diff --git a/src/main/java/org/mtransit/commons/FeatureFlags.kt b/src/main/java/org/mtransit/commons/FeatureFlags.kt
index fc5b498..62a3dc9 100644
--- a/src/main/java/org/mtransit/commons/FeatureFlags.kt
+++ b/src/main/java/org/mtransit/commons/FeatureFlags.kt
@@ -28,5 +28,8 @@ object FeatureFlags {
     // const val F_AVOID_DATA_CHANGED = false
     const val F_AVOID_DATA_CHANGED = true // WIP
 
+    const val F_EXPORT_SERVICE_ID_INTS = false
+    // const val F_EXPORT_SERVICE_ID_INTS = true // WIP
+
     // @formatter:on
 }
\ No newline at end of file
diff --git a/src/main/java/org/mtransit/commons/GTFSCommons.kt b/src/main/java/org/mtransit/commons/GTFSCommons.kt
index c6705e9..bbb7fdc 100644
--- a/src/main/java/org/mtransit/commons/GTFSCommons.kt
+++ b/src/main/java/org/mtransit/commons/GTFSCommons.kt
@@ -198,32 +198,67 @@ object GTFSCommons {
 
     // endregion Direction Stops
 
+    // region Service IDs
+
+    const val T_SERVICE_IDS = "service_ids"
+    const val T_SERVICE_IDS_K_ID_INT = "service_id_int"
+    const val T_SERVICE_IDS_K_ID = "service_id"
+
+    @JvmStatic
+    val T_SERVICE_IDS_SQL_CREATE = SQLCreateBuilder.getNew(T_SERVICE_IDS).apply {
+        appendColumn(T_SERVICE_IDS_K_ID_INT, SQLUtils.INT) // TODO INT_PK_AUTO?
+        appendColumn(T_SERVICE_IDS_K_ID, SQLUtils.TXT, unique = true)
+    }.build()
+
+    @JvmStatic
+    val T_SERVICE_IDS_SQL_INSERT = SQLInsertBuilder.getNew(T_SERVICE_IDS).apply {
+        appendColumn(T_SERVICE_IDS_K_ID_INT)
+        appendColumn(T_SERVICE_IDS_K_ID)
+    }.build()
+
+    @JvmStatic
+    val T_SERVICE_IDS_SQL_DROP = SQLUtils.getSQLDropIfExistsQuery(T_SERVICE_IDS)
+
+    // endregion Service IDs
+
     // region Service Dates
 
     const val T_SERVICE_DATES = "service_dates"
     const val T_SERVICE_DATES_K_SERVICE_ID = "service_id"
+    const val T_SERVICE_DATES_K_SERVICE_ID_INT = "service_id_int"
     const val T_SERVICE_DATES_K_DATE = "date"
     const val T_SERVICE_DATES_K_EXCEPTION_TYPE = "exception_type"
 
+    // https://gtfs.org/documentation/schedule/reference/#calendar_datestxt
+    const val EXCEPTION_TYPE_DEFAULT = 0 // default schedule // added by MT
+    const val EXCEPTION_TYPE_ADDED = 1
+    const val EXCEPTION_TYPE_REMOVED = 2
+
     @JvmStatic
     val T_SERVICE_DATES_SQL_CREATE = SQLCreateBuilder.getNew(T_SERVICE_DATES).apply {
-        appendColumn(T_SERVICE_DATES_K_SERVICE_ID, SQLUtils.TXT)
+        if (FeatureFlags.F_EXPORT_SERVICE_ID_INTS) {
+            appendColumn(T_SERVICE_DATES_K_SERVICE_ID_INT, SQLUtils.INT)
+        } else {
+            appendColumn(T_SERVICE_DATES_K_SERVICE_ID, SQLUtils.TXT)
+        }
         appendColumn(T_SERVICE_DATES_K_DATE, SQLUtils.INT)
         appendColumn(T_SERVICE_DATES_K_EXCEPTION_TYPE, SQLUtils.INT)
+        if (FeatureFlags.F_EXPORT_SERVICE_ID_INTS) {
+            appendForeignKey(T_SERVICE_DATES_K_SERVICE_ID_INT, T_SERVICE_IDS, T_SERVICE_IDS_K_ID_INT)
+        }
     }.build()
 
     @JvmStatic
     val T_SERVICE_DATES_SQL_INSERT = SQLInsertBuilder.getNew(T_SERVICE_DATES).apply {
-        appendColumn(T_SERVICE_DATES_K_SERVICE_ID)
+        if (FeatureFlags.F_EXPORT_SERVICE_ID_INTS) {
+            appendColumn(T_SERVICE_DATES_K_SERVICE_ID_INT)
+        } else {
+            appendColumn(T_SERVICE_DATES_K_SERVICE_ID)
+        }
         appendColumn(T_SERVICE_DATES_K_DATE)
         appendColumn(T_SERVICE_DATES_K_EXCEPTION_TYPE)
     }.build()
 
-    // https://gtfs.org/documentation/schedule/reference/#calendar_datestxt
-    const val EXCEPTION_TYPE_DEFAULT = 0 // default schedule // added by MT
-    const val EXCEPTION_TYPE_ADDED = 1
-    const val EXCEPTION_TYPE_REMOVED = 2
-
     @JvmStatic
     val T_SERVICE_DATES_SQL_DROP = SQLUtils.getSQLDropIfExistsQuery(T_SERVICE_DATES)
 
diff --git a/src/main/java/org/mtransit/commons/sql/SQLCreateBuilder.kt b/src/main/java/org/mtransit/commons/sql/SQLCreateBuilder.kt
index 2eb0f85..f48a853 100644
--- a/src/main/java/org/mtransit/commons/sql/SQLCreateBuilder.kt
+++ b/src/main/java/org/mtransit/commons/sql/SQLCreateBuilder.kt
@@ -14,11 +14,15 @@ class SQLCreateBuilder private constructor(table: String) {
 
     private var nbColumn = 0
 
-    fun appendColumn(name: String, type: String): SQLCreateBuilder {
+    @JvmOverloads
+    fun appendColumn(name: String, type: String, unique: Boolean = false): SQLCreateBuilder {
         if (nbColumn > 0) {
             sqlCreateSb.append(SQLUtils.COLUMN_SEPARATOR)
         }
         sqlCreateSb.append(name).append(type)
+        if (unique) {
+            sqlCreateSb.append(SQLUtils.UNIQUE)
+        }
         nbColumn++
         return this
     }
diff --git a/src/main/java/org/mtransit/commons/sql/SQLUtils.kt b/src/main/java/org/mtransit/commons/sql/SQLUtils.kt
index 91f15c0..33264fb 100644
--- a/src/main/java/org/mtransit/commons/sql/SQLUtils.kt
+++ b/src/main/java/org/mtransit/commons/sql/SQLUtils.kt
@@ -13,6 +13,7 @@ object SQLUtils {
     const val INT_PK_AUTO = "$INT_PK AUTOINCREMENT"
     const val TXT = " text"
     const val REAL = " real"
+    const val UNIQUE = " unique"
 
     const val STRING_DELIMITER = "'"
     const val STRING_DELIMITER_ESCAPED = '\''