4kw+的Company数据，8kw+的Person数据，和20kw左右的关系数据。
$ head company.csv
id:ID,name,:LABEL
00002cefc5e2d05b9311a791fd009160,"岳阳市岳阳楼区亿诺厨房电器总经销",Company
00002ebe645c0f777887ff17d525ba6b,"禄丰县碧城镇零点俱乐部",Company
000037a77f24a10153dcb4c2e7ae082d,"淄川将军路星显日用品经营部",Company
0000a82f6261107197cb386c5e5e01bc,"上海高易电子有限公司",Company
0000b340976a6425d4a4be58c119b445,"木垒县阿合杰乐看民族用品店",Company
0000cc18233fd6d22b418ad49a4b0829,"萍乡市晴瑞商贸有限公司",Company
00010eb2bdb567719240bde6ea69f1b0,"西宁市城西区毳毳母婴用品经营部",Company
000150a5c28756610a4fb825f5b0e0fa,"昆明市金丛林公众电脑屋",Company
0001ac7561867af639293a1917129126,"凌海市大凌河创启教育咨询中心",Company
$ head person.csv
id:ID,name,:LABEL
00000006f2943d149920c79adec497ac,"顾海庆",Person
0000000a6a9b6a1d25b4f3fe9f783998,"刘士辉",Person
0000003beffacaeafb73ee32985202f3,"郑乃忠",Person
0000007ab0d18f3a68328b17a3378e74,"刘艳青",Person
000001719da1825fee8c986f47244745,"黄军良",Person
000001dd6ac4e639751df87b6ec3682e,"吴邦华",Person
00000250374ae5e560c68309e27cdc04,"辛均良",Person
0000028a45f28c45414adf07ce2cdc57,"王广",Person
000002afcb526d6fc4209ebf12f2decc,"朱义",Person
$ head relation.csv
:START_ID,:TYPE,:END_ID,from,to
000003cfc523f8a9c7fcad2e0c305e13,7,3b7bb5f7c992f7b51a2d060e227cc96b,000003cfc523f8a9c7fcad2e0c305e13,3b7bb5f7c992f7b51a2d060e227cc96b
000006fd2cb0bc23b6c7d974310a67fe,7,0641095a8f9698e9f52108a681746621,000006fd2cb0bc23b6c7d974310a67fe,0641095a8f9698e9f52108a681746621
000010f9b795c7a48b0ec2672bd53bf1,7,5b060d65359641193ba3f01b55f8bfea,000010f9b795c7a48b0ec2672bd53bf1,5b060d65359641193ba3f01b55f8bfea
000015763acdc7958a797198338a5f9c,7,ad8df642cb3aaadf5216f16eb6d9436f,000015763acdc7958a797198338a5f9c,ad8df642cb3aaadf5216f16eb6d9436f
000021ca5107086c623b880ac846f056,7,08dce64cc5b6c7c46b5935fdd1522c15,000021ca5107086c623b880ac846f056,08dce64cc5b6c7c46b5935fdd1522c15
00006057e098b1936447f8ce1f81038d,5,c0c328ec63b5c039a55458bfd9f8242e,00006057e098b1936447f8ce1f81038d,c0c328ec63b5c039a55458bfd9f8242e
00007e02109d6dc8fc3accddc15e1299,7,50f222e1c1fb5af8875edcbd9977db3a,00007e02109d6dc8fc3accddc15e1299,50f222e1c1fb5af8875edcbd9977db3a
00008e8236b86d868c8e52b50f9a25f3,7,2b74ec85d562c81b7ac02d9a06e8d09d,00008e8236b86d868c8e52b50f9a25f3,2b74ec85d562c81b7ac02d9a06e8d09d
00008f88b5974fb0f09412c49355f0d1,7,9402285be44bbb0e654968dfa37890cd,00008f88b5974fb0f09412c49355f0d1,9402285be44bbb0e654968dfa37890cd
使用neo4j-import大概16分钟左右可以灌完：
$ bin/neo4j-admin import --ignore-missing-nodes=true --nodes /Users/argan/Data/company.csv --nodes /Users/argan/Data/person.csv --relationships /Users/argan/Data/relation.csv
...
IMPORT DONE in 19m 17s 939ms.
Imported:
128880304 nodes
196234357 relationships
650229322 properties
Peak memory usage: 1.70 GB
然后执行查询:
MATCH (n:Company)
WHERE n.id='0afa4218343abd81efe4881917412222'
RETURN n
非常慢，耗时大概60s左右。
对Company和Person的id字段构建索引：
CREATE INDEX ON :Company(id);
CREATE INDEX ON :Person(id);
然后再执行查询:
MATCH (n:Company)
WHERE n.id='0afa4218343abd81efe4881917412222'
RETURN n
这次就非常快了：
neo4j> PROFILE MATCH (n:Company) WHERE n.id='0afa4218343abd81efe4881917412222' RETURN n;
+-----------------------------------------------------------------------------------------+
| Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows |
+-----------------------------------------------------------------------------------------+
| "PROFILE" | "READ_ONLY" | "CYPHER 3.3" | "COST" | "INTERPRETED" | 10 | 0 | 1 |
+-----------------------------------------------------------------------------------------+
+-----------------+----------------+------+---------+-----------+-------------+-------------------+
| Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Other |
+-----------------+----------------+------+---------+-----------+-------------+-------------------+
| +ProduceResults | 1 | 1 | 0 | 0/0 | n | 0.0 |
| | +----------------+------+---------+-----------+-------------+-------------------+
| +NodeIndexSeek | 1 | 1 | 2 | 0/0 | n | 0.0; :Company(id) |
+-----------------+----------------+------+---------+-----------+-------------+-------------------+
+-------------------------------------------------------------------------+
| n |
+-------------------------------------------------------------------------+
| (:Company {name: "??????????", id: "0afa4218343abd81efe4881917412222"}) |
+-------------------------------------------------------------------------+
1 row available after 9 ms, consumed after another 1 ms
或者这样子写也是等价的：
neo4j> profile match (n) where n.id = '0afa4218343abd81efe4881917412222' and n:Company return n;
+-----------------------------------------------------------------------------------------+
| Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows |
+-----------------------------------------------------------------------------------------+
| "PROFILE" | "READ_ONLY" | "CYPHER 3.3" | "COST" | "INTERPRETED" | 23 | 0 | 0 |
+-----------------------------------------------------------------------------------------+
+-----------------+----------------+------+---------+-----------+-------------+-------------------+
| Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Other |
+-----------------+----------------+------+---------+-----------+-------------+-------------------+
| +ProduceResults | 1 | 0 | 0 | 0/0 | n | 0.0 |
| | +----------------+------+---------+-----------+-------------+-------------------+
| +NodeIndexSeek | 1 | 0 | 1 | 0/0 | n | 0.0; :Company(id) |
+-----------------+----------------+------+---------+-----------+-------------+-------------------+
0 rows available after 23 ms, consumed after another 0 ms
走不走索引果然性能差异巨大。
但是neo4j的schema index是挂载在label下的，如果不指定label，那么还是会走不到索引：
neo4j> profile match (n) where n.id = '0afa4218343abd81efe4881917412222' return n;
+-------------------------------------------------------------------------------------------+
| Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows |
+-------------------------------------------------------------------------------------------+
| "PROFILE" | "READ_ONLY" | "CYPHER 3.3" | "COST" | "INTERPRETED" | 180646 | 0 | 0 |
+-------------------------------------------------------------------------------------------+
+-----------------+----------------+-----------+-----------+-----------+-------------+-----------------------------+
| Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Other |
+-----------------+----------------+-----------+-----------+-----------+-------------+-----------------------------+
| +ProduceResults | 12888030 | 0 | 0 | 0/0 | n | 0.0 |
| | +----------------+-----------+-----------+-----------+-------------+-----------------------------+
| +Filter | 12888030 | 0 | 128880304 | 0/0 | n | 0.0; n.id = { AUTOSTRING0} |
| | +----------------+-----------+-----------+-----------+-------------+-----------------------------+
| +AllNodesScan | 128880304 | 128880304 | 128880305 | 0/0 | n | 0.0 |
+-----------------+----------------+-----------+-----------+-----------+-------------+-----------------------------+
0 rows available after 43 ms, consumed after another 180603 ms
虽然neo4j如果没有指定label语义上是检索所有的label（对比Aerospike，没有指定label是检索null label），这个是我们预期的。但是没有走索引，对所有节点进行了全部扫描，性能根本没法接受。
怎么办呢？最简单的方式就是让用户查询的时候必须指定label，这样就可以走该label下的相应索引了。
那么用户能不能指定多个label呢？
neo4j的multi-labels match默认是AND操作，而这里我们要的OR的关系，所以这样子查询虽然会走索引(:Company(id))但是是查询不到结果的(被:Person filter掉了)：
neo4j> profile match (n:Company:Person) where n.id = '0afa4218343abd81efe4881917412222' return n;
+-----------------------------------------------------------------------------------------+
| Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows |
+-----------------------------------------------------------------------------------------+
| "PROFILE" | "READ_ONLY" | "CYPHER 3.3" | "COST" | "INTERPRETED" | 24 | 0 | 0 |
+-----------------------------------------------------------------------------------------+
+-----------------+----------------+------+---------+-----------+-------------+-------------------+
| Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Other |
+-----------------+----------------+------+---------+-----------+-------------+-------------------+
| +ProduceResults | 1 | 0 | 0 | 0/0 | n | 0.0 |
| | +----------------+------+---------+-----------+-------------+-------------------+
| +Filter | 1 | 0 | 0 | 0/0 | n | 0.0; n:Person |
| | +----------------+------+---------+-----------+-------------+-------------------+
| +NodeIndexSeek | 1 | 0 | 1 | 0/0 | n | 0.0; :Company(id) |
+-----------------+----------------+------+---------+-----------+-------------+-------------------+
0 rows available after 24 ms, consumed after another 0 ms
但是改写成OR操作发现居然走不了索引（这个很诡异，应该是neo4j的bug..）:
neo4j> profile match (n) where n.id = '0afa4218343abd81efe4881917412222' and (n:Company OR n:Person) return n;
+-------------------------------------------------------------------------------------------+
| Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows |
+-------------------------------------------------------------------------------------------+
| "PROFILE" | "READ_ONLY" | "CYPHER 3.3" | "COST" | "INTERPRETED" | 702694 | 0 | 0 |
+-------------------------------------------------------------------------------------------+
+--------------------+----------------+-----------+-----------+-----------+-------------+-----------------------------+
| Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Other |
+--------------------+----------------+-----------+-----------+-----------+-------------+-----------------------------+
| +ProduceResults | 9891053 | 0 | 0 | 0/0 | n | 0.0 |
| | +----------------+-----------+-----------+-----------+-------------+-----------------------------+
| +Filter | 9891053 | 0 | 128880304 | 0/0 | n | 0.0; n.id = { AUTOSTRING0} |
| | +----------------+-----------+-----------+-----------+-------------+-----------------------------+
| +Distinct | 98910532 | 128880304 | 0 | 0/0 | n | 0.0; n |
| | +----------------+-----------+-----------+-----------+-------------+-----------------------------+
| +Union | 47410183 | 128880304 | 0 | 0/0 | n | 0.0 |
| |\ +----------------+-----------+-----------+-----------+-------------+-----------------------------+
| | +NodeByLabelScan | 81470121 | 81470121 | 81470122 | 0/0 | n | 0.0; :Person |
| | +----------------+-----------+-----------+-----------+-------------+-----------------------------+
| +NodeByLabelScan | 47410183 | 47410183 | 47410184 | 0/0 | n | 0.0; :Company |
+--------------------+----------------+-----------+-----------+-----------+-------------+-----------------------------+
0 rows available after 107 ms, consumed after another 702587 ms
看来只能针对每个label单独查询，最后进行合并了。但是查看了一下，neo4j倒是支持这个union的，所以不需要在业务层处理了：
neo4j> PROFILE
MATCH (n:Company)
WHERE n.id='0afa4218343abd81efe4881917412222'
RETURN n limit 10
UNION MATCH (n:Person)
WHERE n.id='0afa4218343abd81efe4881917412222'
RETURN n limit 10
;
+-----------------------------------------------------------------------------------------+
| Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows |
+-----------------------------------------------------------------------------------------+
| "PROFILE" | "READ_ONLY" | "CYPHER 3.3" | "COST" | "INTERPRETED" | 5 | 0 | 1 |
+-----------------------------------------------------------------------------------------+
+------------------+----------------+------+---------+-----------+-------------+--------------------+
| Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Other |
+------------------+----------------+------+---------+-----------+-------------+--------------------+
| +ProduceResults | 1 | 1 | 0 | 0/0 | n | 0.0 |
| | +----------------+------+---------+-----------+-------------+--------------------+
| +Distinct | 1 | 1 | 0 | 0/0 | n | 0.0; n |
| | +----------------+------+---------+-----------+-------------+--------------------+
| +Union | 1 | 1 | 0 | 0/0 | n | 0.0 |
| |\ +----------------+------+---------+-----------+-------------+--------------------+
| | +Projection | 1 | 0 | 0 | 0/0 | n, n | 0.0; {n : n@116} |
| | | +----------------+------+---------+-----------+-------------+--------------------+
| | +Limit | 1 | 0 | 0 | 0/0 | n | 0.0; 10 |
| | | +----------------+------+---------+-----------+-------------+--------------------+
| | +NodeIndexSeek | 1 | 0 | 1 | 0/0 | n | 0.0; :Person(id) |
| | +----------------+------+---------+-----------+-------------+--------------------+
| +Projection | 1 | 1 | 0 | 0/0 | n, n | 0.0; {n : n@7} |
| | +----------------+------+---------+-----------+-------------+--------------------+
| +Limit | 1 | 1 | 0 | 0/0 | n | 0.0; 10 |
| | +----------------+------+---------+-----------+-------------+--------------------+
| +NodeIndexSeek | 1 | 1 | 2 | 0/0 | n | 0.0; :Company(id) |
+------------------+----------------+------+---------+-----------+-------------+--------------------+
+-------------------------------------------------------------------------+
| n |
+-------------------------------------------------------------------------+
| (:Company {name: "??????????", id: "0afa4218343abd81efe4881917412222"}) |
+-------------------------------------------------------------------------+
1 row available after 4 ms, consumed after another 1 ms
或者使用collect将两个查询结果汇总也可以：
neo4j> PROFILE
OPTIONAL MATCH (n1:Company)
WHERE n1.id='0afa4218343abd81efe4881917412222'
WITH collect(n1) as c1
OPTIONAL MATCH (n2:Person)
WHERE n2.id='0afa4218343abd81efe4881917412222'
WITH collect(n2) + c1 as c2
return c2
;
+-----------------------------------------------------------------------------------------+
| Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows |
+-----------------------------------------------------------------------------------------+
| "PROFILE" | "READ_ONLY" | "CYPHER 3.3" | "COST" | "INTERPRETED" | 5 | 0 | 1 |
+-----------------------------------------------------------------------------------------+
+-------------------+----------------+------+---------+-----------+--------------------------+-------------------+
| Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Other |
+-------------------+----------------+------+---------+-----------+--------------------------+-------------------+
| +ProduceResults | 1 | 1 | 0 | 0/0 | anon[178], anon[192], c2 | 0.0 |
| | +----------------+------+---------+-----------+--------------------------+-------------------+
| +Projection | 1 | 1 | 0 | 0/0 | anon[178], anon[192], c2 | 0.0; {c2 : + } |
| | +----------------+------+---------+-----------+--------------------------+-------------------+
| +EagerAggregation | 1 | 1 | 0 | 0/0 | anon[178], anon[192] | 0.0; anon[192] |
| | +----------------+------+---------+-----------+--------------------------+-------------------+
| +Apply | 1 | 1 | 0 | 0/0 | c1, n2 | 0.0 |
| |\ +----------------+------+---------+-----------+--------------------------+-------------------+
| | +Optional | 1 | 1 | 0 | 0/0 | n2 | 0.0 |
| | | +----------------+------+---------+-----------+--------------------------+-------------------+
| | +NodeIndexSeek | 1 | 0 | 1 | 0/0 | n2 | 0.0; :Person(id) |
| | +----------------+------+---------+-----------+--------------------------+-------------------+
| +EagerAggregation | 1 | 1 | 0 | 0/0 | c1 | 0.0 |
| | +----------------+------+---------+-----------+--------------------------+-------------------+
| +Optional | 1 | 1 | 0 | 0/0 | n1 | 0.0 |
| | +----------------+------+---------+-----------+--------------------------+-------------------+
| +NodeIndexSeek | 1 | 1 | 2 | 0/0 | n1 | 0.0; :Company(id) |
+-------------------+----------------+------+---------+-----------+--------------------------+-------------------+
+---------------------------------------------------------------------------+
| c2 |
+---------------------------------------------------------------------------+
| [(:Company {name: "??????????", id: "0afa4218343abd81efe4881917412222"})] |
+---------------------------------------------------------------------------+
1 row available after 4 ms, consumed after another 1 ms
注意：这种方式必须是OPTIONAL MATCH，否则只要有一个查询没有结果，就全部为空了。另外，也需要注意到这里返回的是一个数组了，而不是一个个的元素。如果想保持一致，只需要再UNWIND一下就可以了:
PROFILE
OPTIONAL MATCH (n1:Company)
WHERE n1.id='0afa4218343abd81efe4881917412222'
WITH collect(n1) as c1
OPTIONAL MATCH (n2:Person)
WHERE n2.id='0afa4218343abd81efe4881917412222'
WITH collect(n2) + c1 as c2
UNWIND(c2) AS n
return n
;
虽然本质上还是每个label查询了一次，N个label就需要查询N次，但是在label不多的情况下，性能还是相当不错的。
进一步的，假设说用户并不知道要查询哪个label，能不能提供针对库里所有label的检索呢？比如用户传递了一个 vertexLabel=all 的参数。
答案似乎是可以的，其实就是多了一个操作而已：先把neo4j的所有labels查询出来，然后针对这些labels进行前面的操作。
Cypher中获取某个节点的labels的函数是：lables(node)，但是我们是想获取db中所有的labels，cypher也提供了db.lables函数：
neo4j> call db.labels;
+-----------+
| label |
+-----------+
| "Company" |
| "Person" |
+-----------+
2 rows available after 33 ms, consumed after another 0 ms
NOTES
StackOverflow上有人提供的答案是根据labels(node)实现的：
neo4j> MATCH (n) RETURN distinct labels(n);
+-------------+
| labels(n) |
+-------------+
| ["Company"] |
| ["Person"] |
+-------------+
2 rows available after 102 ms, consumed after another 271604 ms
这个会做全表扫描，非常非常慢。千万不要使用。
但是有个问题就是cypher并不支持动态label（neo4j如何批量导入JSON数据 》4、neo4j如何支持动态node label？），所以这样子的语句是查询不到结果的：
neo4j> PROFILE
CALL db.labels() YIELD label
MATCH (n:label)
WHERE n.id='0afa4218343abd81efe4881917412222'
RETURN n;
+-----------------------------------------------------------------------------------------+
| Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows |
+-----------------------------------------------------------------------------------------+
| "PROFILE" | "READ_ONLY" | "CYPHER 3.3" | "COST" | "INTERPRETED" | 11 | 0 | 0 |
+-----------------------------------------------------------------------------------------+
+--------------------+----------------+------+---------+-----------+-------------+---------------------------------------+
| Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Other |
+--------------------+----------------+------+---------+-----------+-------------+---------------------------------------+
| +ProduceResults | 0 | 0 | 0 | 0/0 | label, n | 0.0 |
| | +----------------+------+---------+-----------+-------------+---------------------------------------+
| +Filter | 0 | 0 | 0 | 0/0 | label, n | 0.0; n.id = { AUTOSTRING0} |
| | +----------------+------+---------+-----------+-------------+---------------------------------------+
| +Apply | 0 | 0 | 0 | 0/0 | label, n | 0.0 |
| |\ +----------------+------+---------+-----------+-------------+---------------------------------------+
| | +NodeByLabelScan | 10000 | 0 | 2 | 0/0 | label, n | 0.0; :label |
| | +----------------+------+---------+-----------+-------------+---------------------------------------+
| +ProcedureCall | 10000 | 2 | 1 | 0/0 | label | 0.0; db.labels() :: (label :: String) |
+--------------------+----------------+------+---------+-----------+-------------+---------------------------------------+
0 rows available after 10 ms, consumed after another 1 ms
必须使用procedure进行服务端拼接。这里可以使用 APOC Procedures’ cypher.run():
neo4j> PROFILE
CALL db.labels() YIELD label
WITH label
CALL apoc.cypher.run("match (n:" + label + ") where n.id=" + "'0afa4218343abd81efe4881917412222'" + " return n", null) YIELD value
RETURN value.n AS node
;
+-----------------------------------------------------------------------------------------+
| Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows |
+-----------------------------------------------------------------------------------------+
| "PROFILE" | "READ_ONLY" | "CYPHER 3.3" | "COST" | "INTERPRETED" | 24 | 0 | 1 |
+-----------------------------------------------------------------------------------------+
+-----------------+----------------+------+---------+-----------+--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Other |
+-----------------+----------------+------+---------+-----------+--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| +ProduceResults | 10000 | 1 | 0 | 0/0 | label, node, value | 0.0 |
| | +----------------+------+---------+-----------+--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| +Projection | 10000 | 1 | 0 | 0/0 | label, node, value | 0.0; {node : value.n} |
| | +----------------+------+---------+-----------+--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| +ProcedureCall | 10000 | 1 | 2 | 0/0 | label, value | 0.0; apoc.cypher.run(CoerceTo(Add(Add(Add(Add(Parameter( AUTOSTRING0,String),Variable(label)),Parameter( AUTOSTRING1,String)),Parameter( AUTOSTRING2,String)),Parameter( AUTOSTRING3,String)),String), CoerceTo(Null(),Map)) :: (value :: Map) |
| | +----------------+------+---------+-----------+--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| +ProcedureCall | 10000 | 2 | 1 | 0/0 | label | 0.0; db.labels() :: (label :: String) |
+-----------------+----------------+------+---------+-----------+--------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+-------------------------------------------------------------------------+
| node |
+-------------------------------------------------------------------------+
| (:Company {name: "??????????", id: "0afa4218343abd81efe4881917412222"}) |
+-------------------------------------------------------------------------+
1 row available after 19 ms, consumed after another 5 ms
当然，你也可以在应用层分两步处理。先获取所有的labels，然后再使用前面那种指定多个label的方法。这样就不需要服务端动态拼接了。
TIPS 在cypher-shell中如何绑定变量
调试cypher最好的方式就是先在cypher-shell中测试通过，再在代码中拼装。那么如何在cypher中指定绑定参数呢？答案是跟web界面一样，使用:param语句。
neo4j> :param id: "0afa4218343abd81efe4881917412222"
neo4j> CALL db.labels() YIELD label
WITH label
CALL apoc.cypher.run('match (n:' + label + ') where n.id = {id} return n', {id: {id}}) YIELD value
RETURN value.n AS node
;
+-------------------------------------------------------------------------+
| node |
+-------------------------------------------------------------------------+
| (:Company {name: "??????????", id: "0afa4218343abd81efe4881917412222"}) |
+-------------------------------------------------------------------------+
1 row available after 1 ms, consumed after another 2 ms
neo4j> :param batch: {id: "0afa4218343abd81efe4881917412222"}
neo4j> UNWIND {batch} as row
CALL db.labels() YIELD label
WITH label ,row
CALL apoc.cypher.run('match (n:' + label + ') where n.id = {id} return n', {id: row.id}) YIELD value
RETURN value.n AS node
;
+-------------------------------------------------------------------------+
| node |
+-------------------------------------------------------------------------+
| (:Company {name: "??????????", id: "0afa4218343abd81efe4881917412222"}) |
+-------------------------------------------------------------------------+
1 row available after 21 ms, consumed after another 2 ms
也可以绑定数组变量：
:param batch: [{properties: {name: "argan", label: "Person", id: "1", age: 31}}, {properties: {name: "magi", label: "Person", id: "2", age: 28}}]
注意
cypher的变量绑定有点恶心，param的key注意不要加双引号，否则会报错：
neo4j> :param batch: {id: "0afa4218343abd81efe4881917412222"}
neo4j> :params
batch: {id=0afa4218343abd81efe4881917412222}
neo4j> :param batch: {"id": "0afa4218343abd81efe4881917412222"}
Invalid input '"': expected whitespace, an identifier, UnsignedDecimalInteger, a property key name or '}' (line 1, column 9 (offset: 8))
"RETURN {"id": "0afa4218343abd81efe4881917412222"} as batch"
^
java代码的拼接就可以这么写：
/**
* 因为Neo4j的索引是跟label绑定的，而且label又不支持动态绑定。所以这里采用了比较恶心的方式处理，服务端枚举所有的label，动态拼接。。
*/
@Override
public List<Vertex> getVertices(String...ids) {
StatementBuilder sb = new StatementBuilder();
sb.append("UNWIND {batch} as row ") //
.append(" CALL db.labels() YIELD label ") //
.append(" WITH label, row ") //
.append(" CALL apoc.cypher.run(" //
+ "'match (n:`' + label + '`) where n.id = {id} return n', {id: row.id}" //
+ ") YIELD value") //
.append(" RETURN value.n AS node");
String statement = sb.toString();
Map<String, Object> params = new HashMap<>();
List<Map<String, Object>> batch = new ArrayList<>();
for (String id : ids) {
Map<String, Object> map = new HashMap<>();
map.put("id", id);
batch.add(map);
}
params.put("batch", batch);
return cypher.query(statement, params, new StatementResultMapper<List<Vertex>>() {
@Override
public List<Vertex> mapResult(StatementResult result) {
List<Vertex> vs = new ArrayList<>();
while (result.hasNext()) {
Record record = result.next();
for (Value val : record.values()) {
if (!StringUtils.equalsIgnoreCase(val.type().name(), "NODE")) {
throw new RuntimeException("value should be a NODE");
}
Vertex v = ModelUtil.toVertex(val.asNode());
vs.add(v);
}
}
return vs;
}
});
}
