diff --git a/src/cache/CacheChannel.php b/src/cache/CacheChannel.php
index 91f021d..68fde79 100644
--- a/src/cache/CacheChannel.php
+++ b/src/cache/CacheChannel.php
@@ -10,19 +10,6 @@ use nulib\php\func;
 use Traversable;
 
 class CacheChannel extends CapacitorChannel implements IteratorAggregate {
-  const NAME = "cache";
-  const TABLE_NAME = "cache";
-
-  const COLUMN_DEFINITIONS = [
-    "group_id" => "varchar(32) not null", // groupe de curseur
-    "id" => "varchar(128) not null", // nom du curseur
-    "key_index" => "integer not null",
-    "key" => "varchar(128) not null",
-    "search" => "varchar(255)",
-
-    "primary key (group_id, id, key_index)",
-  ];
-
   static function with(?iterable $rows=null, $cursorId=null, ?CapacitorStorage $storage=null): self {
     $storage ??= cache::storage();
     $channel = (new static($cursorId))->initStorage($storage);
@@ -30,23 +17,53 @@ class CacheChannel extends CapacitorChannel implements IteratorAggregate {
     return $channel;
   }
 
+  const NAME = "cache";
+  const TABLE_NAME = "cache";
+
+  const COLUMN_DEFINITIONS = [
+    "group_id_" => "varchar(32) not null", // groupe de curseur
+    "id_" => "varchar(128) not null", // nom du curseur
+    "key_index_" => "integer not null",
+    "key_" => "varchar(128) not null",
+    "search_" => "varchar(255)",
+
+    "primary key (group_id_, id_, key_index_)",
+  ];
+
+  const ADD_COLUMNS = null;
+
+  protected function COLUMN_DEFINITIONS(): ?array {
+    return cl::merge(self::COLUMN_DEFINITIONS, static::ADD_COLUMNS);
+  }
+
   /**
    * @param array|string $cursorId
    */
   function __construct($cursorId) {
     parent::__construct();
     cache::verifix_id($cursorId);
-    $this->cursorId = $cursorId;
+    [
+      "group_id" => $this->groupId,
+      "id" => $this->id,
+    ] = $cursorId;
   }
 
-  protected array $cursorId;
+  protected string $groupId;
+
+  protected string $id;
 
   function getCursorId(): array {
-    return $this->cursorId;
+    return [
+      "group_id" => $this->groupId,
+      "id" => $this->id,
+    ];
   }
 
   function getBaseFilter(): ?array {
-    return $this->cursorId;
+    return [
+      "group_id_" => $this->groupId,
+      "id_" => $this->id,
+    ];
   }
 
   protected int $index = 0;
@@ -61,10 +78,17 @@ class CacheChannel extends CapacitorChannel implements IteratorAggregate {
     $index = $this->index++;
     $key = $key ?? $index;
     $key = substr(strval($key), 0, 128);
-    return cl::merge($this->cursorId, [
-      "key_index" => $index,
-      "key" => $key,
-      "search" => $this->getSearch($item),
+    $addColumns = static::ADD_COLUMNS ?? [];
+    $addColumns = cl::select($item,
+      array_filter(array_keys($addColumns), function ($key) {
+        return is_string($key);
+      }));
+    return cl::merge($addColumns, [
+      "group_id_" => $this->groupId,
+      "id_" => $this->id,
+      "key_index_" => $index,
+      "key_" => $key,
+      "search_" => $this->getSearch($item),
     ]);
   }
 
@@ -85,18 +109,18 @@ class CacheChannel extends CapacitorChannel implements IteratorAggregate {
   }
 
   function build(?iterable $items): self {
-    $this->reset(true);
+    $this->delete(null);
     $this->chargeAll($items);
     return $this;
   }
 
   function getIterator(): Traversable {
     $rows = $this->dbAll([
-      "cols" => ["key", "item__"],
+      "cols" => ["key_", "item__"],
       "where" => $this->getBaseFilter(),
     ]);
     foreach ($rows as $row) {
-      $key = $row["key"];
+      $key = $row["key_"];
       $item = $this->unserialize($row["item__"]);
       yield $key => $item;
     }
diff --git a/src/cache/TODO.md b/src/cache/TODO.md
deleted file mode 100644
index 4f8f006..0000000
--- a/src/cache/TODO.md
+++ /dev/null
@@ -1,6 +0,0 @@
-# nulib\cache
-
-* CacheChannel
-  * spécifier des clés supplémentaires utilisable dans la recherche
-
--*- coding: utf-8 mode: markdown -*- vim:sw=4:sts=4:et:ai:si:sta:fenc=utf-8:noeol:binary
\ No newline at end of file
diff --git a/src/cache/cache.php b/src/cache/cache.php
index fa0991f..b0a25c2 100644
--- a/src/cache/cache.php
+++ b/src/cache/cache.php
@@ -64,14 +64,14 @@ class cache {
 
   static function get(callable $compute, $dataId=null, ?string $file=null) {
     self::verifix_id($dataId);
-    $file ??= "{$dataId["group_id"]}-{$dataId["id"]}";
+    $file ??= "{$dataId["group_id"]}_{$dataId["id"]}";
     $noCache = !self::should_cache($dataId["id"], $dataId["group_id"]);
     return CacheFile::with($compute, $file)->get(null, $noCache);
   }
 
   static function all(?iterable $rows, $cursorId=null, ?string $file=null): iterable {
     self::verifix_id($cursorId);
-    $file ??= "{$cursorId["group_id"]}-{$cursorId["id"]}--rows";
+    $file ??= "{$cursorId["group_id"]}_{$cursorId["id"]}_rows";
     $ccursorId = new CacheFile($file, function() use ($rows, $cursorId) {
       CacheChannel::with(null, $cursorId)->build($rows);
       return $cursorId;
diff --git a/tests/.gitignore b/tests/.gitignore
new file mode 100644
index 0000000..69bea44
--- /dev/null
+++ b/tests/.gitignore
@@ -0,0 +1,2 @@
+*.db*
+*.cache
diff --git a/tests/cache/.gitignore b/tests/cache/.gitignore
deleted file mode 100644
index d540dae..0000000
--- a/tests/cache/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-/*.db*
-/*.cache
diff --git a/tests/cache/CacheChannelTest.php b/tests/cache/CacheChannelTest.php
new file mode 100644
index 0000000..2de3842
--- /dev/null
+++ b/tests/cache/CacheChannelTest.php
@@ -0,0 +1,38 @@
+<?php
+namespace nulib\cache;
+
+use nulib\output\msg;
+
+class CacheChannelTest extends _TestCase {
+  const DATA = [
+    "fr" => ["a" => "un", "b" => "deux"],
+    "eng" => ["a" => "one", "b" => "two"],
+    ["a" => 1, "b" => 2],
+  ];
+
+  function testUsage() {
+    $channel = CacheChannel::with(self::DATA, "numbers", self::$storage);
+    $count = 0;
+    foreach ($channel as $key => $item) {
+      msg::info("one: $key => {$item["a"]}");
+      $count++;
+    }
+    self::assertSame(3, $count);
+  }
+
+  function testAddColumns() {
+    $channel = (new class("numbers") extends CacheChannel {
+      const NAME = "numbersac";
+      const TABLE_NAME = self::NAME;
+      const ADD_COLUMNS = [
+        "a" => "varchar(30)",
+      ];
+    })->initStorage(self::$storage)->build(self::DATA);
+    $count = 0;
+    foreach ($channel as $key => $item) {
+      msg::info("one: $key => {$item["a"]}");
+      $count++;
+    }
+    self::assertSame(3, $count);
+  }
+}
diff --git a/tests/cache/CursorChannelTest.php b/tests/cache/CursorChannelTest.php
deleted file mode 100644
index 6a1aeee..0000000
--- a/tests/cache/CursorChannelTest.php
+++ /dev/null
@@ -1,22 +0,0 @@
-<?php
-namespace nulib\cache;
-
-use nulib\output\msg;
-
-class CursorChannelTest extends _TestCase {
-  function testUsage() {
-    $data = [
-      "fr" => ["a" => "un", "b" => "deux"],
-      "eng" => ["a" => "one", "b" => "two"],
-      ["a" => 1, "b" => 2],
-    ];
-
-    $channel = CacheChannel::with($data, "numbers", self::$storage);
-    $count = 0;
-    foreach ($channel as $key => $item) {
-      msg::info("one: $key => {$item["a"]}");
-      $count++;
-    }
-    self::assertSame(3, $count);
-  }
-}