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...
《Using Writeable CTEs to Improve Performance in PostgreSQL 》 介绍:使用CTEs来提升你的数据库性能《Fast pagination on PostgreSQL》 介绍:PostgreSQL的快速分页《Upgrading your PostgreSQL cluster from 9.3 to 9.4 》 介绍:把你的PostgreSQL集群从9.3升级到9.4....
(t.arrival - s.arrival)) calculates the difference in seconds between the actual and scheduled arrivals for each stop along a route.where date_part('seconds',(t.arrival - s.arrival)) > 58 and s.run = 1order by route, t.arrival, s.rtstop;...
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...
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
LLVMModuleRef llvm_mutable_module(LLVMJitContext *context) { llvm_assert_in_fatal_section(); /* * If there's no in-progress module, create a new one. */ if (!context->module) { context->compiled = false; context->module_generation = llvm_generation++; context->module = LLVMModuleCrea...
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...
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、介绍 PostgreSQL是一个功能强大的开源的关系型数据库。底层基于C实现。PostgreSQL的开源协议和Linux内核...