Lesson Learned #448:Implementing Retry Logic for BCP Command in Linux

When dealing with data migration or integration tasks, it's common to encounter transient issues that may cause the process to fail. One common tool used for data migration is the Bulk Copy Program (BCP) in SQL Server. In this blog post, we will discuss how to implement a retry logic for BCP commands in a Linux environment, to handle temporary failures and ensure data is transferred successfully.

Creating a Sample Table and Data File: Before we proceed with the retry logic, let's first create a sample SQL Server table and a text file with data to be imported.

1.  
2. Sample SQL Server Table:

CREATE TABLE MyTable2 (
    ID INT PRIMARY KEY,
    Name VARCHAR(50),
    Age INT,
    Birthdate DATE
);

2. Sample Data File (Data.txt):-

1|John|25|1998-03-15
2|Jane|30|1993-01-20
3|Charlie|28|1995-08-10

In this example, we are using the | character as a delimiter, as specified in our BCP command with the -t| option.

Implementing Retry Logic for BCP Command: Now, let's create a bash script to implement the retry logic for the BCP command.

#!/bin/bash

# Configuration
max_retries=3
wait_time=5  # seconds

# bcp command
bcp_command="bcp MyTable2 IN data.txt -c -t, -eTB2C_bcp.ldrlog -U username -d dbname -P password -S servername.database.windows.net"

# Initialization
retries=0

# Retry loop
while true; do
    # Execute bcp command
    $bcp_command
    status=$?

    # Check result
    if [[ $status -eq 0 ]]; then
        echo "bcp command executed successfully"
        break
    else
        if [[ $retries -lt $max_retries ]]; then
            echo "bcp command failed. Retrying in $wait_time seconds..."
            ((retries++))
            sleep $wait_time
        else
            echo "bcp command failed after $max_retries retries. Aborting."
            exit 1
        fi
    fi
done

In this script, we have configured the maximum number of retries (max_retries) and the wait time between retries (wait_time). The script will execute the BCP command, and if it fails, it will wait for the specified amount of time before retrying. If the command continues to fail after the maximum number of retries, the script will exit with an error.

Conclusion:

Implementing a retry logic for BCP commands in Linux can help to handle transient failures and ensure that data is transferred successfully. By using a simple bash script, we can easily automate this process and improve the reliability of our data migration tasks.