py2neo缓存烧死了我吗? [英] Is py2neo caching burning me?

问题描述

我正在运行以下代码:

c = """
    match(r:XX)
    optional match(r)-[]-(m) with count(m) as mc, r match(x)
    return count(x) as all, r, mc
    """
        (snip!)
        while(True):
            tx = remote_graph.cypher.begin()
            res = remote_graph.cypher.execute(c)
            tx.rollback()
            time.sleep(15)
        (snip!)

事实上，XX节点的属性每秒都在变化-守护进程正在运行.但是，当我运行此命令时，总是在res 中获得相同的值，但仅对于r -all正在更改.查询没有改变.我想知道py2neo是否注意到了这一点并且没有执行查询，但是返回的是缓存副本吗?如果是这样，我该如何阻止这种情况发生?

I know for a fact the XX node's properties are changing every second - there a daemon running. However, when I run this, I always get the same values back in res but for r only - all is changing. The query isn't changing. I wonder if py2neo is noticing this and not executing the query, but is returning me a cached copy? If so, how do I stop this from happening?

编辑-更多信息-我从ipython中运行了以上内容.

EDIT - more info - I ran the above from within ipython.

推荐答案

有趣的是，当您返回节点时，py2neo会记住"该节点:

Interesting enough, py2neo 'remembers' the node when you return the node:

MATCH (n:Node) RETURN n

但是当您返回单个属性时，它们将始终被更新:

But when you return individual properties, they will always be updated:

MATCH (n:Node) RETURN n.value

对于您的查询，这意味着在while循环中两次返回同一节点时必须运行my_node.pull():

For your query that means you have to run my_node.pull() when you return the same node twice in a while loop:

while True:
    q = "MATCH (n:Node) RETURN n"
    result = graph.cypher.execute(q)
    my_node = result[0][0]
    my_node.pull()
    print(my_node)

您还可以将pull()以外的所有内容移出循环:

You can also move everything besides the pull() out of the loop:

q = "MATCH (n:Node) RETURN n"
result = graph.cypher.execute(q)
my_node = result[0][0]

while True:
    my_node.pull()
    print(my_node)

这是描述行为的最小示例: http://paste.ubuntu.com/14015568/

Here is a minimal example describing the behaviour: http://paste.ubuntu.com/14015568/

我不太确定为什么py2neo在运行新查询时为什么不返回更新的节点数据.

I'm not really sure why py2neo does not return updated node data when you run a new query.

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