PostgreSQL , in , = any (array()) , hash table , subplan , initplan 背景 数据库SQL也算一门比较神奇的语言了,比如很多需求可以有不同的SQL来实现: 我之前有输出过一个IN的测试,这里面实际上也涉及到多个语法,实现同一个功能点。测试CASE是1亿 in 100万的多种写法的性能差异。 《HTAP数据库 PostgreS...
1 EXPLAIN ANALYZE SELECT * FROM emp WHERE gen = ANY(ARRAY['M','F']); is resulting in implicit datatype conversion of the values of the fields to text. Shell 1 2 Seq Scan on emp (cost=0.00..1.04 rows=2 width=43) (actual time=0.023..0.026 rows=3 loops=1) Filter: ((gen)::te...
在原文评论中,有人提到可以用where id = any()来代替where id in ..,理由是这样在 pg_stat_activity 里面相似查询只会有一个 query id,便于查找问题 SQL。它俩的具体区别可参考下面这个问题: sql - IN vs ANY operator in PostgreSQL - Stack Overflow 这算是一个知识点,但更重要的是 pg_stat_activity ...
《REST API for any Postgres database》 介绍:pg的一个非官方REST API,此外推荐RADIP RESTful API for PostgreSQL.《Pg_clog异步提交一致性、原子操作与fsync》 介绍:Pg_clog分析.《Pg的checkpoint的调度》 介绍:同步机制分析.《PostgreSQL Foreign Data Wrappers》 介绍:PostgreSQL外部数据封装器介绍....
You see any errors in the PG logs of both Master and Standby ? 0 Reply geno 5 years ago “listen_addresses : Set it to * or the range of IP Addresses that need to be whitelisted to connect to your master PostgreSQL server. Your slave IP should be whitelisted too, else, the slave...
(pg_Ident.conf)# MAPNAME Ident-USERNAME PG-USERNAME mymap robert robert mymap postgres robertExample 3: A domain socket connection enforces that unix account can connect to any database with its postgres database namesake using thekeyword “sameuser”. pg_Ident.conf is not necessary here. ...
typedefstructRelOptInfo{NodeTag type;//节点标识RelOptKind reloptkind;//RelOpt类型/* all relations included in this RelOptInfo */Relids relids;/*Relids(rtindex)集合 set of base relids (rangetable indexes) *//* size estimates generated by planner */doublerows;/*结果元组的估算数量 estimated...
WeakAnyLinkage, ///< Keep one copy of named function when linking (weak) WeakODRLinkage, ///< Same, but only replaced by something equivalent. AppendingLinkage, ///< Special purpose, only applies to global arrays InternalLinkage, ///< Rename collisions when linking (static functions). Priva...
The first time someone stores any character that it’s 7-bit ASCII, the probability for mayhem goes up considerably, and it’s very hard to fix this once it happens. You will get sortation in a way that doesn’t match any natural language (except maybe US English), and can be very ...
一、简介 PostgreSQL 提供了多个系统管理函数来查看表,索引,表空间及数据库的大小,下面详细介绍一下。 二、数据库对象尺寸函数 函数名 返回类型 描述 pg_column_size(any) int 存储一个指定的数值需要的字节数(可能压缩过) pg_database_size(oid) b