PG fdw連線建立與關閉
阿新 • • 發佈：2018-11-28
PG本地啟動psql, 並訪問外部表，然後退出
PG 與 remotePG的連線，隨著客戶端psql的退出而斷開。
PG本地啟動多個psql, 每個psql都訪問一次外部表
檢視remotePG 程序
[email protected]:~$ ps -ef|grep post
root 134 89 0 09:36 pts/0 00:00:00 su postgres
postgres 135 134 0 09:36 pts/0 00:00:00 bash
postgres 150 1 0 09:37 pts/0 00:00:01 /usr/lib/postgresql/10/bin/postgres -D /usr/local/pgsql/data
postgres 152 150 0 09:37 ? 00:00:00 postgres: checkpointer process
postgres 153 150 0 09:37 ? 00:00:00 postgres: writer process
postgres 154 150 0 09:37 ? 00:00:00 postgres: wal writer process
postgres 155 150 0 09:37 ? 00:00:00 postgres: autovacuum launcher process
postgres 156 150 0 09:37 ? 00:00:02 postgres: stats collector process
postgres 157 150 0 09:37 ? 00:00:00 postgres: bgworker: logical replication launcher
postgres 389 150 0 10:19 ? 00:00:00 postgres: postgres postgres 192.168.55.60(55814) idle
postgres 392 150 0 10:19 ? 00:00:00 postgres: postgres postgres 192.168.55.60(55816) idle
postgres 478 135 0 11:00 pts/0 00:00:00 ps -ef
postgres 479 135 0 11:00 pts/0 00:00:00 grep post
檢視本地PG程序
[[email protected]lhost ~]# ps -ef|grep post postgres 1098 1 0 21:39 ? 00:00:00 /usr/local/postgresql/bin/postmaster -D /usr/local/postgresql/data postgres 1124 1098 0 21:39 ? 00:00:00 postgres: checkpointer process postgres 1125 1098 0 21:39 ? 00:00:00 postgres: writer process postgres 1126 1098 0 21:39 ? 00:00:00 postgres: wal writer process postgres 1127 1098 0 21:39 ? 00:00:00 postgres: autovacuum launcher process postgres 1128 1098 0 21:39 ? 00:00:00 postgres: stats collector process postgres 1129 1098 0 21:39 ? 00:00:00 postgres: bgworker: logical replication launcher root 1247 1 0 21:39 ? 00:00:00 /usr/libexec/postfix/master -w postfix 1251 1247 0 21:39 ? 00:00:00 pickup -l -t unix -u postfix 1252 1247 0 21:39 ? 00:00:00 qmgr -l -t unix -u root 1959 1920 0 21:54 pts/0 00:00:00 su postgres postgres 1961 1959 0 21:54 pts/0 00:00:00 bash root 2081 2064 0 22:18 pts/2 00:00:00 su postgres postgres 2082 2081 0 22:18 pts/2 00:00:00 bash postgres 2097 2082 0 22:18 pts/2 00:00:00 psql postgres 2098 1098 0 22:18 ? 00:00:00 postgres: postgres postgres [local] idle postgres 2099 1961 0 22:18 pts/0 00:00:00 psql postgres 2100 1098 0 22:18 ? 00:00:00 postgres: postgres postgres [local] idle root 2180 2007 0 23:02 pts/1 00:00:00 grep --color=auto post
檢視本地PG子程序埠，確認PG--> remotePG之間 是通過子程序連線
[[email protected] ~]# lsof -i:55814 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME postmaste 2098 postgres 5u IPv4 29227 0t0 TCP localhost.localdomain:55814->192.168.55.55:postgres (ESTABLISHED) [[email protected] ~]# lsof -i:55816 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME postmaste 2100 postgres 5u IPv4 29279 0t0 TCP localhost.localdomain:55816->192.168.55.55:postgres (ESTABLISHED)
檢視本地PG子程序動態庫載入
[[email protected] ~]# pldd 2098
2098: /usr/local/postgresql/bin/postgres
linux-vdso.so.1
/lib64/libpthread.so.0
/lib64/librt.so.1
/lib64/libdl.so.2
/lib64/libm.so.6
/lib64/libc.so.6
/lib64/ld-linux-x86-64.so.2
/lib64/libnss_files.so.2
/usr/local/postgresql/lib/postgres_fdw.so
/usr/local/postgresql/lib/libpq.so.5
[[email protected] ~]# pldd 2100
2100: /usr/local/postgresql/bin/postgres
linux-vdso.so.1
/lib64/libpthread.so.0
/lib64/librt.so.1
/lib64/libdl.so.2
/lib64/libm.so.6
/lib64/libc.so.6
/lib64/ld-linux-x86-64.so.2
/lib64/libnss_files.so.2
/usr/local/postgresql/lib/postgres_fdw.so
/usr/local/postgresql/lib/libpq.so.5
[[email protected] ~]# 由此可見
一個會話一個子程序， 一個子程序獨立載入postgre_fdw.so, 並使之連線remote PG.
連線不會斷開，除非會話斷開，子程序消失。
所以，如果自己實現fdw.so . 想在fdw.so中實現服務，有點難，因為不能基於會話在實現服務。