WIP Prepare postgres for migration by replication

site-cookbooks/kosmos_postgresql/files/create_publications.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+set -e
+
+echo "== Creating publication in each database =="
+
+for db in $(psql -Atqc "SELECT datname FROM pg_database WHERE datallowconn AND datname NOT IN ('template0','template1')"); do
+  echo "Processing DB: $db"
+
+  # Create publication (idempotent)
+  psql -d "$db" -v ON_ERROR_STOP=1 <<SQL
+DO \$\$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM pg_publication WHERE pubname = 'migrate_pub'
+  ) THEN
+    CREATE PUBLICATION migrate_pub FOR ALL TABLES;
+  END IF;
+END
+\$\$;
+SQL
+
+  # Create logical replication slot (idempotent-ish)
+  SLOT="migrate_slot_${db}"
+
+  if ! psql -d "$db" -Atqc "SELECT 1 FROM pg_replication_slots WHERE slot_name = '$SLOT'" | grep -q 1; then
+    echo "  Creating slot: $SLOT"
+    psql -d "$db" -c "SELECT pg_create_logical_replication_slot('$SLOT', 'pgoutput');"
+  else
+    echo "  Slot already exists: $SLOT"
+  fi
+
+done
+
+echo "== Done =="