT TAG INDEX nebula_index_1 ON player(name);
  25. //重建全文索引。
  26. nebula> REBUILD FULLTEXT INDEX;
  28. //查看全文索引。
  29. nebula> SHOW FULLTEXT INDEXES;
  30. +------------------+-------------+-------------+--------+
  31. | Name             | Schema Type | Schema Name | Fields |
  32. +------------------+-------------+-------------+--------+
  33. | "nebula_index_1" | "Tag"       | "player"    | "name" |
  34. +------------------+-------------+-------------+--------+
  36. //插入测试数据。
  37. nebula> INSERT VERTEX player(name, age) VALUES \
  38.   "Russell Westbrook": ("Russell Westbrook", 30), \
  39.   "Chris Paul": ("Chris Paul", 33),\
  40.   "Boris Diaw": ("Boris Diaw", 36),\
  41.   "David West": ("David West", 38),\
  42.   "Danny Green": ("Danny Green", 31),\
  43.   "Tim Duncan": ("Tim Duncan", 42),\
  44.   "James Harden": ("James Harden", 29),\
  45.   "Tony Parker": ("Tony Parker", 36),\
  46.   "Aron Baynes": ("Aron Baynes", 32),\
  47.   "Ben Simmons": ("Ben Simmons", 22),\
  48.   "Blake Griffin": ("Blake Griffin", 30);
  50. //测试查询
  51. nebula> LOOKUP ON player WHERE PREFIX(player.name, "B");
  52. +-----------------+
  53. | _vid            |
  54. +-----------------+
  55. | "Boris Diaw"    |
  56. +-----------------+
  57. | "Ben Simmons"   |
  58. +-----------------+
  59. | "Blake Griffin" |
  60. +-----------------+
  62. nebula> LOOKUP ON player WHERE WILDCARD(player.name, "*ri*") YIELD player.name, player.age;
  63. +-----------------+-----------------+-----+
  64. | _vid            | name            | age |
  65. +-----------------+-----------------+-----+
  66. | "Chris Paul"    | "Chris Paul"    | 33  |
  67. +-----------------+-----------------+-----+
  68. | "Boris Diaw"    | "Boris Diaw"    | 36  |
  69. +-----------------+-----------------+-----+
  70. | "Blake Griffin" | "Blake Griffin" | 30  |
  71. +-----------------+-----------------+-----+
  73. nebula> LOOKUP ON player WHERE WILDCARD(player.name, "*ri*") | YIELD count(*);
  74. +----------+
  75. | count(*) |
  76. +----------+
  77. | 3        |
  78. +----------+
  80. nebula> LOOKUP ON player WHERE REGEXP(player.name, "R.*") YIELD player.name, player.age;
  81. +---------------------+---------------------+-----+
  82. | _vid                | name                | age |
  83. +---------------------+---------------------+-----+
  84. | "Russell Westbrook" | "Russell Westbrook" | 30  |
  85. +---------------------+---------------------+-----+
  87. nebula> LOOKUP ON player WHERE REGEXP(player.name, ".*");
  88. +---------------------+
  89. | _vid                |
  90. +---------------------+
  91. | "Danny Green"       |
  92. +---------------------+
  93. | "David West"        |
  94. +---------------------+
  95. | "Russell Westbrook" |
  96. +---------------------+
  97. ...
  99. nebula> LOOKUP ON player WHERE FUZZY(player.name, "Tim Dunncan", AUTO, OR) YIELD player.name;
  100. +--------------+--------------+
  101. | _vid         | name         |
  102. +--------------+--------------+
  103. | "Tim Duncan" | "Tim Duncan" |
  104. +--------------+--------------+
  106. //删除全文索引。
  107. nebula> DROP FULLTEXT INDEX nebula_index_1;

最后更新: September 26, 2021