postgresql FRONTEND、EXEC_BACKEND宏定义的作用 FONTEND宏主要用于标记某些可能会在libpq客户端使用的场景,虽然他们主要用于服务端。如下: /** Although this header file is nominally backend-only, certain frontend * programs like pg_controldata inc
pid_t pid;char*av[10];intac =0;chartypebuf[32];/** Set up command-line arguments for subprocess*/av[ac++] ="postgres"; #ifdef EXEC_BACKEND av[ac++] ="--forkboot"; av[ac++] = NULL;/*filled in by postmaster_forkexec*/#endifsnprintf(typebuf,sizeof(typebuf),"-x%d", type);...
按i 进入编辑模式,找到 Backend Connection Settings ,进行以下修改: # - Backend Connection Settings - #backend_hostname0 = '主节点 ip 地址' # Host name or IP address to connect to for backend 0 #backend_port0 = 5432 # Port number for backend 0 #backend_weight0 = 1 # Weight for ...
PostgreSQL 是多进程架构,守护进程 Postmaster 为每个连接分配一个后台进程(backend),后台进程的分配是在协议处理之前进行的,每个后台进程自行负责协议的处理。在 PostgreSQL 源码或者文档中,通常认为 'backend' 和 'server' 是等价的,表示服务端;同样,'frontend' 和 'client' 是等价的,表示客户端。 协议基础 PostgreS...
EXEC_BACKEND */pid=fork_process();if(pid ==0)/*child*/{ IsUnderPostmaster=true;/*we are a postmaster subprocess now*//*Close the postmaster's sockets*/ClosePostmasterPorts(false);/*Lose the postmaster's on-exit routines and port connections*/on_exit_reset();/*Release postmaster's ...
* the pointer by fork from the postmaster (except in the EXEC_BACKEND case, * where we have special measures to pass it down). */ LWLockPadded*MainLWLockArray=NULL; //src/backend/storage/Imgr/lwlocknames.c constchar*constMainLWLockNames[]={"<unassigned:0>","ShmemIndexLock","OidGenLock"...
intmain(int argc,char*argv[]){#ifdefEXEC_BACKENDif(argc>1&&strncmp(argv[1],"--fork",6)==0)SubPostmasterMain(argc,argv);/* does not return */#endif}voidSubPostmasterMain(int argc,char*argv[]){CreateSharedMemoryAndSemaphores();}voidCreateSharedMemoryAndSemaphores(void){XLOGShmemInit()}voi...
当客户端应用与数据库进行连接时,PostgreSQL会为该用户(假设已经验证完成)创建一个Postgres的服务进程。这里面的函数调用关系如下:\text{main->PostmasterMain->ServerLoop->BackendStartup->BackendRun->PostgresMain} 辅助进程 PostgreSQL的各个辅助进程完成各种细节的任务,并且没有辅助进程都有一个全局变量形式的进程号...
PostgreSQL系统的主要功能都集中于Postgres程序,其入口是Main模块(src/backend/main/main.c)中的main函数,在初始化数据集簇、启动数据库服务器时,都将从这里开始执行。Main模块主要的工作是确定当前的操作系统平台,并据此做一些平台相关的环境变量设置和初始化,然后通过对命令行参数的判断,将控制转到相应的模块中去。PG...
ORDER BY 1;",,,"exec_simple_query, postgres.c:1045","psql" 查看主备库同步的差异情况: select client_addr,application_name, pg_wal_lsn_diff(pg_current_wal_lsn(), flush_lsn) as diff, sync_state from pg_stat_replication; client_addr...