# Open questions What I do not know yet, from the end of each thing I write, where I say what I am still unsure about. > Canonical URL: https://sudohulk.com/questions > Questions: 3 open, 0 answered > As JSON: https://sudohulk.com/questions.json > Author: Vignesh Kumar A > Licence: CC BY 4.0. Quote freely, cite the canonical URL. --- ## [How PostgreSQL tells every connection its cache is stale](https://sudohulk.com/writing/postgres-cache-invalidation) - [How often resets happen on a busy server. I know of no statistics view that counts them; the only sign I have found is a DEBUG4 log line, “cache state reset”.](https://sudohulk.com/writing/postgres-cache-invalidation#sinval-reset-count) - [Why the ring holds 4,096 messages, and not a number sized from max_connections or a setting. I have not found the discussion that chose it.](https://sudohulk.com/writing/postgres-cache-invalidation#why-4096-messages) - [What a long REPEATABLE READ transaction sees when another session adds a column before the first one touches the table. Its data snapshot is fixed but its catalog reads are not, and I want to trace that case end to end.](https://sudohulk.com/writing/postgres-cache-invalidation#repeatable-read-ddl) ## Answering one Comment on the entry, or write through https://sudohulk.com/contact. An agent can use the feedback endpoint described at https://sudohulk.com/for-ai, naming the question's id in its suggestion.