Comment by pgedge_postgres
3 days ago
Getting some examples of real-world cases to share and will comment back with them ASAP; in the meantime, would you mind sharing what undocumented edge cases you came across and what solutions you explored to handle them? It would help with sharing super relevant use cases :-)
I tried to escape this world as quickly as possible, realizing how horrible it was, but the largest issue I ran into was around IO. Creating an environment that was highly tolerant to fault while having little to no replication delay meant checking in on the master database frequently. Keeping in mind this was around 2010 I found that the IO load on these databases was substantially larger than any database that i had ever worked on before. Things like available file handlers and other related performance problems came up more frequently than I’ve ever experienced before and frankly more frequently than I’ve ever experienced since.
If I was to summarize it, I would just say the performance characteristics were not something I was used to experiencing and often they would surprise me when they occurred, which meant having a good quality of a while for running this application was very challenging.