本篇主要分析PG的统计信息。
ORACLE统计信息迁移到PG(不接触用户数据),应用场景比较特殊,不再赘述。...准备
drop table mapping;
create table mapping(id0 int, id1 int, id2 int, info varchar(32));
insert into...(8, 24, 999, 'gggg');
insert into mapping values(9, 24, NULL, 'hhh');
insert into mapping values(0, 19..., NULL, 'zzz');
-- 便于直观看到统计信息,先查一下pg_stats这个视图
postgres=# select * from pg_stats where tablename='mapping...0.7
most_common_vals | {23,24}
most_common_freqs | {0.3,0.2}
histogram_bounds | {17,19,39,43,93