ClickHouse/src/Storages/StorageURL.cpp

#include <Storages/StorageURL.h>
#include <Processors/Transforms/AddingDefaultsTransform.h>
#include <Storages/PartitionedSink.h>
#include <Storages/checkAndGetLiteralArgument.h>

#include <Interpreters/evaluateConstantExpression.h>
#include <Interpreters/threadPoolCallbackRunner.h>
#include <Parsers/ASTCreateQuery.h>
#include <Parsers/ASTInsertQuery.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTIdentifier.h>

#include <IO/ConnectionTimeouts.h>
#include <IO/ConnectionTimeoutsContext.h>
#include <IO/IOThreadPool.h>
#include <IO/ParallelReadBuffer.h>
#include <IO/WriteBufferFromHTTP.h>
#include <IO/WriteHelpers.h>

#include <Formats/FormatFactory.h>
#include <Formats/ReadSchemaUtils.h>
#include <Processors/Formats/IInputFormat.h>
#include <Processors/Formats/IOutputFormat.h>
#include <Processors/Executors/PullingPipelineExecutor.h>
#include <Processors/ISource.h>

#include <Common/ThreadStatus.h>
#include <Common/parseRemoteDescription.h>
#include <IO/HTTPCommon.h>
#include <IO/ReadWriteBufferFromHTTP.h>

#include <algorithm>
#include <QueryPipeline/QueryPipelineBuilder.h>
#include <Common/logger_useful.h>
#include <Poco/Net/HTTPRequest.h>


namespace DB
{
namespace ErrorCodes
{
    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
    extern const int NETWORK_ERROR;
    extern const int BAD_ARGUMENTS;
    extern const int LOGICAL_ERROR;
}

static constexpr auto bad_arguments_error_message = "Storage URL requires 1-4 arguments: "
    "url, name of used format (taken from file extension by default), "
    "optional compression method, optional headers (specified as `headers('name'='value', 'name2'='value2')`)";

static bool urlWithGlobs(const String & uri)
{
    return (uri.find('{') != std::string::npos && uri.find('}') != std::string::npos) || uri.find('|') != std::string::npos;
}


IStorageURLBase::IStorageURLBase(
    const String & uri_,
    ContextPtr context_,
    const StorageID & table_id_,
    const String & format_name_,
    const std::optional<FormatSettings> & format_settings_,
    const ColumnsDescription & columns_,
    const ConstraintsDescription & constraints_,
    const String & comment,
    const String & compression_method_,
    const ReadWriteBufferFromHTTP::HTTPHeaderEntries & headers_,
    const String & http_method_,
    ASTPtr partition_by_)
    : IStorage(table_id_)
    , uri(uri_)
    , compression_method(compression_method_)
    , format_name(format_name_)
    , format_settings(format_settings_)
    , headers(headers_)
    , http_method(http_method_)
    , partition_by(partition_by_)
{
    FormatFactory::instance().checkFormatName(format_name);
    StorageInMemoryMetadata storage_metadata;

    if (columns_.empty())
    {
        auto columns = getTableStructureFromData(format_name, uri, compression_method, headers, format_settings, context_);
        storage_metadata.setColumns(columns);
    }
    else
        storage_metadata.setColumns(columns_);

    storage_metadata.setConstraints(constraints_);
    storage_metadata.setComment(comment);
    setInMemoryMetadata(storage_metadata);
}


namespace
{
    ReadWriteBufferFromHTTP::HTTPHeaderEntries getHeaders(const ReadWriteBufferFromHTTP::HTTPHeaderEntries & headers_)
    {
        ReadWriteBufferFromHTTP::HTTPHeaderEntries headers(headers_.begin(), headers_.end());
        // Propagate OpenTelemetry trace context, if any, downstream.
        if (CurrentThread::isInitialized())
        {
            const auto & thread_trace_context = CurrentThread::get().thread_trace_context;
            if (thread_trace_context.trace_id != UUID())
            {
                headers.emplace_back("traceparent", thread_trace_context.composeTraceparentHeader());

                if (!thread_trace_context.tracestate.empty())
                {
                    headers.emplace_back("tracestate", thread_trace_context.tracestate);
                }
            }
        }
        return headers;
    }


    class StorageURLSource : public ISource
    {
        using URIParams = std::vector<std::pair<String, String>>;

    public:
        struct URIInfo
        {
            using FailoverOptions = std::vector<String>;
            std::vector<FailoverOptions> uri_list_to_read;
            std::atomic<size_t> next_uri_to_read = 0;
        };
        using URIInfoPtr = std::shared_ptr<URIInfo>;

        void onCancel() override
        {
            std::lock_guard lock(reader_mutex);
            if (reader)
                reader->cancel();
        }

        static void setCredentials(Poco::Net::HTTPBasicCredentials & credentials, const Poco::URI & request_uri)
        {
            const auto & user_info = request_uri.getUserInfo();
            if (!user_info.empty())
            {
                std::size_t n = user_info.find(':');
                if (n != std::string::npos)
                {
                    credentials.setUsername(user_info.substr(0, n));
                    credentials.setPassword(user_info.substr(n + 1));
                }
            }
        }

        StorageURLSource(
            URIInfoPtr uri_info_,
            const std::string & http_method,
            std::function<void(std::ostream &)> callback,
            const String & format,
            const std::optional<FormatSettings> & format_settings,
            String name_,
            const Block & sample_block,
            ContextPtr context,
            const ColumnsDescription & columns,
            UInt64 max_block_size,
            const ConnectionTimeouts & timeouts,
            const String & compression_method,
            size_t download_threads,
            const ReadWriteBufferFromHTTP::HTTPHeaderEntries & headers_ = {},
            const URIParams & params = {},
            bool glob_url = false)
            : ISource(sample_block), name(std::move(name_)), uri_info(uri_info_)
        {
            auto headers = getHeaders(headers_);

            /// Lazy initialization. We should not perform requests in constructor, because we need to do it in query pipeline.
            initialize = [=, this](const URIInfo::FailoverOptions & uri_options)
            {
                if (uri_options.empty())
                    throw Exception(ErrorCodes::LOGICAL_ERROR, "Got empty url list");

                auto first_option = uri_options.begin();
                read_buf = getFirstAvailableURLReadBuffer(
                    first_option,
                    uri_options.end(),
                    context,
                    params,
                    http_method,
                    callback,
                    timeouts,
                    compression_method,
                    credentials,
                    headers,
                    glob_url,
                    uri_options.size() == 1,
                    download_threads);

                auto input_format
                    = FormatFactory::instance().getInput(format, *read_buf, sample_block, context, max_block_size, format_settings);
                QueryPipelineBuilder builder;
                builder.init(Pipe(input_format));

                builder.addSimpleTransform(
                    [&](const Block & cur_header)
                    { return std::make_shared<AddingDefaultsTransform>(cur_header, columns, *input_format, context); });

                pipeline = std::make_unique<QueryPipeline>(QueryPipelineBuilder::getPipeline(std::move(builder)));
                reader = std::make_unique<PullingPipelineExecutor>(*pipeline);
            };
        }

        String getName() const override { return name; }

        Chunk generate() override
        {
            while (true)
            {
                if (!reader)
                {
                    auto current_uri_pos = uri_info->next_uri_to_read.fetch_add(1);
                    if (current_uri_pos >= uri_info->uri_list_to_read.size())
                        return {};

                    auto current_uri = uri_info->uri_list_to_read[current_uri_pos];

                    std::lock_guard lock(reader_mutex);
                    initialize(current_uri);
                }

                Chunk chunk;
                std::lock_guard lock(reader_mutex);
                if (reader->pull(chunk))
                    return chunk;

                pipeline->reset();
                reader.reset();
            }
        }

        static std::unique_ptr<ReadBuffer> getFirstAvailableURLReadBuffer(
            std::vector<String>::const_iterator & option,
            const std::vector<String>::const_iterator & end,
            ContextPtr context,
            const URIParams & params,
            const String & http_method,
            std::function<void(std::ostream &)> callback,
            const ConnectionTimeouts & timeouts,
            const String & compression_method,
            Poco::Net::HTTPBasicCredentials & credentials,
            const ReadWriteBufferFromHTTP::HTTPHeaderEntries & headers,
            bool glob_url,
            bool delay_initialization,
            size_t download_threads)
        {
            String first_exception_message;
            ReadSettings read_settings = context->getReadSettings();

            size_t options = std::distance(option, end);
            for (; option != end; ++option)
            {
                bool skip_url_not_found_error = glob_url && read_settings.http_skip_not_found_url_for_globs && option == std::prev(end);
                auto request_uri = Poco::URI(*option);

                for (const auto & [param, value] : params)
                    request_uri.addQueryParameter(param, value);

                setCredentials(credentials, request_uri);

                const auto settings = context->getSettings();
                try
                {
                    if (download_threads > 1)
                    {
                        try
                        {
                            ReadWriteBufferFromHTTP buffer(
                                request_uri,
                                Poco::Net::HTTPRequest::HTTP_HEAD,
                                callback,
                                timeouts,
                                credentials,
                                settings.max_http_get_redirects,
                                DBMS_DEFAULT_BUFFER_SIZE,
                                read_settings,
                                headers,
                                ReadWriteBufferFromHTTP::Range{0, std::nullopt},
                                &context->getRemoteHostFilter(),
                                true,
                                /* use_external_buffer */ false,
                                /* skip_url_not_found_error */ skip_url_not_found_error);

                            Poco::Net::HTTPResponse res;

                            for (size_t i = 0; i < settings.http_max_tries; ++i)
                            {
                                try
                                {
                                    buffer.callWithRedirects(res, Poco::Net::HTTPRequest::HTTP_HEAD, true);
                                    break;
                                }
                                catch (const Poco::Exception & e)
                                {
                                    LOG_TRACE(
                                        &Poco::Logger::get("StorageURLSource"),
                                        "HTTP HEAD request to `{}` failed at try {}/{}. "
                                        "Error: {}.",
                                        request_uri.toString(),
                                        i + 1,
                                        settings.http_max_tries,
                                        e.displayText());
                                    if (!ReadWriteBufferFromHTTP::isRetriableError(res.getStatus()))
                                    {
                                        throw;
                                    }
                                }
                            }

                            // to check if Range header is supported, we need to send a request with it set
                            const bool supports_ranges = (res.has("Accept-Ranges") && res.get("Accept-Ranges") == "bytes")
                                || (res.has("Content-Range") && res.get("Content-Range").starts_with("bytes"));
                            LOG_TRACE(
                                &Poco::Logger::get("StorageURLSource"),
                                fmt::runtime(supports_ranges ? "HTTP Range is supported" : "HTTP Range is not supported"));


                            if (supports_ranges && res.getStatus() == Poco::Net::HTTPResponse::HTTP_PARTIAL_CONTENT
                                && res.hasContentLength())
                            {
                                LOG_TRACE(
                                    &Poco::Logger::get("StorageURLSource"),
                                    "Using ParallelReadBuffer with {} workers with chunks of {} bytes",
                                    download_threads,
                                    settings.max_download_buffer_size);

                                auto read_buffer_factory = std::make_unique<RangedReadWriteBufferFromHTTPFactory>(
                                    res.getContentLength(),
                                    settings.max_download_buffer_size,
                                    request_uri,
                                    http_method,
                                    callback,
                                    timeouts,
                                    credentials,
                                    settings.max_http_get_redirects,
                                    DBMS_DEFAULT_BUFFER_SIZE,
                                    read_settings,
                                    headers,
                                    &context->getRemoteHostFilter(),
                                    delay_initialization,
                                    /* use_external_buffer */ false,
                                    /* skip_url_not_found_error */ skip_url_not_found_error);

                                return wrapReadBufferWithCompressionMethod(
                                    std::make_unique<ParallelReadBuffer>(
                                        std::move(read_buffer_factory),
                                        threadPoolCallbackRunner(IOThreadPool::get()),
                                        download_threads),
                                    chooseCompressionMethod(request_uri.getPath(), compression_method),
                                    settings.zstd_window_log_max);
                            }
                        }
                        catch (const Poco::Exception & e)
                        {
                            LOG_TRACE(
                                &Poco::Logger::get("StorageURLSource"),
                                "Failed to setup ParallelReadBuffer because of an exception:\n{}.\nFalling back to the single-threaded "
                                "buffer",
                                e.displayText());
                        }
                    }

                    LOG_TRACE(&Poco::Logger::get("StorageURLSource"), "Using single-threaded read buffer");

                    return wrapReadBufferWithCompressionMethod(
                        std::make_unique<ReadWriteBufferFromHTTP>(
                            request_uri,
                            http_method,
                            callback,
                            timeouts,
                            credentials,
                            settings.max_http_get_redirects,
                            DBMS_DEFAULT_BUFFER_SIZE,
                            read_settings,
                            headers,
                            ReadWriteBufferFromHTTP::Range{},
                            &context->getRemoteHostFilter(),
                            delay_initialization,
                            /* use_external_buffer */ false,
                            /* skip_url_not_found_error */ skip_url_not_found_error),
                        chooseCompressionMethod(request_uri.getPath(), compression_method),
                        settings.zstd_window_log_max);
                }
                catch (...)
                {
                    if (first_exception_message.empty())
                        first_exception_message = getCurrentExceptionMessage(false);

                    if (options == 1)
                        throw;

                    tryLogCurrentException(__PRETTY_FUNCTION__);
                }
            }

            throw Exception(ErrorCodes::NETWORK_ERROR, "All uri ({}) options are unreachable: {}", options, first_exception_message);
        }

    private:
        using InitializeFunc = std::function<void(const URIInfo::FailoverOptions &)>;
        InitializeFunc initialize;

        String name;
        URIInfoPtr uri_info;

        std::unique_ptr<ReadBuffer> read_buf;
        std::unique_ptr<QueryPipeline> pipeline;
        std::unique_ptr<PullingPipelineExecutor> reader;
        /// onCancell and generate can be called concurrently and both of them
        /// have R/W access to reader pointer.
        std::mutex reader_mutex;

        Poco::Net::HTTPBasicCredentials credentials;
    };
}

StorageURLSink::StorageURLSink(
    const String & uri,
    const String & format,
    const std::optional<FormatSettings> & format_settings,
    const Block & sample_block,
    ContextPtr context,
    const ConnectionTimeouts & timeouts,
    const CompressionMethod compression_method,
    const String & http_method)
    : SinkToStorage(sample_block)
{
    std::string content_type = FormatFactory::instance().getContentType(format, context, format_settings);
    std::string content_encoding = toContentEncodingName(compression_method);

    write_buf = wrapWriteBufferWithCompressionMethod(
        std::make_unique<WriteBufferFromHTTP>(Poco::URI(uri), http_method, content_type, content_encoding, timeouts),
        compression_method,
        3);
    writer = FormatFactory::instance().getOutputFormat(format, *write_buf, sample_block, context, {} /* write callback */, format_settings);
}


void StorageURLSink::consume(Chunk chunk)
{
    std::lock_guard lock(cancel_mutex);
    if (cancelled)
        return;
    writer->write(getHeader().cloneWithColumns(chunk.detachColumns()));
}

void StorageURLSink::onCancel()
{
    std::lock_guard lock(cancel_mutex);
    finalize();
    cancelled = true;
}

void StorageURLSink::onException()
{
    std::lock_guard lock(cancel_mutex);
    finalize();
}

void StorageURLSink::onFinish()
{
    std::lock_guard lock(cancel_mutex);
    finalize();
}

void StorageURLSink::finalize()
{
    if (!writer)
        return;

    try
    {
        writer->finalize();
        writer->flush();
        write_buf->finalize();
    }
    catch (...)
    {
        /// Stop ParallelFormattingOutputFormat correctly.
        writer.reset();
        throw;
    }
}

class PartitionedStorageURLSink : public PartitionedSink
{
public:
    PartitionedStorageURLSink(
        const ASTPtr & partition_by,
        const String & uri_,
        const String & format_,
        const std::optional<FormatSettings> & format_settings_,
        const Block & sample_block_,
        ContextPtr context_,
        const ConnectionTimeouts & timeouts_,
        const CompressionMethod compression_method_,
        const String & http_method_)
        : PartitionedSink(partition_by, context_, sample_block_)
        , uri(uri_)
        , format(format_)
        , format_settings(format_settings_)
        , sample_block(sample_block_)
        , context(context_)
        , timeouts(timeouts_)
        , compression_method(compression_method_)
        , http_method(http_method_)
    {
    }

    SinkPtr createSinkForPartition(const String & partition_id) override
    {
        auto partition_path = PartitionedSink::replaceWildcards(uri, partition_id);
        context->getRemoteHostFilter().checkURL(Poco::URI(partition_path));
        return std::make_shared<StorageURLSink>(
            partition_path, format, format_settings, sample_block, context, timeouts, compression_method, http_method);
    }

private:
    const String uri;
    const String format;
    const std::optional<FormatSettings> format_settings;
    const Block sample_block;
    ContextPtr context;
    const ConnectionTimeouts timeouts;

    const CompressionMethod compression_method;
    const String http_method;
};

std::string IStorageURLBase::getReadMethod() const
{
    return Poco::Net::HTTPRequest::HTTP_GET;
}

std::vector<std::pair<std::string, std::string>> IStorageURLBase::getReadURIParams(
    const Names & /*column_names*/,
    const StorageSnapshotPtr & /*storage_snapshot*/,
    const SelectQueryInfo & /*query_info*/,
    ContextPtr /*context*/,
    QueryProcessingStage::Enum & /*processed_stage*/,
    size_t /*max_block_size*/) const
{
    return {};
}

std::function<void(std::ostream &)> IStorageURLBase::getReadPOSTDataCallback(
    const Names & /*column_names*/,
    const ColumnsDescription & /* columns_description */,
    const SelectQueryInfo & /*query_info*/,
    ContextPtr /*context*/,
    QueryProcessingStage::Enum & /*processed_stage*/,
    size_t /*max_block_size*/) const
{
    return nullptr;
}


ColumnsDescription IStorageURLBase::getTableStructureFromData(
    const String & format,
    const String & uri,
    const String & compression_method,
    const ReadWriteBufferFromHTTP::HTTPHeaderEntries & headers,
    const std::optional<FormatSettings> & format_settings,
    ContextPtr context)
{
    context->getRemoteHostFilter().checkURL(Poco::URI(uri));

    Poco::Net::HTTPBasicCredentials credentials;

    std::vector<String> urls_to_check;
    if (urlWithGlobs(uri))
    {
        size_t max_addresses = context->getSettingsRef().glob_expansion_max_elements;
        auto uri_descriptions = parseRemoteDescription(uri, 0, uri.size(), ',', max_addresses);
        for (const auto & description : uri_descriptions)
        {
            auto options = parseRemoteDescription(description, 0, description.size(), '|', max_addresses);
            urls_to_check.insert(urls_to_check.end(), options.begin(), options.end());
        }
    }
    else
    {
        urls_to_check = {uri};
    }

    std::optional<ColumnsDescription> columns_from_cache;
    if (context->getSettingsRef().schema_inference_use_cache_for_url)
        columns_from_cache = tryGetColumnsFromCache(urls_to_check, headers, credentials, format, format_settings, context);

    ReadBufferIterator read_buffer_iterator = [&, it = urls_to_check.cbegin()](ColumnsDescription &) mutable -> std::unique_ptr<ReadBuffer>
    {
        if (it == urls_to_check.cend())
            return nullptr;

        auto buf = StorageURLSource::getFirstAvailableURLReadBuffer(
            it,
            urls_to_check.cend(),
            context,
            {},
            Poco::Net::HTTPRequest::HTTP_GET,
            {},
            ConnectionTimeouts::getHTTPTimeouts(context),
            compression_method,
            credentials,
            headers,
            false,
            false,
            context->getSettingsRef().max_download_threads);\
        ++it;
        return buf;
    };

    ColumnsDescription columns;
    if (columns_from_cache)
        columns = *columns_from_cache;
    else
        columns = readSchemaFromFormat(format, format_settings, read_buffer_iterator, urls_to_check.size() > 1, context);

    if (context->getSettingsRef().schema_inference_use_cache_for_url)
        addColumnsToCache(urls_to_check, columns, format, format_settings, context);

    return columns;
}

bool IStorageURLBase::supportsSubsetOfColumns() const
{
    return FormatFactory::instance().checkIfFormatSupportsSubsetOfColumns(format_name);
}

Pipe IStorageURLBase::read(
    const Names & column_names,
    const StorageSnapshotPtr & storage_snapshot,
    SelectQueryInfo & query_info,
    ContextPtr local_context,
    QueryProcessingStage::Enum processed_stage,
    size_t max_block_size,
    unsigned num_streams)
{
    auto params = getReadURIParams(column_names, storage_snapshot, query_info, local_context, processed_stage, max_block_size);

    ColumnsDescription columns_description;
    Block block_for_format;
    if (supportsSubsetOfColumns())
    {
        columns_description = storage_snapshot->getDescriptionForColumns(column_names);
        block_for_format = storage_snapshot->getSampleBlockForColumns(columns_description.getNamesOfPhysical());
    }
    else
    {
        columns_description = storage_snapshot->metadata->getColumns();
        block_for_format = storage_snapshot->metadata->getSampleBlock();
    }

    size_t max_download_threads = local_context->getSettingsRef().max_download_threads;

    if (urlWithGlobs(uri))
    {
        size_t max_addresses = local_context->getSettingsRef().glob_expansion_max_elements;
        auto uri_descriptions = parseRemoteDescription(uri, 0, uri.size(), ',', max_addresses);

        if (num_streams > uri_descriptions.size())
            num_streams = uri_descriptions.size();

        /// For each uri (which acts like shard) check if it has failover options
        auto uri_info = std::make_shared<StorageURLSource::URIInfo>();
        for (const auto & description : uri_descriptions)
            uri_info->uri_list_to_read.emplace_back(parseRemoteDescription(description, 0, description.size(), '|', max_addresses));

        Pipes pipes;
        pipes.reserve(num_streams);

        size_t download_threads = num_streams >= max_download_threads ? 1 : (max_download_threads / num_streams);
        for (size_t i = 0; i < num_streams; ++i)
        {
            pipes.emplace_back(std::make_shared<StorageURLSource>(
                uri_info,
                getReadMethod(),
                getReadPOSTDataCallback(column_names, columns_description, query_info, local_context, processed_stage, max_block_size),
                format_name,
                format_settings,
                getName(),
                block_for_format,
                local_context,
                columns_description,
                max_block_size,
                ConnectionTimeouts::getHTTPTimeouts(local_context),
                compression_method,
                download_threads,
                headers,
                params,
                /* glob_url */ true));
        }
        return Pipe::unitePipes(std::move(pipes));
    }
    else
    {
        auto uri_info = std::make_shared<StorageURLSource::URIInfo>();
        uri_info->uri_list_to_read.emplace_back(std::vector<String>{uri});
        return Pipe(std::make_shared<StorageURLSource>(
            uri_info,
            getReadMethod(),
            getReadPOSTDataCallback(column_names, columns_description, query_info, local_context, processed_stage, max_block_size),
            format_name,
            format_settings,
            getName(),
            block_for_format,
            local_context,
            columns_description,
            max_block_size,
            ConnectionTimeouts::getHTTPTimeouts(local_context),
            compression_method,
            max_download_threads,
            headers,
            params));
    }
}


Pipe StorageURLWithFailover::read(
    const Names & column_names,
    const StorageSnapshotPtr & storage_snapshot,
    SelectQueryInfo & query_info,
    ContextPtr local_context,
    QueryProcessingStage::Enum processed_stage,
    size_t max_block_size,
    unsigned /*num_streams*/)
{
    ColumnsDescription columns_description;
    Block block_for_format;
    if (supportsSubsetOfColumns())
    {
        columns_description = storage_snapshot->getDescriptionForColumns(column_names);
        block_for_format = storage_snapshot->getSampleBlockForColumns(columns_description.getNamesOfPhysical());
    }
    else
    {
        columns_description = storage_snapshot->metadata->getColumns();
        block_for_format = storage_snapshot->metadata->getSampleBlock();
    }

    auto params = getReadURIParams(column_names, storage_snapshot, query_info, local_context, processed_stage, max_block_size);

    auto uri_info = std::make_shared<StorageURLSource::URIInfo>();
    uri_info->uri_list_to_read.emplace_back(uri_options);
    auto pipe = Pipe(std::make_shared<StorageURLSource>(
        uri_info,
        getReadMethod(),
        getReadPOSTDataCallback(column_names, columns_description, query_info, local_context, processed_stage, max_block_size),
        format_name,
        format_settings,
        getName(),
        block_for_format,
        local_context,
        columns_description,
        max_block_size,
        ConnectionTimeouts::getHTTPTimeouts(local_context),
        compression_method,
        local_context->getSettingsRef().max_download_threads,
        headers,
        params));
    std::shuffle(uri_options.begin(), uri_options.end(), thread_local_rng);
    return pipe;
}


SinkToStoragePtr IStorageURLBase::write(const ASTPtr & query, const StorageMetadataPtr & metadata_snapshot, ContextPtr context)
{
    if (http_method.empty())
        http_method = Poco::Net::HTTPRequest::HTTP_POST;

    bool has_wildcards = uri.find(PartitionedSink::PARTITION_ID_WILDCARD) != String::npos;
    const auto * insert_query = dynamic_cast<const ASTInsertQuery *>(query.get());
    auto partition_by_ast = insert_query ? (insert_query->partition_by ? insert_query->partition_by : partition_by) : nullptr;
    bool is_partitioned_implementation = partition_by_ast && has_wildcards;

    if (is_partitioned_implementation)
    {
        return std::make_shared<PartitionedStorageURLSink>(
            partition_by_ast,
            uri,
            format_name,
            format_settings,
            metadata_snapshot->getSampleBlock(),
            context,
            ConnectionTimeouts::getHTTPTimeouts(context),
            chooseCompressionMethod(uri, compression_method),
            http_method);
    }
    else
    {
        return std::make_shared<StorageURLSink>(
            uri,
            format_name,
            format_settings,
            metadata_snapshot->getSampleBlock(),
            context,
            ConnectionTimeouts::getHTTPTimeouts(context),
            chooseCompressionMethod(uri, compression_method),
            http_method);
    }
}

SchemaCache & IStorageURLBase::getSchemaCache(const ContextPtr & context)
{
    static SchemaCache schema_cache(context->getConfigRef().getUInt("schema_inference_cache_max_elements_for_url", DEFAULT_SCHEMA_CACHE_ELEMENTS));
    return schema_cache;
}

std::optional<ColumnsDescription> IStorageURLBase::tryGetColumnsFromCache(
    const Strings & urls,
    const ReadWriteBufferFromHTTP::HTTPHeaderEntries & headers,
    const Poco::Net::HTTPBasicCredentials & credentials,
    const String & format_name,
    const std::optional<FormatSettings> & format_settings,
    const ContextPtr & context)
{
    auto & schema_cache = getSchemaCache(context);
    for (const auto & url : urls)
    {
        auto get_last_mod_time = [&]() -> std::optional<time_t>
        {
            auto last_mod_time = getLastModificationTime(url, headers, credentials, context);
            /// Some URLs could not have Last-Modified header, in this case we cannot be sure that
            /// data wasn't changed after adding it's schema to cache. Use schema from cache only if
            /// special setting for this case is enabled.
            if (!last_mod_time && !context->getSettingsRef().schema_inference_cache_require_modification_time_for_url)
                return 0;
            return last_mod_time;
        };

        String cache_key = getKeyForSchemaCache(url, format_name, format_settings, context);
        auto columns = schema_cache.tryGet(cache_key, get_last_mod_time);
        if (columns)
            return columns;
    }

    return std::nullopt;
}

void IStorageURLBase::addColumnsToCache(
    const Strings & urls,
    const ColumnsDescription & columns,
    const String & format_name,
    const std::optional<FormatSettings> & format_settings,
    const ContextPtr & context)
{
    auto & schema_cache = getSchemaCache(context);
    Strings cache_keys = getKeysForSchemaCache(urls, format_name, format_settings, context);
    schema_cache.addMany(cache_keys, columns);
}

std::optional<time_t> IStorageURLBase::getLastModificationTime(
    const String & url,
    const ReadWriteBufferFromHTTP::HTTPHeaderEntries & headers,
    const Poco::Net::HTTPBasicCredentials & credentials,
    const ContextPtr & context)
{
    try
    {
        ReadWriteBufferFromHTTP buf(
            Poco::URI(url),
            Poco::Net::HTTPRequest::HTTP_GET,
            {},
            ConnectionTimeouts::getHTTPTimeouts(context),
            credentials,
            context->getSettingsRef().max_http_get_redirects,
            DBMS_DEFAULT_BUFFER_SIZE,
            context->getReadSettings(),
            headers,
            ReadWriteBufferFromHTTP::Range{},
            &context->getRemoteHostFilter(),
            true,
            false,
            false);

        return buf.getLastModificationTime();
    }
    catch (...)
    {
        return std::nullopt;
    }
}

StorageURL::StorageURL(
    const String & uri_,
    const StorageID & table_id_,
    const String & format_name_,
    const std::optional<FormatSettings> & format_settings_,
    const ColumnsDescription & columns_,
    const ConstraintsDescription & constraints_,
    const String & comment,
    ContextPtr context_,
    const String & compression_method_,
    const ReadWriteBufferFromHTTP::HTTPHeaderEntries & headers_,
    const String & http_method_,
    ASTPtr partition_by_)
    : IStorageURLBase(
        uri_,
        context_,
        table_id_,
        format_name_,
        format_settings_,
        columns_,
        constraints_,
        comment,
        compression_method_,
        headers_,
        http_method_,
        partition_by_)
{
    context_->getRemoteHostFilter().checkURL(Poco::URI(uri));
}


StorageURLWithFailover::StorageURLWithFailover(
    const std::vector<String> & uri_options_,
    const StorageID & table_id_,
    const String & format_name_,
    const std::optional<FormatSettings> & format_settings_,
    const ColumnsDescription & columns_,
    const ConstraintsDescription & constraints_,
    ContextPtr context_,
    const String & compression_method_)
    : StorageURL("", table_id_, format_name_, format_settings_, columns_, constraints_, String{}, context_, compression_method_)
{
    for (const auto & uri_option : uri_options_)
    {
        Poco::URI poco_uri(uri_option);
        context_->getRemoteHostFilter().checkURL(poco_uri);
        LOG_DEBUG(&Poco::Logger::get("StorageURLDistributed"), "Adding URL option: {}", uri_option);
        uri_options.emplace_back(uri_option);
    }
}


FormatSettings StorageURL::getFormatSettingsFromArgs(const StorageFactory::Arguments & args)
{
    // Use format settings from global server context + settings from
    // the SETTINGS clause of the create query. Settings from current
    // session and user are ignored.
    FormatSettings format_settings;
    if (args.storage_def->settings)
    {
        FormatFactorySettings user_format_settings;

        // Apply changed settings from global context, but ignore the
        // unknown ones, because we only have the format settings here.
        const auto & changes = args.getContext()->getSettingsRef().changes();
        for (const auto & change : changes)
        {
            if (user_format_settings.has(change.name))
            {
                user_format_settings.set(change.name, change.value);
            }
        }

        // Apply changes from SETTINGS clause, with validation.
        user_format_settings.applyChanges(args.storage_def->settings->changes);

        format_settings = getFormatSettings(args.getContext(), user_format_settings);
    }
    else
    {
        format_settings = getFormatSettings(args.getContext());
    }

    return format_settings;
}

ASTs::iterator StorageURL::collectHeaders(
    ASTs & url_function_args, URLBasedDataSourceConfiguration & configuration, ContextPtr context)
{
    ASTs::iterator headers_it = url_function_args.end();

    for (auto arg_it = url_function_args.begin(); arg_it != url_function_args.end(); ++arg_it)
    {
        const auto * headers_ast_function = (*arg_it)->as<ASTFunction>();
        if (headers_ast_function && headers_ast_function->name == "headers")
        {
            if (headers_it != url_function_args.end())
                throw Exception(
                    ErrorCodes::BAD_ARGUMENTS,
                    "URL table function can have only one key-value argument: headers=(). {}",
                    bad_arguments_error_message);

            const auto * headers_function_args_expr = assert_cast<const ASTExpressionList *>(headers_ast_function->arguments.get());
            auto headers_function_args = headers_function_args_expr->children;

            for (auto & header_arg : headers_function_args)
            {
                const auto * header_ast = header_arg->as<ASTFunction>();
                if (!header_ast || header_ast->name != "equals")
                    throw Exception(ErrorCodes::BAD_ARGUMENTS, "Headers argument is incorrect. {}", bad_arguments_error_message);

                const auto * header_args_expr = assert_cast<const ASTExpressionList *>(header_ast->arguments.get());
                auto header_args = header_args_expr->children;
                if (header_args.size() != 2)
                    throw Exception(
                        ErrorCodes::BAD_ARGUMENTS,
                        "Headers argument is incorrect: expected 2 arguments, got {}",
                        header_args.size());

                auto ast_literal = evaluateConstantExpressionOrIdentifierAsLiteral(header_args[0], context);
                auto arg_name_value = ast_literal->as<ASTLiteral>()->value;
                if (arg_name_value.getType() != Field::Types::Which::String)
                    throw Exception(ErrorCodes::BAD_ARGUMENTS, "Expected string as header name");
                auto arg_name = arg_name_value.safeGet<String>();

                ast_literal = evaluateConstantExpressionOrIdentifierAsLiteral(header_args[1], context);
                auto arg_value = ast_literal->as<ASTLiteral>()->value;
                if (arg_value.getType() != Field::Types::Which::String)
                    throw Exception(ErrorCodes::BAD_ARGUMENTS, "Expected string as header value");

                configuration.headers.emplace_back(arg_name, arg_value);
            }

            headers_it = arg_it;

            continue;
        }

        (*arg_it) = evaluateConstantExpressionOrIdentifierAsLiteral((*arg_it), context);
    }

    return headers_it;
}

URLBasedDataSourceConfiguration StorageURL::getConfiguration(ASTs & args, ContextPtr local_context)
{
    URLBasedDataSourceConfiguration configuration;

    if (auto named_collection = getURLBasedDataSourceConfiguration(args, local_context))
    {
        auto [common_configuration, storage_specific_args] = named_collection.value();
        configuration.set(common_configuration);

        if (!configuration.http_method.empty() && configuration.http_method != Poco::Net::HTTPRequest::HTTP_POST
            && configuration.http_method != Poco::Net::HTTPRequest::HTTP_PUT)
            throw Exception(
                ErrorCodes::BAD_ARGUMENTS,
                "Http method can be POST or PUT (current: {}). For insert default is POST, for select GET",
                configuration.http_method);

        if (!storage_specific_args.empty())
        {
            String illegal_args;
            for (const auto & arg : storage_specific_args)
            {
                if (!illegal_args.empty())
                    illegal_args += ", ";
                illegal_args += arg.first;
            }
            throw Exception(ErrorCodes::BAD_ARGUMENTS, "Unknown argument `{}` for storage URL", illegal_args);
        }
    }
    else
    {
        if (args.empty() || args.size() > 3)
            throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH, bad_arguments_error_message);

        auto header_it = collectHeaders(args, configuration, local_context);
        if (header_it != args.end())
            args.erase(header_it);

        configuration.url = checkAndGetLiteralArgument<String>(args[0], "url");
        if (args.size() > 1)
            configuration.format = checkAndGetLiteralArgument<String>(args[1], "format");
        if (args.size() == 3)
            configuration.compression_method = checkAndGetLiteralArgument<String>(args[2], "compression_method");
    }

    if (configuration.format == "auto")
        configuration.format = FormatFactory::instance().getFormatFromFileName(configuration.url, true);

    return configuration;
}


void registerStorageURL(StorageFactory & factory)
{
    factory.registerStorage(
        "URL",
        [](const StorageFactory::Arguments & args)
        {
            ASTs & engine_args = args.engine_args;
            auto configuration = StorageURL::getConfiguration(engine_args, args.getLocalContext());
            auto format_settings = StorageURL::getFormatSettingsFromArgs(args);

            ReadWriteBufferFromHTTP::HTTPHeaderEntries headers;
            for (const auto & [header, value] : configuration.headers)
            {
                auto value_literal = value.safeGet<String>();
                if (header == "Range")
                    throw Exception(ErrorCodes::BAD_ARGUMENTS, "Range headers are not allowed");
                headers.emplace_back(std::make_pair(header, value_literal));
            }

            ASTPtr partition_by;
            if (args.storage_def->partition_by)
                partition_by = args.storage_def->partition_by->clone();

            return std::make_shared<StorageURL>(
                configuration.url,
                args.table_id,
                configuration.format,
                format_settings,
                args.columns,
                args.constraints,
                args.comment,
                args.getContext(),
                configuration.compression_method,
                headers,
                configuration.http_method,
                partition_by);
        },
        {
            .supports_settings = true,
            .supports_schema_inference = true,
            .source_access_type = AccessType::URL,
        });
}
}