查询neo4j索引时获取NotInTransactionException [英] Getting NotInTransactionException while querying neo4j index

问题描述

我当前正在使用neo4j 1.8.1.当我查询neo4j索引以获取一些节点时，我得到了NotInTransactionException.

I am currently using neo4j 1.8.1 . I am getting NotInTransactionException , when I am querying the neo4j index to get some nodes.

以下是一个简单的查询，我正在neo4j上执行

Following is a simple query , which i am executing on neo4j

 if (graphDb.index().existsForNodes("NODEINDEX")) {
  IndexHits<Node> hits = graphDb.index().forNodes(NODEINDEX).query(query);
}

以下是异常的堆栈跟踪.

The following is stacktrace for the exception.

"message" : "Error fetching transaction for current thread",
"exception" : "NotInTransactionException",
"stacktrace" : [ "org.neo4j.kernel.impl.index.IndexConnectionBroker.getCurrentTransaction(IndexConnectionBroker.java:134)", "org.neo4j.kernel.impl.index.IndexConnectionBroker.acquireReadOnlyResourceConnection(IndexConnectionBroker.java:84)", "org.neo4j.index.impl.lucene.LuceneIndex.getReadOnlyConnection(LuceneIndex.java:105)", "org.neo4j.index.impl.lucene.LuceneIndex.query(LuceneIndex.java:245)", "org.neo4j.index.impl.lucene.LuceneIndex.query(LuceneIndex.java:227)", "org.neo4j.index.impl.lucene.LuceneIndex.query(LuceneIndex.java:238)", "com.uprr.netcontrol.starmap.neo4j.plugins.aggregate_node_status.NodeStatusHelper.getGraphNodes(NodeStatusHelper.java:39)", 

我在Neo4j api中发现了以下内容.

I found the following in Neo4j api.

 private Transaction getCurrentTransaction() throws NotInTransactionException
{
    try
    {
        return transactionManager.getTransaction();
    }
    catch ( SystemException se )
    {
        throw new NotInTransactionException(
                "Error fetching transaction for current thread", se );
    }
}

我们是否需要显式启动事务以查询neo4j索引?
有什么想法吗?
谢谢

Do we need to explicitly start a transaction for querying neo4j index?
Any thoughts?
Thanks

推荐答案

这里是一个理论:我不知道这只是粘贴在这里的代码的问题，而是检查:

Here's a theory: I don't know if this is only an issue with the code pasted here but the check:

if (graphDb.index().existsForNodes("NODEINDEX"))

检查名为"NODEINDEX"的索引，但检查实际的查询

checks for the index named "NODEINDEX", however the actual query

graphDb.index().forNodes(NODEINDEX).query(query);

检查常量NODEINDEX中是否命名的索引.这两个可能不相同，因此它会尝试为您创建该索引，但由于未进行交易而失败.

checks for the index named whatever is in the constant NODEINDEX. Those two are probably not the same and so it tries to create that index for you and fails due to not being in a transaction.

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