fix prisma session race condition error

[kriscarle]

I'm getting this error in the logs, seems to be related to a race condition, with multiple processes updating the sessions

{
  code: 'P2025',
  meta: { modelName: 'SessionData', operation: 'an update' },
  clientVersion: '6.19.0',
  name: 'PrismaClientKnownRequestError',
  message: '\n' +
    'Invalid `prisma.sessionData.update()` invocation:\n' +
    '\n' +
    '\n' +
    'An operation failed because it depends on one or more records that were required but not found. No record was found for an update.',
  stack: 'PrismaClientKnownRequestError: \n' +
    'Invalid `prisma.sessionData.update()` invocation:\n' +
    '\n' +
    '\n' +
    'An operation failed because it depends on one or more records that were required but not found. No record was found for an update.\n' +
    '    at di.handleRequestError (/app/node_modules/.pnpm/@[email protected][email protected][email protected][email protected]/node_modules/@prisma/client/runtime/client.js:81:7268)\n' +
    '    at di.handleAndLogRequestError (/app/node_modules/.pnpm/@[email protected][email protected][email protected][email protected]/node_modules/@prisma/client/runtime/client.js:81:6593)\n' +
    '    at di.request (/app/node_modules/.pnpm/@[email protected][email protected][email protected][email protected]/node_modules/@prisma/client/runtime/client.js:81:6300)\n' +
    '    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n' +
    '    at async a (/app/node_modules/.pnpm/@[email protected][email protected][email protected][email protected]/node_modules/@prisma/client/runtime/client.js:90:9551)\n' +
    '    at async m (/app/.next/server/chunks/[root-of-the-server]__e72b30ae._.js:1859:904)\n' +
    '    at async k (/app/.next/server/chunks/[root-of-the-server]__4217576a._.js:11:38087)\n' +
    '    at async rN.do (/app/node_modules/.pnpm/[email protected]_@[email protected][email protected][email protected][email protected][email protected]/node_modules/next/dist/compiled/next-server/app-route-turbo.runtime.prod.js:5:21042)\n' +
    '    at async rN.handle (/app/node_modules/.pnpm/[email protected]_@[email protected][email protected][email protected][email protected][email protected]/node_modules/next/dist/compiled/next-server/app-route-turbo.runtime.prod.js:5:25860)\n' +
    '    at async d (/app/.next/server/chunks/[root-of-the-server]__ffe8fc2e._.js:1:3076)'
}

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[greptile-apps]

Greptile Overview

Greptile Summary

Replaced the query-then-update pattern with a more resilient updateMany-then-create approach to handle session data persistence. The key improvement is using a compound where clause (sessionId, dataKey) directly in updateMany instead of relying on cached record IDs from a previous findMany query, which significantly reduces the race condition window and eliminates "Record not found" errors when records are modified between queries.

Key Changes:

• Removed upfront findMany query that cached all existing records
• Replaced update by ID with updateMany by compound where clause
• updateMany returns a count instead of throwing errors, making the code more resilient
• Reduced race condition window by eliminating the stale data dependency

Confidence Score: 4/5

• This PR is safe to merge with good improvements to error handling and race condition mitigation
• Score reflects solid improvement over previous implementation by eliminating "Record not found" errors and reducing race window, though a complete solution would require database-level unique constraints on (sessionId, dataKey)
• No files require special attention - the single file change is straightforward and improves resilience

Important Files Changed

File Analysis

Filename	Score	Overview
src/queries/sql/sessions/saveSessionData.ts	3/5	Replaced query-then-update pattern with updateMany-then-create to reduce race condition window, though without unique constraint or transaction, small race window remains between updateMany and create operations

Sequence Diagram

sequenceDiagram
    participant Client
    participant API as saveSessionData
    participant DB as Prisma/Database

    Client->>API: saveSessionData(sessionData)
    
    Note over API: Flatten JSON into key-value pairs
    API->>API: flattenJSON(sessionData)
    API->>API: Generate UUIDs for each record
    
    loop For each flattened data item
        API->>DB: updateMany({sessionId, dataKey})
        DB-->>API: {count: n}
        
        alt count === 0 (no existing record)
            API->>DB: create(newRecord)
            DB-->>API: Created record
        else count > 0 (record updated)
            Note over API: Record already updated, continue
        end
    end
    
    API-->>Client: Success

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[greptile-apps]

Additional Comments (1)

1. src/queries/sql/sessions/saveSessionData.ts, line 54-69 (link)

   logic: race condition still possible: if two requests both get count === 0 between lines 54-65, both will execute create at line 66-68, creating duplicate records with same sessionId+dataKey. without a unique constraint on (sessionId, dataKey) in the database schema or wrapping this in a transaction, duplicates can still occur. consider adding @@unique([sessionId, dataKey]) to the SessionData model in schema.prisma, then use Prisma's upsert instead of this pattern.

_{1 file reviewed, 1 comment}

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[mikecao]

👍 Thanks