User guide

• If you created your Amazon Redshift cluster in a VPC, you need to add your client CIDR/IP address
to the VPC security group in Amazon VPC. For more information about configuring VPC security groups
for your cluster, see Managing Clusters in an Amazon Virtual Private Cloud (VPC) (p. 32).
• If you created your Amazon Redshift cluster outside a VPC, you need to add your client CIDR/IP address
to the cluster security group in Amazon Redshift. For more information about configuring cluster security
groups, see Amazon Redshift Cluster Security Groups (p. 43).
If you attempt to connect to the cluster from a client tool in an Amazon EC2 instance, you must add an
ingress rule to the cluster security group for the Amazon EC2 security group that is associated with the
Amazon EC2 instance. For more information about configuring cluster security groups, see Amazon
Redshift Cluster Security Groups (p. 43).
Additionally, if you have a layer between your client and server, such as a firewall, make sure that the
firewall accepts inbound connections over the port that you configured for your cluster.
The Client and Driver Are Incompatible
Example error:
"The specified DSN contains an architecture mismatch between the Driver and Application."
Possible solution:
When you get attempt to connect and get an error about an architecture mismatch, this means that the
client tool and the driver are not compatible because their system architecture does not match. For
example, this can happen if you have a 32-bit client tool but have installed the 64-bit version of the driver.
Sometimes 64-bit client tools can use 32-bit drivers, but you cannot use 32-bit applications with 64-bit
drivers. Make sure that the driver and client tool are using the same version of the system architecture.
Queries Appear to Hang in the Client and Do Not Reach the
Cluster
Example issue:
Users experience issues with their queries completing. The queries appear to be running and hang in
the user's SQL client tool, but they aren't logged or found running in the system tables and Amazon
Redshift console.
Possible solution:
Set the size of the maximum transmission unit (MTU) to 1500 on the network interface (NIC) of the Amazon
EC2 instances from which you connect to your Amazon Redshift cluster. The MTU size determines the
maximum size, in bytes, of a packet that can be transferred in one Ethernet frame over your network
connection. If your MTU size is too large for the connection, you might experience incomplete query
results, your query might hang, or the connection might be dropped altogether. Some Amazon EC2
instance types provide 1500 MTU (Ethernet v2 frames), and other instance types provide 9001 MTU
(TCP/IP jumbo frames).We recommend always disabling TCP/IP jumbo frames to ensure that connections
consistently use the same packet size.
Set MTU on a Microsoft Windows Operating System
If your client runs in a Microsoft Windows operating system, you can review and set the MTU value for
the Ethernet adapter by using the netsh command. Run the following command to determine the current
MTU value:
netsh interface ipv4 show subinterfaces
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Amazon Redshift Management Guide
Troubleshooting Connection Issues in Amazon Redshift