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这篇文章主要介绍“怎么使用PostgreSQL contrib中的dblink插件”，在日常操作中，相信很多人在怎么使用PostgreSQL contrib中的dblink插件问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”怎么使用PostgreSQL contrib中的dblink插件”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
该插件可用于连接远程PG数据库,看起来像是Oracle的DBLink.
安装
进入dblink目录,make & make install
[root@localhost contrib]# cd dblink/ [root@localhost dblink]# ls dblink--1.0--1.1.sql dblink--1.1--1.2.sql dblink--1.2.sql dblink.c dblink.control dblink--unpackaged--1.0.sql expected input Makefile output pg_service.conf sql [root@localhost dblink]# [root@localhost dblink]# make make -C ../../src/backend generated-headers make[1]: Entering directory `/data/source/postgresql-12beta1/src/backend' make -C catalog distprep generated-header-symlinks make[2]: Entering directory `/data/source/postgresql-12beta1/src/backend/catalog' make[2]: Nothing to be done for `distprep'. make[2]: Nothing to be done for `generated-header-symlinks'. make[2]: Leaving directory `/data/source/postgresql-12beta1/src/backend/catalog' make -C utils distprep generated-header-symlinks make[2]: Entering directory `/data/source/postgresql-12beta1/src/backend/utils' make[2]: Nothing to be done for `distprep'. make[2]: Nothing to be done for `generated-header-symlinks'. make[2]: Leaving directory `/data/source/postgresql-12beta1/src/backend/utils' make[1]: Leaving directory `/data/source/postgresql-12beta1/src/backend' make -C ../../src/interfaces/libpq all make[1]: Entering directory `/data/source/postgresql-12beta1/src/interfaces/libpq' make -C ../../../src/port all make[2]: Entering directory `/data/source/postgresql-12beta1/src/port' make[2]: Nothing to be done for `all'. make[2]: Leaving directory `/data/source/postgresql-12beta1/src/port' make -C ../../../src/common all make[2]: Entering directory `/data/source/postgresql-12beta1/src/common' make[2]: Nothing to be done for `all'. make[2]: Leaving directory `/data/source/postgresql-12beta1/src/common' make[1]: Leaving directory `/data/source/postgresql-12beta1/src/interfaces/libpq' gcc -std=gnu99 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -g -O0 -DOPTIMIZER_DEBUG -g3 -gdwarf-2 -fPIC -I../../src/interfaces/libpq -I. -I. -I../../src/include -D_GNU_SOURCE -I/usr/include/libxml2 -c -o dblink.o dblink.c -MMD -MP -MF .deps/dblink.Po gcc -std=gnu99 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -g -O0 -DOPTIMIZER_DEBUG -g3 -gdwarf-2 -fPIC -shared -o dblink.so dblink.o -L../../src/port -L../../src/common -L../../src/interfaces/libpq -lpq -Wl,--as-needed -Wl,-rpath,'/appdb/xdb/pg12beta1/lib',--enable-new-dtags [root@localhost dblink]# make install make -C ../../src/backend generated-headers make[1]: Entering directory `/data/source/postgresql-12beta1/src/backend' make -C catalog distprep generated-header-symlinks make[2]: Entering directory `/data/source/postgresql-12beta1/src/backend/catalog' make[2]: Nothing to be done for `distprep'. make[2]: Nothing to be done for `generated-header-symlinks'. make[2]: Leaving directory `/data/source/postgresql-12beta1/src/backend/catalog' make -C utils distprep generated-header-symlinks make[2]: Entering directory `/data/source/postgresql-12beta1/src/backend/utils' make[2]: Nothing to be done for `distprep'. make[2]: Nothing to be done for `generated-header-symlinks'. make[2]: Leaving directory `/data/source/postgresql-12beta1/src/backend/utils' make[1]: Leaving directory `/data/source/postgresql-12beta1/src/backend' make -C ../../src/interfaces/libpq all make[1]: Entering directory `/data/source/postgresql-12beta1/src/interfaces/libpq' make -C ../../../src/port all make[2]: Entering directory `/data/source/postgresql-12beta1/src/port' make[2]: Nothing to be done for `all'. make[2]: Leaving directory `/data/source/postgresql-12beta1/src/port' make -C ../../../src/common all make[2]: Entering directory `/data/source/postgresql-12beta1/src/common' make[2]: Nothing to be done for `all'. make[2]: Leaving directory `/data/source/postgresql-12beta1/src/common' make[1]: Leaving directory `/data/source/postgresql-12beta1/src/interfaces/libpq' /usr/bin/mkdir -p '/appdb/xdb/pg12beta1/lib/postgresql' /usr/bin/mkdir -p '/appdb/xdb/pg12beta1/share/postgresql/extension' /usr/bin/mkdir -p '/appdb/xdb/pg12beta1/share/postgresql/extension' /usr/bin/install -c -m 755 dblink.so '/appdb/xdb/pg12beta1/lib/postgresql/dblink.so' /usr/bin/install -c -m 644 ./dblink.control '/appdb/xdb/pg12beta1/share/postgresql/extension/' /usr/bin/install -c -m 644 ./dblink--1.2.sql ./dblink--1.1--1.2.sql ./dblink--1.0--1.1.sql ./dblink--unpackaged--1.0.sql '/appdb/xdb/pg12beta1/share/postgresql/extension/' [root@localhost dblink]#
简介
dblink可以让PG具备在远程数据库上执行查询的能力,其语法如下:
dblink(text connname, text sql [, bool fail_on_error]) returns setof record dblink(text connstr, text sql [, bool fail_on_error]) returns setof record dblink(text sql [, bool fail_on_error]) returns setof record
其中,输入参数:connname为连接名称,connstr是连接串,sql为查询语句,fail_on_error标记出现错误是否停止;输出参数是产生的行,Record类型.由于返回没有列信息,因此使用时需指定columns信息.
使用
远程PG数据库部署在26.26上,希望在PG中查询该26.26实例testdb数据库public模式下的t1表.
testdb=# select * from t1; id ---- 1 (1 row) testdb=# \d+ t1 Table "public.t1" Column | Type | Collation | Nullable | Default | Storage | Stats target | Description --------+---------+-----------+----------+---------+---------+--------------+------------- id | integer | | | | plain | | testdb=# select * from t1; id ---- 1 (1 row)
在本机执行以下查询:
testdb=# create extension dblink;
CREATE EXTENSION
testdb=# select t1.* from dblink('host=192.168.26.26 port=5432 dbname=testdb user=xdb','select * from t1') as t1(id int);
id
----
1
(1 row)由于需要显式的指定的返回数据行的元数据,使用起来有些啰嗦.
到此，关于“怎么使用PostgreSQL contrib中的dblink插件”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注创新互联-成都网站建设公司网站，小编会继续努力为大家带来更多实用的文章！
