feat: grow txn_table

src/txn_table.zig

@@ -950,3 +950,80 @@ test "TableTxn put is restricted from changing a UNIQUE foreign key target a com
     var db = try openTemp(&tmp, allocator);
     defer db.close();
 
+    {
+        var products = try querymod.Table.open(&db, allocator, "products");
+        defer products.deinit();
+        try products.createUniqueIndex("sku");
+        try products.put(.{ .int = 1 }, &.{.{ .name = "sku", .value = .{ .text = "WIDGET-1" } }});
+
+        var lineItems = try querymod.Table.open(&db, allocator, "line_items");
+        defer lineItems.deinit();
+        try lineItems.createForeignKey("product_sku", "products", "sku", .restrict);
+        try lineItems.put(.{ .int = 1 }, &.{.{ .name = "product_sku", .value = .{ .text = "WIDGET-1" } }});
+    }
+
+    var txn = Transaction.begin(&db);
+    defer txn.deinit();
+    var t = try TableTxn.open(&txn, allocator, "products");
+    defer t.deinit();
+
+    try std.testing.expectError(error.ForeignKeyInUse, t.put(.{ .int = 1 }, &.{
+        .{ .name = "sku", .value = .{ .text = "WIDGET-2" } },
+    }));
+    // Unchanged is always exempt.
+    try t.put(.{ .int = 1 }, &.{.{ .name = "sku", .value = .{ .text = "WIDGET-1" } }});
+    try txn.commit();
+
+    var plain = try querymod.Table.open(&db, allocator, "products");
+    defer plain.deinit();
+    var stillThere = (try plain.get(.{ .int = 1 })).?;
+    defer stillThere.deinit();
+    try std.testing.expectEqualStrings("WIDGET-1", stillThere.get("sku").?.text);
+}
+
+test "TableTxn put update-restrict sees a child row staged earlier in the same uncommitted transaction" {
+    const allocator = std.testing.allocator;
+    var tmp = std.testing.tmpDir(.{});
+    defer tmp.cleanup();
+    var db = try openTemp(&tmp, allocator);
+    defer db.close();
+
+    {
+        var products = try querymod.Table.open(&db, allocator, "products");
+        defer products.deinit();
+        try products.createUniqueIndex("sku");
+        try products.put(.{ .int = 1 }, &.{.{ .name = "sku", .value = .{ .text = "WIDGET-1" } }});
+
+        var lineItems = try querymod.Table.open(&db, allocator, "line_items");
+        defer lineItems.deinit();
+        try lineItems.createForeignKey("product_sku", "products", "sku", .restrict);
+    }
+
+    var txn = Transaction.begin(&db);
+    defer txn.deinit();
+
+    // The line item referencing "WIDGET-1" is only staged in this SAME
+    // transaction's write set, never committed - `Transaction.scanPrefix`
+    // is what makes this count as a live reference before commit.
+    var lineItemsTxn = try TableTxn.open(&txn, allocator, "line_items");
+    defer lineItemsTxn.deinit();
+    try lineItemsTxn.put(.{ .int = 1 }, &.{.{ .name = "product_sku", .value = .{ .text = "WIDGET-1" } }});
+
+    var productsTxn = try TableTxn.open(&txn, allocator, "products");
+    defer productsTxn.deinit();
+    try std.testing.expectError(error.ForeignKeyInUse, productsTxn.put(.{ .int = 1 }, &.{
+        .{ .name = "sku", .value = .{ .text = "WIDGET-2" } },
+    }));
+
+    // Once the referencing line item is removed in the same transaction,
+    // the rename goes through.
+    try lineItemsTxn.delete(.{ .int = 1 });
+    try productsTxn.put(.{ .int = 1 }, &.{.{ .name = "sku", .value = .{ .text = "WIDGET-2" } }});
+    try txn.commit();
+
+    var plain = try querymod.Table.open(&db, allocator, "products");
+    defer plain.deinit();
+    var renamed = (try plain.get(.{ .int = 1 })).?;
+    defer renamed.deinit();
+    try std.testing.expectEqualStrings("WIDGET-2", renamed.get("sku").?.text);
+}