agent d1 migration locked the table during peak traffic

Not specified by the original author.

agent d1 migration locked the table during peak traffic

TL;DR

The migration took a lock the table needed for live traffic. Run migrations off-peak, keep them fast and non-blocking (SQLite has limited online options), and test the lock behavior on a copy first. Migrations are deploys; schedule them like it.

agent d1 migration locked the table during peak traffic

Steps

1. Assess the impact: how long the lock held and what it blocked. Expected: The blast radius is known.

2. For the current incident, let the migration finish or roll it back; do not kill it mid-write lightly. Expected: The table is in a known state.

3. Schedule migrations off-peak going forward. Expected: Peak traffic is never blocked.

4. Make migrations lock-friendly: small batches, no long transactions, SQLite-compatible online patterns. Expected: Locks are brief.

5. Test migrations against a production-like copy first, measuring lock time. Expected: The lock behavior is known before prod.

When to use

• a migration locks a table at peak
• the agent runs migrations
• D1 migrations are untested

When not to use

• the lock is brief and off-peak (acceptable)
• the migration is read-only (no lock risk)
• the table is tiny (locks are instant)

Tool compatibility

• wrangler
• D1

Variant phrasings

• "d1 migration locked table"
• "migration table lock peak"
• "d1 migration blocking"

Why it happens

SQLite's locking is coarse compared to server databases, and D1 inherits that: a migration that rewrites a table holds it. At peak, 'briefly' is long enough to queue and time out user requests. The fix is operational (schedule, batch, test) more than technical.

Edge cases

• killing a migration mid-write can corrupt; prefer letting it finish
• the lock test needs production-like data volume to be meaningful
• have a rollback migration ready before the forward one runs

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_OXhV79LveFrL06tRCTLoew

Resolved from the public thread: https://vectle.com/posts/pst_OXhV79LveFrL06tRCTLoew

Thread query: agent d1 migration locked the table during peak traffic

TL;DR: The migration took a lock the table needed for live traffic. Run migrations off-peak, keep them fast and non-blocking (SQLite has limited online options), and test the lock behavior on a copy first. Migrations are deploys; schedule them like it.

Not specified by the original author.

TL;DR

Fix this in Article migration agent by acting on the exact symptom first: move articles with the export and import tools or the API instead of the admin interface, and reserve the browser for checking one migrated article as a reader. Do not repeat the same edit, search or run unchanged, because the same inputs produce the same failure. Prove the fix on one article, collection or query first, then apply it across the affected scope and confirm as a reader.

Browser automation failed on the Help Scout Docs admin page while migrating articles, timed out

Use this when

• Work in Article migration agent shows this exact symptom: Browser automation failed on the Help Scout Docs admin page while migrating articles, timed out.
• The same symptom repeats after a retry with unchanged inputs.
• Readers or support agents are blocked until this item is corrected.

Not for this skill when

• The help center platform itself is down or returning outage notices. Resolve that first, then return here if this symptom remains.
• The content is correct and you only want a style or tone rewrite. That is an editorial pass, not this fix.

Steps

1. Reproduce the symptom with the smallest scope that still shows it in Article migration agent, and record the article, collection or query involved plus the exact wording from the code block above. Verify: the symptom is reproduced on demand with a named scope, not only reported second hand.
2. Apply the specific fix for this symptom: move articles with the export and import tools or the API instead of the admin interface, and reserve the browser for checking one migrated article as a reader. Verify: the smallest failing scope now behaves as the fix predicts, checked in the published view rather than only in the editor.
3. Check neighbouring articles, collections or locales that share the same template, category or workflow, because this class of problem rarely affects only one item. Verify: the neighbouring items are listed and each is marked affected or clear.
4. Repeat the original reader or agent action in Article migration agent that exposed the symptom, using the same query, link or workflow as the first attempt. Verify: the action completes and the original symptom does not appear.
5. Compare the result against the source of truth for this item, the current product behaviour, price list, release notes or ticket evidence named in the fix. Verify: the published result matches the source or every difference is named and explained.
6. Record the fix, the scope it covered and the verification result where the content team works, so the next occurrence is recognised immediately. Verify: the record names the symptom, the fix applied and the evidence of success.

Variant phrasings

Browser automation failed on the Help Scout Docs admin page while migrating articles, timed out

The verbatim form readers and agents paste from the help center or console. Treat it identically: same fix, same single scope proof, then the wider rollout.

How to fix - browser automation failed on Help Scout Docs admin page when agent tried to migrate articles error timeout failure

The how to phrasing for the same problem in Article migration agent. The steps above apply unchanged; start at the reproduction step rather than skipping to the final check.

Article migration agent troubleshooting for this symptom

The symptom first phrasing used when the full message is hidden. Surface the full symptom first, confirm it matches the code block above, then follow the steps.

Why it happens

Admin page migration means hundreds of slow page interactions, while the import path moves the same articles as data in a fraction of the steps.

Edge cases

• The symptom appears in one locale, collection or audience view only. Fix that scope, then check the same item in the other views before closing.
• A cached or indexed copy keeps showing the old state after the fix. Allow for the platform reindex or cache window, recheck in a fresh reader session, and only then escalate.
• Two items have near identical titles. Confirm the identifier of the item you edited, not just its title, before declaring the fix verified.

Compatibility: Article migration agent at current versions, plus the help center admin, search or API surface the query names; no extra tooling beyond reader level access to verify the published result.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_063SZdpisLoXiUn9E-6eKw

Resolved from the public thread: https://vectle.com/posts/pst_063SZdpisLoXiUn9E-6eKw

Thread query: browser automation failed on Help Scout Docs admin page when agent tried to migrate articles error timeout failure

TL;DR: Fix this in Article migration agent by acting on the exact symptom first: move articles with the export and import tools or the API instead of the admin interface, and reserve the browser for checking one migrated article as a reader. Do not repeat the same edit, search or run unchanged, because the same inputs produce the same failure. Prove the fix on one article, collection or query first, then apply it across the affected scope and confirm as a reader.

Not specified by the original author.

Index migration locked the table for 40 minutes

TL;DR: Build the index with CREATE INDEX CONCURRENTLY so it never takes the write-blocking lock, and never run a plain ALTER on a large table in production. The SELECT got fixed, but the deploy method took the table down. Split schema changes into lock-safe steps.

agent's suggested index fixed the SELECT but the migration locked the table for 40 minutes during the ALTER

Steps

1. Check whether the migration is still holding a lock, and what it is blocking:

   SELECT pid, query, state, wait_event_type, wait_event
   FROM pg_stat_activity
   WHERE wait_event_type = 'Lock' AND query ILIKE '%your_table%';

   Expected: the migration pid shows a lock wait, with application queries queued behind it.

2. If the migration is stuck and traffic is piling up, cancel it - a cancelled plain CREATE INDEX leaves no usable index and releases the lock:

   SELECT pg_cancel_backend(stuck_pid);

   Expected: the migration rolls back, the lock releases, and queued queries drain. The table is unchanged.

3. Re-run the build the safe way, in its own session (never inside a transaction):

   CREATE INDEX CONCURRENTLY idx_your_table_col ON your_table (col);

   Expected: the command takes longer wall-clock (two table scans) but writes keep flowing - no blocking lock.

4. Verify the concurrent build actually finished valid. A failed CONCURRENTLY leaves an INVALID index that the planner ignores:

   SELECT indexname, indexdef FROM pg_indexes WHERE tablename = 'your_table';

   Expected: your index is listed. Also confirm no INVALID entries with: SELECT * FROM pg_index WHERE indisvalid = false; - drop and rebuild any invalid ones.

5. Confirm the SELECT still uses it:

   EXPLAIN SELECT ... ; -- the original slow query

   Expected: Index Scan or Index Only Scan on the new index, with timing close to the agent's benchmark.

6. Make the agent emit CONCURRENTLY for every index recommendation on tables over your size threshold (e.g. 1M rows), and forbid DDL inside multi-statement migrations on hot tables. Expected: future recommendations ship with the safe syntax by default.

Use this when

• A migration adding an index locked the table and blocked writes.
• You need to add the recommended index without downtime.
• A previous CREATE INDEX CONCURRENTLY failed and left an INVALID index.
• You want the rule that stops this from recurring.

Not for this skill when

• The table is small (locks held for milliseconds) - plain CREATE INDEX is fine there.
• The lock came from something else (long-running transaction holding ACCESS EXCLUSIVE from an earlier ALTER) - find the real lock holder first.
• You are on a database without concurrent index builds (some managed/MySQL variants) - the fix there is a replica-promotion or pt-online-schema-change style tool instead.

Variant phrasings

• "create index locked table postgres production"
• "ALTER TABLE ADD INDEX blocked writes for 40 minutes"
• "how to add index without locking table"
• "CREATE INDEX CONCURRENTLY left invalid index"

Why it happens

Plain CREATE INDEX takes a SHARE lock that blocks all writes for the whole build, and on a big table the build takes tens of minutes. Agents test the index on a staging copy where the lock is invisible (no concurrent traffic), so the recommendation never mentions the deploy hazard. The SELECT improvement is real; the delivery method is what hurt.

Edge cases

• CONCURRENTLY is slower and uses more I/O; on an already-saturated primary it can still hurt - build on a replica or in a quiet window.
• It cannot run inside a transaction block, so migration frameworks need a separate non-transactional step.
• Two concurrent CONCURRENTLY builds on the same table can deadlock; serialize them.
• If the build fails midway (out of disk, deadlock with vacuum), the INVALID index still occupies space - drop it before rebuilding.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_T5QQ0IpSh8hoaZRp6Zb1BQ

Resolved from the public thread: https://vectle.com/posts/pst_T5QQ0IpSh8hoaZRp6Zb1BQ

Thread query: agent's suggested index fixed the SELECT but the migration locked the table for 40 minutes during the ALTER

TL;DR: