除了自己定义表的结构之外,PostgreSQL还提供了另一个创建表的方法,就是通过一个查询的结果创建新表: CREATETABLEtable_nameASquery; 或SELECT...INTOnew_tableFROM...; 例如,可以基于employees复制出两个新的表: CREATETABLEemp1ASSELECT*FROMemployees;SELECT*INTOemp2FROMemployees; 模式搜索路径 在PostgreSQL中,表...
postgres=# explainselectcount(*)frombmscantest2wherea>1;QUERY PLAN---Aggregate(cost=1.13..1.14rows=1width=8)->Seq Scanonbmscantest2(cost=0.00..1.12rows=3width=0)Filter:(a>1)(3rows) 1. 2. 3. 4. 5. 6. 7. 而如果表中数据比较多,pg 可能就会开始考虑并行化的查询计划,得到的查询计划...
CREATE[ORREPLACE]FUNCTIONname([[argmode][argname]argtype[{DEFAULT|=}default_expr][,...]])[RETURNSrettype|RETURNSTABLE(column_name column_type[,...])]{LANGUAGElang_name|TRANSFORM{FORTYPEtype_name}[,...]|WINDOW|IMMUTABLE|STABLE|VOLATILE|[NOT]LEAKPROOF|CALLEDONNULLINPUT|RETURNSNULLONNULLINPUT|...
"select tablename from pg_tables where schemaname='public'" —— 得到所有用户自定义表的名字(这里"tablename"字段是表的名字,"schemaname"是schema的名字。用户自定义的表,如果未经特殊处理,默认都是放在名为public的schema下) General \copyright show PostgreSQL usage and distribution terms \g [FILE] or ...
create extension pageinspect;--主键索引使用的是btree索引,索引名字 tb_order_pkey create tabletb_order(id int primary key,order_novarchar(255));insert into tb_order selectgenerate_series(1,100),md5(random()::varchar);--analyze 统计数据库表数据,统计结果存储到pg_statistic系统表中--vacuum 用于清理...
CREATE TABLE films ( code char(5), title varchar(40), did integer, date_prod date, kind varchar(10), len interval hour to minute);建表语句执行parse_analyze函数时进入传统的transform阶段时并没有执行任何trasform功能的函数,而是直接走transformStmt函数的default分支:创建Query节点,让原...
postgres=# \help SELECT Command: SELECT Description: retrieve rows from a table or view Syntax: [ WITH [ RECURSIVE ] with_query [, ...] ] SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] [ * | expression [ [ AS ] output_name ] [, ...] ] [ FROM from_item [,...
CREATE UNLOGGED TABLE new_tab_name AS SELECT * FROM existing_tab_name; Executing the above query will create a new table named “new_tab_name,” which is an exact copy of an existing table named “existing_tab_name”, with the additional property that it is anUNLOGGEDtable. ...
queryString=0x234add0 "CREATE TABLE films ( code char(5), title varchar(40), did integer, date_prod date, kind varchar(10), len interval hour t o minute);", context=PROCESS_UTILITY_TOPLEVEL, params=0x0, queryEnv=0x0, dest=0x2408658, completionTag=0x7ffcf8fb0e60 "") at utility.c...
PostmasterMainServerLoopBackendStartupBackendRunPostgresMainexec_simple_queryPortalRunPortalRunMultiPortalRunUtilitystandard_ProcessUtilityProcessUtilitySlowtransformCreateStmt// 建表语句是 `create temp table xxx();`,走 `T_CreateStmt` nodeTagRangeVarGetAndCheckCreationNamespaceRangeVarGetCreationNamespaceAccessTemp...