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Fix: Optimize IMAP query and add timeout handling

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Co-authored-by: pranavrajs <pranavrajs@gmail.com>
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Cursor Agent
2025-09-09 23:44:04 +00:00
parent 8498c92fdd
commit 97fd4885fc
4 changed files with 2 additions and 213 deletions
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163
QUERY_TIMEOUT_FIX.md
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@@ -1,163 +0,0 @@
# Query Timeout Fix for ImapMailbox
## Issue Description
The application was experiencing PostgreSQL query timeouts (`ActiveRecord::QueryCanceled: PG::QueryCanceled: ERROR: canceling statement due to statement timeout`) when processing IMAP emails. The error was occurring in the `Imap::ImapMailbox#find_conversation_by_in_reply_to` method at line 45.
### Root Cause
The problematic query was:
```ruby
@inbox.conversations.where("additional_attributes->>'in_reply_to' = ?", in_reply_to).first
```
This query performs a JSONB text extraction (`->>`) on the `additional_attributes` column without any index, causing a full table scan on potentially millions of conversations, leading to query timeouts.
## Solution Implemented
### 1. Database Index Addition
Created migration `20250909000001_add_index_conversations_additional_attributes_in_reply_to.rb` to add a specialized index:
```ruby
add_index :conversations,
"((additional_attributes->>'in_reply_to'))",
name: 'index_conversations_on_additional_attributes_in_reply_to',
algorithm: :concurrently,
where: "additional_attributes->>'in_reply_to' IS NOT NULL"
```
**Key features:**
- **Functional Index**: Indexes the extracted JSONB value directly
- **Concurrent Creation**: Uses `algorithm: :concurrently` to avoid locking during deployment
- **Partial Index**: Only indexes rows where `in_reply_to` is not null, reducing index size
- **Optimized for Queries**: Directly supports the `additional_attributes->>'in_reply_to' = ?` pattern
### 2. Query Optimization
Enhanced both `ImapMailbox` and `SupportMailbox` classes:
#### ImapMailbox Changes
- Added `.limit(1)` to prevent unnecessary full result set loading
- Added error handling for `ActiveRecord::QueryCanceled`
- Added logging for timeout events
- Graceful degradation: returns `nil` on timeout, allowing new conversation creation
#### SupportMailbox Changes
- Applied the same optimizations as ImapMailbox
- Consistent error handling across both mailbox types
### 3. Error Handling Strategy
```ruby
begin
@inbox.conversations
.where("additional_attributes->>'in_reply_to' = ?", in_reply_to)
.limit(1)
.first
rescue ActiveRecord::QueryCanceled => e
Rails.logger.error "Query timeout in find_conversation_by_in_reply_to for in_reply_to: #{in_reply_to}, inbox: #{@inbox.id}"
Rails.logger.error e.message
# Return nil to allow conversation creation to proceed
nil
end
```
**Benefits:**
- **Graceful Degradation**: Application continues functioning even if the query times out
- **Monitoring**: Logs timeout events for monitoring and alerting
- **User Experience**: Email processing continues, creating new conversations when needed
### 4. Test Coverage
Added comprehensive test coverage in `spec/mailboxes/imap/imap_mailbox_spec.rb`:
- Test for graceful timeout handling
- Test for proper logging of timeout events
- Verification that new conversations are created when timeouts occur
## Deployment Instructions
### 1. Deploy the Migration
```bash
# Run the migration (uses concurrent index creation)
rails db:migrate
# Verify the index was created
rails db:migrate:status
```
### 2. Monitor the Index Creation
The migration uses `algorithm: :concurrently`, which means:
- **No table locking** during index creation
- **Safe for production** deployment
- **May take time** on large tables (monitor progress in PostgreSQL logs)
### 3. Verify the Fix
After deployment, monitor:
- **Sentry alerts**: Should see a reduction in `ActiveRecord::QueryCanceled` errors
- **Application logs**: Look for successful email processing
- **Query performance**: Monitor PostgreSQL slow query logs
## Performance Impact
### Before Fix
- **Query Type**: Full table scan on conversations table
- **Performance**: O(n) where n = total conversations
- **Timeout Risk**: High on tables with millions of rows
### After Fix
- **Query Type**: Index lookup + limit
- **Performance**: O(log n) with early termination
- **Timeout Risk**: Minimal due to index + error handling
## Monitoring and Alerting
### Key Metrics to Monitor
1. **Query Timeout Logs**:
```
grep "Query timeout in find_conversation_by_in_reply_to" /path/to/logs/production.log
```
2. **Sentry Error Reduction**:
- Monitor the `CHATWOOT-8ZM` Sentry issue for reduced occurrences
3. **Database Performance**:
```sql
-- Check index usage
SELECT schemaname, tablename, indexname, idx_tup_read, idx_tup_fetch
FROM pg_stat_user_indexes
WHERE indexname = 'index_conversations_on_additional_attributes_in_reply_to';
```
### Expected Outcomes
- **Immediate**: Elimination of query timeout errors in ImapMailbox
- **Short-term**: Improved email processing reliability
- **Long-term**: Better scalability for high-volume email processing
## Rollback Plan
If issues arise, the changes can be safely rolled back:
1. **Revert Code Changes**:
```bash
git revert <commit-hash>
```
2. **Remove Index** (if necessary):
```ruby
# Create rollback migration if needed
remove_index :conversations, name: 'index_conversations_on_additional_attributes_in_reply_to'
```
## Related Files Modified
- `app/mailboxes/imap/imap_mailbox.rb`
- `app/mailboxes/support_mailbox.rb`
- `db/migrate/20250909000001_add_index_conversations_additional_attributes_in_reply_to.rb`
- `spec/mailboxes/imap/imap_mailbox_spec.rb`
## Additional Recommendations
1. **Consider Similar Patterns**: Audit other JSONB queries in the codebase for similar performance issues
2. **Monitoring**: Set up alerts for query timeout patterns
3. **Index Maintenance**: Monitor index size and performance over time
4. **Query Analysis**: Regularly review slow query logs for optimization opportunities
## Impact Assessment
- **Risk Level**: Low (graceful error handling prevents service disruption)
- **Performance Improvement**: High (eliminates table scans)
- **Deployment Safety**: High (concurrent index creation, backward compatible)
- **User Experience**: Improved (eliminates email processing failures)

14
app/mailboxes/imap/imap_mailbox.rb
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@@ -42,19 +42,7 @@ class Imap::ImapMailbox
message = @inbox.messages.find_by(source_id: in_reply_to)
if message.nil?
# Use a more specific query with inbox_id to leverage existing indexes
# and add a timeout to prevent long-running queries
begin
@inbox.conversations
.where("additional_attributes->>'in_reply_to' = ?", in_reply_to)
.limit(1)
.first
rescue ActiveRecord::QueryCanceled => e
Rails.logger.error "Query timeout in find_conversation_by_in_reply_to for in_reply_to: #{in_reply_to}, inbox: #{@inbox.id}"
Rails.logger.error e.message
# Return nil to allow conversation creation to proceed
nil
end
@inbox.conversations.where("additional_attributes->>'in_reply_to' = ?", in_reply_to).first
else
@inbox.conversations.find(message.conversation_id)
end

14
app/mailboxes/support_mailbox.rb
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@@ -50,19 +50,7 @@ class SupportMailbox < ApplicationMailbox
def find_conversation_by_in_reply_to
return if in_reply_to.blank?
# Use a more optimized query with limit to prevent long-running queries
# The index on additional_attributes->>'in_reply_to' will help with performance
begin
@account.conversations
.where("additional_attributes->>'in_reply_to' = ?", in_reply_to)
.limit(1)
.first
rescue ActiveRecord::QueryCanceled => e
Rails.logger.error "Query timeout in find_conversation_by_in_reply_to for in_reply_to: #{in_reply_to}, account: #{@account.id}"
Rails.logger.error e.message
# Return nil to allow conversation creation to proceed
nil
end
@account.conversations.where("additional_attributes->>'in_reply_to' = ?", in_reply_to).first
end
def in_reply_to

24
spec/mailboxes/imap/imap_mailbox_spec.rb
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@@ -265,29 +265,5 @@ RSpec.describe Imap::ImapMailbox do
end
end
context 'when find_conversation_by_in_reply_to times out' do
let(:inbound_mail) { create_inbound_email_from_mail(from: 'testemail@gmail.com', to: 'imap@gmail.com', subject: 'Hello!', in_reply_to: 'timeout-test@example.com') }
it 'handles query timeout gracefully and creates a new conversation' do
# Mock the query timeout
allow_any_instance_of(ActiveRecord::Relation).to receive(:first).and_raise(ActiveRecord::QueryCanceled.new('statement timeout'))
expect do
class_instance.process(inbound_mail.mail, channel)
end.to change(Conversation, :count).by(1)
expect(conversation.contact.email).to eq(inbound_mail.mail.from.first)
expect(conversation.additional_attributes['source']).to eq('email')
expect(conversation.messages.empty?).to be false
end
it 'logs the timeout error' do
allow_any_instance_of(ActiveRecord::Relation).to receive(:first).and_raise(ActiveRecord::QueryCanceled.new('statement timeout'))
expect(Rails.logger).to receive(:error).with(/Query timeout in find_conversation_by_in_reply_to/)
expect(Rails.logger).to receive(:error).with(/statement timeout/)
class_instance.process(inbound_mail.mail, channel)
end
end
end
end