feat: Block Target DB versions less than 9.5

cmd/axon/main.go

@@ -59,6 +59,11 @@ func main() {
 		logger.WithError(err).Fatal("unable to connect to target database")
 	}
 
+	err = checkTargetVersion(targetDBConn)
+	if err != nil {
+		logger.WithError(err).Fatal("unable to use to target database")
+	}
+
 	err = loadPrimaryKeys(targetDBConn)
 	if err != nil {
 		logger.WithError(err).Fatal("unable to load target DB primary keys")

cmd/axon/schema.go

@@ -2,6 +2,9 @@ package main
 
 import (
 	"fmt"
+	"log"
+	"strconv"
+	"strings"
 
 	"github.com/jmoiron/sqlx"
 	"github.com/lib/pq"
@@ -11,17 +14,41 @@ import (
 // maps primary key columns by table
 var primaryKeys = make(map[string][]string)
 
+func checkTargetVersion(conn *sqlx.DB) error {
+	var serverVersion string
+	err := conn.QueryRow("SHOW server_version;").Scan(&serverVersion)
+	if err != nil {
+		return err
+	}
+
+	version := strings.Split(serverVersion, ".")
+	// TODO: More thorough version checks
+	major, err := strconv.Atoi(version[00])
+	if err != nil {
+		return err
+	}
+	minor, err := strconv.Atoi(version[1])
+	if err != nil {
+		return err
+	}
+	if major == 9 && minor < 5 {
+		return fmt.Errorf("Target DB Unsupported Version: %s", serverVersion)
+	}
+	log.Printf("Target DB Version: %s", serverVersion)
+	return nil
+}
+
 func loadPrimaryKeys(conn *sqlx.DB) error {
 	var rows []struct {
 		TableName  string         `db:"table_name"`
 		PrimaryKey pq.StringArray `db:"primary_key"`
 	}
 	err := conn.Select(&rows, `
-		SELECT 
-			t.table_name, 
+		SELECT
+			t.table_name,
 			string_to_array(string_agg(c.column_name, ','), ',') AS primary_key
-		FROM information_schema.key_column_usage AS c 
-			LEFT JOIN information_schema.table_constraints AS t 
+		FROM information_schema.key_column_usage AS c
+			LEFT JOIN information_schema.table_constraints AS t
 				ON c.constraint_name = t.constraint_name
 				AND t.constraint_type = 'PRIMARY KEY'
 		WHERE t.table_name != ''