我的密码查询
EXPLAIN MATCH (b:Block)<-[:INCLUDED_IN]-(tx:Transaction {pstype: 0})
WHERE 1540512000 <= b.time < 1540598400
RETURN count(tx);
产生以下执行计划
--------------------------------------------+
| Operator | Estimated Rows | Identifiers | Other |
+-------------------+----------------+-----------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| +ProduceResults | 12 | count(tx) | |
| | +----------------+-----------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| +EagerAggregation | 12 | count(tx) | |
| | +----------------+-----------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| +Filter | 136 | anon[16], b, tx | AndedPropertyInequalities(Variable(b),Property(Variable(b),PropertyKeyName(time)),GreaterThanOrEqual(Property(Variable(b),PropertyKeyName(time)),Parameter( AUTOINT2,Integer)), LessThan(Property(Variable(b),PropertyKeyName(time)),Parameter( AUTOINT1,Integer))) |
| | +----------------+-----------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| +Expand(All) | 9052 | anon[16], b, tx | (tx)-[anon[16]:INCLUDED_IN]->(b) |
| | +----------------+-----------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| +NodeIndexSeek | 9052 | tx | :Transaction(pstype) |
+-------------------+----------------+-----------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
执行速度太慢，因为第一个NodeIndexSeekByRange返回数千万个节点而不是9052。在b：Block（time）上使用NodeIndexSeekByRange将产生大约600个节点。
我尝试强制执行计划从b：Block（time）开始，但是它仍然在tx：Transaction（pstype）上继续使用NodeIndexSeek：
EXPLAIN MATCH (b:Block)<-[:INCLUDED_IN]-(tx:Transaction {pstype: 0})
USING INDEX b:Block(time)
WHERE 1540512000 <= b.time < 1540598400
RETURN count(tx);
产生
+-------------------------+----------------+-----------------+--------------------------------------------------------------+
| Operator | Estimated Rows | Identifiers | Other |
+-------------------------+----------------+-----------------+--------------------------------------------------------------+
| +ProduceResults | 12 | count(tx) | |
| | +----------------+-----------------+--------------------------------------------------------------+
| +EagerAggregation | 12 | count(tx) | |
| | +----------------+-----------------+--------------------------------------------------------------+
| +NodeHashJoin | 136 | anon[16], b, tx | b |
| |\ +----------------+-----------------+--------------------------------------------------------------+
| | +NodeIndexSeekByRange | 14703 | b | :Block(time) >= { AUTOINT2} AND :Block(time) < { AUTOINT1} |
| | +----------------+-----------------+--------------------------------------------------------------+
| +Expand(All) | 9052 | anon[16], b, tx | (tx)-[anon[16]:INCLUDED_IN]->(b) |
| | +----------------+-----------------+--------------------------------------------------------------+
| +NodeIndexSeek | 9052 | tx | :Transaction(pstype) |
+-------------------------+----------------+-----------------+--------------------------------------------------------------+
让它快速运行的唯一方法是使用规则计划器：（速度快几个数量级）
CYPHER planner=rule MATCH (b:Block)
WHERE 1540512000 <= b.time < 1540598400
WITH b
MATCH (b)<-[:INCLUDED_IN]-(tx:Transaction {pstype: 0})
RETURN count(tx);
使用费用计划程序时是否可以使其正常工作？
：Block（time）和：Transaction（pstype）都被索引。
答案 0 :(得分：0)
您可以尝试在tx上使用join hint以及索引提示，这样可以确保只从一个方向扩展：
EXPLAIN
MATCH (b:Block)<-[:INCLUDED_IN]-(tx:Transaction {pstype: 0})
USING INDEX b:Block(time)
USING JOIN ON tx
WHERE 1540512000 <= b.time < 1540598400
RETURN count(tx);
或者，您可以稍微调整查询的结构，以使tx节点最初不是该模式的一部分，而是在WHERE子句中强制执行。您需要将MATCH拆分为2，但我认为您不需要任何计划者提示：
EXPLAIN
MATCH (tx:Transaction {pstype: 0})
MATCH (b:Block)<-[:INCLUDED_IN]-(x)
WHERE 1540512000 <= b.time < 1540598400
AND x = tx
RETURN count(tx);
编辑
好的，那就让我们尝试另一种方法：
EXPLAIN
MATCH (b:Block)<-[:INCLUDED_IN]-(x)
WHERE 1540512000 <= b.time < 1540598400
AND x.pstype = 0 // AND 'Transaction' in labels(x)
RETURN count(tx);
如果我们不使用标签，则无法使用索引查找。如果除：Transaction节点以外，还有其他具有pstype属性的节点，您可以尝试取消注释该行，在该行中，我们使用另一种方式查看该节点是否具有该标签（我认为这不会使用索引）查找，但不能完全确定）。
另一种方法（不确定是否可行）是使用模式理解（在找到与b的初始匹配项之后）从模式中获取结果列表，并对结果大小求和：
EXPLAIN
MATCH (b:Block)
WHERE 1540512000 <= b.time < 1540598400
RETURN sum(size([(b)<-[:INCLUDED_IN]-(x:Transaction) WHERE x.pstype = 0 | x])) as count