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¶
ngql
CREATE FULLTEXT {TAG | EDGE} INDEX <index_name> ON {<tag_name> | <edge_name>} ([<prop_name_list>]);
显示全文索引¶
ngql
SHOW FULLTEXT INDEXES;
重建全文索引¶
ngql
REBUILD FULLTEXT INDEX;
删除全文索引¶
ngql
DROP FULLTEXT INDEX <index_name>;
使用查询选项¶
```ngql
LOOKUP ON {
- 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¶
```ngql //创建图空间。 nebula> CREATE SPACE IF NOT EXISTS basketballplayer (partition_num=3,replica_factor=1, vid_type=fixed_string(30));
//登录文本搜索客户端。 nebula> SIGN IN TEXT SERVICE (127.0.0.1:9200, HTTP);
//切换图空间。 nebula> USE basketballplayer;
//添加 listener 到 Nebula Graph 集群。 nebula> ADD LISTENER ELASTICSEARCH 192.168.8.5:9789;
//创建 Tag。 nebula> CREATE TAG IF NOT EXISTS player(name string, age int);
//创建原生索引。 nebula> CREATE TAG INDEX IF NOT EXISTS name ON player(name(20));
//重建原生索引。 nebula> REBUILD TAG INDEX;
//创建全文索引,索引名称需要以 nebula 开头。 nebula> CREATE FULLTEXT TAG INDEX nebula_index_1 ON player(name);
//重建全文索引。 nebula> REBUILD FULLTEXT INDEX;
//查看全文索引。 nebula> SHOW FULLTEXT INDEXES; +------------------+-------------+-------------+--------+ | Name | Schema Type | Schema Name | Fields | +------------------+-------------+-------------+--------+ | "nebula_index_1" | "Tag" | "player" | "name" | +------------------+-------------+-------------+--------+
//插入测试数据。 nebula> INSERT VERTEX player(name, age) VALUES \ "Russell Westbrook": ("Russell Westbrook", 30), \ "Chris Paul": ("Chris Paul", 33),\ "Boris Diaw": ("Boris Diaw", 36),\ "David West": ("David West", 38),\ "Danny Green": ("Danny Green", 31),\ "Tim Duncan": ("Tim Duncan", 42),\ "James Harden": ("James Harden", 29),\ "Tony Parker": ("Tony Parker", 36),\ "Aron Baynes": ("Aron Baynes", 32),\ "Ben Simmons": ("Ben Simmons", 22),\ "Blake Griffin": ("Blake Griffin", 30);
//测试查询 nebula> LOOKUP ON player WHERE PREFIX(player.name, "B") YIELD id(vertex); +-----------------+ | id(VERTEX) | +-----------------+ | "Boris Diaw" | | "Ben Simmons" | | "Blake Griffin" | +-----------------+
nebula> LOOKUP ON player WHERE WILDCARD(player.name, "ri") YIELD player.name, player.age; +-----------------+-----+ | name | age | +-----------------+-----+ | "Chris Paul" | 33 | | "Boris Diaw" | 36 | | "Blake Griffin" | 30 | +-----------------+-----+
nebula> LOOKUP ON player WHERE WILDCARD(player.name, "ri") | YIELD count(); +----------+ | count() | +----------+ | 3 | +----------+
nebula> LOOKUP ON player WHERE REGEXP(player.name, "R.*") YIELD player.name, player.age; +---------------------+-----+ | name | age | +---------------------+-----+ | "Russell Westbrook" | 30 | +---------------------+-----+
nebula> LOOKUP ON player WHERE REGEXP(player.name, ".*") YIELD id(vertex); +---------------------+ | id(VERTEX) | +---------------------+ | "Danny Green" | | "David West" | | "Russell Westbrook" | +---------------------+ ...
nebula> LOOKUP ON player WHERE FUZZY(player.name, "Tim Dunncan", AUTO, OR) YIELD player.name; +--------------+ | name | +--------------+ | "Tim Duncan" | +--------------+
//删除全文索引。 nebula> DROP FULLTEXT INDEX nebula_index_1; ```