pg_stat_slru
Also called: SLRU statistics view
pg_stat_slru is a system view (PostgreSQL 13+) that reports activity for each internal SLRU cache, one row per cache (CommitTs, MultiXactMember, MultiXactOffset, Subtrans, Xact, and others). Its columns count buffer hits, disk reads, writes, and pages zeroed.
What this means
A system view (PG13+) that reports how hard each internal SLRU cache is working, one row per cache (commit log, multixact, subtrans, and others), counting buffer hits, disk reads, writes, and pages zeroed. It's where you look to find out whether one of those little caches has quietly become a bottleneck.
Why it matters operationally
It is the instrument for diagnosing SLRU contention. Rising blks_read on the Subtrans row points to subtransaction overflow; growth on the MultiXact* rows points to heavy row-share locking. Without this view, SLRU pressure is nearly invisible, with it, you can target exactly which cache to enlarge (PG17 buffer GUCs) or which workload to fix.