feature: support resuming interrupted downloads via HTTP Range headers (--resume)

Feature Request

Describe the feature you'd like
Add a --resume (or -c) flag to databusclient download that uses HTTP Range request headers to resume partially downloaded files instead of restarting from byte 0.

Why is this feature important?
DBpedia Databus datasets (such as Live Fusion dumps or Wikipedia extractions) are often multi-gigabyte files. Currently, in databusclient/api/download.py (lines 576–585), files are always opened in "wb" mode without checking existing file sizes.

If a network drop, timeout, or interruption occurs midway through a large download, re-running databusclient download truncates the partial file and re-downloads the entire dataset from scratch, wasting significant network bandwidth and time.

Describe alternatives you've considered
Users currently have to download files using external tools like curl -C - or wget -c outside of databusclient, which loses Databus metadata tracking, checksum validation, and manifest recording.

Additional context

Affected files: databusclient/api/download.py and databusclient/cli.py.
If the target file already exists partially on disk and --resume is enabled:
1. Send Range: bytes=<existing_size>- in the HTTP GET request.
2. If the server returns 206 Partial Content, open the file in "ab" mode and update the tqdm progress bar with initial=existing_size.
3. If the server does not support Range requests (returns 200 OK), fallback gracefully to normal full download.

@yush-1018

Hey @yush-1018 this looks like a great first issue for me to dig into I've just gotten my dev environment set up for this project. Would you be open to assigning this to me... I'll get started on the --resume flag using Range headers as you described

@alankrittiwari6969-ai

Hey @alankrittiwari6969-ai !

I have actually already implemented this feature and opened a pull request here: #94.

I am new to the GSOC can. You guide me little bit I want to participate and contribute to the organisation

…

On Fri, 18 Sept, 2026, 1:17 am Ayush Raj, ***@***.***> wrote: *yush-1018* left a comment (dbpedia/databus-python-client#93) <#93 (comment)> Hey @alankrittiwari6969-ai <https://github.com/alankrittiwari6969-ai> ! I have actually already implemented this feature and opened a pull request here: #94 <#94>. — Reply to this email directly, view it on GitHub <#93?email_source=notifications&email_token=CFJE2BUMGMGJ3JWM2PIZUCL5PQ5V7A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKNZSGAZDKNJVG442M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-5720255579>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/CFJE2BSC74ZQKG5XIQBEI5T5PQ5V7AVCNFSNUABFKJSXA33TNF2G64TZHM3DANJWGA2TANBRHNEXG43VMU5TKNBTGE3DKNBVGY2KC5QC> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/CFJE2BXHIIOT63CXXQNAGBL5PQ5V7A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKNZSGAZDKNJVG442M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/CFJE2BWIQZP4O7XNC4VLUC35PQ5V7A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKNZSGAZDKNJVG442M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you were mentioned.Message ID: ***@***.***>

First, go through the repo and set up the project locally. You can check the open issues to see if there is anything available to work on, or explore the codebase to find bugs and improvements, discuss them by creating an issue first, and then open a PR.

Good luck!

Thanks, I will.

…

On Fri, 18 Sept, 2026, 10:38 am Ayush Raj, ***@***.***> wrote: *yush-1018* left a comment (dbpedia/databus-python-client#93) <#93 (comment)> First, go through the repo and set up the project locally. You can check the open issues to see if there is anything available to work on, or explore the codebase to find bugs and improvements, discuss them by creating an issue first, and then open a PR. Good luck! — Reply to this email directly, view it on GitHub <#93?email_source=notifications&email_token=CFJE2BQB4RF3TBU4DB4WIUD5PS7NXA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKNZSGU2DMNBSG44KM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-5725464278>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/CFJE2BVRLSVGZJRAWHVOX3T5PS7NXAVCNFSNUABFKJSXA33TNF2G64TZHM3DANJWGA2TANBRHNEXG43VMU5TKNBTGE3DKNBVGY2KC5QC> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/CFJE2BUDNLCGAXOOSH65VST5PS7NXA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKNZSGU2DMNBSG44KM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/CFJE2BXRXCAHSWFTA4BMEZ35PS7NXA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKNZSGU2DMNBSG44KM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you were mentioned.Message ID: ***@***.***>

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feature: support resuming interrupted downloads via HTTP Range headers (--resume) #93

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feature: support resuming interrupted downloads via HTTP Range headers (--resume) #93

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alankrittiwari6969-ai commented on Sep 17, 2026

yush-1018 commented on Sep 17, 2026

alankrittiwari6969-ai commented on Sep 17, 2026

yush-1018 commented on Sep 18, 2026

alankrittiwari6969-ai commented on Sep 18, 2026

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