I'm already stuck for a couple of days with a performance problem, or even
queries that do not produce predictable results. I posted this one before,
but now, after upgrading the machine from 2 to 8GB (hoping it was a lack of
memory issue) , I don't know how to solve this.
*Environment : *
Cloudserver with : 8GB Ram 40GB SSD Disk Ubuntu 13.10 x64
Version : Neo4j 2.1.0-M01
*Settings adapted from defaults*
in neo4j-wrapper.conf
wrapper.java.initmemory=4096
wrapper.java.maxmemory=4096
in neo4j.properties
neostore.nodestore.db.mapped_memory=50M
neostore.relationshipstore.db.mapped_memory=100M
neostore.propertystore.db.mapped_memory=180M
neostore.propertystore.db.strings.mapped_memory=260M
neostore.propertystore.db.arrays.mapped_memory=260M
*Server info:*
HeapMemoryUsage
committed 4260102144
init 4294967296
max 4260102144
used 302304640
NonHeapMemoryUsage
committed 64909312
init 24313856
max 136314880
used 54561464
*Size of database*
Primitive count
NumberOfRelationshipIdsInUse 1294128
NumberOfNodeIdsInUse 55746
NumberOfPropertyIdsInUse 55036
NumberOfRelationshipTypeIdsInUse 11
*Model*
about 10k :jurt (= some kind of document) nodes and 12k :Term nodes, with
about 1.2M (jurt)-[:HAS_TERM]->(term) rels
*Use*
Find similar jurts based on number of common terms, like this:
match (j1:jurt)-[:HAS_TERM]->(t:Term)<-[:HAS_TERM]-(j2:jurt)
where NOT j1=j2 AND j1.jurt_id = {jurtid}
with j1,j2,count(t) as commonterms
return j1.jurt_id,j2.jurt_id,commonterms
order by commonterms desc
limit 3
the query above takes 5-6 secs, way too long I guess.
*Query plan*
{
"columns" : [ "j1.jurt_id", "j2.jurt_id", "commonterms" ],
"data" : [ [ "J70000", "J72191", 68 ], [ "J70000", "J73483", 67 ], [
"J70000", "J72924", 66 ] ],
"plan" : {
"args" : {
"returnItemNames" : [ "j1.jurt_id", "j2.jurt_id", "commonterms" ],
"_rows" : 3,
"_db_hits" : 0,
"symKeys" : [ "j1", "j2.jurt_id", "j1.jurt_id", "commonterms", "j2" ]
},
"dbHits" : 0,
"name" : "ColumnFilter",
"children" : [ {
"args" : {
"limit" : "Literal(3)",
"orderBy" : [ "SortItem(commonterms,false)" ],
"_rows" : 3,
"_db_hits" : 0
},
"dbHits" : 0,
"name" : "Top",
"children" : [ {
"args" : {
"_rows" : 9992,
"_db_hits" : 19984,
"exprKeys" : [ "j1.jurt_id", "j2.jurt_id" ],
"symKeys" : [ "j1", "j2", "commonterms" ]
},
"dbHits" : 19984,
"name" : "Extract",
"children" : [ {
"args" : {
"returnItemNames" : [ "j1", "j2", "commonterms" ],
"_rows" : 9992,
"_db_hits" : 0,
"symKeys" : [ "j1", "j2", "
INTERNAL_AGGREGATE8b273443-699b-4262-8a48-41d7a316fa44" ]
},
"dbHits" : 0,
"name" : "ColumnFilter",
"children" : [ {
"args" : {
"keys" : [ "j1", "j2" ],
"_rows" : 9992,
"aggregates" : [ "(
INTERNAL_AGGREGATE8b273443-699b-4262-8a48-41d7a316fa44,Count(t))" ],
"_db_hits" : 0
},
"dbHits" : 0,
"name" : "EagerAggregation",
"children" : [ {
"args" : {
"_rows" : 478380,
"_db_hits" : 0,
"pred" : "(NOT(j1 == j2) AND hasLabel(j2:jurt(3)))"
},
"dbHits" : 0,
"name" : "Filter",
"children" : [ {
"args" : {
"start" : {
"identifiers" : [ "j1" ],
"query" : "{jurtid}",
"producer" : "SchemaIndex",
"property" : "jurt_id",
"label" : "jurt"
},
"trail" : "(j1)-[ UNNAMED15:HAS_TERM WHERE
(hasLabel(NodeIdentifier():Term(1)) AND hasLabel(NodeIdentifier():Term(1)))
AND true]->(t)<-[ UNNAMED37:HAS_TERM WHERE
hasLabel(NodeIdentifier():jurt(3)) AND true]-(j2)",
"_rows" : 478380,
"_db_hits" : 478518
},
"dbHits" : 478518,
"name" : "TraversalMatcher",
"children" : [ ],
"rows" : 478380
} ],
"rows" : 478380
} ],
"rows" : 9992
} ],
"rows" : 9992
} ],
"rows" : 9992
} ],
"rows" : 3
} ],
"rows" : 3
}
}
Every time I change the value of the {jurtid} param, the first run of the
query returns different results then the subsequent runs
When I provide two params, like this:
match (j1:jurt)-[:HAS_TERM]->(t:Term)<-[:HAS_TERM]-(j2:jurt)
where NOT j1=j2 AND ((j1.jurt_id = {id1}) OR (j1.jurt_id = {id2}))
with j1,j2,count(t) as commonterms
return j1.jurt_id,j2.jurt_id,commonterms
order by commonterms desc limit 3
it doesn't even return anything in the shell in the browser I get an
"Unknown error"
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