OrientDB導入Neo4j（官方Importer使用）

最近在研究圖計算相關技術，前一階段學了Neo4j的知識，在學習的過程也對比一些其它的開源圖數據庫，如OrientDB，還有一些通用框架TinkerPop。

在OrientDB的對比學習過程當中，但願首先把已有的數據導入到新的數據庫中，還好OrientDB官方提供了Neo4j數據導入工具orientdb-neo4j-importer。然而一切皆有坑...

按照官方文檔進行數據導入，執行命令：

sh orientdb-neo4j-importer-2.2.31/bin/orientdb-neo4j-importer.sh -neo4jdbdir ../graph.db/ -neo4jlibdir ../neo4jlib/

出現如下報錯：

Exception in thread "main" java.lang.NoClassDefFoundError: com/orientechnologies/orient/core/OConstants
    at com.orientechnologies.orient.neo4jimporter.ONeo4jImporterMain.main(ONeo4jImporterMain.java:15)
Caused by: java.lang.ClassNotFoundException: com.orientechnologies.orient.core.OConstants
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 1 more

嘗試把importer/lib/orientdb-neo4j-importer-2.2.31.jar拷貝到orientdb安裝目錄的lib文件夾下，再次執行仍是一樣的報錯。

查看源代碼也沒發現此處有問題，再經過sh打印詳細信息發現環境變量ORIENTDB_HOME設置有問題，執行如下命令定義環境變量：

export ORIENTDB_HOME=/root/orientdb-community-importers-2.2.31

再次執行命令，順利經過！

[root@datanode orientdb-community-importers-2.2.31]# sh -x orientdb-neo4j-importer-2.2.31/bin/orientdb-neo4j-importer.sh -neo4jdbdir ../graph.db/ -neo4jlibdir ../neo4jlib/
+ PRG=orientdb-neo4j-importer-2.2.31/bin/orientdb-neo4j-importer.sh
+ '[' -h orientdb-neo4j-importer-2.2.31/bin/orientdb-neo4j-importer.sh ']'
++ dirname orientdb-neo4j-importer-2.2.31/bin/orientdb-neo4j-importer.sh
+ PRGDIR=orientdb-neo4j-importer-2.2.31/bin
+ '[' -f /root/orientdb-community-importers-2.2.31/lib/orientdb-neo4j-importer-2.2.31.jar ']'
+ export ORIENTDB_HOME
+ '[' -f /usr/java/jdk1.8.0_91/bin/java ']'
+ JAVA=/usr/java/jdk1.8.0_91/bin/java
+ export JAVA
+ LOG_FILE=/root/orientdb-community-importers-2.2.31/config/orientdb-neo4j-importer-log.properties
+ JAVA_MAX_DIRECT=-XX:MaxDirectMemorySize=512g
+ JAVA_OPTS_SCRIPT='-XX:MaxDirectMemorySize=512g -Djava.util.logging.config.file=/root/orientdb-community-importers-2.2.31/config/orientdb-neo4j-importer-log.properties'
+ ARGS=
+ for var in '"$@"'
+ ARGS=' -neo4jdbdir'
+ for var in '"$@"'
+ ARGS=' -neo4jdbdir ../graph.db/'
+ for var in '"$@"'
+ ARGS=' -neo4jdbdir ../graph.db/ -neo4jlibdir'
+ for var in '"$@"'
+ ARGS=' -neo4jdbdir ../graph.db/ -neo4jlibdir ../neo4jlib/'
+ [[ 4 -gt 1 ]]
+ key=-neo4jdbdir
+ case $key in
+ shift
+ [[ 3 -gt 1 ]]
+ key=../graph.db/
+ case $key in
+ shift
+ [[ 2 -gt 1 ]]
+ key=-neo4jlibdir
+ case $key in
+ NEO4JLIB=../neo4jlib/
+ shift
+ shift
+ [[ 0 -gt 1 ]]
+ exec /usr/java/jdk1.8.0_91/bin/java -client -cp '../neo4jlib//*:/root/orientdb-community-importers-2.2.31/lib/*' -XX:MaxDirectMemorySize=512g -Djava.util.logging.config.file=/root/orientdb-community-importers-2.2.31/config/orientdb-neo4j-importer-log.properties com.orientechnologies.orient.neo4jimporter.ONeo4jImporterMain -neo4jdbdir ../graph.db/ -neo4jlibdir ../neo4jlib/

Neo4j to OrientDB Importer v.2.2.31 (build 285537d2767275f460df32c6a3be01bfff6a517c, branch 2.2.x) - Copyrights (c) 2016 OrientDB LTD

WARNING: 'o' option not found. Defaulting to 'false'.

WARNING: 'i' option not found. Defaulting to 'false'.

WARNING: 'odbdir' option not found. Defaulting to '/root/databases/neo4j_import'.

Please make sure that there are no running servers on:
  '../graph.db' (Neo4j)
and:
  '/root/databases/neo4j_import' (OrientDB)

Initializing Neo4j...Done

Initializing OrientDB...Done

Importing Neo4j database:
  '../graph.db'
into OrientDB database:
  '/root/databases/neo4j_import'

Getting all Nodes from Neo4j and creating corresponding Vertices in OrientDB...
  4 OrientDB Vertices have been created (100% done)
Done

Creating internal Indices on properties 'Neo4jNodeID' & 'Neo4jLabelList' on all OrientDB Vertices Classes...
  4 OrientDB Indices have been created (100% done)
Done

Getting all Relationships from Neo4j and creating corresponding Edges in OrientDB...
  2 OrientDB Edges have been created (100% done)
Done

Getting Constraints from Neo4j and creating corresponding ones in OrientDB...
  0 OrientDB UNIQUE Indices have been created
Done

Getting Indices from Neo4j and creating corresponding ones in OrientDB...
  0 OrientDB Indices have been created
Done

Import completed!

Shutting down OrientDB...Done
Shutting down Neo4j...Done

===============
Import Summary:
===============

- Found Neo4j Nodes                                                                           : 4
-- With at least one Label                                                                    :  4
--- With multiple Labels                                                                      :   0
-- Without Labels                                                                             :  0
- Imported OrientDB Vertices                                                                  : 4 (100%)

- Found Neo4j Relationships                                                                   : 2
- Imported OrientDB Edges                                                                     : 2 (100%)

- Found Neo4j Constraints                                                                     : 0
- Imported OrientDB Constraints (UNIQUE Indices created)                                      : 0
- NOT UNIQUE Indices created due to failure in creating UNIQUE Indices                        : 0

- Found Neo4j (non-constraint) Indices                                                        : 0
- Imported OrientDB Indices                                                                   : 0

- Additional internal Indices created                                                         : 4

- Total Import time:                                                                          : 6 seconds
-- Initialization time                                                                        :  5 seconds
-- Time to Import Nodes                                                                       :  0 seconds (35.4 nodes/sec)
-- Time to Import Relationships                                                               :  0 seconds (22.47 rels/sec)
-- Time to Import Constraints and Indices                                                     :  0 seconds (0 indices/sec)
-- Time to Create Internal Indices (on vertex properties 'Neo4jNodeID' & 'Neo4jLabelList')    :  1 seconds (7.01 indices/sec)

覺得一切搞定，啓動OrientDB數據庫，並無看到新導入的數據庫... 再仔細查看發現沒有添加選項-odbdir（可是默認值應該是DB_HOME/databases/neo4j_import，不知道爲什麼沒有生效...），數據庫導入到其它路徑下，拷貝過來後能夠正常使用了。

（如圖，neo4j_import數據庫）