Neo4j Cypher query sort order -

in neo4j/sdn project have following mode:

decision entity contains child decision , characteristic entities.

each pair of child decision , characteristic can have value node assigned.

i have created 3 child decision nodes, example

childdecision1 childdecision2 childdecision3 

and 1 characteristic:

characterisitc1

i have assigned following values following pairs:

childdecision2 + characterisitc1 = value(integer 10) childdecision3 + characterisitc1 = value(integer 25) 

i'm executing following cypher query(with order sortvalue88.value asc):

match (parentd)-[:contains]->(childd:decision)-[ru:created_by]->(u:user)  id(parentd) = {decisionid}  optional match (childd)<-[:set_for]->(sortvalue88:value)-[:set_on]->(sortcharacteristic88:characteristic)  id(sortcharacteristic88) = 88 ru, u, childd , sortvalue88  order sortvalue88.value asc skip 0 limit 100  return ru, u, childd decision, [ (parentd)<-[:defined_by]-(entity)<-[:commented_on]-(comg:commentgroup)-[:commented_for]->(childd) | {entityid: id(entity),  types: labels(entity), totalcomments: toint(comg.totalcomments)} ] commentgroups, [ (parentd)<-[:defined_by]-(c1:criterion)<-[:voted_on]-(vg1:votegroup)-[:voted_for]->(childd) | {criterionid: id(c1),  weight: vg1.avgvotesweight, totalvotes: toint(vg1.totalvotes)} ] weightedcriteria, [ (parentd)<-[:defined_by]-(ch1:characteristic)<-[:set_on]-(v1:value)-[:set_for]->(childd) | {characteristicid: id(ch1),  value: v1.value, valuetype: ch1.valuetype, visualmode: ch1.visualmode} ] valuedcharacteristics 

as result have:

childdecision2 (value = 10) childdecision3 (value = 25) childdecision1 (no value provided) 

so far works fine.

right i'm going change sort order direction asc desc:

match (parentd)-[:contains]->(childd:decision)-[ru:created_by]->(u:user)  id(parentd) = {decisionid} optional match (childd)<-[:set_for]->(sortvalue88:value)-[:set_on]->(sortcharacteristic88:characteristic)  id(sortcharacteristic88) = 88 ru, u, childd , sortvalue88  order sortvalue88.value desc skip 0 limit 100  return ru, u, childd decision, [ (parentd)<-[:defined_by]-(entity)<-[:commented_on]-(comg:commentgroup)-[:commented_for]->(childd) | {entityid: id(entity),  types: labels(entity), totalcomments: toint(comg.totalcomments)} ] commentgroups, [ (parentd)<-[:defined_by]-(c1:criterion)<-[:voted_on]-(vg1:votegroup)-[:voted_for]->(childd) | {criterionid: id(c1),  weight: vg1.avgvotesweight, totalvotes: toint(vg1.totalvotes)} ] weightedcriteria, [ (parentd)<-[:defined_by]-(ch1:characteristic)<-[:set_on]-(v1:value)-[:set_for]->(childd) | {characteristicid: id(ch1),  value: v1.value, valuetype: ch1.valuetype, visualmode: ch1.visualmode} ] valuedcharacteristics 

as result have:

childdecision1 (no value provided) childdecision3 (value = 25) childdecision2 (value = 10) 

right don't understand why childdecision1 hold first place expect childdecision3 instead there.

could please explain/fix behavior ?

because: when sorting result set, null come @ end of result set ascending sorting, , first when doing descending sort.

so need know minimum possible value sorting. example, if values not less zero

with [1, 0, 2, null, 4] cs unwind range(0, size(cs)-1) return i,         case when cs[i] null -1 else cs[i] end sortvalue order sortvalue desc