util for janusgraph to import data and so on
--into /path/to/data \
--janus-config-file janusgraph.properties \
--skip-duplicate-nodes true \
--skip-bad-edges true \
--ignore-extra-columns true \
--ignore-empty-strings true \
--bulk-loading true \
--bad-tolerance 10000000 \
--processors 1 \
--id-type string \
--max-memory 2G \
--drop-keyspace-if-exists true \
--nodes:titan src/main/resources/v_titan.csv \
--nodes:location src/main/resources/v_location.csv \
--nodes:god src/main/resources/v_god.csv \
--nodes:demigod src/main/resources/v_demigod.csv \
--nodes:human src/main/resources/v_human.csv \
--nodes:monster src/main/resources/v_monster.csv \
--edges:father src/main/resources/e_god_titan_father.csv \
--edges:father src/main/resources/e_demigod_god_father.csv \
--edges:mother src/main/resources/e_demigod_human_mother.csv \
--edges:lives src/main/resources/e_god_location_lives.csv \
--edges:lives src/main/resources/e_monster_location_lives.csv \
--edges:brother src/main/resources/e_god_god_brother.csv \
--edges:battled src/main/resources/e_demigod_monster_battled.csv \
--edges:pet src/main/resources/e_god_monster_pet.csv
> /path/to/log.log 2>&1 &into : to specify a directory to store SSTable files, this directory should not exists
janus-config-file : to specify your janusgraph config file, you can use janus-config:key value to specify every key
janus-config:key :to specify your janusgraph config if --janus-config-file is missing
ignore-empty-strings : empty strings in csv file will be ignored
bulk-loading: if true, will generator SSTable(cassandra) or HFile(Hbase) instead of insert one by one; if false, vertices and edges will be inserted into DB one by one through transaction.
max-memory: the max offheap memory, this should be lager than 64*NumberOfNodes
processors: Number of Thread
drop-keyspace-if-exists: this should only be used when test
bad-tolerance : if the edge data can't be found in vertex data, it is an bad data bad-tolerance means how many we can tolerance
nodes:key value: the key is the vertex Label, and the value is the csv file, more than one file should separate by ",", for expmple:--nodes:food "food_header.csv,food_fruit.csv,food_meat.csv,food_other.csv"
edges:key value: similar to nodes.
id-type string :this is necessary, and now we just support string as id.
csv file header of node files, for example name:ID(god),age:Int, name is the property, and it is a primary key of node so
there is ID behind name, and the (god) represent Label, it's unnecessary sometimes.
csv file header of edge files, for example god:START_ID(god),monster:END_ID(monster), START_ID means the start node
of the edge, END_ID means the end node of the edge, (god) and (monster) represent the label of nodes,
god and monster are property name, which are meaningless, so you can use :START_ID(god),:END_ID(monster) instead.
if you set bulk-loading=true, you can just use Cassandra as backend db.
if you set bulk-loading=false, you can use any bigtable that janusgraph support as backend.
if you got error like this:Input error: Could not find implementation class: org.janusgraph.diskstorage.cql.CQLStoreManager
you can add some dependency to pom.xml
<groupId>org.janusgraph</groupId>
<artifactId>janusgraph-cql</artifactId>直接使用命令运行就可以，注意配置项 bulk-loading 默认为 false，如果改成 true，可以实现快速导数据到 Cassandra， 原理是使用Cassandra提供的 SSTableloader。目前只支持 Cassandra 的快速导入，Hbase 的 HFile 无法完成。 如果 bulk-loading 设置为 false，则会一条一条插入 数据库，使用任何一种 JanusGraph 支持的后端存储都可以。
- 如果配置为 false 会使用
TxImportStoreImpl，会将数据写入 janusgraph，支持所有的存储。 - 如果配置为 true 会使用
BulkImportStoreImpl就会将数据写为 SSTable，然后需要使用命令行导入cassandra，目前只支持 Cassandra。 - 注意 cassandra 的 SSTableWriter 有 bug，如果数据量大会出错。
如果有类似的错误： Input error: Could not find implementation class: org.janusgraph.diskstorage.cql.CQLStoreManager。 很明显是因为你 bulk-loading 设置为 false 然后使用了 CQLStoreManager 写数据，但是没有加入 CQLStoreManager 的依赖。只需要加上即可：
<groupId>org.janusgraph</groupId>
<artifactId>janusgraph-cql</artifactId>these code are most copy from neo4j ![http://github.com/Neo4j/neo4j] ,so you can only use it for learn instead of commercial purpose 代码是从neo4j复制过来进行的修改，所以只能用于学习不能商用