By Mouhamadou Diaw

I was looking for a build-in function to get the hostname of the server hosting my PostgreSQL cluster.
But seems that there is no build-in function. Looking in the extensions, I find the extension hostname which can allow to get the database server host name.
In this this blog I am explaining how to install and how to use it. The installation is very easy. The first step is to download it here .

After let’s go to the directory where the archive was decompressed and let’s run the command make

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master/pg-hostname-master/ [PG1] ls
Changes  doc  hostname.control  Makefile  META.json  README.md  sql  src  test
14:46:26 postgres@dbi-pg-essentials:/home/postgres/pg-hostname-master/pg-hostname-master/ [PG1] ls
Changes  doc  hostname.control  Makefile  META.json  README.md  sql  src  test
14:46:48 postgres@dbi-pg-essentials:/home/postgres/pg-hostname-
master/pg-hostname-master/ [PG1] make
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -O2 -fpic -I. -I./ -I/u01/app/postgres/product/95/db_0/include/server -I/u01/app/postgres/product/95/db_0/include/internal -D_GNU_SOURCE -I/usr/include/libxml2   -c -o src/hostname.o src/hostname.c
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -O2 -fpic -L/u01/app/postgres/product/95/db_0/lib -Wl,--as-needed -Wl,-rpath,'/u01/app/postgres/product/95/db_0/lib',--enable-new-dtags  -shared -o src/hostname.so src/hostname.o
cp sql/hostname.sql sql/hostname--1.0.0.sql
14:46:55 postgres@dbi-pg-essentials:/home/postgres/pg-hostname-

Once done let’s run the command make install

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pg-hostname-master/ [PG1] make install
/bin/mkdir -p '/u01/app/postgres/product/95/db_0/share/extension'
/bin/mkdir -p '/u01/app/postgres/product/95/db_0/share/extension'
/bin/mkdir -p '/u01/app/postgres/product/95/db_0/lib'
/bin/mkdir -p '/u01/app/postgres/product/95/db_0/share/doc/extension'
/bin/install -c -m 644 .//hostname.control '/u01/app/postgres/product/95/db_0/share/extension/'
/bin/install -c -m 644 .//sql/hostname--1.0.0.sql .//sql/hostname--unpackaged--1.0.0.sql  '/u01/app/postgres/product/95/db_0/share/extension/'
/bin/install -c -m 755  src/hostname.so '/u01/app/postgres/product/95/db_0/lib/'
/bin/install -c -m 644 .//doc/hostname.mmd '/u01/app/postgres/product/95/db_0/share/doc/extension/'
14:47:29 postgres@dbi-pg-essentials:/home/postgres/pg-hostname-master/pg-hostname-master/ [PG1]

If everything is ok we should now have the extension in our $PGHOME/share/extension

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15:02:39 postgres@dbi-pg-essentials:[PG1] ls -ltra *hostname*
-rw-r--r--. 1 postgres postgres 140 Dec  5 14:47 hostname.control
-rw-r--r--. 1 postgres postgres  96 Dec  5 14:47 hostname--1.0.0.sql
-rw-r--r--. 1 postgres

And that’s all. We just have now have to install the extension in the database

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postgres=# CREATE EXTENSION hostname;
CREATE EXTENSION

And then now we can have the hostname of our the server

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postgres=# SELECT hostname();
     hostname
-------------------
 dbi-pg-essentials
(1 row)
postgres=#
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