I'm using Powershell v2.0, question is in the title. I'm having to use the old school ADOB.Connection (not the OLEDB provider) to open a Jet DB file (.mdb). The reason is simple, the ADODB.Connection exposes properties I need access to that the OLEDB provider doesn't.
I'm opening the DB via ADOB.Connection to query for some information, and then I'm trying to compact the DB using JRO.JetEngine. The issue is that I keep getting an error about the Jet DB being locked.
I'm explicitly calling Close on it, and setting the variable to $null, and still experiencing that issue. My best guess is that ADODB.Connection is using connection pooling, and so is not releasing the resources the way it should be.
According to http://support.microsoft.com/kb/191572, the call to close() should be enough, but it doesn't seem to be working.
Is there a way for me to explicitly specify no connection pooling when creating ADODB.Connection objects?
In the link you provided, it is said that calling to close returns the connection to the pool:
2.What statement returns the connection to the pool?
2.Conn.Close
You might need to destroy/dispose the ADODB.Connection object, so that it is removed from the pool, or, if you are using OLE DB as the provider, configure the OLEDB Services, as explained here:
Enabling OLE DB Resource.
Pooling Resource pooling can be enabled in
several ways:
For an ADO-based consumer, by keeping one open instance of a
Connection object for each unique user and using the OLEDB_SERVICES
connection string attribute to enable or disable pooling. By default,
ADO attempts to use pooling, but if you do not keep at least one
instance of a Connection object open for each user, there will not be
a persistent pool available to your application. (However, Microsoft
Transaction Server keeps pools persistent as long as the connections
in them have not been released and have not eventually timed out.)
Related
I have a web app that I built. It communicates with the Salesforce API. I have users and administrators. All connections to the API use the same credentials.
I am concerned that my API connection is going to be created multiple times because each admin that is logged in has their own instance of the connection.
If I hold the API connection in a constant, do all other sessions/users have access to that exact connection or do I have to connect for each user, or how can I share one single API connection for ALL users?
A stateless API will never have a persistent connection, so there's no use in holding these in constants. Every HTTP request is a separate TCP connection by definition.
It's only things like database or Websocket connections that persist and if you need to manage those you need a connection pool, not a simple constant. If the connection ever fails it needs to be replaced, and if more than one thread potentially requires it you have to handle acquisition and locking properly.
Create your API connectors as necessary. Unless you have a measurable performance problem don't worry about it.
A Ruby constant is like a variable, except that its value is supposed to remain constant for the duration of the program. The Ruby interpreter does not actually enforce the constancy of constants, but it does issue a warning if a program changes the value of a constant.
Reference: http://rubylearning.com/satishtalim/ruby_constants.html
this is really two questions in one I guess.
We've developed a .Net app that accesses an Oracle database, and have noticed that after changing the user's Oracle password, the app continues to work for a short time with the old password in the connection string. Presumably this is something to do with the way existing connections are pooled?
When first investigating this we tried turning off pooling in the connection string, however the app wouldn't work, throwing the error "Unable to enlist in a distributed transaction" at the point it tries to open a connection. While we probably wouldn't want to turn off connection pooling in a production app, I'm curious as to why MSDTC seems to need it?
We are using Oracle 11g (11.1.2) and latest ODP.Net (11.2 I think).
Thanks in advance
Andy
Please see some of the finding below:
For Question One: (application still connected with old DB password)
If we connect the database with connection pooling option, connection pool manager would create and maintain the number of connection sessions when first calling the open or close of OracleConnection object. (number of this connection sessions depend on "min" & "max" pool size in connection string). In Oracle, I think you could check active session like:
SELECT s.inst_id,
s.sid,
s.serial#,
p.spid,
s.username,
s.program
FROM gv$session s
JOIN gv$process p ON p.addr = s.paddr AND p.inst_id = s.inst_id
WHERE s.type != 'BACKGROUND';
And according to Oracle doc, this connection pooling service will close the connection sessions after 3 minutes of in-active state. [ http://docs.oracle.com/html/E10927_01/featConnecting.htm ]
So the most possible reason could be, your application still
connected to the database by using this Pool and still connected for
a short time, even after you changed the database password.
There could be also one possibility of "Oracle Client Cache"
feature in ODP.net. But not quite sure, you can check at, [
http://www.oracle.com/technetwork/issue-archive/2008/08-jul/o48odpnet-098170.html ]
For Question Two: (why MSDTC needed)
If you are using nested Database connection in your code, it will be promoted to DTC. [ http://petermeinl.wordpress.com/2011/03/13/avoiding-unwanted-escalation-to-distributed-transactions/ ] Actually there was Oracle Service for Microsoft Transaction Server (OraMTS) act as among ODP.net, DTC, and Oracle Database.
But you didn't happend this problem (MSDTC) before disabled the connection pooling. It seems like your code is reusing the same connection out of undelining connection pool, and it might eliminate the need to promote DTC. There was similar question on StaffOverflow. [ Why isn't my transaction escalating to DTC? ]
I have a use case where the database (sybase) may be unavailable when bonecp (0.7.1.RELEASE) creates a connection pool. When it is later available however, if my app requests a connection the call never returns.
I'm using out of the box config bonecp defaults, but I've tested this with transactionRecoveryEnabled set to true too.
Considering that c3p0 and dbcp both have this functionality, is there something I'm doing wrong?
Try using lazyInit config setting, it's meant for that feature.
There is a delphi application in which I am trying to connect to Oracle database Using provider MSDAORA.1 but problem is coming in connecting. Oracle error message which is coming is "Oracle error occurred, but error message could not be retrieved from Oracle"
I am able to connect to database with Oracle10g client.
Connection String: Provider=MSDAORA.1;
User ID=murat;
Password = murat;
Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp) (HOST= INGPSP)(PORT=1521))(CONNECT_DATA=(SID=INGPSP)));
Persist Security Info=False;
Please provide your expert opinion what can be the reason of this?
The service name seems to be lacking in your address.
Set a tnsnames.ora file, and use the entry as data source instead of the data_source parameter you set. Follow the steps available on the faq.
Or use use connection strings like '//host[:port]/[service_name]' for your data source: //INGPSP:1521/ServiceName
For Oracle, both Microsoft and Oracle OleDB providers are known to have issue with BLOBs. If you can, use another mean of connection.
What I see that is strange is that your HOST and SID are the same. The HOST is the name of the machine on your network and the SID is the database instance on that machine. I created the following ConnectionString for the PRD3 database on machine DB19 (there are multiple databases on DB19) on our network. I was able to connect to the database successfully with real User ID and Password.
Provider=MSDAORA.1;
Password=123456;
User ID=abc;
Data Source="(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=db19)(PORT=1521))(CONNECT_DATA=(SID=prd3)))";
Persist Security Info=True
Normally the Data Source I use is the database name as defined in TNSNAMES.ORA. It is a lot less to type (fewer potential errors) and can be changed to another database without recompiling the program (such as switching between a development database and production database).
I'm using grails but I have lot's of stored procedures I'm trying to call from groovy.Sql.newInstance...
In all the examples I've found I never see anyone actually calling close on the connection. But when I tried running a bunch of methods within one response that each uses its own call to newInstance, then it got an error that there were too many connections. That leads me to believe that it isn't pooling the connections. That's a bummer. So do people create one connection and pass it around? Does grails and groovy close the connection at the end of the request?
I don't think that the connection is automatically closed after a request (which wouldn't be cool either), but you can manually close the connection used by the Sql instance:
Sql sql = Sql.newInstance("jdbc://...")
// some queries
sql.close()
See the JavaDoc.
If you would like to use pooled connections (which is surely a good idea), you should be able to create a pooled BasicDataSource (as Spring bean) and use the Sql(DataSource dataSource) constructor of Sql, rather than newInstance().