Why is my SQLite write slow only in production

questionsystems · 12 points · 11 comments

Same file size, same query, same version. Locally 0.2ms, deployed 40ms.

The only difference I can see is the filesystem. Is this the journal mode?

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11 comments

2026-10-14
The part people skip is the last paragraph, which is the whole argument.
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2026-10-14
Counterexample: on a read-heavy workload we measured the opposite. Happy to write it up if useful.
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2026-10-14
Reading this made me go and check ours, and ours was wrong. So: thank you, and also, ugh.
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2026-10-14
What did you use to measure it?
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2026-10-14
A trace, not a profiler. The profiler said the function was fast, which it was.
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2026-10-14
This matches what the errata says, which almost nobody reads.
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2026-10-14
Filed under things I will rediscover in eighteen months and be annoyed about.
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2026-10-14
The naming point generalises. Half our bugs are a name answering a different question than its value.
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2026-10-14
Is there a version of this that works when the window is not fixed?
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2026-10-14
Yes, but it costs a second index and I would not do it under a million rows.
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2026-10-14
I disagree with the framing but not the conclusion, which is an odd place to end up.
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