I am getting the ORA-24778: cannot open connections, what are the possible causes?
We have a number of applications deployed in WAS7 profile and they connect to a number of schemas in Oracle 11g.
One of the schema is connecting through other schema via public DB link.
I cannot identify a solution for this cause.
After restarting the WAS7 profile, it is ok for a while and again start hitting the error.
Pls help!!
I assume you missed to tell us a few details:
You are using XA
You are using XA in combination with database links
You are using shared database links
The ora-24778 is not happening all the time
Either you haven't configured shared server option or you are not connected to a shared server. However Oracle requires you to user shared server if you want to use XA and database links.
Or the parameter OPEN_LINKS_PER_INSTANCE is not set sufficiently. Keep in mind mind that there is also a open_links init.ora parameter. The open_links parameter does not apply to XA.
This error can occur when you invoke a dblink in a existing transaction.
Related
I have been searching for an answer on MS, SE and Google and cannot find it. I want to use the GRS option for Azure Storage (Cloud Block Blobs) but I cannot figure out how to properly do that.
I created my storage object in Azure and chose the GRS option.
I get that I have a primary and secondary connection string and know how to get that from the Azure portal.
What I do not know, in ASP.NET 4.0, is how to set both connection strings in the CloudBlockClient and gracefully handle the primary storage being unavailable.
--What exception is thrown and where, when primary is unavailable? Is this thrown when I create the client, or when I try to get a blob reference?
-- How do I then use the secondary?
Do I have to just test for any old exception and then try using the secondary connection string in a new CloudBlockClient if the primary does not work? Or is there anything in the API for this. I would think there would be but I cannot find it.
None of the "How to use Azure Storage" tutorials I have seen go into this. Most of the documentation seems to date from before mid-2014 when this feature became generally available.
This blog post should help you. In short if you want to read from both primary and secondary you want to enable RA-GRS - essentially read access from the secondary. If you are using out storage client libraries you can also enable a retry policy that will first try to read from a primary and then from the secondary if the first read fails.
Apparently, using AttachDbFilename and user instance in your connection string is a bad way to connect to a DB. I'm using SQL server express on my local machine and it all seems to work fine. But what's the proper way to connect to SQL server then?
Thanks for your explanation.
Using User Instance means that SQL Server is creating a special copy of that database file for use by your program. If you have two different programs using that same connection string, they get two entirely different copies of the database. This leads to a lot of confusion, as people will test updating data with their program, then connect to a different copy of their database in Management Studio, and complain that their update isn't working. This sends them through a flawed series of wild goose chase steps trying to troubleshoot the wrong problem.
This article goes into more depth about how to use this feature, but heed the very first note: the User Instance feature has been deprecated. In SQL Server 2012, the preferred alternatives are (in this order, IMHO):
Create or attach your database to a real instance of SQL Server. Your connection string will then just need to specify the instance name, the database name, and credentials. There will be no mixup as Management Studio, Visual Studio and your program(s) will all be connecting to a single copy of the database.
Use a container for local development. Here's a great starter video by Anna Hoffman and Anthony Nocentino, and I have some other resources here, here, and here. If you're on an M1 Mac, you won't be able to use a full-blown SQL Server instance, but you can use Azure SQL Edge if you can get by with most SQL Server functionality (the omissions are enumerated here).
Use SqlLocalDb for local development. I believe I pointed you to this article yesterday: "Getting Started with SQL Server 2012 Express LocalDB."
Use SQL Server Compact. I like this option the least because the functionality and syntax is not the same - so it's not necessarily going to provide you with all the functionality you're ultimately going to want to deploy. Compact Edition is also deprecated, so there's that.
Of course if you are using a version < SQL Server 2012, SqlLocalDb is not an option - so you should be creating a real database and using that consistently. I only mention the Compact option for completeness - I think that can be almost as bad an idea as using AttachDbFileName.
EDIT: I've blogged about this here:
Bad Habits : Using AttachDBFileName
In case someone had the problem.
When attaching the database with a connection string containing AttachDBFile
with SQLEXPRESS, I noticed this connection was exclusive to the ASP.NET application that was using the database. The connection did block the access to all other processes on the file level when made with System.Data.SqlClient as provider.
In order to assure the connection to be shareable with other processes
instead use DataBase to specify the database name in your connection string
Example or connection string :
Data Source=.\SQLEXPRESS;DataBase=PlaCliGen;User ID=XXX;password=ZZZ; Connect Timeout=30
,where PlaCliGen is the name (or logical name) by which SQLEXPRESS server knows the database.
By connecting to the data base with AttachDBFile giving the path to the .mdf file
(namely : replacing DataBase = PlacliGen by AttachDBFile = c:\vs\placligen\app_data\placligen.mdf) the File was connected exclusively and no other process could connect to the database.
Try to be more clear, I'm in lack of ideas in this problem, even it sounds like a classic.
My application is running on weblogic 10.3.3 application server, and for database I am using Oracle database 11g. My problem is that there is table in db, let's say "user.", there is column, let's say "columnA", in this table. This table is updating by some module of application.
What I want if when value of column is "abc.", then I have to show alert to console(IP). {IP can be retrieved from DB as it is configured in DB. this ip will be other linux system other than linux machine where oracle database is installed.} Updating is continuously done on my table from module of application. Please tell me from where should I start?, what should I read. I am not able to understand what should be approach. Any help is much appreciated.
Can u provide me any begginner.s link of oracle db listener?
You probably want to look at setting up a Trigger in the database
http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28370/triggers.htm
An alternative to a trigger would be to log update queries against the table (to a log file) and have a process monitor the log, sending out alerts when something happens.
I have a Sql Server 2008 Express database file that's currently being used by an ASP.NET application, and I'm not sure how to query the database without taking the website down.
I'm unable to copy the database files (.mdf and .ldf files) to another directory, since they're in use by the web server. Also, if I attach the databases to an instance of the sql server (using the 'Create Database [DB name] on (filename = '[DB filename.mdf]') for attach;' command at the sqlcmd prompt), then the application pool user becomes unable to access the database (i.e. the webpages start producing http 500 errors. I think this might have to do with the username for the application pool becoming somehow divorced from the login credentials in the sql server database).
Any suggestions? I realize this is probably a newbie question, since it seems like a rather fundamental task. However, due to my inexperience, I really don't know what the answer is, and I'm pretty stumped at this point, since I've tried a couple of different things.
Thanks!
Andrew
if I attach the databases to an instance of the sql server (using the 'Create Database [DB name] on (filename = '[DB filename.mdf]') for attach;' command at the sqlcmd prompt),
Don't do this to a live database - it's attempting to be setup an MDF to be written to by two different databases...
Use Backup/Restore
As you've found, Attach/ReAttach requires the database to be offline - use the Backup/Restore functionality:
MSDN: Using SSMS to Backup the Database
MSDN: Using SSMs to Restore the Backup
Be aware that the backup/restore doesn't maintain logins (& jobs if you have any associated with the database) - you'll have to recreate & sync if using an account other than those with uber access.
Maybe Linked Server would work?
Another alternative would be to setup another SQL Server Express/etc instance on a different box, and use the Linked Server functionality to create a connection to the live/prod data. Use a different account than the one used for the ASP application...
I have an ASP.NET app that uses a SQL Server database. I now need to pull data from Sybase ASE into that SQL Server database for my app to consume, and I'm not having any success with my ideas.
Has anyone done this? Any ideas/suggestions/tips?
You can configure a linked server from SQL Server to Sybase. It should be fairly vanilla using the Sybase provider on the MS side.
Okay, I've finally (through lame trial and error) found out how to link my Sybase ASE (12.5) server to my SQL Server (2008) which will allow the integration I want. Here's roughly how I did it:
Logged in to Sybase ASE OLE DB Configuration Manager (this is like the Sybase version of Windows' ODBC Data Sources) and added an OLE DB data source. I believe you must be an admin on the PC to do this.
In SQL Server 2008 Management Studio, went to Server Objects > Linked Servers. Right click and select "New Linked Server".
In the Linked Server Properties, I set the following properties:
General:
--Linked server: the name of your linked server as you want it to appear in your linked server list
--Provider: Select Sybase ASE OLE DB Provider from the dropdown list.
--Product name: The exact name of the OLD DB data source you just created in Sybase ASE OLE DB Configuration Manager.
--Data source: Same as Product name.
--Provider string: I left this blank
--Location: I left this blank
--Catalog: The default database (master or whatever) to log on to.
Security:
--You need to map a valid SQL Server logon to a valid Sybase logon. I did not use impersonation (which does a credentials pass-thru).
--I chose my connection Be made without using a security context.
Server Options:
--All the defaults worked for me.
Throughout, the standard SQL Server help worked fairly well as a guide. Though not always true, F1 was my friend here.
I can now do distributed queries, DTS or SSIS packages, and use SSRS. This takes a lot of the suck out of Sybase ASE.
Of course the above can be done via the command line using sp_linkserver, but the GUI is more comfortable for a lowly dev like me.
Use Management Studio or Enterprise Manager to import the data using the data importation wizard. That should be it, just make sure you pick the right data provider in the wizard and you should be good to go.
If you want this to be a live feed create a small windows service to manage the exchange of information. It should be relatively simple to do, just a little bit of leg work on your end. If you are adverse to that there are plenty of off the shelf solutions that can do this for you.
The question is a little vague on specifics:
Is this a one time conversion or part of a repeated process.
Is the source machine "reachable" from your destination machine (can you connect the two or do you need to read in files)
With most conversions there are two parts:
Physically getting data from the source into the destination.
Mapping data from the source to the destination tables.
It is hard to make any recommendations without more info. What would be fine for a one time conversion would not work if you need to read in data all day every day. Also, if the source database can not be connected to and you have to pass files, they methods change.