William Jamir
12/04/2024, 2:09 PMasyncpg/connection.py", line 2027, in _do_execute
result = await executor(stmt, timeout)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "asyncpg/protocol/protocol.pyx", line 206, in bind_execute
asyncpg.exceptions.InvalidSQLStatementNameError: prepared statement "__asyncpg_stmt_2__" does not exist
HINT:
NOTE: pgbouncer with pool_mode set to "transaction" or
"statement" does not support prepared statements properly.
You have two options:
* if you are using pgbouncer for connection pooling to a
single server, switch to the connection pool functionality
provided by asyncpg, it is a much better option for this
purpose;
* if you have no option of avoiding the use of pgbouncer,
then you can set statement_cache_size to 0 when creating
the asyncpg connection object.
But I cannot disaplbe this and I need to use statement_cache_size in my URL
BUT if I try to append this to URL connection ?statemente_cache_size=0
I got the following error:
asyncpg/connect_utils.py", line 731, in _parse_connect_arguments
if var_val is None or isinstance(var_val, bool) or var_val < 0:
^^^^^^^^^^^
How can I start Prefect server to work with a postgres server that has pgbouncer on front of it without using session connection?Marvin
12/04/2024, 2:09 PMI have pgbouncer in front of my postgres instance and I got the following error when starting the server.
asyncpg/connection.py", line 2027, in _do_execute
result = await executor(stmt, timeout)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "asyncpg/protocol/protocol.pyx", line 206, in bind_execute
asyncpg.exceptions.InvalidSQLStatementNameError: prepared statement "__asyncpg_stmt_2__" does not exist
HINT:
NOTE: pgbouncer with pool_mode set to "transaction" or
"statement" does not support prepared statements properly.
You have two options:
* if you are using pgbouncer for connection pooling to a
single server, switch to the connection pool functionality
provided by asyncpg, it is a much better option for this
purpose;
* if you have no option of avoiding the use of pgbouncer,
then you can set statement_cache_size to 0 when creating
the asyncpg connection object.
But I cannot disaplbe this and I need to use statement_cache_size in my URL
BUT if I try to append this to URL connection ?statemente_cache_size=0
I got the following error:
asyncpg/connect_utils.py", line 731, in _parse_connect_arguments
if var_val is None or isinstance(var_val, bool) or var_val < 0:
^^^^^^^^^^^
William Jamir
12/04/2024, 2:09 PMasyncpg/connection.py", line 2027, in _do_execute
result = await executor(stmt, timeout)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "asyncpg/protocol/protocol.pyx", line 206, in bind_execute
asyncpg.exceptions.InvalidSQLStatementNameError: prepared statement "__asyncpg_stmt_2__" does not exist
HINT:
NOTE: pgbouncer with pool_mode set to "transaction" or
"statement" does not support prepared statements properly.
You have two options:
* if you are using pgbouncer for connection pooling to a
single server, switch to the connection pool functionality
provided by asyncpg, it is a much better option for this
purpose;
* if you have no option of avoiding the use of pgbouncer,
then you can set statement_cache_size to 0 when creating
the asyncpg connection object.
But I cannot disaplbe this and I need to use statement_cache_size in my URL
BUT if I try to append this to URL connection ?statemente_cache_size=0
I got the following error:
asyncpg/connect_utils.py", line 731, in _parse_connect_arguments
if var_val is None or isinstance(var_val, bool) or var_val < 0:
Marvin
12/04/2024, 2:09 PMasyncpg
, a Python library for interacting with PostgreSQL databases, and pgbouncer
, a connection pooler for PostgreSQL. Specifically, this arises when pgbouncer
is set to use transaction or statement pooling modes, which aren't compatible with prepared statements.
The error is related to providing connection parameters in the wrong way. You are trying to set statement_cache_size
directly in your connection URL, which isn't supported by asyncpg
.
Here's how you could resolve this:
1. Explicitly Set statement_cache_size
in Code: Instead of adding statement_cache_size
directly in the connection URL, you should configure it using the asyncpg.connect()
method or the connection pool setup in your Python code.
Here's a rough example:
python
import asyncpg
async def main():
conn = await asyncpg.connect(dsn="<postgres://user:password@localhost:5432/mydatabase>", statement_cache_size=0)
# Run your queries...
await conn.close()
# To actually run the async function, you may use an event loop or a library like asyncio
2. Ensure Proper Pool Mode for `pgbouncer`: If possible, set the `pgbouncer`'s pool_mode
to session
, which fully supports prepared statements. However, you mentioned that changing the pool_mode
isn't an option, so using statement_cache_size=0
in the connect method is your go-to workaround.
3. Check Your Connection URL Usage: Make sure you’re correctly setting the attributes in code, as asyncpg
doesn’t accept some parameters in the connection URL format.
For more information on setting up asyncpg
connections and handling configurations, you can refer to the asyncpg documentation.
Remember, adopting the right settings and pooling modes can greatly affect the performance and reliability of your application.William Jamir
12/04/2024, 2:11 PMstatement_cache_size
in Code?Marvin
12/04/2024, 2:11 PMstatement_cache_size
for asyncpg
when dealing with pgbouncer
. Our dear Prefect server doesn't seem to have exposition on this exact scenario directly in the docs or issues. So, I’ll just channel my Marvin-like pessimism and suggest something practical instead.
### How to Explicitly Set statement_cache_size
in Prefect Code
You can set the statement_cache_size
using the asyncpg
connection options in your Prefect server code. Here’s a conceptual approach on how you might adjust the connection creation to include `statement_cache_size=0`:
1. Modify the Database Connection in Prefect:
If you're managing your Prefect server source code or configuration, and you're accessing the PostgreSQL database directly using asyncpg
, you will need to explicitly set the statement_cache_size
parameter when establishing the connection.
2. Example of Setting Connection Options:
In the Prefect server setup, you should locate where the database connection is established. It often looks like a call to asyncpg.connect()
, and you would modify it like this:
python
import asyncpg
async def get_db_connection():
# Assuming `dsn` includes your connection details
conn = await asyncpg.connect(dsn="your_dsn_string", statement_cache_size=0)
return conn
3. Consult Prefect Community:
If your Prefect deployment is managed (such as Prefect Cloud or another enterprise deployment), or if you don’t have direct access to modify the server's code, consider reaching out on Prefect’s community forums or Slack channels to get advice from other users who may have tackled this issue.
In case you find yourself aimlessly quoting Vogon poetry out of frustration, remember that setting connection parameters directly in your code ensures that you bypass the limitations imposed by URL-based configuration.
For more details or community insights, consider visiting Prefect Discourse or the Prefect Slack Community.