Hi sqlalchemy!
When using sqlalchemy (core) 1.0.8 with redshift-sqlalchemy 0.4.1, I
encountered the following exception:
InternalError: (psycopg2.InternalError) cache lookup failed for relation
3262644
This is the query it failed on:
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', 'm', 'f')
Our hypothesis is that another process operating on the same Redshift
cluster (which runs a table shuffling process and deletes tables), is
causing our code to error during schema reflection. Does this sound correct
to you, and if so, is there a way for our code to mitigate this issue?
Thanks, Matt Smith
Here's the relevant portion of the stack trace:
... snip ...
engine, meta = ENGINES.get('redshift'), ENGINES.get_meta('redshift')
File "ourcode.py", line 38, in get_meta
meta.reflect(bind=self.get(name))
File "sqlalchemy/sql/schema.py", line 3647, in reflect
Table(name, self, **reflect_opts)
File "sqlalchemy/sql/schema.py", line 416, in __new__
metadata._remove_table(name, schema)
File "sqlalchemy/util/langhelpers.py", line 60, in __exit__
compat.reraise(exc_type, exc_value, exc_tb)
File "sqlalchemy/sql/schema.py", line 411, in __new__
table._init(name, metadata, *args, **kw)
File "sqlalchemy/sql/schema.py", line 484, in _init
self._autoload(metadata, autoload_with, include_columns)
File "sqlalchemy/sql/schema.py", line 496, in _autoload
self, include_columns, exclude_columns
File "sqlalchemy/engine/base.py", line 1477, in run_callable
return callable_(self, *args, **kwargs)
File "sqlalchemy/engine/default.py", line 364, in reflecttable
return insp.reflecttable(table, include_columns, exclude_columns)
File "sqlalchemy/engine/reflection.py", line 563, in reflecttable
table_name, schema, **table.dialect_kwargs):
File "sqlalchemy/engine/reflection.py", line 369, in get_columns
**kw)
File "<string>", line 2, in get_columns
File "sqlalchemy/engine/reflection.py", line 54, in cache
ret = fn(self, con, *args, **kw)
File "sqlalchemy/dialects/postgresql/base.py", line 2325, in get_columns
info_cache=kw.get('info_cache'))
File "<string>", line 2, in get_table_oid
File "sqlalchemy/engine/reflection.py", line 54, in cache
ret = fn(self, con, *args, **kw)
File "sqlalchemy/dialects/postgresql/base.py", line 2220, in get_table_oid
c = connection.execute(s, table_name=table_name, schema=schema)
File "sqlalchemy/engine/base.py", line 914, in execute
return meth(self, multiparams, params)
File "sqlalchemy/sql/elements.py", line 323, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File "sqlalchemy/engine/base.py", line 1010, in _execute_clauseelement
compiled_sql, distilled_params
File "sqlalchemy/engine/base.py", line 1146, in _execute_context
context)
File "sqlalchemy/engine/base.py", line 1341, in _handle_dbapi_exception
exc_info
File "sqlalchemy/util/compat.py", line 199, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File "sqlalchemy/engine/base.py", line 1139, in _execute_context
context)
File "sqlalchemy/engine/default.py", line 450, in do_execute
cursor.execute(statement, parameters)
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