# Question about eg2: Fetch single message from disk **URL:** \ **Category:** Challenges\ **Tags:** challenge:kafka\ **Created:** [November 26, 2024, 9:49pm UTC](https://forum.codecrafters.io/t/question-about-eg2-fetch-single-message-from-disk/3154 "2024-11-26T21:49:14Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![gokul-j99](https://yyz1.discourse-cdn.com/flex003/user_avatar/forum.codecrafters.io/gokul-j99/32/3087_2.png) [@gokul-j99](https://forum.codecrafters.io/u/gokul-j99)\ **Post date:** [November 26, 2024, 9:49pm UTC](https://forum.codecrafters.io/t/question-about-eg2-fetch-single-message-from-disk/3154/1 "2024-11-26T21:49:14Z")
I’m getting CRC mismatch error. I’m implementing it in Java. The messages are correct but just missing in CRC calculation. Can some one guide? ![Screenshot 2024-11-26 at 4.50.15 PM](https://canada1.discourse-cdn.com/flex003/uploads/codecrafters/original/2X/5/51906f6ef226e536a471798b5cfb1b95eda763e6.jpeg) ---
**Author:** ![andy1li](https://yyz1.discourse-cdn.com/flex003/user_avatar/forum.codecrafters.io/andy1li/32/10_2.png) [@andy1li](https://forum.codecrafters.io/u/andy1li)\ **Post date:** [November 26, 2024, 10:03pm UTC](https://forum.codecrafters.io/t/question-about-eg2-fetch-single-message-from-disk/3154/2 "2024-11-26T22:03:45Z")
Hi @gokul-j99, Could you [upload your code to GitHub](https://docs.codecrafters.io/features/publish-to-github) and share the link? It will be much easier to debug if I can run it directly. ---
**Author:** ![gokul-j99](https://yyz1.discourse-cdn.com/flex003/user_avatar/forum.codecrafters.io/gokul-j99/32/3087_2.png) [@gokul-j99](https://forum.codecrafters.io/u/gokul-j99)\ **Post date:** [November 26, 2024, 11:34pm UTC](https://forum.codecrafters.io/t/question-about-eg2-fetch-single-message-from-disk/3154/3 "2024-11-26T23:34:46Z")
HI @andy1li Thanks for reply. My code: [https://github.com/gokul-j99/code-crafter-kafka/tree/master](https://github.com/gokul-j99/code-crafter-kafka/tree/master) ---
**Author:** ![andy1li](https://yyz1.discourse-cdn.com/flex003/user_avatar/forum.codecrafters.io/andy1li/32/10_2.png) [@andy1li](https://forum.codecrafters.io/u/andy1li)\ **Post date:** [November 27, 2024, 12:36am UTC](https://forum.codecrafters.io/t/question-about-eg2-fetch-single-message-from-disk/3154/4 "2024-11-27T00:36:37Z")
Thanks for sharing the link! I’ll take a look and get back to you by the end of the week. ---
**Author:** ![gokul-j99](https://yyz1.discourse-cdn.com/flex003/user_avatar/forum.codecrafters.io/gokul-j99/32/3087_2.png) [@gokul-j99](https://forum.codecrafters.io/u/gokul-j99)\ **Post date:** [November 29, 2024, 1:20am UTC](https://forum.codecrafters.io/t/question-about-eg2-fetch-single-message-from-disk/3154/5 "2024-11-29T01:20:14Z")
Hi, @andy1li Could you identify the issue? ---
**Author:** ![andy1li](https://yyz1.discourse-cdn.com/flex003/user_avatar/forum.codecrafters.io/andy1li/32/10_2.png) [@andy1li](https://forum.codecrafters.io/u/andy1li)\ **Post date:** [December 2, 2024, 6:51am UTC](https://forum.codecrafters.io/t/question-about-eg2-fetch-single-message-from-disk/3154/7 "2024-12-02T06:51:22Z")
**EDIT:** The correct approach is to read the entire RecordBatch from disk and return it as-is, without parsing and re-serializing it. In other words, there’s **no need to implement CRC** for this stage. * * * Sorry for the delayed response! It seems that your code hasn’t implemented CRC yet. The CRC value should be calculated over all the bytes that **follow** the CRC field in the record batch. This ensures the integrity of the entire payload after the CRC field. For reference, you can review the Go implementation in our tester: > ---
**Author:** ![gokul-j99](https://yyz1.discourse-cdn.com/flex003/user_avatar/forum.codecrafters.io/gokul-j99/32/3087_2.png) [@gokul-j99](https://forum.codecrafters.io/u/gokul-j99)\ **Post date:** [December 4, 2024, 5:25am UTC](https://forum.codecrafters.io/t/question-about-eg2-fetch-single-message-from-disk/3154/9 "2024-12-04T05:25:21Z")
Thanks, issue resolved ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex003/uploads/codecrafters/original/3X/7/0/700657133935c15703e22c7c8870394f6e6dc27d.svg) [@system](https://forum.codecrafters.io/u/system)\ **Post date:** [December 9, 2024, 5:25am UTC](https://forum.codecrafters.io/t/question-about-eg2-fetch-single-message-from-disk/3154/10 "2024-12-09T05:25:28Z")
Closed on December 9, 2024, 5:25am UTC This topic was automatically closed 5 days after the last reply. New replies are no longer allowed.