Use ON UPDATE CASCADE for foreign keys

schema.sql

@@ -7,7 +7,7 @@ CREATE TABLE host (
 CREATE TABLE host_uptime (
     id SERIAL PRIMARY KEY,
     created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
-    host_id INT NOT NULL REFERENCES host(id),
+    host_id INT NOT NULL REFERENCES host(id) ON UPDATE CASCADE,
     -- uptime in seconds
     uptime INT NOT NULL
 );
@@ -16,7 +16,7 @@ CREATE INDEX host_uptime_host_id_created_at_idx ON host_uptime(host_id, created_
 CREATE TABLE host_mem (
     id SERIAL PRIMARY KEY,
     created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
-    host_id INT NOT NULL REFERENCES host(id),
+    host_id INT NOT NULL REFERENCES host(id) ON UPDATE CASCADE,
     -- available memory in kB
     mem_avail INT NOT NULL
 );
@@ -25,7 +25,7 @@ CREATE INDEX host_mem_host_id_created_at_idx ON host_mem(host_id, created_at);
 CREATE TABLE host_disk (
     id SERIAL PRIMARY KEY,
     created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
-    host_id INT NOT NULL REFERENCES host(id),
+    host_id INT NOT NULL REFERENCES host(id) ON UPDATE CASCADE,
     -- free disk space in kB
     disk_free INT NOT NULL
 );
@@ -34,7 +34,7 @@ CREATE INDEX host_disk_host_id_created_at_idx ON host_disk(host_id, created_at);
 CREATE TABLE host_cpu (
     id SERIAL PRIMARY KEY,
     created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
-    host_id INT NOT NULL REFERENCES host(id),
+    host_id INT NOT NULL REFERENCES host(id) ON UPDATE CASCADE,
     -- cpu load for last minute
     cpu_load_1m FLOAT NOT NULL
 );

status

@@ -5,49 +5,34 @@ set -e
 export $(cat .env | xargs)
 
 psql -w <<EOF
-    WITH host_upsert AS (
-        INSERT INTO host (name) VALUES ('$(hostname)')
-        ON CONFLICT (name) DO UPDATE SET name = EXCLUDED.name
-        RETURNING id
-    )
+    INSERT INTO host (name) VALUES ('$(hostname)')
+    ON CONFLICT (name) DO NOTHING;
+EOF
+
+psql -w <<EOF
     INSERT INTO host_uptime (host_id, uptime)
     SELECT id, '$(cat /proc/uptime | awk -F. '{print $1}')'
-    FROM host_upsert
+    FROM host WHERE name = '$(hostname)'
     RETURNING *;
 EOF
 
 psql -w <<EOF
-    WITH host_upsert AS (
-        INSERT INTO host (name) VALUES ('$(hostname)')
-        ON CONFLICT (name) DO UPDATE SET name = EXCLUDED.name
-        RETURNING id
-    )
     INSERT INTO host_mem (host_id, mem_avail)
     SELECT id, '$(cat /proc/meminfo | grep 'MemAvailable' | awk '{print $2}')'
-    FROM host_upsert
+    FROM host WHERE name = '$(hostname)'
     RETURNING *;
 EOF
 
 psql -w <<EOF
-    WITH host_upsert AS (
-        INSERT INTO host (name) VALUES ('$(hostname)')
-        ON CONFLICT (name) DO UPDATE SET name = EXCLUDED.name
-        RETURNING id
-    )
     INSERT INTO host_disk (host_id, disk_free)
     SELECT id, '$(df / | awk 'NR==2{print $4}')'
-    FROM host_upsert
+    FROM host WHERE name = '$(hostname)'
     RETURNING *;
 EOF
 
 psql -w <<EOF
-    WITH host_upsert AS (
-        INSERT INTO host (name) VALUES ('$(hostname)')
-        ON CONFLICT (name) DO UPDATE SET name = EXCLUDED.name
-        RETURNING id
-    )
     INSERT INTO host_cpu (host_id, cpu_load_1m)
     SELECT id, '$(top -bn1 | head -1 | awk -F'load average: ' '{print $2}' | awk -F, '{print $1}')'
-    FROM host_upsert
+    FROM host WHERE name = '$(hostname)'
     RETURNING *;
 EOF