Merge branch 'master' of github.com:ClickHouse/ClickHouse

2024-10-21 07:50:49 +00:00 · 2019-12-04 16:38:19 +03:00 · 2019-12-04 16:38:19 +03:00 · b7794a1d36
commit b7794a1d36
parent 3724b8ba30 a651a1e05b
34 changed files with 673 additions and 21 deletions
--- a/README.md
+++ b/README.md
@ -14,5 +14,4 @@ ClickHouse is an open-source column-oriented database management system that all

 ## Upcoming Events

-* [ClickHouse Meetup in San Francisco](https://www.eventbrite.com/e/clickhouse-december-meetup-registration-78642047481) on December 3.
 * [ClickHouse Meetup in Moscow](https://yandex.ru/promo/clickhouse/moscow-december-2019) on December 11.
--- a/dbms/programs/server/Server.cpp
+++ b/dbms/programs/server/Server.cpp
@ -243,6 +243,8 @@ int Server::main(const std::vector<std::string> & /*args*/)
    }
 #endif

+    global_context->setRemoteHostFilter(config());
+
    std::string path = getCanonicalPath(config().getString("path", DBMS_DEFAULT_PATH));
    std::string default_database = config().getString("default_database", "default");

--- a/dbms/programs/server/config.xml
+++ b/dbms/programs/server/config.xml
@ -3,6 +3,25 @@
  NOTE: User and query level settings are set up in "users.xml" file.
 -->
 <yandex>
+	<!-- The list of hosts allowed to use in URL-related storage engines and table functions.
+		If this section is not present in configuration, all hosts are allowed.
+	-->
+	<remote_url_allow_hosts>
+		<!-- Host should be specified exactly as in URL. The name is checked before DNS resolution.
+			Example: "yandex.ru", "yandex.ru." and "www.yandex.ru" are different hosts.
+            		If port is explicitly specified in URL, the host:port is checked as a whole.
+            		If host specified here without port, any port with this host allowed.
+            		"yandex.ru" -> "yandex.ru:443", "yandex.ru:80" etc. is allowed, but "yandex.ru:80" -> only "yandex.ru:80" is allowed. 
+			If the host is specified as IP address, it is checked as specified in URL. Example: "[2a02:6b8:a::a]".
+			If there are redirects and support for redirects is enabled, every redirect (the Location field) is checked. 
+		-->
+
+		<!-- Regular expression can be specified. RE2 engine is used for regexps.
+			Regexps are not aligned: don't forget to add ^ and $. Also don't forget to escape dot (.) metacharacter
+			(forgetting to do so is a common source of error).
+		-->
+	</remote_url_allow_hosts>
+
    <logger>
        <!-- Possible levels: https://github.com/pocoproject/poco/blob/develop/Foundation/include/Poco/Logger.h#L105 -->
        <level>trace</level>
@ -15,7 +34,6 @@
    <!--display_name>production</display_name--> <!-- It is the name that will be shown in the client -->
    <http_port>8123</http_port>
    <tcp_port>9000</tcp_port>
-
    <!-- For HTTPS and SSL over native protocol. -->
    <!--
    <https_port>8443</https_port>
--- a/dbms/src/Common/ErrorCodes.cpp
+++ b/dbms/src/Common/ErrorCodes.cpp
@ -465,6 +465,7 @@ namespace ErrorCodes
    extern const int UNKNOWN_DICTIONARY = 488;
    extern const int INCORRECT_DICTIONARY_DEFINITION = 489;
    extern const int CANNOT_FORMAT_DATETIME = 490;
+    extern const int UNACCEPTABLE_URL = 491;

    extern const int KEEPER_EXCEPTION = 999;
    extern const int POCO_EXCEPTION = 1000;
--- a/dbms/src/Common/RemoteHostFilter.cpp
+++ b/dbms/src/Common/RemoteHostFilter.cpp
@ -0,0 +1,62 @@
+#include <re2/re2.h>
+#include <Common/RemoteHostFilter.h>
+#include <Poco/URI.h>
+#include <Formats/FormatFactory.h>
+#include <Poco/Util/AbstractConfiguration.h>
+#include <Common/StringUtils/StringUtils.h>
+#include <Common/Exception.h>
+#include <IO/WriteHelpers.h>
+
+namespace DB
+{
+namespace ErrorCodes
+{
+    extern const int UNACCEPTABLE_URL;
+}
+
+void RemoteHostFilter::checkURL(const Poco::URI & uri) const
+{
+    if (!checkForDirectEntry(uri.getHost()) &&
+        !checkForDirectEntry(uri.getHost() + ":" + toString(uri.getPort())))
+        throw Exception("URL \"" + uri.toString() + "\" is not allowed in config.xml", ErrorCodes::UNACCEPTABLE_URL);
+}
+
+void RemoteHostFilter::checkHostAndPort(const std::string & host, const std::string & port) const
+{
+    if (!checkForDirectEntry(host) &&
+        !checkForDirectEntry(host + ":" + port))
+        throw Exception("URL \"" + host + ":" + port + "\" is not allowed in config.xml", ErrorCodes::UNACCEPTABLE_URL);
+}
+
+void RemoteHostFilter::setValuesFromConfig(const Poco::Util::AbstractConfiguration & config)
+{
+    if (config.has("remote_url_allow_hosts"))
+    {
+        std::vector<std::string> keys;
+        config.keys("remote_url_allow_hosts", keys);
+        for (auto key : keys)
+        {
+            if (startsWith(key, "host_regexp"))
+                regexp_hosts.push_back(config.getString("remote_url_allow_hosts." + key));
+            else if (startsWith(key, "host"))
+                primary_hosts.insert(config.getString("remote_url_allow_hosts." + key));
+        }
+    }
+}
+
+bool RemoteHostFilter::checkForDirectEntry(const std::string & str) const
+{
+    if (!primary_hosts.empty() || !regexp_hosts.empty())
+    {
+        if (primary_hosts.find(str) == primary_hosts.end())
+        {
+            for (size_t i = 0; i < regexp_hosts.size(); ++i)
+                if (re2::RE2::FullMatch(str, regexp_hosts[i]))
+                    return true;
+            return false;
+        }
+        return true;
+    }
+    return true;
+}
+}
--- a/dbms/src/Common/RemoteHostFilter.h
+++ b/dbms/src/Common/RemoteHostFilter.h
@ -0,0 +1,30 @@
+#pragma once
+
+#include <vector>
+#include <unordered_set>
+#include <Poco/URI.h>
+#include <Poco/Util/AbstractConfiguration.h>
+
+
+namespace DB
+{
+class RemoteHostFilter
+{
+/**
+ * This class checks if url is allowed.
+ * If primary_hosts and regexp_hosts are empty all urls are allowed.
+ */
+public:
+    void checkURL(const Poco::URI & uri) const; /// If URL not allowed in config.xml throw UNACCEPTABLE_URL Exception
+
+    void setValuesFromConfig(const Poco::Util::AbstractConfiguration & config);
+
+    void checkHostAndPort(const std::string & host, const std::string & port) const; /// Does the same as checkURL, but for host and port.
+
+private:
+    std::unordered_set<std::string> primary_hosts;      /// Allowed primary (<host>) URL from config.xml
+    std::vector<std::string> regexp_hosts;              /// Allowed regexp (<hots_regexp>) URL from config.xml
+
+    bool checkForDirectEntry(const std::string & str) const; /// Checks if the primary_hosts and regexp_hosts contain str. If primary_hosts and regexp_hosts are empty return true.
+};
+}
--- a/dbms/src/Core/SettingsCollection.cpp
+++ b/dbms/src/Core/SettingsCollection.cpp
@ -62,7 +62,7 @@ void SettingNumber<Type>::set(const Field & x)
 template <typename Type>
 void SettingNumber<Type>::set(const String & x)
 {
-    set(parse<Type>(x));
+    set(completeParse<Type>(x));
 }

 template <>
--- a/dbms/src/IO/ReadBufferFromS3.cpp
+++ b/dbms/src/IO/ReadBufferFromS3.cpp
@ -14,10 +14,12 @@ const int DEFAULT_S3_MAX_FOLLOW_GET_REDIRECT = 2;
 ReadBufferFromS3::ReadBufferFromS3(const Poco::URI & uri_,
    const String & access_key_id_,
    const String & secret_access_key_,
-    const ConnectionTimeouts & timeouts)
+    const ConnectionTimeouts & timeouts,
+    const RemoteHostFilter & remote_host_filter_)
    : ReadBuffer(nullptr, 0)
    , uri {uri_}
    , session {makeHTTPSession(uri_, timeouts)}
+    , remote_host_filter {remote_host_filter_}
 {
    Poco::Net::HTTPResponse response;
    std::unique_ptr<Poco::Net::HTTPRequest> request;
@ -52,6 +54,7 @@ ReadBufferFromS3::ReadBufferFromS3(const Poco::URI & uri_,
            break;

        uri = location_iterator->second;
+        remote_host_filter.checkURL(uri);
        session = makeHTTPSession(uri, timeouts);
    }

--- a/dbms/src/IO/ReadBufferFromS3.h
+++ b/dbms/src/IO/ReadBufferFromS3.h
@ -21,11 +21,14 @@ protected:
    std::istream * istr; /// owned by session
    std::unique_ptr<ReadBuffer> impl;

+    RemoteHostFilter remote_host_filter;
+
 public:
    explicit ReadBufferFromS3(const Poco::URI & uri_,
        const String & access_key_id_,
        const String & secret_access_key_,
-        const ConnectionTimeouts & timeouts = {});
+        const ConnectionTimeouts & timeouts = {},
+        const RemoteHostFilter & remote_host_filter_ = {});

    bool nextImpl() override;
 };
--- a/dbms/src/IO/ReadHelpers.h
+++ b/dbms/src/IO/ReadHelpers.h
@ -877,6 +877,30 @@ inline T parse(const char * data, size_t size)
    return res;
 }

+/// Read something from text format, but expect complete parse of given text
+/// For example: 723145 -- ok, 213MB -- not ok
+template <typename T>
+inline T completeParse(const char * data, size_t size)
+{
+    T res;
+    ReadBufferFromMemory buf(data, size);
+    readText(res, buf);
+    assertEOF(buf);
+    return res;
+}
+
+template <typename T>
+inline T completeParse(const String & s)
+{
+    return completeParse<T>(s.data(), s.size());
+}
+
+template <typename T>
+inline T completeParse(const char * data)
+{
+    return completeParse<T>(data, strlen(data));
+}
+
 template <typename T>
 inline T parse(const char * data)
 {
@ -916,12 +940,12 @@ void skipToUnescapedNextLineOrEOF(ReadBuffer & buf);
 template <class TReadBuffer, class... Types>
 std::unique_ptr<ReadBuffer> getReadBuffer(const DB::CompressionMethod method, Types&&... args)
 {
-if (method == DB::CompressionMethod::Gzip)
-{
+    if (method == DB::CompressionMethod::Gzip)
+    {
        auto read_buf = std::make_unique<TReadBuffer>(std::forward<Types>(args)...);
        return std::make_unique<ZlibInflatingReadBuffer>(std::move(read_buf), method);
-}
-return std::make_unique<TReadBuffer>(args...);
+    }
+    return std::make_unique<TReadBuffer>(args...);
 }

 /** This function just copies the data from buffer's internal position (in.position())
--- a/dbms/src/IO/ReadWriteBufferFromHTTP.h
+++ b/dbms/src/IO/ReadWriteBufferFromHTTP.h
@ -101,6 +101,7 @@ namespace detail
        const Poco::Net::HTTPBasicCredentials & credentials;
        std::vector<Poco::Net::HTTPCookie> cookies;
        HTTPHeaderEntries http_header_entries;
+        RemoteHostFilter remote_host_filter;

        std::istream * call(const Poco::URI uri_, Poco::Net::HTTPResponse & response)
        {
@ -157,7 +158,8 @@ namespace detail
            OutStreamCallback out_stream_callback_ = {},
            const Poco::Net::HTTPBasicCredentials & credentials_ = {},
            size_t buffer_size_ = DBMS_DEFAULT_BUFFER_SIZE,
-            HTTPHeaderEntries http_header_entries_ = {})
+            HTTPHeaderEntries http_header_entries_ = {},
+            const RemoteHostFilter & remote_host_filter_ = {})
            : ReadBuffer(nullptr, 0)
            , uri {uri_}
            , method {!method_.empty() ? method_ : out_stream_callback_ ? Poco::Net::HTTPRequest::HTTP_POST : Poco::Net::HTTPRequest::HTTP_GET}
@ -165,6 +167,7 @@ namespace detail
            , out_stream_callback {out_stream_callback_}
            , credentials {credentials_}
            , http_header_entries {http_header_entries_}
+            , remote_host_filter {remote_host_filter_}
        {
            Poco::Net::HTTPResponse response;

@ -173,6 +176,7 @@ namespace detail
            while (isRedirect(response.getStatus()))
            {
                Poco::URI uri_redirect(response.get("Location"));
+                remote_host_filter.checkURL(uri_redirect);

                session->updateSession(uri_redirect);

@ -243,8 +247,9 @@ public:
        const DB::SettingUInt64 max_redirects = 0,
        const Poco::Net::HTTPBasicCredentials & credentials_ = {},
        size_t buffer_size_ = DBMS_DEFAULT_BUFFER_SIZE,
-        const HTTPHeaderEntries & http_header_entries_ = {})
-        : Parent(std::make_shared<UpdatableSession>(uri_, timeouts, max_redirects), uri_, method_, out_stream_callback_, credentials_, buffer_size_, http_header_entries_)
+        const HTTPHeaderEntries & http_header_entries_ = {},
+        const RemoteHostFilter & remote_host_filter_ = {})
+        : Parent(std::make_shared<UpdatableSession>(uri_, timeouts, max_redirects), uri_, method_, out_stream_callback_, credentials_, buffer_size_, http_header_entries_, remote_host_filter_)
    {
    }
 };
--- a/dbms/src/IO/WriteBufferFromS3.cpp
+++ b/dbms/src/IO/WriteBufferFromS3.cpp
@ -34,7 +34,8 @@ WriteBufferFromS3::WriteBufferFromS3(
    const String & access_key_id_,
    const String & secret_access_key_,
    size_t minimum_upload_part_size_,
-    const ConnectionTimeouts & timeouts_)
+    const ConnectionTimeouts & timeouts_,
+    const RemoteHostFilter & remote_host_filter_)
    : BufferWithOwnMemory<WriteBuffer>(DBMS_DEFAULT_BUFFER_SIZE, nullptr, 0)
    , uri {uri_}
    , access_key_id {access_key_id_}
@ -43,6 +44,7 @@ WriteBufferFromS3::WriteBufferFromS3(
    , timeouts {timeouts_}
    , temporary_buffer {std::make_unique<WriteBufferFromString>(buffer_string)}
    , last_part_size {0}
+    , remote_host_filter(remote_host_filter_)
 {
    initiate();

@ -134,6 +136,7 @@ void WriteBufferFromS3::initiate()
            break;

        initiate_uri = location_iterator->second;
+        remote_host_filter.checkURL(initiate_uri);
    }
    assertResponseIsOk(*request_ptr, response, *istr);

--- a/dbms/src/IO/WriteBufferFromS3.h
+++ b/dbms/src/IO/WriteBufferFromS3.h
@ -28,6 +28,7 @@ private:
    String buffer_string;
    std::unique_ptr<WriteBufferFromString> temporary_buffer;
    size_t last_part_size;
+    RemoteHostFilter remote_host_filter;

    /// Upload in S3 is made in parts.
    /// We initiate upload, then upload each part and get ETag as a response, and then finish upload with listing all our parts.
@ -39,7 +40,8 @@ public:
        const String & access_key_id,
        const String & secret_access_key,
        size_t minimum_upload_part_size_,
-        const ConnectionTimeouts & timeouts = {});
+        const ConnectionTimeouts & timeouts = {},
+        const RemoteHostFilter & remote_host_filter_ = {});

    void nextImpl() override;

--- a/dbms/src/Interpreters/Context.cpp
+++ b/dbms/src/Interpreters/Context.cpp
@ -53,7 +53,7 @@
 #include <Common/ShellCommand.h>
 #include <Common/TraceCollector.h>
 #include <common/logger_useful.h>
-
+#include <Common/RemoteHostFilter.h>

 namespace ProfileEvents
 {
@ -158,8 +158,9 @@ struct ContextShared
    ActionLocksManagerPtr action_locks_manager;             /// Set of storages' action lockers
    std::optional<SystemLogs> system_logs;                  /// Used to log queries and operations on parts

-    std::unique_ptr<TraceCollector> trace_collector;        /// Thread collecting traces from threads executing queries
+    RemoteHostFilter remote_host_filter; /// Allowed URL from config.xml

+    std::unique_ptr<TraceCollector> trace_collector;        /// Thread collecting traces from threads executing queries
    /// Named sessions. The user could specify session identifier to reuse settings and temporary tables in subsequent requests.

    class SessionKeyHash
@ -1583,6 +1584,16 @@ String Context::getInterserverScheme() const
    return shared->interserver_scheme;
 }

+void Context::setRemoteHostFilter(const Poco::Util::AbstractConfiguration & config)
+{
+    shared->remote_host_filter.setValuesFromConfig(config);
+}
+
+const RemoteHostFilter & Context::getRemoteHostFilter() const
+{
+    return shared->remote_host_filter;
+}
+
 UInt16 Context::getTCPPort() const
 {
    auto lock = getLock();
--- a/dbms/src/Interpreters/Context.h
+++ b/dbms/src/Interpreters/Context.h
@ -22,6 +22,7 @@
 #include <mutex>
 #include <optional>
 #include <thread>
+#include <Common/RemoteHostFilter.h>


 namespace Poco
@ -77,6 +78,7 @@ using ActionLocksManagerPtr = std::shared_ptr<ActionLocksManager>;
 class ShellCommand;
 class ICompressionCodec;
 class SettingsConstraints;
+class RemoteHostFilter;

 class IOutputFormat;
 using OutputFormatPtr = std::shared_ptr<IOutputFormat>;
@ -354,6 +356,10 @@ public:
    void setInterserverScheme(const String & scheme);
    String getInterserverScheme() const;

+    /// Storage of allowed hosts from config.xml
+    void setRemoteHostFilter(const Poco::Util::AbstractConfiguration & config);
+    const RemoteHostFilter & getRemoteHostFilter() const;
+
    /// The port that the server listens for executing SQL queries.
    UInt16 getTCPPort() const;

--- a/dbms/src/Storages/StorageHDFS.cpp
+++ b/dbms/src/Storages/StorageHDFS.cpp
@ -49,6 +49,7 @@ StorageHDFS::StorageHDFS(const String & uri_,
    , context(context_)
    , compression_method(compression_method_)
 {
+    context.getRemoteHostFilter().checkURL(Poco::URI(uri));
    setColumns(columns_);
    setConstraints(constraints_);
 }
--- a/dbms/src/Storages/StorageS3.cpp
+++ b/dbms/src/Storages/StorageS3.cpp
@ -43,7 +43,7 @@ namespace
            const CompressionMethod compression_method)
            : name(name_)
        {
-            read_buf = getReadBuffer<ReadBufferFromS3>(compression_method, uri, access_key_id, secret_access_key, timeouts);
+            read_buf = getReadBuffer<ReadBufferFromS3>(compression_method, uri, access_key_id, secret_access_key, timeouts, context.getRemoteHostFilter());
            reader = FormatFactory::instance().getInput(format, *read_buf, sample_block, context, max_block_size);
        }

@ -98,7 +98,8 @@ namespace
                access_key_id,
                secret_access_key,
                min_upload_part_size,
-                timeouts);
+                timeouts,
+                context.getRemoteHostFilter());
            writer = FormatFactory::instance().getOutput(format, *write_buf, sample_block, context);
        }

@ -155,6 +156,7 @@ StorageS3::StorageS3(
    , min_upload_part_size(min_upload_part_size_)
    , compression_method(compression_method_)
 {
+    context_global.getRemoteHostFilter().checkURL(uri_);
    setColumns(columns_);
    setConstraints(constraints_);
 }
--- a/dbms/src/Storages/StorageURL.cpp
+++ b/dbms/src/Storages/StorageURL.cpp
@ -24,6 +24,7 @@ namespace DB
 namespace ErrorCodes
 {
    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
+    extern const int UNACCEPTABLE_URL;
 }

 IStorageURLBase::IStorageURLBase(
@ -37,6 +38,7 @@ IStorageURLBase::IStorageURLBase(
    const String & compression_method_)
    : uri(uri_), context_global(context_), compression_method(compression_method_), format_name(format_name_), table_name(table_name_), database_name(database_name_)
 {
+    context_global.getRemoteHostFilter().checkURL(uri);
    setColumns(columns_);
    setConstraints(constraints_);
 }
@ -58,7 +60,18 @@ namespace
            const CompressionMethod compression_method)
            : name(name_)
        {
-            read_buf = getReadBuffer<ReadWriteBufferFromHTTP>(compression_method, uri, method, callback, timeouts, context.getSettingsRef().max_http_get_redirects);
+            read_buf = getReadBuffer<ReadWriteBufferFromHTTP>(
+                compression_method,
+                uri,
+                method,
+                callback,
+                timeouts,
+                context.getSettingsRef().max_http_get_redirects,
+                Poco::Net::HTTPBasicCredentials{},
+                DBMS_DEFAULT_BUFFER_SIZE,
+                ReadWriteBufferFromHTTP::HTTPHeaderEntries{},
+                context.getRemoteHostFilter());
+
            reader = FormatFactory::instance().getInput(format, *read_buf, sample_block, context, max_block_size);
        }

--- a/dbms/src/TableFunctions/TableFunctionRemote.cpp
+++ b/dbms/src/TableFunctions/TableFunctionRemote.cpp
@ -155,6 +155,20 @@ StoragePtr TableFunctionRemote::executeImpl(const ASTPtr & ast_function, const C
            throw Exception("Shard list is empty after parsing first argument", ErrorCodes::BAD_ARGUMENTS);

        auto maybe_secure_port = context.getTCPPortSecure();
+
+        /// Check host and port on affiliation allowed hosts.
+        for (auto hosts : names)
+        {
+            for (auto host : hosts)
+            {
+                size_t colon = host.find(':');
+                if (colon == String::npos)
+                    context.getRemoteHostFilter().checkHostAndPort(host, toString((secure ? (maybe_secure_port ? *maybe_secure_port : DBMS_DEFAULT_SECURE_PORT) : context.getTCPPort())));
+                else
+                    context.getRemoteHostFilter().checkHostAndPort(host.substr(0, colon), host.substr(colon + 1));
+            }
+        }
+
        cluster = std::make_shared<Cluster>(context.getSettings(), names, username, password, (secure ? (maybe_secure_port ? *maybe_secure_port : DBMS_DEFAULT_SECURE_PORT) : context.getTCPPort()), false, secure);
    }

--- a/dbms/tests/integration/test_allowed_url_from_config/init.py
+++ b/dbms/tests/integration/test_allowed_url_from_config/init.py
--- a/dbms/tests/integration/test_allowed_url_from_config/configs/config_for_redirect.xml
+++ b/dbms/tests/integration/test_allowed_url_from_config/configs/config_for_redirect.xml
@ -0,0 +1,5 @@
+<yandex>
+    <remote_url_allow_hosts>
+        <host>hdfs1:50070</host>
+    </remote_url_allow_hosts>    
+</yandex>
--- a/dbms/tests/integration/test_allowed_url_from_config/configs/config_for_remote.xml
+++ b/dbms/tests/integration/test_allowed_url_from_config/configs/config_for_remote.xml
@ -0,0 +1,10 @@
+<yandex>
+    <remote_url_allow_hosts>
+        <host>localhost:9000</host>
+        <host>localhost:9440</host>
+        <host>example01-01-1</host>
+        <host>example01-01-2</host>
+        <host>example01-02-1</host>
+        <host>example01-02-2</host>
+    </remote_url_allow_hosts>
+</yandex>
--- a/dbms/tests/integration/test_allowed_url_from_config/configs/config_with_hosts.xml
+++ b/dbms/tests/integration/test_allowed_url_from_config/configs/config_with_hosts.xml
@ -0,0 +1,7 @@
+<yandex>
+    <remote_url_allow_hosts>
+        <host>host:80</host>
+        <host_regexp>^[a-z]*\.ru$</host_regexp>
+    </remote_url_allow_hosts>
+</yandex>
+
--- a/dbms/tests/integration/test_allowed_url_from_config/configs/config_with_only_primary_hosts.xml
+++ b/dbms/tests/integration/test_allowed_url_from_config/configs/config_with_only_primary_hosts.xml
@ -0,0 +1,8 @@
+<yandex> 
+    <remote_url_allow_hosts>
+        <host>host:80</host>
+        <host>host:123</host>
+        <host>yandex.ru</host>
+    </remote_url_allow_hosts>
+</yandex>
+
--- a/dbms/tests/integration/test_allowed_url_from_config/configs/config_with_only_regexp_hosts.xml
+++ b/dbms/tests/integration/test_allowed_url_from_config/configs/config_with_only_regexp_hosts.xml
@ -0,0 +1,7 @@
+<yandex>
+    <remote_url_allow_hosts>
+        <host_regexp>^[a-z]*:80$</host_regexp>
+        <host_regexp>^[a-z]*\.ru$</host_regexp>
+    </remote_url_allow_hosts>
+</yandex>
+
--- a/dbms/tests/integration/test_allowed_url_from_config/configs/config_without_allowed_hosts.xml
+++ b/dbms/tests/integration/test_allowed_url_from_config/configs/config_without_allowed_hosts.xml
@ -0,0 +1,5 @@
+<yandex>
+    <remote_url_allow_hosts>
+    </remote_url_allow_hosts> 
+</yandex>
+
--- a/dbms/tests/integration/test_allowed_url_from_config/test.py
+++ b/dbms/tests/integration/test_allowed_url_from_config/test.py
@ -0,0 +1,74 @@
+import time
+import pytest
+
+from helpers.hdfs_api import HDFSApi
+from helpers.cluster import ClickHouseCluster
+
+cluster = ClickHouseCluster(__file__)
+node1 = cluster.add_instance('node1', main_configs=['configs/config_with_hosts.xml'])
+node2 = cluster.add_instance('node2', main_configs=['configs/config_with_only_primary_hosts.xml'])
+node3 = cluster.add_instance('node3', main_configs=['configs/config_with_only_regexp_hosts.xml'])
+node4 = cluster.add_instance('node4', main_configs=['configs/config_without_allowed_hosts.xml'])
+node6 = cluster.add_instance('node6', main_configs=['configs/config_for_remote.xml'])
+node7 = cluster.add_instance('node7', main_configs=['configs/config_for_redirect.xml'], with_hdfs=True)
+
+
+@pytest.fixture(scope="module")
+def start_cluster():
+    try:
+        cluster.start()
+        yield cluster
+    finally:
+        cluster.shutdown()
+
+def test_config_with_hosts(start_cluster):
+    assert node1.query("CREATE TABLE table_test_1_1 (word String) Engine=URL('http://host:80', HDFS)") == ""
+    assert node1.query("CREATE TABLE table_test_1_2 (word String) Engine=URL('https://yandex.ru', CSV)") == ""
+    assert "not allowed" in node1.query_and_get_error("CREATE TABLE table_test_1_4 (word String) Engine=URL('https://host:123', S3)")
+    assert "not allowed" in node1.query_and_get_error("CREATE TABLE table_test_1_4 (word String) Engine=URL('https://yandex2.ru', CSV)")
+
+def test_config_with_only_primary_hosts(start_cluster):
+    assert node2.query("CREATE TABLE table_test_2_1 (word String) Engine=URL('https://host:80', CSV)") == ""
+    assert node2.query("CREATE TABLE table_test_2_2 (word String) Engine=URL('https://host:123', S3)") == ""
+    assert node2.query("CREATE TABLE table_test_2_3 (word String) Engine=URL('https://yandex.ru', CSV)") == ""
+    assert node2.query("CREATE TABLE table_test_2_4 (word String) Engine=URL('https://yandex.ru:87', HDFS)") == ""
+    assert "not allowed" in node2.query_and_get_error("CREATE TABLE table_test_2_5 (word String) Engine=URL('https://host', HDFS)")
+    assert "not allowed" in node2.query_and_get_error("CREATE TABLE table_test_2_5 (word String) Engine=URL('https://host:234', CSV)")
+    assert "not allowed" in node2.query_and_get_error("CREATE TABLE table_test_2_6 (word String) Engine=URL('https://yandex2.ru', S3)")
+
+def test_config_with_only_regexp_hosts(start_cluster):
+    assert node3.query("CREATE TABLE table_test_3_1 (word String) Engine=URL('https://host:80', HDFS)") == ""
+    assert node3.query("CREATE TABLE table_test_3_2 (word String) Engine=URL('https://yandex.ru', CSV)") == ""
+    assert "not allowed" in node3.query_and_get_error("CREATE TABLE table_test_3_3 (word String) Engine=URL('https://host', CSV)")
+    assert "not allowed" in node3.query_and_get_error("CREATE TABLE table_test_3_4 (word String) Engine=URL('https://yandex2.ru', S3)") 
+
+def test_config_without_allowed_hosts(start_cluster):
+    assert node4.query("CREATE TABLE table_test_4_1 (word String) Engine=URL('https://host:80', CSV)") == ""
+    assert node4.query("CREATE TABLE table_test_4_2 (word String) Engine=URL('https://host', HDFS)") == ""
+    assert node4.query("CREATE TABLE table_test_4_3 (word String) Engine=URL('https://yandex.ru', CSV)") == ""
+    assert node4.query("CREATE TABLE table_test_4_4 (word String) Engine=URL('ftp://something.com', S3)") == ""
+
+def test_table_function_remote(start_cluster):
+    assert node6.query("SELECT * FROM remote('localhost', system, events)") != ""
+    assert node6.query("SELECT * FROM remoteSecure('localhost', system, metrics)") != ""
+    assert "URL \"localhost:800\" is not allowed in config.xml" in node6.query_and_get_error("SELECT * FROM remoteSecure('localhost:800', system, events)")
+    assert "URL \"localhost:800\" is not allowed in config.xml" in node6.query_and_get_error("SELECT * FROM remote('localhost:800', system, metrics)")
+    assert "not allowed in config.xml" not in node6.query_and_get_error("SELECT * FROM remoteSecure('example01-01-1,example01-02-1', system, events)")
+    assert "not allowed in config.xml" not in node6.query_and_get_error("SELECT * FROM remote('example01-0{1,2}-1', system, events")
+    assert "not allowed in config.xml" not in node6.query_and_get_error("SELECT * FROM remoteSecure('example01-01-{1|2}', system, events)")
+    assert "not allowed in config.xml" not in node6.query_and_get_error("SELECT * FROM remote('example01-0{1,2}-{1|2}', system, events)")
+    assert "not allowed in config.xml" not in node6.query_and_get_error("SELECT * FROM remoteSecure('example01-{01..02}-{1|2}', system, events)")
+    assert "not allowed" in node6.query_and_get_error("SELECT * FROM remoteSecure('example01-01-1,example01-03-1', system, events)")
+    assert "not allowed" in node6.query_and_get_error("SELECT * FROM remote('example01-01-{1|3}', system, events)")
+    assert "not allowed" in node6.query_and_get_error("SELECT * FROM remoteSecure('example01-0{1,3}-1', system, metrics)")
+
+def test_redirect(start_cluster):
+    hdfs_api = HDFSApi("root")
+    hdfs_api.write_data("/simple_storage", "1\t\n")
+    assert hdfs_api.read_data("/simple_storage") == "1\t\n"
+    node7.query("CREATE TABLE table_test_7_1 (word String) ENGINE=URL('http://hdfs1:50070/webhdfs/v1/simple_storage?op=OPEN&namenoderpcaddress=hdfs1:9000&offset=0', CSV)")
+    assert "not allowed" in node7.query_and_get_error("SET max_http_get_redirects=1; SELECT * from table_test_7_1")
+
+def test_HDFS(start_cluster):
+    assert "not allowed" in node7.query_and_get_error("CREATE TABLE table_test_7_2 (word String) ENGINE=HDFS('http://hdfs1:50075/webhdfs/v1/simple_storage?op=OPEN&namenoderpcaddress=hdfs1:9000&offset=0', 'CSV')")
+    assert "not allowed" in node7.query_and_get_error("SELECT * FROM hdfs('http://hdfs1:50075/webhdfs/v1/simple_storage?op=OPEN&namenoderpcaddress=hdfs1:9000&offset=0', 'TSV', 'word String')")
--- a/dbms/tests/integration/test_storage_s3/configs/config_for_test_remote_host_filter.xml
+++ b/dbms/tests/integration/test_storage_s3/configs/config_for_test_remote_host_filter.xml
@ -0,0 +1,5 @@
+<yandex>
+    <remote_url_allow_hosts>
+        <host_regexp>^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.|$)){4}$</host_regexp>
+    </remote_url_allow_hosts>
+</yandex>
--- a/dbms/tests/integration/test_storage_s3/test.py
+++ b/dbms/tests/integration/test_storage_s3/test.py
@ -86,6 +86,7 @@ def get_nginx_access_logs():
 def cluster():
    try:
        cluster = ClickHouseCluster(__file__)
+        cluster.add_instance("restricted_dummy", main_configs=["configs/config_for_test_remote_host_filter.xml"], with_minio=True)
        cluster.add_instance("dummy", with_minio=True)
        logging.info("Starting cluster...")
        cluster.start()
@ -232,3 +233,15 @@ def test_multipart_put(cluster, maybe_auth, positive):
        assert uploaded_parts > 1

        assert csv_data == get_s3_file_content(cluster, bucket, filename)
+
+
+def test_remote_host_filter(cluster):
+    instance = cluster.instances["restricted_dummy"]
+    format = "column1 UInt32, column2 UInt32, column3 UInt32"
+
+    query = "select *, column1*column2*column3 from s3('http://{}:{}/', 'CSV', '{}')".format("invalid_host", cluster.minio_redirect_port, format)
+    assert "not allowed in config.xml" in instance.query_and_get_error(query)
+
+    other_values = "(1, 1, 1), (1, 1, 1), (11, 11, 11)"
+    query = "insert into table function s3('http://{}:{}/{}/test.csv', 'CSV', '{}') values {}".format("invalid_host", cluster.minio_port, cluster.minio_bucket, format, other_values)
+    assert "not allowed in config.xml" in instance.query_and_get_error(query)
--- a/dbms/tests/queries/0_stateless/01039_test_setting_parse.reference
+++ b/dbms/tests/queries/0_stateless/01039_test_setting_parse.reference
@ -0,0 +1,2 @@
+10000000001
+10000000001
--- a/dbms/tests/queries/0_stateless/01039_test_setting_parse.sql
+++ b/dbms/tests/queries/0_stateless/01039_test_setting_parse.sql
@ -0,0 +1,7 @@
+SET max_memory_usage = 10000000001;
+
+SELECT value FROM system.settings WHERE name = 'max_memory_usage';
+
+SET max_memory_usage = '1G'; -- { serverError 27 }
+
+SELECT value FROM system.settings WHERE name = 'max_memory_usage';
--- a/docs/en/operations/settings/settings.md
+++ b/docs/en/operations/settings/settings.md
@ -1022,6 +1022,17 @@ Lower values mean higher priority. Threads with low `nice` priority values are e

 Default value: 0.

+## allow_introspection_functions {#settings-allow_introspection_functions}
+
+Enables of disables [introspections functions](../../query_language/functions/introspection.md) for query profiling.
+
+Possible values:
+
+- 1 — Introspection functions enabled.
+- 0 — Introspection functions disabled.
+
+Default value: 0.
+
 ## input_format_parallel_parsing

 - Type: bool
--- a/docs/en/query_language/functions/introspection.md
+++ b/docs/en/query_language/functions/introspection.md
@ -0,0 +1,298 @@
+# Introspection Functions
+
+You can use functions described in this chapter to introspect [ELF](https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) and [DWARF](https://en.wikipedia.org/wiki/DWARF) for query profiling.
+
+!!! warning "Warning"
+    These functions are slow and may impose security considerations.
+
+For proper operation of introspection functions:
+
+- Install the `clickhouse-common-static-dbg` package.
+- Set the [allow_introspection_functions](../../operations/settings/settings.md#settings-allow_introspection_functions) setting to 1.
+
+    For security reasons introspection functions are disabled by default.
+
+ClickHouse saves profiler reports to the [trace_log](../../operations/system_tables.md#system_tables-trace_log) system table. Make sure the table and profiler are configured properly.
+
+## addressToLine {#addresstoline}
+
+Converts virtual memory address inside ClickHouse server process to the filename and the line number in ClickHouse source code.
+
+If you use official ClickHouse packages, you need to install the `clickhouse-common-static-dbg` package.
+
+**Syntax**
+
+```sql
+addressToLine(address_of_binary_instruction)
+```
+
+**Parameters**
+
+- `address_of_binary_instruction` ([UInt64](../../data_types/int_uint.md)) — Address of instruction in a running process.
+
+**Returned value**
+
+- Source code filename and the line number in this file delimited by colon.
+
+    For example, `/build/obj-x86_64-linux-gnu/../dbms/src/Common/ThreadPool.cpp:199`, where `199` is a line number.
+
+- Name of a binary, if the function couldn't find the debug information.
+- Empty string, if the address is not valid.
+
+Type: [String](../../data_types/string.md).
+
+**Example**
+
+Enabling introspection functions:
+
+```sql
+SET allow_introspection_functions=1
+```
+
+Selecting the first string from the `trace_log` system table:
+
+```sql
+SELECT * FROM system.trace_log LIMIT 1 \G
+```
+```text
+Row 1:
+──────
+event_date:              2019-11-19
+event_time:              2019-11-19 18:57:23
+revision:                54429
+timer_type:              Real
+thread_number:           48
+query_id:                421b6855-1858-45a5-8f37-f383409d6d72
+trace:                   [140658411141617,94784174532828,94784076370703,94784076372094,94784076361020,94784175007680,140658411116251,140658403895439]
+```
+
+The `trace` field contains the stack trace at the moment of sampling.
+
+Getting the source code filename and the line number for a single address:
+
+```sql
+SELECT addressToLine(94784076370703) \G
+```
+```text
+Row 1:
+──────
+addressToLine(94784076370703): /build/obj-x86_64-linux-gnu/../dbms/src/Common/ThreadPool.cpp:199
+```
+
+Applying the function to the whole stack trace:
+
+```sql
+SELECT 
+    arrayStringConcat(arrayMap(x -> addressToLine(x), trace), '\n') AS trace_source_code_lines  
+FROM system.trace_log 
+LIMIT 1 
+\G
+```
+
+The [arrayMap](higher_order_functions.md#higher_order_functions-array-map) function allows to process each individual element of the `trace` array by the `addressToLine` function. The result of this processing you see in the `trace_source_code_lines` column of output.
+
+```text
+Row 1:
+──────
+trace_source_code_lines: /lib/x86_64-linux-gnu/libpthread-2.27.so
+/usr/lib/debug/usr/bin/clickhouse
+/build/obj-x86_64-linux-gnu/../dbms/src/Common/ThreadPool.cpp:199
+/build/obj-x86_64-linux-gnu/../dbms/src/Common/ThreadPool.h:155
+/usr/include/c++/9/bits/atomic_base.h:551
+/usr/lib/debug/usr/bin/clickhouse
+/lib/x86_64-linux-gnu/libpthread-2.27.so
+/build/glibc-OTsEL5/glibc-2.27/misc/../sysdeps/unix/sysv/linux/x86_64/clone.S:97
+```
+
+## addressToSymbol {#addresstosymbol}
+
+Converts virtual memory address inside ClickHouse server process to the symbol from ClickHouse object files.
+
+
+**Syntax**
+
+```sql
+addressToSymbol(address_of_binary_instruction)
+```
+
+**Parameters**
+
+- `address_of_binary_instruction` ([UInt64](../../data_types/int_uint.md)) — Address of instruction in a running process.
+
+**Returned value**
+
+- Symbol from ClickHouse object files.
+- Empty string, if the address is not valid.
+
+Type: [String](../../data_types/string.md).
+
+**Example**
+
+Enabling introspection functions:
+
+```sql
+SET allow_introspection_functions=1
+```
+
+Selecting the first string from the `trace_log` system table:
+
+```sql
+SELECT * FROM system.trace_log LIMIT 1 \G
+```
+```text
+Row 1:
+──────
+event_date:    2019-11-20
+event_time:    2019-11-20 16:57:59
+revision:      54429
+timer_type:    Real
+thread_number: 48
+query_id:      724028bf-f550-45aa-910d-2af6212b94ac
+trace:         [94138803686098,94138815010911,94138815096522,94138815101224,94138815102091,94138814222988,94138806823642,94138814457211,94138806823642,94138814457211,94138806823642,94138806795179,94138806796144,94138753770094,94138753771646,94138753760572,94138852407232,140399185266395,140399178045583]
+```
+
+The `trace` field contains the stack trace at the moment of sampling.
+
+Getting a symbol for a single address:
+
+```sql
+SELECT addressToSymbol(94138803686098) \G
+```
+```text
+Row 1:
+──────
+addressToSymbol(94138803686098): _ZNK2DB24IAggregateFunctionHelperINS_20AggregateFunctionSumImmNS_24AggregateFunctionSumDataImEEEEE19addBatchSinglePlaceEmPcPPKNS_7IColumnEPNS_5ArenaE
+```
+
+Applying the function to the whole stack trace:
+
+```sql
+SELECT 
+    arrayStringConcat(arrayMap(x -> addressToSymbol(x), trace), '\n') AS trace_symbols
+FROM system.trace_log
+LIMIT 1
+\G
+```
+
+The [arrayMap](higher_order_functions.md#higher_order_functions-array-map) function allows to process each individual element of the `trace` array by the `addressToSymbols` function. The result of this processing you see in the `trace_symbols` column of output.
+
+
+```text
+Row 1:
+──────
+trace_symbols: _ZNK2DB24IAggregateFunctionHelperINS_20AggregateFunctionSumImmNS_24AggregateFunctionSumDataImEEEEE19addBatchSinglePlaceEmPcPPKNS_7IColumnEPNS_5ArenaE
+_ZNK2DB10Aggregator21executeWithoutKeyImplERPcmPNS0_28AggregateFunctionInstructionEPNS_5ArenaE
+_ZN2DB10Aggregator14executeOnBlockESt6vectorIN3COWINS_7IColumnEE13immutable_ptrIS3_EESaIS6_EEmRNS_22AggregatedDataVariantsERS1_IPKS3_SaISC_EERS1_ISE_SaISE_EERb
+_ZN2DB10Aggregator14executeOnBlockERKNS_5BlockERNS_22AggregatedDataVariantsERSt6vectorIPKNS_7IColumnESaIS9_EERS6_ISB_SaISB_EERb
+_ZN2DB10Aggregator7executeERKSt10shared_ptrINS_17IBlockInputStreamEERNS_22AggregatedDataVariantsE
+_ZN2DB27AggregatingBlockInputStream8readImplEv
+_ZN2DB17IBlockInputStream4readEv
+_ZN2DB26ExpressionBlockInputStream8readImplEv
+_ZN2DB17IBlockInputStream4readEv
+_ZN2DB26ExpressionBlockInputStream8readImplEv
+_ZN2DB17IBlockInputStream4readEv
+_ZN2DB28AsynchronousBlockInputStream9calculateEv
+_ZNSt17_Function_handlerIFvvEZN2DB28AsynchronousBlockInputStream4nextEvEUlvE_E9_M_invokeERKSt9_Any_data
+_ZN14ThreadPoolImplI20ThreadFromGlobalPoolE6workerESt14_List_iteratorIS0_E
+_ZZN20ThreadFromGlobalPoolC4IZN14ThreadPoolImplIS_E12scheduleImplIvEET_St8functionIFvvEEiSt8optionalImEEUlvE1_JEEEOS4_DpOT0_ENKUlvE_clEv
+_ZN14ThreadPoolImplISt6threadE6workerESt14_List_iteratorIS0_E
+execute_native_thread_routine
+start_thread
+clone
+```
+
+## demangle {#demangle}
+
+Converts a symbol that you can get using the [addressToSymbol](#addresstosymbol) function to the C++ function name.
+
+
+**Syntax**
+
+```sql
+demangle(symbol)
+```
+
+**Parameters**
+
+- `symbol` ([String](../../data_types/string.md)) — Symbol from an object file.
+
+**Returned value**
+
+- Name of the C++ function.
+- Empty string if a symbol is not valid.
+
+Type: [String](../../data_types/string.md).
+
+**Example**
+
+Enabling introspection functions:
+
+```sql
+SET allow_introspection_functions=1
+```
+
+Selecting the first string from the `trace_log` system table:
+
+```sql
+SELECT * FROM system.trace_log LIMIT 1 \G
+```
+```text
+Row 1:
+──────
+event_date:    2019-11-20
+event_time:    2019-11-20 16:57:59
+revision:      54429
+timer_type:    Real
+thread_number: 48
+query_id:      724028bf-f550-45aa-910d-2af6212b94ac
+trace:         [94138803686098,94138815010911,94138815096522,94138815101224,94138815102091,94138814222988,94138806823642,94138814457211,94138806823642,94138814457211,94138806823642,94138806795179,94138806796144,94138753770094,94138753771646,94138753760572,94138852407232,140399185266395,140399178045583]
+```
+
+The `trace` field contains the stack trace at the moment of sampling.
+
+Getting a function name for a single address:
+
+```sql
+SELECT demangle(addressToSymbol(94138803686098)) \G
+```
+```text
+Row 1:
+──────
+demangle(addressToSymbol(94138803686098)): DB::IAggregateFunctionHelper<DB::AggregateFunctionSum<unsigned long, unsigned long, DB::AggregateFunctionSumData<unsigned long> > >::addBatchSinglePlace(unsigned long, char*, DB::IColumn const**, DB::Arena*) const
+```
+
+Applying the function to the whole stack trace:
+
+```sql
+SELECT 
+    arrayStringConcat(arrayMap(x -> demangle(addressToSymbol(x)), trace), '\n') AS trace_functions
+FROM system.trace_log
+LIMIT 1
+\G
+```
+
+The [arrayMap](higher_order_functions.md#higher_order_functions-array-map) function allows to process each individual element of the `trace` array by the `demangle` function. The result of this processing you see in the `trace_functions` column of output.
+
+```text
+Row 1:
+──────
+trace_functions: DB::IAggregateFunctionHelper<DB::AggregateFunctionSum<unsigned long, unsigned long, DB::AggregateFunctionSumData<unsigned long> > >::addBatchSinglePlace(unsigned long, char*, DB::IColumn const**, DB::Arena*) const
+DB::Aggregator::executeWithoutKeyImpl(char*&, unsigned long, DB::Aggregator::AggregateFunctionInstruction*, DB::Arena*) const
+DB::Aggregator::executeOnBlock(std::vector<COW<DB::IColumn>::immutable_ptr<DB::IColumn>, std::allocator<COW<DB::IColumn>::immutable_ptr<DB::IColumn> > >, unsigned long, DB::AggregatedDataVariants&, std::vector<DB::IColumn const*, std::allocator<DB::IColumn const*> >&, std::vector<std::vector<DB::IColumn const*, std::allocator<DB::IColumn const*> >, std::allocator<std::vector<DB::IColumn const*, std::allocator<DB::IColumn const*> > > >&, bool&)
+DB::Aggregator::executeOnBlock(DB::Block const&, DB::AggregatedDataVariants&, std::vector<DB::IColumn const*, std::allocator<DB::IColumn const*> >&, std::vector<std::vector<DB::IColumn const*, std::allocator<DB::IColumn const*> >, std::allocator<std::vector<DB::IColumn const*, std::allocator<DB::IColumn const*> > > >&, bool&)
+DB::Aggregator::execute(std::shared_ptr<DB::IBlockInputStream> const&, DB::AggregatedDataVariants&)
+DB::AggregatingBlockInputStream::readImpl()
+DB::IBlockInputStream::read()
+DB::ExpressionBlockInputStream::readImpl()
+DB::IBlockInputStream::read()
+DB::ExpressionBlockInputStream::readImpl()
+DB::IBlockInputStream::read()
+DB::AsynchronousBlockInputStream::calculate()
+std::_Function_handler<void (), DB::AsynchronousBlockInputStream::next()::{lambda()#1}>::_M_invoke(std::_Any_data const&)
+ThreadPoolImpl<ThreadFromGlobalPool>::worker(std::_List_iterator<ThreadFromGlobalPool>)
+ThreadFromGlobalPool::ThreadFromGlobalPool<ThreadPoolImpl<ThreadFromGlobalPool>::scheduleImpl<void>(std::function<void ()>, int, std::optional<unsigned long>)::{lambda()#3}>(ThreadPoolImpl<ThreadFromGlobalPool>::scheduleImpl<void>(std::function<void ()>, int, std::optional<unsigned long>)::{lambda()#3}&&)::{lambda()#1}::operator()() const
+ThreadPoolImpl<std::thread>::worker(std::_List_iterator<std::thread>)
+execute_native_thread_routine
+start_thread
+clone
+```
--- a/docs/toc_en.yml
+++ b/docs/toc_en.yml
@ -119,6 +119,7 @@ nav:
    - 'Working with geographical coordinates': 'query_language/functions/geo.md'
    - 'Working with Nullable arguments': 'query_language/functions/functions_for_nulls.md'
    - 'Machine Learning Functions': 'query_language/functions/machine_learning_functions.md'
+    - 'Introspection': 'query_language/functions/introspection.md'
    - 'Other': 'query_language/functions/other_functions.md'
  - 'Aggregate Functions':
    - 'Introduction': 'query_language/agg_functions/index.md'