From 8b2a1f25d9db25f264ea0a975de6d5e86b28e2ac Mon Sep 17 00:00:00 2001
From: Karun Anantharaman <105210556+karunmotorq@users.noreply.github.com>
Date: Tue, 6 Jan 2026 06:27:13 +0000
Subject: [PATCH] Fix nested namespace encoding in REST catalog

Add encodeNamespaceForURI function to properly encode multi-level
namespaces using the unit separator (%1F) as required by the Iceberg
REST Catalog API specification.

This fixes the issue where tables in nested namespaces (e.g.,
teslasource.kafkav6.source-data) were not discoverable because
ClickHouse was using dot separators in the URL path instead of %1F.

Fixes: Tables in hierarchical namespaces return 404 errors
Reference: https://github.com/apache/iceberg/blob/main/open-api/rest-catalog-open-api.yaml
---
 src/Databases/Iceberg/RestCatalog.cpp | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/Databases/Iceberg/RestCatalog.cpp b/src/Databases/Iceberg/RestCatalog.cpp
index 5ea25a663bac..b7111d01b5af 100644
--- a/src/Databases/Iceberg/RestCatalog.cpp
+++ b/src/Databases/Iceberg/RestCatalog.cpp
@@ -84,6 +84,24 @@ std::string correctAPIURI(const std::string & uri)
     return std::filesystem::path(uri) / "v1";
 }
 
+/// Encode namespace for use in URL path.
+/// According to the Iceberg REST Catalog spec, multi-level namespaces
+/// should be joined with the unit separator character (0x1F) which is
+/// URL-encoded as %1F.
+/// https://github.com/apache/iceberg/blob/main/open-api/rest-catalog-open-api.yaml
+String encodeNamespaceForURI(const String & namespace_name)
+{
+    String encoded;
+    for (const auto & ch : namespace_name)
+    {
+        if (ch == '.')
+            encoded += "%1F";
+        else
+            encoded.push_back(ch);
+    }
+    return encoded;
+}
+
 }
 
 std::string RestCatalog::Config::toString() const
@@ -468,7 +486,8 @@ RestCatalog::Namespaces RestCatalog::parseNamespaces(DB::ReadBuffer & buf, const
 
 DB::Names RestCatalog::getTables(const std::string & base_namespace, size_t limit) const
 {
-    const std::string endpoint = std::filesystem::path(NAMESPACES_ENDPOINT) / base_namespace / "tables";
+    auto encoded_namespace = encodeNamespaceForURI(base_namespace);
+    const std::string endpoint = std::filesystem::path(NAMESPACES_ENDPOINT) / encoded_namespace / "tables";
 
     auto buf = createReadBuffer(config.prefix / endpoint);
     return parseTables(*buf, base_namespace, limit);
@@ -562,7 +581,8 @@ bool RestCatalog::getTableMetadataImpl(
         headers.emplace_back("X-Iceberg-Access-Delegation", "vended-credentials");
     }
 
-    const std::string endpoint = std::filesystem::path(NAMESPACES_ENDPOINT) / namespace_name / "tables" / table_name;
+    auto encoded_namespace = encodeNamespaceForURI(namespace_name);
+    const std::string endpoint = std::filesystem::path(NAMESPACES_ENDPOINT) / encoded_namespace / "tables" / table_name;
     auto buf = createReadBuffer(config.prefix / endpoint, /* params */{}, headers);
 
     if (buf->eof())