date:20230608

Re: [sqlalchemy] connection pooling

2023-06-08 Thread Mike Bayer



On Thu, Jun 8, 2023, at 12:47 PM, Suraj Shaw wrote:
> Hi Mike,
> 
> One more update.
> I am using DRCP functionality of oracle so i have to add :pooled at the end 
> of connect string.
> If you run without using :pooled it is running correctly with output as 
> (datetime.datetime(2023, 6, 8, 22, 13, 56, 762291),)
> 
> (datetime.datetime(2023, 6, 8, 22, 13, 57, 376310),)
> 
> 
> 
> But when i am using :pooled i am getting
> 

OK, then please test the Oracle connection pool directly to debug this case, 
I'm not familiar with ":pooled" nor can I test here locally.   

SQLAlchemy does nothing whatsoever with the Oracle connection pool, it only 
emits statements on the connection and calls .close() on the connection (not 
the pool, which it has no access to, or knowledge of) at the end. 


> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> (datetime.datetime(2023, 6, 8, 22, 16, 58, 683404),)
> 
> 
> 
> Traceback (most recent call last):
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
>  line 1968, in _exec_single_context
> 
> self.dialect.do_execute(
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/default.py",
>  line 920, in do_execute
> 
> cursor.execute(statement, parameters)
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/oracledb/cursor.py",
>  line 378, in execute
> 
> impl.execute(self)
> 
>   File "src/oracledb/impl/thin/cursor.pyx", line 138, in 
> oracledb.thin_impl.ThinCursorImpl.execute
> 
>   File "src/oracledb/impl/thin/protocol.pyx", line 382, in 
> oracledb.thin_impl.Protocol._process_single_message
> 
>   File "src/oracledb/impl/thin/protocol.pyx", line 383, in 
> oracledb.thin_impl.Protocol._process_single_message
> 
>   File "src/oracledb/impl/thin/protocol.pyx", line 343, in 
> oracledb.thin_impl.Protocol._process_message
> 
>   File "src/oracledb/impl/thin/protocol.pyx", line 321, in 
> oracledb.thin_impl.Protocol._process_message
> 
>   File "src/oracledb/impl/thin/protocol.pyx", line 389, in 
> oracledb.thin_impl.Protocol._receive_packet
> 
>   File "src/oracledb/impl/thin/packet.pyx", line 559, in 
> oracledb.thin_impl.ReadBuffer.receive_packet
> 
>   File "src/oracledb/impl/thin/packet.pyx", line 358, in 
> oracledb.thin_impl.ReadBuffer._receive_packet_helper
> 
>   File "src/oracledb/impl/thin/packet.pyx", line 205, in 
> oracledb.thin_impl.ReadBuffer._get_data_from_socket
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/oracledb/errors.py",
>  line 118, in _raise_err
> 
> raise exc_type(_Error(message)) from cause
> 
> oracledb.exceptions.DatabaseError: DPY-4011: the database or network closed 
> the connection
> 
> 
> 
> The above exception was the direct cause of the following exception:
> 
> 
> 
> Traceback (most recent call last):
> 
>   File "/Users/apple/bofa/bofa_drcp1.py", line 23, in 
> 
> result = (conn.execute(text("select current_timestamp from dual")))
> 
>   
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
>  line 1413, in execute
> 
> return meth(
> 
>^
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/sql/elements.py",
>  line 483, in _execute_on_connection
> 
> return connection._execute_clauseelement(
> 
>^^
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
>  line 1637, in _execute_clauseelement
> 
> ret = self._execute_context(
> 
>   ^^
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
>  line 1846, in _execute_context
> 
> return self._exec_single_context(
> 
>^^
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
>  line 1987, in _exec_single_context
> 
> self._handle_dbapi_exception(
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
>  line 2344, in _handle_dbapi_exception
> 
> raise sqlalchemy_exception.with_traceback(exc_info[2]) from e
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
>  line 1968, in _exec_single_context
> 
> self.dialect.do_execute(
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/default.py",
>  line 920, in do_execute
> 
> cursor.execute(statement, parameters)
> 
>   File 
> "/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/oracledb/cursor.py",
>  line 378, in execute
> 
> impl.execute(self)
> 
>   File "src/oracledb/impl/thin/cursor.pyx", line 138, in 
> oracledb.thin_impl.ThinCursorImpl.execute
> 
>   File

Re: [sqlalchemy] connection pooling

2023-06-08 Thread Mike Bayer



On Thu, Jun 8, 2023, at 12:38 PM, Suraj Shaw wrote:
> Hi Mike,
> 
> Is it like first conn.close() is closing the pool itself instead of releasing 
> connection back to pool.


SQLAlchemy calls the .close() method on the connection itself.  Per oracledb 
docs at 
https://python-oracledb.readthedocs.io/en/latest/user_guide/connection_handling.html#creating-a-connection-pool

"When your application has finished performing all required database 
operations, the pooled connection should be released to make it available for 
other users of the pool. You can do this with `ConnectionPool.release()` 

 or `Connection.close()` 
."
  

The error you are showing is also not the error that's raised if the pool is 
closed.  here is a demonstration script:


import oracledb
from sqlalchemy import create_engine, text
from sqlalchemy.pool import NullPool

pool = oracledb.create_pool(
user="scott", password="tiger", dsn="oracle18c/xe",
min=2, max=5, increment=1, threaded=True,
encoding="UTF-8", nencoding="UTF-8"
)

def creator():
return pool.acquire(cclass="MYCLASS", purity=oracledb.PURITY_SELF)

engine = create_engine("oracle+oracledb://", creator=creator, 
poolclass=NullPool)

conn = engine.connect()
print(conn.scalar(text("select 1 from dual")))
conn.close()


conn = engine.connect()
print(conn.scalar(text("select 1 from dual")))
conn.close()

input("press enter to see a closed pool try to connect")
pool.close()
conn = engine.connect()


the first two statements succeed.  then key input is requested.  subsequent to 
that, the error message is explicit: "DPY-1002: connection pool is not open".  
this is not the "DPY-4011: the database or network closed the connection" 
message you refer towards:

$ python test3.py 
1
1
press enter to see a closed pool try to connect
Traceback (most recent call last):
  ...
raise exc_type(_Error(message)) from cause
oracledb.exceptions.InterfaceError: DPY-1002: connection pool is not open




I will reiterate my previous post that there's no action for SQLAlchemy to take 
here as of yet and you should post a discussion on the oracledb discussion 
tracker for assistance on what the error message you have actually means, since 
I dont know.





> 
> Thanks
> Suraj
> 
> On Thu, 8 Jun 2023 at 18:34, Mike Bayer  
> wrote:
>> __
>> unknown.  I've run your program exactly as written with SQLAlchemy 2.0.15 
>> and it succeeds on both queries.  I would advise reaching out to 
>> https://github.com/oracle/python-oracledb/discussions for debugging help.   
>> feel free to show them our recipe from 
>> https://docs.sqlalchemy.org/en/20/dialects/oracle.html#using-oracle-database-resident-connection-pooling-drcp
>>  for reference.
>> 
>> On Thu, Jun 8, 2023, at 7:23 AM, Suraj Shaw wrote:
>>> Hi Team,
>>> 
>>> I am using connection pooling in sqlalchemy using oracle own pool.My script 
>>> looks like this.
>>> ```
>>> from sqlalchemy import create_engine,text
>>> from sqlalchemy.pool import NullPool
>>> 
>>> 
>>> 
>>> import oracledb
>>> 
>>> 
>>> pool = oracledb.create_pool(user='XXX', password='XXX',dsn='XXX:1521/XXX', 
>>> min=1, max=5, increment=1)
>>> 
>>> def creator():
>>> 
>>> return pool.acquire(cclass="MYAPP",purity=oracledb.PURITY_SELF)
>>> 
>>> 
>>> 
>>> engine = create_engine("oracle+oracledb://", creator=creator, 
>>> poolclass=NullPool)
>>> 
>>> 
>>> 
>>> conn = engine.connect()
>>> 
>>> result = (conn.execute(text("select current_timestamp from dual"))) 
>>> 
>>> for row in result:#first query
>>> 
>>> print(row)
>>> 
>>> conn.close()
>>> 
>>> 
>>> 
>>> conn = engine.connect()
>>> 
>>> result = (conn.execute(text("select current_timestamp from dual")))
>>> 
>>> for row in result: #second query
>>> 
>>> print(row)
>>> 
>>> 
>>> 
>>> conn.close()
>>> 
>>> ```
>>> 
>>> 
>>> 
>>> Here the first query in running perfectly when the second time when i am 
>>> doing it then it is rasing the folowing error
>>> 
>>> 
>>> 
>>> sqlalchemy.exc.DatabaseError: (oracledb.exceptions.DatabaseError) DPY-4011: 
>>> the database or network closed the connection
>>> 
>>> Why is this issue coming.
>>> 
>>> Is it because of conn.close(). Here the conn.close() is not releasing 
>>> connection back to the pool.
>>> 
>>> Thanks
>>> 
>>> 
>>> 
>>> 
>>> --
>>> SQLAlchemy -
>>> The Python SQL Toolkit and Object Relational Mapper
>>>  
>>> http://www.sqlalchemy.org/
>>>  
>>> To post example code, please provide an MCVE: Minimal, Complete, and 
>>> Verifiable Example. See http://stackoverflow.com/help/mcve for a full 
>>> description.
>>> ---
>>> You received this message because you are subscribed to the Google Groups 
>>> "sqlalchemy" group.
>>> To unsubscribe from this group and stop receiving emails from it, send an 
>>> email to sqlalchemy+unsubscr...@googlegroups.com.
>>> To

Re: [sqlalchemy] connection pooling

2023-06-08 Thread Suraj Shaw

Hi Mike,

One more update.
I am using DRCP functionality of oracle so i have to add :pooled at the end
of connect string.
If you run without using :pooled it is running correctly with output as

(datetime.datetime(2023, 6, 8, 22, 13, 56, 762291),)

(datetime.datetime(2023, 6, 8, 22, 13, 57, 376310),)



But when i am using :pooled i am getting







(datetime.datetime(2023, 6, 8, 22, 16, 58, 683404),)


Traceback (most recent call last):

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
line 1968, in _exec_single_context

self.dialect.do_execute(

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/default.py",
line 920, in do_execute

cursor.execute(statement, parameters)

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/oracledb/cursor.py",
line 378, in execute

impl.execute(self)

  File "src/oracledb/impl/thin/cursor.pyx", line 138, in
oracledb.thin_impl.ThinCursorImpl.execute

  File "src/oracledb/impl/thin/protocol.pyx", line 382, in
oracledb.thin_impl.Protocol._process_single_message

  File "src/oracledb/impl/thin/protocol.pyx", line 383, in
oracledb.thin_impl.Protocol._process_single_message

  File "src/oracledb/impl/thin/protocol.pyx", line 343, in
oracledb.thin_impl.Protocol._process_message

  File "src/oracledb/impl/thin/protocol.pyx", line 321, in
oracledb.thin_impl.Protocol._process_message

  File "src/oracledb/impl/thin/protocol.pyx", line 389, in
oracledb.thin_impl.Protocol._receive_packet

  File "src/oracledb/impl/thin/packet.pyx", line 559, in
oracledb.thin_impl.ReadBuffer.receive_packet

  File "src/oracledb/impl/thin/packet.pyx", line 358, in
oracledb.thin_impl.ReadBuffer._receive_packet_helper

  File "src/oracledb/impl/thin/packet.pyx", line 205, in
oracledb.thin_impl.ReadBuffer._get_data_from_socket

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/oracledb/errors.py",
line 118, in _raise_err

raise exc_type(_Error(message)) from cause

oracledb.exceptions.DatabaseError: DPY-4011: the database or network closed
the connection


The above exception was the direct cause of the following exception:


Traceback (most recent call last):

  File "/Users/apple/bofa/bofa_drcp1.py", line 23, in 

result = (conn.execute(text("select current_timestamp from dual")))

  

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
line 1413, in execute

return meth(

   ^

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/sql/elements.py",
line 483, in _execute_on_connection

return connection._execute_clauseelement(

   ^^

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
line 1637, in _execute_clauseelement

ret = self._execute_context(

  ^^

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
line 1846, in _execute_context

return self._exec_single_context(

   ^^

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
line 1987, in _exec_single_context

self._handle_dbapi_exception(

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
line 2344, in _handle_dbapi_exception

raise sqlalchemy_exception.with_traceback(exc_info[2]) from e

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/base.py",
line 1968, in _exec_single_context

self.dialect.do_execute(

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/sqlalchemy/engine/default.py",
line 920, in do_execute

cursor.execute(statement, parameters)

  File
"/Users/apple/.virtualenvs/bofa/lib/python3.11/site-packages/oracledb/cursor.py",
line 378, in execute

impl.execute(self)

  File "src/oracledb/impl/thin/cursor.pyx", line 138, in
oracledb.thin_impl.ThinCursorImpl.execute

  File "src/oracledb/impl/thin/protocol.pyx", line 382, in
oracledb.thin_impl.Protocol._process_single_message

  File "src/oracledb/impl/thin/protocol.pyx", line 383, in
oracledb.thin_impl.Protocol._process_single_message

  File "src/oracledb/impl/thin/protocol.pyx", line 343, in
oracledb.thin_impl.Protocol._process_message

  File "src/oracledb/impl/thin/protocol.pyx", line 321, in
oracledb.thin_impl.Protocol._process_message

  File "src/oracledb/impl/thin/protocol.pyx", line 389, in
oracledb.thin_impl.Protocol._receive_packet

  File "src/oracledb/impl/thin/packet.pyx", line 559, in
oracledb.thin_impl.ReadBuffer.receive_packet

  File "src/oracledb/impl/thin/packet.pyx", line 358, in
oracledb.thin_impl.ReadBuffer._receive_packet_helper

  File "src/oracledb/impl/thin/packet.pyx", line 205, in

Re: [sqlalchemy] connection pooling

2023-06-08 Thread Suraj Shaw

Hi Mike,

Is it like first conn.close() is closing the pool itself instead of
releasing connection back to pool.

Thanks
Suraj

On Thu, 8 Jun 2023 at 18:34, Mike Bayer 
wrote:

> unknown.  I've run your program exactly as written with SQLAlchemy 2.0.15
> and it succeeds on both queries.  I would advise reaching out to
> https://github.com/oracle/python-oracledb/discussions for debugging
> help.   feel free to show them our recipe from
> https://docs.sqlalchemy.org/en/20/dialects/oracle.html#using-oracle-database-resident-connection-pooling-drcp
> for reference.
>
> On Thu, Jun 8, 2023, at 7:23 AM, Suraj Shaw wrote:
>
> Hi Team,
>
> I am using connection pooling in sqlalchemy using oracle own pool.My
> script looks like this.
> ```
> from sqlalchemy import create_engine,text
>
> from sqlalchemy.pool import NullPool
>
> import oracledb
>
> pool = oracledb.create_pool(user='XXX', password='XXX',dsn='XXX:1521/XXX',
> min=1, max=5, increment=1)
>
> def creator():
>
> return pool.acquire(cclass="MYAPP",purity=oracledb.PURITY_SELF)
>
>
> engine = create_engine("oracle+oracledb://", creator=creator,
> poolclass=NullPool)
>
>
> conn = engine.connect()
>
> result = (conn.execute(text("select current_timestamp from dual")))
>
> for row in result:#first query
>
> print(row)
>
> conn.close()
>
>
> conn = engine.connect()
>
> result = (conn.execute(text("select current_timestamp from dual")))
>
> for row in result: #second query
>
> print(row)
>
>
> conn.close()
>
> ```
>
>
> Here the first query in running perfectly when the second time when i am
> doing it then it is rasing the folowing error
>
> sqlalchemy.exc.DatabaseError: (oracledb.exceptions.DatabaseError)
> DPY-4011: the database or network closed the connection
>
> Why is this issue coming.
>
> Is it because of conn.close(). Here the conn.close() is not releasing
> connection back to the pool.
>
> Thanks
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
> You received this message because you are subscribed to the Google Groups
> "sqlalchemy" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sqlalchemy+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/sqlalchemy/10098e90-038e-478e-8a7e-db5b8e2f7e07n%40googlegroups.com
> 
> .
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
> You received this message because you are subscribed to the Google Groups
> "sqlalchemy" group.
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> email to sqlalchemy+unsubscr...@googlegroups.com.
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> https://groups.google.com/d/msgid/sqlalchemy/4049c5f7-6369-4251-8de4-b116441fb782%40app.fastmail.com
> 
> .
>

-- 
SQLAlchemy - 
The Python SQL Toolkit and Object Relational Mapper

http://www.sqlalchemy.org/

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable 
Example.  See  http://stackoverflow.com/help/mcve for a full description.
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Re: [sqlalchemy] connection pooling

2023-06-08 Thread Mike Bayer

unknown.  I've run your program exactly as written with SQLAlchemy 2.0.15 and 
it succeeds on both queries.  I would advise reaching out to 
https://github.com/oracle/python-oracledb/discussions for debugging help.   
feel free to show them our recipe from 
https://docs.sqlalchemy.org/en/20/dialects/oracle.html#using-oracle-database-resident-connection-pooling-drcp
 for reference. 

On Thu, Jun 8, 2023, at 7:23 AM, Suraj Shaw wrote:
> Hi Team,
> 
> I am using connection pooling in sqlalchemy using oracle own pool.My script 
> looks like this.
> ```
> from sqlalchemy import create_engine,text
> from sqlalchemy.pool import NullPool
> 
> 
> import oracledb
> 
> pool = oracledb.create_pool(user='XXX', password='XXX',dsn='XXX:1521/XXX', 
> min=1, max=5, increment=1)
> 
> def creator():
> 
> return pool.acquire(cclass="MYAPP",purity=oracledb.PURITY_SELF)
> 
> 
> 
> engine = create_engine("oracle+oracledb://", creator=creator, 
> poolclass=NullPool)
> 
> 
> 
> conn = engine.connect()
> 
> result = (conn.execute(text("select current_timestamp from dual"))) 
> 
> for row in result:#first query
> 
> print(row)
> 
> conn.close()
> 
> 
> 
> conn = engine.connect()
> 
> result = (conn.execute(text("select current_timestamp from dual")))
> 
> for row in result: #second query
> 
> print(row)
> 
> 
> 
> conn.close()
> 
> ```
> 
> 
> 
> Here the first query in running perfectly when the second time when i am 
> doing it then it is rasing the folowing error
> 
> 
> sqlalchemy.exc.DatabaseError: (oracledb.exceptions.DatabaseError) DPY-4011: 
> the database or network closed the connection
> 
> Why is this issue coming.
> 
> Is it because of conn.close(). Here the conn.close() is not releasing 
> connection back to the pool.
> 
> Thanks
> 
> 
> 
> -- 
> SQLAlchemy - 
> The Python SQL Toolkit and Object Relational Mapper
>  
> http://www.sqlalchemy.org/
>  
> To post example code, please provide an MCVE: Minimal, Complete, and 
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full 
> description.
> --- 
> You received this message because you are subscribed to the Google Groups 
> "sqlalchemy" group.
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to sqlalchemy+unsubscr...@googlegroups.com.
> To view this discussion on the web visit 
> https://groups.google.com/d/msgid/sqlalchemy/10098e90-038e-478e-8a7e-db5b8e2f7e07n%40googlegroups.com
>  
> .

-- 
SQLAlchemy - 
The Python SQL Toolkit and Object Relational Mapper

http://www.sqlalchemy.org/

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable 
Example.  See  http://stackoverflow.com/help/mcve for a full description.
--- 
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Re: [sqlalchemy] Sql constructor

2023-06-08 Thread Mike Bayer

we can't take on maintenance for new extensions within the SQLAlchemy project 
directly but I would encourage you to release your extension as its own 
library; see https://pypi.org/search/?q=sqlalchemy for other examples

On Tue, Jun 6, 2023, at 5:34 PM, Nir Assaraf wrote:
> Hey guys,
> 
> As a part of a project that I'm working on, Iv'e created a SQLAlchemy 
> statement builder using the ast (abstract syntax trees) library.
> This constructor will parse strings that are valid python logical statements 
> and will convert them to the appropriate SQLAlchemy objects.
> 
> For example:
> The constructor will take a string of the following format and a list of 
> models/modelbase in which the columns exist.
> 
> string_a = '(column_a == 2 or column_b == 3) or column_c in [1,2,3]'
> 
> and returns the SQLAlchemy objects that defines this logic and can be used in 
> a query's where clause.
> 
> This was used to automate query building for a projects with thousands of 
> different logics that where defined by the client.
> 
> I was just wondering if you think there is a place for something like that in 
> SQLAlchemy or related projects.
> 
> Best regards,
> 
> Nir
> 
> 
> 
> -- 
> SQLAlchemy - 
> The Python SQL Toolkit and Object Relational Mapper
>  
> http://www.sqlalchemy.org/
>  
> To post example code, please provide an MCVE: Minimal, Complete, and 
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full 
> description.
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> .

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http://www.sqlalchemy.org/

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[sqlalchemy] connection pooling

2023-06-08 Thread Suraj Shaw

Hi Team,

I am using connection pooling in sqlalchemy using oracle own pool.My script 
looks like this.
```
from sqlalchemy import create_engine,text

from sqlalchemy.pool import NullPool

import oracledb

pool = oracledb.create_pool(user='XXX', password='XXX',dsn='XXX:1521/XXX', 
min=1, max=5, increment=1)

def creator():

return pool.acquire(cclass="MYAPP",purity=oracledb.PURITY_SELF)


engine = create_engine("oracle+oracledb://", creator=creator, 
poolclass=NullPool)

conn = engine.connect()

result = (conn.execute(text("select current_timestamp from dual"))) 

for row in result:#first query

print(row)

conn.close()


conn = engine.connect()

result = (conn.execute(text("select current_timestamp from dual")))

for row in result: #second query

print(row)

conn.close()

```


Here the first query in running perfectly when the second time when i am 
doing it then it is rasing the folowing error

sqlalchemy.exc.DatabaseError: (oracledb.exceptions.DatabaseError) DPY-4011: 
the database or network closed the connection

Why is this issue coming.

Is it because of conn.close(). Here the conn.close() is not releasing 
connection back to the pool.

Thanks

-- 
SQLAlchemy - 
The Python SQL Toolkit and Object Relational Mapper

http://www.sqlalchemy.org/

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable 
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Re: [sqlalchemy] connection pooling

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[sqlalchemy] connection pooling

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