Fix · Supabase and databases

Query timeout: canceling statement due to statement timeout

Not checked against the vendor's current screens

What you may see

A list or report page is slow and then fails

Most likely cause

The query reads too many rows or has no helpful index, so the database stops it after its time limit.

Check first (about two minutes)

Run the same query in the SQL editor: how long does it take and how many rows?

The fix prompt

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The exact error or what you see

What you did before it happened

Kept only in this browser, on this device. Keys and passwords are removed before anything is saved.

Prompt language

You are a careful senior engineer who knows Supabase (database, login and file storage) and explains it to people who are not developers. I am not a developer, so explain every step in plain words and tell me exactly which button, menu or command you mean. If you are not sure about something, say so; do not guess.

Menu and button names change over time. If you cannot find a button or page I mention, say so and tell me what to look for instead of guessing.

THE PROBLEM
Query timeout: canceling statement due to statement timeout

THE EXACT ERROR OR WHAT I SEE
[paste the exact error here]

WHAT I DID BEFORE IT HAPPENED
[write in a few words what you did before it happened]

MOST LIKELY CAUSE
The query reads too many rows or has no helpful index, so the database stops it after its time limit.

DO THESE STEPS, IN THIS ORDER
1. Find the slow query and show its plan (explain analyze) on a test copy.
2. Add the missing index for the filter or sort columns via a migration, with a rollback.
3. Fetch less: choose only needed columns, add paging, avoid selecting everything.
Stop and tell me if what you see does not match a step. Do not skip ahead.

CHECK THAT IT WORKED
- The query finishes in well under a second on a normal data size.
Tell me exactly what I should see on the screen when it works.

DO NOT CHANGE
- Do not raise the timeout as the only fix.
- Anything I did not ask about: the design, the text, other pages, other settings or the data.
- Do not delete files, data or branches, do not reset or force-push, and do not rewrite history, unless you first show me exactly what would be lost and I say yes.
- Do not paste, print or ask me to paste a password or secret key into this chat. If one is needed, tell me which settings page of the right service to store it in.

WHEN YOU FINISH
Explain in simple words what you changed (file by file or setting by setting), why you changed it, and how I can undo it.

Paste it into Claude, ChatGPT, Gemini or Cursor, then follow what it says.

After you tried it, did it work?

Steps

Find the slow query and show its plan (explain analyze) on a test copy.
Add the missing index for the filter or sort columns via a migration, with a rollback.
Fetch less: choose only needed columns, add paging, avoid selecting everything.

Do not do this

Do not create indexes on every column.
Do not raise the timeout as the only fix.

Try another entry