https://www.postgresscripts.com/tags/pg_buffercache/Recent content in Pg_buffercache on Postgres ScriptsHugo -- gohugo.ioenPostgresScripts.comTue, 08 Sep 2026 00:00:00 +0000https://www.postgresscripts.com/post/summarize-buffer-cache-with-pg-buffercache-summary-function/Tue, 08 Sep 2026 00:00:00 +0000https://www.postgresscripts.com/post/summarize-buffer-cache-with-pg-buffercache-summary-function/ <h2 id="summarize-the-buffer-cache-with-pg_buffercache_summary">Summarize the Buffer Cache with pg_buffercache_summary</h2> <p>PostgreSQL 16 added a shortcut to a question DBAs have always had to answer the expensive way. Before that release, checking how full the shared buffer cache was — how many buffers were dirty, how many pinned, how hot the clock-sweep usage counts were running — meant scanning <a href="https://www.postgresql.org/docs/current/pgbuffercache.html">pg_buffercache</a>, one row per 8KB buffer, and aggregating the result yourself. <code>pg_buffercache_summary()</code> collapses that scan into a single row: how many buffers are used, unused, dirty, and pinned, plus the average clock-sweep usage count across the whole cache — computed inside the function instead of pulled buffer-by-buffer into a client and summed by hand.</p>