It is a critical process to ensure that your version control system remains highly efficient, streamlined, and current over time.
Understanding Data Purge in Source Control
Source control (also known as version control) is the practice of managing and keeping track of different versions of software code. The primary role of the source control system is to enable multiple developers to work simultaneously on a codebase without interfering with each other’s work. This system also allows for previous versions of code to be recalled or restored if needed.
Purging data from source control refers to the process of removing redundant, obsolete, or unnecessary data from the source control repositories. This process is vital for various reasons – it helps maintain the system performance by reducing the burden of unnecessary data, it keeps the codebase clean and readable, and it also aids in cloud compliance where data retention limits are set.
How to Purge Data from Source Control?
There are specific best practice steps one could take to purge data from source control, particularly in the context of using Git, which works with repositories:
- Understand where unnecessary data lies: Use commands like
git count-objectsorgit gc --prune=now --aggressiveto identify data that is not currently used by any branch in the repo and which can be safely deleted. - Backup existing data: Before purging any data, it’s advisable to back it up to prevent any accidental loss. Git doesn’t natively support backing up repos, but you can clone your repo as a backup:
git clone --mirror git://example.com/some-big-repo.git - Perform the purge: To remove specified files from the repository’s history, you can use tools like BFG Repo-Cleaner or ‘git filter-branch’. Below is an example of how BFG Repo-Cleaner can be used:
cd /path/to/your/repo
git clone --mirror git://github.com/yourUsername/repoToPurge.git
bfg --delete-files FILE-TO-PURGE
Once you’ve specified the files you want to delete, push the changes to the master branch with the –force command:git push origin --force --all - Verify the purge: To ensure that the files have been purged successfully, you can use:
git ls-tree -r HEAD
This command shows a list of all files in the current commit—making it easy to verify if the deletions have been successful.
Remember, the primary goal of a purge should not just be to free up space in the control system. It should be aimed at enhancing productivity by keeping the repository streamlined, thereby reducing clone times and making it easier for your team to find and understand the code.
Approach data purging judiciously as an arbitrary process can lead to loss of critical data. Always adopt a systematic, stepped approach, ensuring the preservation of all necessary data and deletion of only the redundant elements.
In the AZ-400 Designing and Implementing Microsoft DevOps Solutions exam, understanding the process of data purging from source control is critical, given its impact on DevOps practices and principles. Always remember, a clean, optimized repository is not just about saving storage—it’s about maximizing the productivity and efficiency of your DevOps system.
Practice Test
True or False: Purging data from source control will delete the data permanently.
- True
- False
Answer: True
Explanation: Purging data from source control removes it entirely. This operation cannot be undone.
Single Select: What does “purge data” operation involve?
- a) Record deletion
- b) Permanent data removal
- c) Temporary data deletion
- d) Copying data
Answer: b) Permanent data removal
Explanation: The term ‘purge data’ refers to the permanent removal of data from a system or database.
Multiple Select: What are the reasons to purge data from source control?
- a) Outdated data
- b) Corrupt data
- c) Data backup
- d) Space saving
- e) Performance improvement
Answer: a) Outdated data, b) Corrupt data, d) Space saving, e) Performance improvement
Explanation: Purging data helps in getting rid of outdated and corrupt data, saving space, and improving the system or database performance.
True or False: Azure DevOps allows purging of data
- True
- False
Answer: True
Explanation: Azure DevOps offers features that allow purging of data in order to manage storage or maintain cleanliness.
Single Select: What feature of Azure DevOps allows purging of data?
- a) Storage management
- b) Data purification
- c) Space cleanup
- d) Data disks
Answer: a) Storage management
Explanation: Azure DevOps provides the data purging feature under its Storage Management capabilities.
True or False: Purging of data from Azure Repos is possible.
- True
- False
Answer: True
Explanation: Azure Repos, as part of Azure DevOps, supports purging data from the repositories.
Single Select: What method does Azure use to purge data?
- a) Soft delete
- b) Hard delete
- c) Temporary delete
- d) Back-up delete
Answer: a) Soft delete
Explanation: Azure uses a strategy called “Soft delete”, which marks the data for deletion without permanently removing it immediately.
True or False: It’s possible to recover data purged from source control in Azure.
- True
- False
Answer: False
Explanation: Data purged from source control is permanently deleted and cannot be recovered.
Multiple Select: Which of the following are best practices before purging data in source control?
- a) Performing backup
- b) Checking dependencies
- c) Notifying concerned teams
- d) Checking data validity
- e) All of the above
Answer: e) All of the above
Explanation: All these are considered best practices before purging data to ensure data safety and continuity.
Single Select: What happens to the dependencies when purging data from source control?
- a) Data deletion is stopped
- b) Data becomes inaccessible
- c) Dependencies are deleted
- d) Dependencies remain unaffected
Answer: b) Data becomes inaccessible
Explanation: When data from source control is purged, the data referred to by the dependencies becomes inaccessible.
True or False: Purging data from source control can improve system performance.
- True
- False
Answer: True
Explanation: By removing irrelevant, outdated, or corrupt data, the performance of the system can be improved.
Single Select: When is the ‘purge data’ operation used in Azure DevOps?
- a) When data is no longer relevant
- b) To make a backup of data
- c) To restore data
- d) To add data
Answer: a) When data is no longer relevant
Explanation: The ‘purge data’ operation is performed in Azure DevOps when data has become irrelevant or corrupted and needs to be removed permanently.
True or False: Purge data operation in Azure DevOps can be executed without any backup.
- True
- False
Answer: False
Explanation: It is highly recommended to have a backup before executing a purge data operation because once the data is purged, it cannot be recovered.
Single Select: What precaution should be taken before purging data from Azure DevOps?
- a) Perform a backup
- b) Check data validity
- c) Notify teams
- d) Turn off the system
Answer: a) Perform a backup
Explanation: Performing a backup is crucial before purging data, as data purged from the source control cannot be recovered.
True or False: Purging data from Azure DevOps requires administrative privileges.
- True
- False
Answer: True
Explanation: Purging data is a major operation and it requires administrative privileges to be executed.
Interview Questions
What is the primary purpose of purging data from source control in Microsoft DevOps?
The primary purpose of purging data from source control in Microsoft DevOps is to manage disk space effectively by deleting unwanted or unnecessary files and keeping the repository clean and optimized.
How can you permanently remove data from a repo in Azure DevOps?
You can permanently remove data from a repository in Azure DevOps using the ‘git filter-branch’ or the ‘BFG Repo-Cleaner’ command.
Is it possible to recover purged data from source control in Azure DevOps?
No, once data has been purged from the source control in Azure DevOps, it cannot be recovered.
In the context of Microsoft DevOps, what is BFG Repo-Cleaner?
BFG Repo-Cleaner is a simpler, faster alternative to ‘git filter-branch’ for cleansing bad data out of your Git repository history.
What is the command to remove files larger than 100M from the Git history?
The command is ‘git filter-branch –index-filter ‘git rm –cached –ignore-unmatch *’ — –all.’
What do you need to do after you have cleaned the data in the Git repository?
After the cleaning process, you should ensure all refs are updated, and all old data that is now unreferenced is really removed with the command ‘git gc –prune=now –aggressive.’
What’s the command line to remove a file from the entire commit history in Git?
The command “git filter-branch –force –index-filter ‘git rm –cached –ignore-unmatch path_to_file’ –prune-empty –tag-name-filter cat — –all” can be used.
What does the ‘git filter-branch’ command do in Microsoft DevOps?
‘git filter-branch’ command rewrites the revision history for the specified branches by applying custom filters on each revision.
How can sensitive data, like passwords, be removed from a repository’s history?
Sensitive data can be removed from a repository’s history using the ‘git filter-branch’ command or the BFG Repo-Cleaner.
What happens if you accidentally commit and push files to Git that contain sensitive data?
If you commit and push files to Git that contains sensitive data, you must remove the sensitive data from your files, commit, and push them again. To remove the sensitive data from your repository’s history, you can use ‘git filter-branch’ or the BFG Repo-Cleaner.
What happens after purging data from source control?
After purging data from source control, the data is permanently removed and the size of the repository is reduced which can increase the performance of repository operations.
What is the purpose of tag-name-filter in git filter-branch command?
The purpose of the tag-name-filter in the git filter-branch command is to specify a shell command to alter tag names.
How to avoid accidental data purging in Azure DevOps?
To avoid accidental data purging in Azure DevOps, maintain a backup of your repository data on a regular basis.
Is purging data from source code a good practice?
Yes, purging data from source code is a good practice as it helps in maintaining a clean and manageable codebase and optimizes disk space.
What is source control in Azure DevOps?
Source control in Azure DevOps is a system for tracking changes to code and coordinating work between different people. It’s a crucial tool for modern software development. Git is the distributed version control system used by Azure DevOps.
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