Question

我正在使用psycopg2从python访问postgresql数据库。当我尝试为最短路径运行pgrouting函数“pgr_astar”时，我收到错误

cur = db.cursor()
psycopg2.InterfaceError: connection already closed

基本上，发生的事情是：当pgr_astar找不到两点之间的路径时，会造成数据库崩溃，并关闭与数据库的连接。

如何避免这种情况？

我尝试用try / except隔离函数并创建自己的连接，所以如果关闭则没问题：

conn = psycopg2.connect(...)
try:
    result = getRecords(conn,query_pgr_astar)
    return float(result[0]['sum'])
except:
    return 500000000.0
conn.close()

但是在这种情况下我收到了

cur.execute(query)
psycopg2.DatabaseError: SSL SYSCALL error: EOF detected

如何管理不可能的路径？

（我对pgdb和旧的shortest_path_astar函数做了同样的事情（我不再使用），我没有问题）

Postgresql日志是：

2013-11-27 15:54:35 CET LOG:  terminating any other active server processes
2013-11-27 15:54:35 CET WARNING:  terminating connection because of crash of another server process
2013-11-27 15:54:35 CET DETAIL:  The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
2013-11-27 15:54:35 CET HINT:  In a moment you should be able to reconnect to the database and repeat your command.
2013-11-27 15:54:35 CET WARNING:  terminating connection because of crash of another server process
2013-11-27 15:54:35 CET DETAIL:  The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
2013-11-27 15:54:35 CET HINT:  In a moment you should be able to reconnect to the database and repeat your command.
2013-11-27 15:54:35 CET LOG:  all server processes terminated; reinitializing
2013-11-27 15:54:35 CET LOG:  database system was interrupted; last known up at 2013-11-27 15:42:01 CET
2013-11-27 15:54:35 CET LOG:  database system was not properly shut down; automatic recovery in progress
2013-11-27 15:54:35 CET LOG:  record with zero length at 65/80875D60
2013-11-27 15:54:35 CET LOG:  redo is not required
2013-11-27 15:54:35 CET LOG:  autovacuum launcher started
2013-11-27 15:54:35 CET LOG:  database system is ready to accept connections

我所做的查询是：

SELECT SUM(t2.length) FROM (SELECT id2 FROM pgr_astar('SELECT edge_id AS id, vertex_id1 AS source, vertex_id2 AS target, ' || '(CASE WHEN door = ''S'' THEN -1.0  ELSE  (length * (CASE network WHEN ''0'' THEN 1.0  WHEN ''10'' THEN 1.2  WHEN ''20'' THEN 1.5  WHEN ''30'' THEN 2.0  ELSE 1.0  END) *  (CASE type WHEN ''9.1'' THEN CASE WHEN level1 < level2 THEN 3.0 ELSE 2.0 END  WHEN ''9.2'' THEN CASE WHEN level1 < level2 THEN 15.0 ELSE 12.0 END  ELSE 1.0  END) +  (CASE type WHEN ''9.3'' THEN 40.0  ELSE 0.0  END)  )  END)::float8 AS cost, ' || '(CASE WHEN door_rev = ''S'' THEN -1.0  ELSE  (length * (CASE network WHEN ''0'' THEN 1.0  WHEN ''10'' THEN 1.2  WHEN ''20'' THEN 1.5  WHEN ''30'' THEN 2.0  ELSE 1.0  END) *  (CASE type WHEN ''9.1'' THEN CASE WHEN level1 < level2 THEN 3.0 ELSE 2.0 END  WHEN ''9.2'' THEN CASE WHEN level1 < level2 THEN 15.0 ELSE 12.0 END  ELSE 1.0  END) +  (CASE type WHEN ''9.3'' THEN 40.0  ELSE 0.0  END)  )  END )::float8 AS reverse_cost, ' || 'x1, y1, x2, y2 FROM edges', " + str(destination_route) + ", " + str(origin_route) + ", TRUE, TRUE)) as t1, edges as t2 where t1.id2 = t2.edge_id

door =''S''表示门关闭，在这种情况下，值为-1。

Answer 1

我假设您可以在python中检查您的连接状态（我不使用python），这样您就可以恢复并做一些合理的事情，比如重新连接。在重新连接之前，您可能需要休眠几秒钟才能使数据库从崩溃中恢复。

关于pgrouting问题，我希望看到一个简单的测试用例可以在pgadmin或psql shell中重现这个问题，并将其作为bug提交，以便我可以查看它。我们的代码永远不会崩溃服务器，但有时它确实会崩溃，我们需要解决这些问题。

psycopg2.InterfaceError：连接已关闭/ pgr_astar

1 个答案: