fix(mysql): adapt tenant shared database fields

server/db/mysql/tenant_tables.go

@@ -0,0 +1,37 @@
+//go:build mysql
+// +build mysql
+
+package mysql
+
+import (
+	"fmt"
+
+	t "github.com/tinode/chat/server/store/types"
+)
+
+func tenantFriendshipsTable(t.TenantID) string {
+	return "im_friendships"
+}
+
+func tenantMessagesTable(t.TenantID) string {
+	return "im_messages"
+}
+
+func tenantGroupMessagesTable(_ t.TenantID, month string) (string, bool) {
+	if !validShardMonth(month) {
+		return "", false
+	}
+	return fmt.Sprintf("im_group_messages_%s", month), true
+}
+
+func validShardMonth(month string) bool {
+	if len(month) != 6 {
+		return false
+	}
+	for i := range month {
+		if month[i] < '0' || month[i] > '9' {
+			return false
+		}
+	}
+	return month[4:] >= "01" && month[4:] <= "12"
+}