I'm connecting to an Azure SQL database serverless instance as a source in Azure Data Factory.
I'm experiencing an issue where the first connection to the database times out as the database is suspended.
How is this typically handled in ADF?
Solution 1 : Increasing the connection timeout to 10minutes or more should solve it.
"connectionString": "Data Source=tcp:.database.windows.net,1433;Initial Catalog=;Connection Timeout=600"
The latency to auto-resume and auto-pause a serverless database is generally order of 1 minute to auto-resume and 1-10 minutes after the expiration of the delay period to auto-pause. - [Reference 1] :https://learn.microsoft.com/en-us/azure/azure-sql/database/serverless-tier-overview?view=azuresql#latency
Storing Connection Strings in Key-Vaults:
[2]:https://learn.microsoft.com/en-us/azure/data-factory/store-credentials-in-key-vault
Connection String- Reference
[3]:https://learn.microsoft.com/en-us/azure/azure-sql/database/connect-query-content-reference-guide?view=azuresql
Solution 2: is to setup the retry on the activities with a higher retry Interval.
I discovered that since NHibernate 5.0 I can call the following code to delete all records of a table:
session.Query<T>().Delete();
It executes the code on the database without copying it across the network, which should improve performance a lot.
But this query times out.
I get the following error:
Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
I've tried setting the Connection Timeout setting in my connectionstring to 0 and to 3600, but it makes no difference.
My table only has about 200 records. But one column is a base64 encoded pdf, so it is quite big and the query would take a few seconds.
What else can I try?
It sounds like you need to increase the command timeout.
Note that there is a difference between connection timeout and command timeout.
You can set the default command timeout (in seconds) for ADO.NET commands created by NHibernate using the command_timeout NHibernate session configuration property. There are multiple ways to do that depending on what method you use to configure NHibernate. Here are the basics: http://nhibernate.info/doc/nhibernate-reference/session-configuration.html
I have a bit a funny situation. Our Azure SQL instance maxes out at 100 DTU for a certain query and the query returns a timeout:
SqlException (0x80131904): Timeout expired. The timeout period
elapsed prior to completion of the operation or the server is not
responding. This failure occurred while attempting to connect to the
routing destination.
If I run exactly the same query (with the parameters hardcoded) in SQL Server Management Studio it still takes the DTU up to 25%, but that's still far away from 100%. Nothing else runs on that server. There are a few other queries that run before/after. But if we just run them, nothing spikes out.
Any ideas?
My analysis of the issue goes like this..
First when DTU's are maxed out and if a query fails due to that,you will not get time out..Below is the error message you will get..
Resource ID: %d. The %s limit for the database is %d and has been reached. For more information
You can try testing that by opening multiple resource intensive queries
Secondly when you get time out's as indicated in your question,this is mostly due to query waiting for resources like say some database IO,memory..
we faced similar time out's ,but most of them are fixed by updating stats and rebuilding indexes,rest of them we optimized
I have the following connection string(get from a property of sql server):
Data Source=(LocalDB)\v11.0;AttachDbFilename=C:\Users\myUser\Desktop\adoBanche\Banche\bin\Debug\banche.mdf;Integrated Security=True;Connect Timeout=30
I don't understand what mean Timeout=30. Someone could explain what means?
That is the timeout to create the connection, NOT a timeout for commands executed over that connection.
See for instance http://www.connectionstrings.com/all-sql-server-connection-string-keywords/
(note that the property is "Connect Timeout" (or "Connection Timeout"), not just "Timeout")
From the comments:
It is not possible to set the command timeout through the connection string. However, the SqlCommand has a CommandTimeout property (derived from DbCommand) where you can set a timeout (in seconds) per command.
Do note that when you loop over query results with Read(), the timeout is reset on every read. The timeout is for each network request, not for the total connection.
Connection Timeout=30 means that the database server has 30 seconds to establish a connection.
Connection Timeout specifies the time limit (in seconds), within which the connection to the specified server must be made, otherwise an exception is thrown i.e. It specifies how long you will allow your program to be held up while it establishes a database connection.
DataSource=server;
InitialCatalog=database;
UserId=username;
Password=password;
Connection Timeout=30
SqlConnection.ConnectionTimeout. specifies how many seconds the SQL Server service has to respond to a connection attempt. This is always set as part of the connection string.
Notes:
The value is expressed in seconds, not milliseconds.
The default value is 30 seconds.
A value of 0 means to wait indefinitely and never time out.
In addition, SqlCommand.CommandTimeout specifies the timeout value of a specific query running on SQL Server, however this is set via the SqlConnection object/setting (depending on your programming language), and not in the connection string i.e. It specifies how long you will allow your program to be held up while the command is run.
Connect Timeout=30 means, within 30second sql server should establish the connection.other wise current connection request will be cancelled.It is used to avoid connection attempt to waits indefinitely.
How a connection works in a nutshell
A connection between a program and a database server relies on a handshake.
What this means is that when a connection is opened then the thread establishing the connection will send network packets to the database server. This thread will then pause until either network packets about this connection are received from the database server or when the connection timeout expires.
The connection timeout
The connection timeout is measured in seconds from the point the connection is opened.
When the timeout expires then the thread will continue, but it will do so having reported a connection failure.
If there is no value specified for connection timeout in the connection string then the default value is 30.
A value greater than zero means how many seconds before it gives up e.g. a value of 10 means to wait 10 seconds.
A value of 0 means to never give up waiting for the connection
Note: A value of 0 is not advised since it is possible for either the connection request packets or the server response packets to get lost. Will you seriously be prepared to wait even a day for a response that may never come?
What should I set my Connection Timeout value to?
This setting should depend on the speed of your network and how long you are prepared to allow a thread to wait for a response.
As an example, on a task that repeats hourly during the day, I know my network has always responded within one second so I set the connection timeout to a value of 2 just to be safe. I will then try again three times before giving up and either raising a support ticket or escalating a similar existing support ticket.
Test your own network speed and consider what to do when a connection fails as a one off, and also when it fails repeatedly and sporadically.
Gets the time to wait while trying to establish a connection before terminating the attempt and generating an error.
http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnection.connectiontimeout%28v=vs.110%29.aspx
Maximum time between connection request and a timeout error. When the client tries to make a connection, if the timeout wait limit is reached, it will stop trying and raise an error.
Gets the time to wait while trying to establish a connection before terminating the attempt and generating an error.
(MSDN, SqlConnection.ConnectionTimeout Property, 2013)
By default connection timeout is 240 but if you are faceing the problem of connection time out then you can increase upto "300"
"Connection Timeout=300"
In My Console application. i am checking media links which is available in my database through openstream.but one error is raising again and again in diffrent diffrent point.that is "Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. The statement has been terminated"
These 2 similar problems/solutions might give you some ideas.
One was fragmented table and the other was a lock by another db operation.
http://forums.asp.net/t/1513085.aspx/1/10
SQL Server simple Insert statement times out