Postgres Heap-Only-Tuples When can you do HOT Updates? BRIN Indexes no longer block HOT Updates in Postgres 16 or newer How do HOT updates exactly work? What we have discussed in this episode of 5mins of…Conti
relpages int4 该数据表或索引所占用的磁盘页面数量,查询规划器会借助该值选择最优路径。 reltuples float4 表中行的数量,该值只是被规划器使用的一个估计值。 reltoastrelid oid pg_class.oid 与此表关联的TOAST表的OID,如果没有为0。TOAST表在一个从属表里"离线"存储大字段。 reltoastidxid ...
Postgres autovacuum cleans up index entries pointing to dead tuples, and marks the entries as reusable. However, it does not compact the index pages and, eventually, index pages may contain few live tuple references. Buffer Cache Hit Rate. Measures the proportion of database reads that are ...
(see attached). > Looking at the formula, this overshoot term is created when we multiply > the old density by the new number of pages. I'm not sure how to fix > this. I think we could average the number of tuples, not the densities. > The attached patch demonstrates what I mean...
Typically there's one > function per expression, and one for each table accessed. Thanks for the explanations. Note that in our config I have set jit_tuple_deforming=off, so I think the table accesses don't use functions, right? Oh...that appears to be relevant somehow: $ PGOPTIONS='...