Recently we were involved in a complex digital transformation project where the client had to rewrite piece by piece a Java/Mysql site into a Node.js/Posgresql site. As we started rewriting the site, we had to keep both the new and old sites up and running. This presented a unique challenge as data was now being written into both old and new db at the same time. With no real time db sync, new db/site would have missing or stale info.
After digging around for a bit for various solutions (including opening up a few API endpoints in the old site), we found zongji, a Mysql binlog listener that detects changes in a Mysql db. We deployed this lib on a heroku instance that listened for changes in the legacy db and wrote those changes to the new db , with no latency and without end user noticing any difference.
We deployed this listener the same day the new site launched and it worked quite well, enabling client to do business as usual while the transformation project continued.
