feat(data-pipeline): ensure large span strings get truncated before encoding#2161
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brettlangdon wants to merge 8 commits into
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feat(data-pipeline): ensure large span strings get truncated before encoding#2161brettlangdon wants to merge 8 commits into
brettlangdon wants to merge 8 commits into
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brettlangdon
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bantonsson
requested changes
Jun 25, 2026
| /// Fields whose Unicode code-point count exceeds this threshold are truncated. | ||
| pub const MAX_SPAN_STRING_LEN: usize = 25_000; | ||
| /// Length (in Unicode code points) to which over-long fields are truncated, including the suffix. | ||
| pub const TRUNCATED_SPAN_STRING_LEN: usize = 2_500; |
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Why is this way shorter than MAX_SPAN_STRING_LEN, we cut if it's more tham 25000 codepoints but keep only the 1st 2500.
Or is this missing a zero maybe?
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This is what we do in Python, I don't remember the original reason
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The PR mentions the agent truncation policy... But it doesn't truncate the same 😅
It truncates at 25K bytes (at the nearest utf8 boundary actually), and not unicode codepoints, which can be significantly smaller for non latin characters and adds "..." after the 25K th character
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yeah, I don't mind diverging a bit from what dd-trace-py does, as long as it aligns with what the trace agent does 👍🏻
bantonsson
approved these changes
Jun 26, 2026
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What does this PR do?
Add truncation of Span strings that are larger than 25k characters long before encoding.
Motivation
In dd-trace-py, this truncation currently happens when we encode Span chunks to hand off to the trace exporter, but as we remove the Python based encoders and give Spans directly to the trace exporter we need to maintain this behavior.
Additional Notes
Anything else we should know when reviewing?
How to test the change?
Describe here in detail how the change can be validated.