SQLAlchemy与PostgreSQL出现错误“无法找到行中的列'attype'”
我正在使用SQLAlchemy来连接一个PostgreSQL数据库。我执行了:
>>> my_engine = create_engine("postgresql://username@localhost:5432/dbname")
>>> my_metadata = MetaData(bind = my_engine)
(这个数据库没有设置密码。)这些操作都没有问题,但我却无法获取表的结构:
>>> my_metadata.reflect()
然后我遇到了这个错误:
sqlalchemy.exc.NoSuchColumnError: "Could not locate column in row for column 'attype'"
是什么原因导致这个问题,我该怎么解决呢?看起来像是和数据库结构有关,但我搞不清楚。我可以顺利连接到MySQL数据库并获取表的结构,没有任何问题。
补充说明:SqlAlchemy版本是0.9.2,psql服务器是9.2.5,psql客户端是8.4.13,psycopg2版本是2.5.1
补充说明:设置了echo=True
INFO:root:Creating music_engine postgresql://postgres@localhost/musicbrainz_db
INFO:sqlalchemy.engine.base.Engine:select version()
INFO:sqlalchemy.engine.base.Engine:{}
INFO:sqlalchemy.engine.base.Engine:select current_schema()
INFO:sqlalchemy.engine.base.Engine:{}
INFO:sqlalchemy.engine.base.Engine:SELECT CAST('test plain returns' AS VARCHAR(60)) AS anon_1
INFO:sqlalchemy.engine.base.Engine:{}
INFO:sqlalchemy.engine.base.Engine:SELECT CAST('test unicode returns' AS VARCHAR(60)) AS anon_1
INFO:sqlalchemy.engine.base.Engine:{}
INFO:sqlalchemy.engine.base.Engine:show standard_conforming_strings
INFO:sqlalchemy.engine.base.Engine:{}
INFO:sqlalchemy.engine.base.Engine:SELECT relname FROM pg_class c WHERE relkind = 'r' AND 'echonest' = (select nspname from pg_namespace n where n.oid = c.re
lnamespace)
INFO:sqlalchemy.engine.base.Engine:{}
INFO:sqlalchemy.engine.base.Engine:
SELECT c.oid
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE (pg_catalog.pg_table_is_visible(c.oid))
AND c.relname = %(table_name)s AND c.relkind in ('r','v')
INFO:sqlalchemy.engine.base.Engine:{'table_name': u'status'}
INFO:sqlalchemy.engine.base.Engine:
SELECT a.attname,
pg_catalog.format_type(a.atttypid, a.atttypmod),
(SELECT pg_catalog.pg_get_expr(d.adbin, d.adrelid)
FROM pg_catalog.pg_attrdef d
WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum
AND a.atthasdef)
AS DEFAULT,
a.attnotnull, a.attnum, a.attrelid as table_oid
FROM pg_catalog.pg_attribute a
WHERE a.attrelid = %(table_oid)s
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
INFO:sqlalchemy.engine.base.Engine:{'table_oid': 19271}
INFO:sqlalchemy.engine.base.Engine:
SELECT t.typname as "name",
pg_catalog.format_type(t.typbasetype, t.typtypmod) as "attype",
not t.typnotnull as "nullable",
t.typdefault as "default",
pg_catalog.pg_type_is_visible(t.oid) as "visible",
n.nspname as "schema"
FROM pg_catalog.pg_type t
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = t.typnamespace
WHERE t.typtype = 'd'
INFO:sqlalchemy.engine.base.Engine:{}
1 个回答
1
这个问题确实和版本有关,但主要是和Python和psycopg2有关,而不是SQLAlchemy或PostgresQL。
我在我的python2.6的库里安装了SQLAlchemy。我设置了PYTHONPATH,所以我以为用python2.6还是python2.7都没关系。然而,实际上是有关系的,因为SQLAlchemy总是会调用python2.6的psycopg2,而为python2.6编译的psycopg2的本地部分和python2.7不兼容。