Fix slow JDBC in Google Apps Script V8. Learn the native SQL JSON trick to boost throughput from 3 to 142 records/sec and bypass the 30-min timeout.
We have regularly featured solutions for connecting external databases to Google Workspace using the JDBC service. Our most recent example include a guide on connecting PostgreSQL to Apps Script [JDBC Guide, February 2026]. While this guide help establish connections, developers running large-scale synchronisations under the modern V8 engine frequently encounter severe performance drops. A detailed post from Pablo Felip analyses this runtime performance gap and provides a helpful workaround that can reduce execution times by over 98%.
Standard database queries in Google Apps Script suffer from severe performance degradation when using the JDBC service because the V8 runtime adds significant latency. To resolve this, Pablo highlights how developers can offload data processing to the database server by using native SQL features like FOR JSON PATH or JSON aggregation functions to bundle query results into a single, efficient JSON string. This approach dramatically reduces the processing, allowing the Apps Script code to fetch data as chunks and use V8’s native JSON parsing to reconstruct the table in memory. By using this approach, developers can achieve massive speed improvements and stay well within execution time limits.
Head over to Pablo’s blog to read the complete post, view the underlying benchmark metrics and see if this approach can speed up your database synchronisation workflows!
