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jodeleeuw merged 2 commits into from
Apr 2, 2026
Merged

docs: add FAQ entry about the 32 MB request size limit #149

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ff89ea1
docs: add FAQ entry about the 32 MB request size limit
jodeleeuw Apr 2, 2026
67b4e2e
fix: resolve race condition in get-condition error log test
jodeleeuw Apr 2, 2026
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2 changes: 2 additions & 0 deletions functions/src/__tests__/get-condition-emulator.test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,8 @@ describe("getCondition", () => {
it("should increment the error log for an experiment when errors are caught", async () => {

const db = getFirestore();
// Wait for any pending logError writes from previous tests to land before deleting
await waitForLog(db, "testexp", "logError", 1);
await db.collection("logs").doc("testexp").delete();

await getCondition({ experimentID: "testexp" });
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44 changes: 44 additions & 0 deletions pages/faq.js
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Expand Up @@ -182,6 +182,50 @@ export default function FAQ() {
active only while you are collecting data.
</Text>
</FAQItem>
<FAQItem value="item-9b" question="Is there a limit on how much data I can send?">
<Text mb={2}>
Yes. DataPipe has a <strong>32 MB limit</strong> on the size of a
single request. This limit is enforced by the server infrastructure
and cannot be increased. Most experiment data is well under this
limit — a typical jsPsych dataset is 50 KB to 5 MB.
</Text>
<Text mb={2}>
If you are using version 0.6.0 or later of the{" "}
<Link
href="https://github.com/jspsych/jspsych-contrib/tree/main/packages/plugin-pipe"
target="_blank"
rel="noopener noreferrer"
>
@jspsych-contrib/plugin-pipe
</Link>{" "}
plugin, request bodies are automatically compressed with gzip before
sending. Text data (JSON, CSV) typically compresses by 2–10x, which
effectively raises the upload limit to roughly 60–300 MB for most
experiment data. Compression is enabled by default and requires no
configuration.
</Text>
<Text mb={2}>
Compression is less effective for binary data sent via the base64
endpoint (e.g., video or audio recordings), because binary data does
not compress as well as text. If you need to send individual files
larger than about 25 MB through the base64 endpoint, they may still
exceed the limit even after compression.
</Text>
<Text>
If you are sending data without the plugin (e.g., using fetch
directly), you can compress the request body yourself using the
browser&apos;s{" "}
<Link
href="https://developer.mozilla.org/en-US/docs/Web/API/CompressionStream"
target="_blank"
rel="noopener noreferrer"
>
CompressionStream API
</Link>{" "}
and setting the <code>Content-Encoding: gzip</code> header. The
server will decompress the body automatically.
</Text>
</FAQItem>
<FAQItem value="item-10" question="How does condition assignment work?">
<Text>
When enabled, DataPipe assigns condition numbers sequentially.
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