Cypher 规划器的索引提示
规划器提示（Planner hint）用于在构建查询执行计划时影响规划器的决策。规划器提示在查询中使用 USING 关键字指定。
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强制规划器行为是一项高级功能，且应仅由经验丰富的开发人员和/或数据库管理员谨慎使用，因为它可能导致查询性能变差。 |
在执行查询时，Neo4j 需要决定从查询图的哪个位置开始匹配。这是通过查看 MATCH 子句和 WHERE 条件，并利用这些信息来寻找有用的索引或其他起始点来完成的。
然而，所选的索引并不总是最佳选择。有时多个索引都是潜在的候选对象，而查询规划器从性能角度来看选择了次优的索引。此外，在某些情况下（尽管很少见），根本不使用索引反而更好。
可以通过 USING 关键字强制 Neo4j 使用特定的起始点。这被称为提供规划器提示。
规划器提示有三种类型：
设置
要复制此页面中的结果，请在空数据库上执行以下查询。
FOREACH(i IN range(1, 100) |
CREATE (:Scientist {born: 1800 + i})-[:RESEARCHED]->
(:Science)<-[:INVENTED_BY {year: 530 + (i % 50), location: 'Location' + i}]-
(:Pioneer {born: 500 + (i % 50)})-[:LIVES_IN]->
(:City)-[:PART_OF]->
(:Country {formed: 400 + i, name:'Country' + i})
);
CREATE RANGE INDEX FOR (s:Scientist) ON (s.born);
CREATE RANGE INDEX FOR (p:Pioneer) ON (p.born);
CREATE RANGE INDEX FOR (c:Country) ON (c.formed);
CREATE RANGE INDEX FOR (c:Country) ON (c.name);
CREATE TEXT INDEX FOR (c:Country) ON (c.name);
CREATE RANGE INDEX FOR ()-[i:INVENTED_BY]-() ON (i.year);
CREATE RANGE INDEX FOR ()-[i:INVENTED_BY]-() ON (i.location);
CREATE TEXT INDEX FOR ()-[i:INVENTED_BY]-() ON (i.location);
CALL db.awaitIndexes;以下查询用于本页面的某些示例中。在没有任何提示的情况下，使用了一个索引，且没有使用连接。
PROFILE
MATCH
(s:Scientist {born: 1850})-[:RESEARCHED]->
(sc:Science)<-[i:INVENTED_BY {year: 560}]-
(p:Pioneer {born: 525})-[:LIVES_IN]->
(c:City)-[:PART_OF]->
(cc:Country {formed: 411})
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +-----------------+----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +-----------------+----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | c, cc, i, p, s, sc | 0 | 0 | 0 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | s.born = $autoint_0 AND s:Scientist | 0 | 0 | 0 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (sc)<-[anon_0:RESEARCHED]-(s) | 0 | 0 | 0 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | i.year = $autoint_1 AND sc:Science | 0 | 0 | 0 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (p)-[i:INVENTED_BY]->(sc) | 0 | 0 | 0 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | p.born = $autoint_2 AND p:Pioneer | 0 | 0 | 2 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (c)<-[anon_1:LIVES_IN]-(p) | 1 | 1 | 3 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | c:City | 1 | 1 | 2 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (cc)<-[anon_2:PART_OF]-(c) | 1 | 1 | 2 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +NodeIndexSeek | RANGE INDEX cc:Country(formed) WHERE formed = $autoint_3 | 1 | 1 | 2 | 120 | 6/1 | 0.506 | Fused in Pipeline 0 | +-----------------+----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 11, total allocated memory: 208
索引提示
索引提示用于指定规划器应将哪个索引作为起始点。这在索引统计信息对于手头查询已知使用的特定值不准确时非常有用，因为这会导致规划器选择非最佳索引。索引提示在适用的 MATCH 子句之后提供。
可用的索引提示如下：
| 提示 | 由以下计划实现 |
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当为提示指定索引类型（例如 RANGE、TEXT 或 POINT）时，只有在指定类型的索引可用时，该提示才能被满足。当未指定索引类型时，该提示可以由任何索引类型满足。
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使用提示绝不能改变查询的结果。因此，只有在规划器确认使用特定类型的索引不会改变结果时，带有指定索引类型的提示才是可满足的。请参阅 索引的使用 以获取更多详细信息。 |
可以提供多个索引提示，但请记住，多个起始点将需要在查询计划的后期使用潜在的昂贵连接操作。
使用节点索引提示的查询
上述查询可以进行调整，以选择不同的索引作为起始点。
查询
PROFILE
MATCH
(s:Scientist {born: 1850})-[:RESEARCHED]->
(sc:Science)<-[i:INVENTED_BY {year: 560}]-
(p:Pioneer {born: 525})-[:LIVES_IN]->
(c:City)-[:PART_OF]->
(cc:Country {formed: 411})
USING INDEX p:Pioneer(born)
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +-----------------+-----------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +-----------------+-----------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | c, cc, i, p, s, sc | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | cc.formed = $autoint_3 AND cc:Country | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (c)-[anon_2:PART_OF]->(cc) | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | c:City | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (p)-[anon_1:LIVES_IN]->(c) | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | s.born = $autoint_0 AND s:Scientist | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (sc)<-[anon_0:RESEARCHED]-(s) | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | i.year = $autoint_1 AND sc:Science | 0 | 0 | 2 | | | | | | | +-----------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (p)-[i:INVENTED_BY]->(sc) | 2 | 2 | 6 | | | | | | | +-----------------------------------------------------+----------------+------+---------+----------------+ | | | | +NodeIndexSeek | RANGE INDEX p:Pioneer(born) WHERE born = $autoint_2 | 2 | 2 | 3 | 120 | 4/1 | 0.491 | Fused in Pipeline 0 | +-----------------+-----------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 11, total allocated memory: 208
使用节点文本索引提示的查询
以下查询可以调整为选择文本索引。
查询
PROFILE
MATCH (c:Country)
USING TEXT INDEX c:Country(name)
WHERE c.name = 'Country7'
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +-----------------+-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +-----------------+-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | c | 1 | 1 | 0 | | | | | | | +-------------------------------------------------------+----------------+------+---------+----------------+ | | | | +NodeIndexSeek | TEXT INDEX c:Country(name) WHERE name = $autostring_0 | 1 | 1 | 2 | 120 | 2/0 | 0.949 | Fused in Pipeline 0 | +-----------------+-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 2, total allocated memory: 184
使用关系索引提示的查询
上述查询可以进行调整，以选择关系索引作为起始点。
查询
PROFILE
MATCH
(s:Scientist {born: 1850})-[:RESEARCHED]->
(sc:Science)<-[i:INVENTED_BY {year: 560}]-
(p:Pioneer {born: 525})-[:LIVES_IN]->
(c:City)-[:PART_OF]->
(cc:Country {formed: 411})
USING INDEX i:INVENTED_BY(year)
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +--------------------------------+---------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +--------------------------------+---------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | c, cc, i, p, s, sc | 0 | 0 | 0 | | | | | | | +---------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | cc.formed = $autoint_3 AND cc:Country | 0 | 0 | 0 | | | | | | | +---------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (c)-[anon_2:PART_OF]->(cc) | 0 | 0 | 0 | | | | | | | +---------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | c:City | 0 | 0 | 0 | | | | | | | +---------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (p)-[anon_1:LIVES_IN]->(c) | 0 | 0 | 0 | | | | | | | +---------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | s.born = $autoint_0 AND s:Scientist | 0 | 0 | 0 | | | | | | | +---------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (sc)<-[anon_0:RESEARCHED]-(s) | 0 | 0 | 0 | | | | | | | +---------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | p.born = $autoint_2 AND sc:Science AND p:Pioneer | 0 | 0 | 4 | | | | | | | +---------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +DirectedRelationshipIndexSeek | RANGE INDEX (p)-[i:INVENTED_BY(year)]->(sc) WHERE year = $autoint_1 | 2 | 2 | 3 | 120 | 5/1 | 0.461 | Fused in Pipeline 0 | +--------------------------------+---------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 7, total allocated memory: 208
使用关系文本索引提示的查询
以下查询可以调整为选择文本索引。
查询
PROFILE
MATCH ()-[i:INVENTED_BY]->()
USING TEXT INDEX i:INVENTED_BY(location)
WHERE i.location = 'Location7'
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +--------------------------------+----------------------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +--------------------------------+----------------------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | i | 1 | 1 | 0 | | | | | | | +----------------------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +DirectedRelationshipIndexSeek | TEXT INDEX (anon_0)-[i:INVENTED_BY(location)]->(anon_1) WHERE location = $autostring_0 | 1 | 1 | 2 | 120 | 3/0 | 1.079 | Fused in Pipeline 0 | +--------------------------------+----------------------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 2, total allocated memory: 184
使用多个索引提示的查询
提供一个索引提示改变了查询的起始点，但计划仍然是线性的，意味着它只有一个起始点。如果我们再给规划器另一个索引提示，我们就会强制它使用两个起始点，匹配的两端各一个。然后它会使用连接运算符将这两个分支合并。
查询
PROFILE
MATCH
(s:Scientist {born: 1850})-[:RESEARCHED]->
(sc:Science)<-[i:INVENTED_BY {year: 560}]-
(p:Pioneer {born: 525})-[:LIVES_IN]->
(c:City)-[:PART_OF]->
(cc:Country {formed: 411})
USING INDEX s:Scientist(born)
USING INDEX cc:Country(formed)
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +------------------+----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +------------------+----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | c, cc, i, p, s, sc | 0 | 0 | 0 | | 0/0 | 0.000 | | | | +----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+ | | +NodeHashJoin | sc | 0 | 0 | 0 | 432 | | | In Pipeline 2 | | |\ +----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | | +Expand(All) | (s)-[anon_0:RESEARCHED]->(sc) | 1 | 0 | 0 | | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | | +NodeIndexSeek | RANGE INDEX s:Scientist(born) WHERE born = $autoint_0 | 1 | 0 | 0 | 120 | 0/0 | 0.000 | Fused in Pipeline 1 | | | +----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +Filter | i.year = $autoint_1 AND sc:Science | 0 | 0 | 0 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (p)-[i:INVENTED_BY]->(sc) | 0 | 0 | 0 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | p.born = $autoint_2 AND p:Pioneer | 0 | 0 | 2 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (c)<-[anon_1:LIVES_IN]-(p) | 1 | 1 | 3 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | c:City | 1 | 1 | 2 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (cc)<-[anon_2:PART_OF]-(c) | 1 | 1 | 2 | | | | | | | +----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +NodeIndexSeek | RANGE INDEX cc:Country(formed) WHERE formed = $autoint_3 | 1 | 1 | 2 | 120 | 7/0 | 0.494 | Fused in Pipeline 0 | +------------------+----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 11, total allocated memory: 768
使用带有析取（OR）的多个索引提示的查询
如果查询的 WHERE 子句中包含析取 (OR)，则提供多个索引提示也很有用。这可以确保所有提示的索引都被使用，并且结果随后通过 Union 和 Distinct 合并在一起。
查询
PROFILE
MATCH (country:Country)
USING INDEX country:Country(name)
USING INDEX country:Country(formed)
WHERE country.formed = 500 OR country.name STARTS WITH "A"
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +-----------------------+------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +-----------------------+------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | country | 1 | 1 | 0 | | | | | | | +------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Distinct | country | 1 | 1 | 0 | 224 | | | | | | +------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Union | | 2 | 1 | 0 | 80 | 1/0 | 0.213 | Fused in Pipeline 2 | | |\ +------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | | +NodeIndexSeek | RANGE INDEX country:Country(formed) WHERE formed = $autoint_0 | 1 | 1 | 2 | 120 | 1/0 | 0.101 | In Pipeline 1 | | | +------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +NodeIndexSeekByRange | RANGE INDEX country:Country(name) WHERE name STARTS WITH $autostring_1 | 1 | 0 | 1 | 120 | 0/1 | 0.307 | In Pipeline 0 | +-----------------------+------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 3, total allocated memory: 320
Cypher® 通常会提供一个在没有提示的情况下对析取使用所有索引的计划。然而，如果谓词看起来不是很有选择性，它可能会决定规划一个 NodeByLabelScan。在这种情况下，索引提示会很有用。
扫描提示
如果您的查询匹配了索引的大部分内容，扫描标签或关系类型并过滤掉不匹配的行可能会更快。要执行此操作，您可以在节点索引的适用 MATCH 子句后使用 USING SCAN variable:Label，对于关系索引，则使用 USING SCAN variable:RELATIONSHIP_TYPE。这将强制 Cypher 不使用本可以使用的索引，而是进行标签扫描/关系类型扫描。您可以使用相同的提示来强制指定没有适用索引的起始点。
提示标签扫描
查询
PROFILE
MATCH
(s:Scientist {born: 1850})-[:RESEARCHED]->
(sc:Science)<-[i:INVENTED_BY {year: 560}]-
(p:Pioneer {born: 525})-[:LIVES_IN]->
(c:City)-[:PART_OF]->
(cc:Country {formed: 411})
USING SCAN s:Scientist
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +------------------+-----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +------------------+-----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | c, cc, i, p, s, sc | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | cc.formed = $autoint_3 AND cc:Country | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (c)-[anon_2:PART_OF]->(cc) | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | c:City | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (p)-[anon_1:LIVES_IN]->(c) | 0 | 0 | 0 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | i.year = $autoint_1 AND p.born = $autoint_2 AND p:Pioneer | 0 | 0 | 1 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (sc)<-[i:INVENTED_BY]-(p) | 1 | 1 | 3 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | sc:Science | 1 | 1 | 2 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (s)-[anon_0:RESEARCHED]->(sc) | 1 | 1 | 2 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | s.born = $autoint_0 | 1 | 1 | 200 | | | | | | | +-----------------------------------------------------------+----------------+------+---------+----------------+ | | | | +NodeByLabelScan | s:Scientist | 100 | 100 | 101 | 120 | 11/0 | 0.512 | Fused in Pipeline 0 | +------------------+-----------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 309, total allocated memory: 216
提示关系类型扫描
查询
PROFILE
MATCH
(s:Scientist {born: 1850})-[:RESEARCHED]->
(sc:Science)<-[i:INVENTED_BY {year: 560}]-
(p:Pioneer {born: 525})-[:LIVES_IN]->
(c:City)-[:PART_OF]->
(cc:Country {formed: 411})
USING SCAN i:INVENTED_BY
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +-------------------------------+--------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +-------------------------------+--------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | c, cc, i, p, s, sc | 0 | 0 | 0 | | | | | | | +--------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | cc.formed = $autoint_3 AND cc:Country | 0 | 0 | 0 | | | | | | | +--------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (c)-[anon_2:PART_OF]->(cc) | 0 | 0 | 0 | | | | | | | +--------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | c:City | 0 | 0 | 0 | | | | | | | +--------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (p)-[anon_1:LIVES_IN]->(c) | 0 | 0 | 0 | | | | | | | +--------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | s.born = $autoint_0 AND s:Scientist | 0 | 0 | 0 | | | | | | | +--------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (sc)<-[anon_0:RESEARCHED]-(s) | 0 | 0 | 0 | | | | | | | +--------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | i.year = $autoint_1 AND p.born = $autoint_2 AND sc:Science AND p:Pioneer | 0 | 0 | 204 | | | | | | | +--------------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +DirectedRelationshipTypeScan | (p)-[i:INVENTED_BY]->(sc) | 100 | 100 | 101 | 120 | 9/0 | 0.910 | Fused in Pipeline 0 | +-------------------------------+--------------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 305, total allocated memory: 208
使用带有析取（OR）的多个扫描提示的查询
如果查询的 WHERE 子句中包含析取 (OR)，则提供多个扫描提示也很有用。这可以确保所有相关的标签谓词都通过 UnionNodeByLabelsScan 解决。
查询
PROFILE
MATCH (person)
USING SCAN person:Pioneer
USING SCAN person:Scientist
WHERE person:Pioneer OR person:Scientist
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +------------------------+--------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +------------------------+--------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | person | 180 | 200 | 0 | | | | | | | +--------------------------+----------------+------+---------+----------------+ | | | | +UnionNodeByLabelsScan | person:Pioneer|Scientist | 180 | 200 | 202 | 120 | 6/0 | 1.740 | Fused in Pipeline 0 | +------------------------+--------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 202, total allocated memory: 184
Cypher 通常会提供一个在没有提示的情况下对析取使用扫描的计划。然而，如果标签谓词看起来不是很有选择性，它可能会决定规划一个 AllNodeScan 后跟一个 Filter。在这种情况下，扫描提示会很有用。
连接提示
连接提示是最高级的提示类型，它们不是用来寻找查询执行计划的起始点，而是强制在指定点进行连接。这意味着计划中必须有多个起始点（叶子），以便查询能够连接从这些叶子上升的两个分支。由于这种性质，连接（以及随后的连接提示）将强制规划器寻找额外的起始点；如果不存在好的起始点，可能会导致规划器选择一个非常糟糕的起始点，从而对查询性能产生负面影响。在其他情况下，提示可能会迫使规划器选择一个看似糟糕但实际上证明非常好的起始点。
提示在单个节点上进行连接
在上面使用多个索引提示的示例中，我们看到规划器选择进行连接，但不是在 p 节点上。通过在索引提示之外额外提供连接提示，我们可以强制连接在 p 节点上发生。
查询
PROFILE
MATCH
(s:Scientist {born: 1850})-[:RESEARCHED]->
(sc:Science)<-[i:INVENTED_BY {year: 560}]-
(p:Pioneer {born: 525})-[:LIVES_IN]->
(c:City)-[:PART_OF]->
(cc:Country {formed: 411})
USING INDEX s:Scientist(born)
USING INDEX cc:Country(formed)
USING JOIN ON p
RETURN *查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +------------------+------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +------------------+------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | c, cc, i, p, s, sc | 0 | 0 | 0 | | 0/0 | 0.000 | | | | +------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+ | | +NodeHashJoin | p | 0 | 0 | 0 | 432 | | | In Pipeline 2 | | |\ +------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | | +Filter | cache[p.born] = $autoint_2 | 1 | 0 | 0 | | | | | | | | +------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | | +Expand(All) | (c)<-[anon_1:LIVES_IN]-(p) | 1 | 0 | 0 | | | | | | | | +------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | | +Filter | c:City | 1 | 0 | 0 | | | | | | | | +------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | | +Expand(All) | (cc)<-[anon_2:PART_OF]-(c) | 1 | 0 | 0 | | | | | | | | +------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | | +NodeIndexSeek | RANGE INDEX cc:Country(formed) WHERE formed = $autoint_3 | 1 | 0 | 0 | 120 | 0/0 | 0.000 | Fused in Pipeline 1 | | | +------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +Filter | i.year = $autoint_1 AND cache[p.born] = $autoint_2 AND p:Pioneer | 0 | 0 | 1 | | | | | | | +------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (sc)<-[i:INVENTED_BY]-(p) | 1 | 1 | 3 | | | | | | | +------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Filter | sc:Science | 1 | 1 | 2 | | | | | | | +------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +Expand(All) | (s)-[anon_0:RESEARCHED]->(sc) | 1 | 1 | 2 | | | | | | | +------------------------------------------------------------------+----------------+------+---------+----------------+ | | | | +NodeIndexSeek | RANGE INDEX s:Scientist(born) WHERE born = $autoint_0 | 1 | 1 | 2 | 120 | 6/1 | 0.515 | Fused in Pipeline 0 | +------------------+------------------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 10, total allocated memory: 768
提示为 OPTIONAL MATCH 进行连接
连接提示也可以用来强制规划器选择 NodeLeftOuterHashJoin 或 NodeRightOuterHashJoin 来解决 OPTIONAL MATCH。在大多数情况下，规划器会倾向于使用 OptionalExpand。
查询
PROFILE
MATCH (s:Scientist {born: 1850})
OPTIONAL MATCH (s)-[:RESEARCHED]->(sc:Science)
RETURN *在没有任何提示的情况下，规划器没有使用连接来解决 OPTIONAL MATCH。
查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +----------------------+-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +----------------------+-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | s, sc | 1 | 1 | 0 | | | | | | | +-------------------------------------------------------+----------------+------+---------+----------------+ | | | | +OptionalExpand(All) | (s)-[anon_0:RESEARCHED]->(sc) WHERE sc:Science | 1 | 1 | 4 | | | | | | | +-------------------------------------------------------+----------------+------+---------+----------------+ | | | | +NodeIndexSeek | RANGE INDEX s:Scientist(born) WHERE born = $autoint_0 | 1 | 1 | 2 | 120 | 6/0 | 0.560 | Fused in Pipeline 0 | +----------------------+-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 6, total allocated memory: 184
查询
PROFILE
MATCH (s:Scientist {born: 1850})
OPTIONAL MATCH (s)-[:RESEARCHED]->(sc:Science)
USING JOIN ON s
RETURN *现在规划器使用连接来解决 OPTIONAL MATCH。
查询计划
Planner COST Runtime PIPELINED Runtime version 2026.03 Batch size 128 +------------------------+-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | Operator | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline | +------------------------+-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +ProduceResults | s, sc | 1 | 1 | 0 | | 2/0 | 0.213 | | | | +-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+ | | +NodeLeftOuterHashJoin | s | 1 | 1 | 0 | 3112 | | 0.650 | In Pipeline 2 | | |\ +-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | | +Expand(All) | (sc)<-[anon_0:RESEARCHED]-(s) | 100 | 100 | 300 | | | | | | | | +-------------------------------------------------------+----------------+------+---------+----------------+ | | | | | +NodeByLabelScan | sc:Science | 100 | 100 | 101 | 120 | 4/0 | 0.786 | Fused in Pipeline 1 | | | +-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ | +NodeIndexSeek | RANGE INDEX s:Scientist(born) WHERE born = $autoint_0 | 1 | 1 | 2 | 120 | 1/0 | 0.214 | In Pipeline 0 | +------------------------+-------------------------------------------------------+----------------+------+---------+----------------+------------------------+-----------+---------------------+ Total database accesses: 403, total allocated memory: 3192