ClickHouse/src/Interpreters/ClusterProxy/executeQuery.cpp

#include <Interpreters/ClusterProxy/executeQuery.h>
#include <Interpreters/ClusterProxy/IStreamFactory.h>
#include <Core/Settings.h>
#include <Interpreters/Context.h>
#include <Interpreters/Cluster.h>
#include <Interpreters/IInterpreter.h>
#include <Interpreters/ProcessList.h>
#include <Parsers/queryToString.h>
#include <Processors/Pipe.h>
#include <Processors/QueryPlan/QueryPlan.h>
#include <Processors/QueryPlan/ReadFromPreparedSource.h>
#include <Processors/QueryPlan/UnionStep.h>
#include <Storages/SelectQueryInfo.h>


namespace DB
{

namespace ClusterProxy
{

Context updateSettingsForCluster(const Cluster & cluster, const Context & context, const Settings & settings, Poco::Logger * log)
{
    Settings new_settings = settings;
    new_settings.queue_max_wait_ms = Cluster::saturate(new_settings.queue_max_wait_ms, settings.max_execution_time);

    /// If "secret" (in remote_servers) is not in use,
    /// user on the shard is not the same as the user on the initiator,
    /// hence per-user limits should not be applied.
    if (cluster.getSecret().empty())
    {
        /// Does not matter on remote servers, because queries are sent under different user.
        new_settings.max_concurrent_queries_for_user = 0;
        new_settings.max_memory_usage_for_user = 0;

        /// Set as unchanged to avoid sending to remote server.
        new_settings.max_concurrent_queries_for_user.changed = false;
        new_settings.max_memory_usage_for_user.changed = false;
    }

    if (settings.force_optimize_skip_unused_shards_nesting && settings.force_optimize_skip_unused_shards)
    {
        if (new_settings.force_optimize_skip_unused_shards_nesting == 1)
        {
            new_settings.force_optimize_skip_unused_shards = false;
            new_settings.force_optimize_skip_unused_shards.changed = false;

            if (log)
                LOG_TRACE(log, "Disabling force_optimize_skip_unused_shards for nested queries (force_optimize_skip_unused_shards_nesting exceeded)");
        }
        else
        {
            --new_settings.force_optimize_skip_unused_shards_nesting.value;
            new_settings.force_optimize_skip_unused_shards_nesting.changed = true;

            if (log)
                LOG_TRACE(log, "force_optimize_skip_unused_shards_nesting is now {}", new_settings.force_optimize_skip_unused_shards_nesting);
        }
    }

    if (settings.optimize_skip_unused_shards_nesting && settings.optimize_skip_unused_shards)
    {
        if (new_settings.optimize_skip_unused_shards_nesting == 1)
        {
            new_settings.optimize_skip_unused_shards = false;
            new_settings.optimize_skip_unused_shards.changed = false;

            if (log)
                LOG_TRACE(log, "Disabling optimize_skip_unused_shards for nested queries (optimize_skip_unused_shards_nesting exceeded)");
        }
        else
        {
            --new_settings.optimize_skip_unused_shards_nesting.value;
            new_settings.optimize_skip_unused_shards_nesting.changed = true;

            if (log)
                LOG_TRACE(log, "optimize_skip_unused_shards_nesting is now {}", new_settings.optimize_skip_unused_shards_nesting);
        }
    }

    Context new_context(context);
    new_context.setSettings(new_settings);

    return new_context;
}

void executeQuery(
    QueryPlan & query_plan,
    IStreamFactory & stream_factory, Poco::Logger * log,
    const ASTPtr & query_ast, const Context & context, const SelectQueryInfo & query_info)
{
    assert(log);

    const Settings & settings = context.getSettingsRef();

    std::vector<QueryPlanPtr> plans;
    Pipes remote_pipes;
    Pipes delayed_pipes;

    const std::string query = queryToString(query_ast);

    Context new_context = updateSettingsForCluster(*query_info.cluster, context, settings, log);

    ThrottlerPtr user_level_throttler;
    if (auto * process_list_element = context.getProcessListElement())
        user_level_throttler = process_list_element->getUserNetworkThrottler();

    /// Network bandwidth limit, if needed.
    ThrottlerPtr throttler;
    if (settings.max_network_bandwidth || settings.max_network_bytes)
    {
        throttler = std::make_shared<Throttler>(
                settings.max_network_bandwidth,
                settings.max_network_bytes,
                "Limit for bytes to send or receive over network exceeded.",
                user_level_throttler);
    }
    else
        throttler = user_level_throttler;

    for (const auto & shard_info : query_info.cluster->getShardsInfo())
        stream_factory.createForShard(shard_info, query, query_ast, new_context, throttler, query_info, plans, remote_pipes, delayed_pipes);

    if (!remote_pipes.empty())
    {
        auto plan = std::make_unique<QueryPlan>();
        auto read_from_remote = std::make_unique<ReadFromPreparedSource>(Pipe::unitePipes(std::move(remote_pipes)));
        read_from_remote->setStepDescription("Read from remote replica");
        plan->addStep(std::move(read_from_remote));
        plans.emplace_back(std::move(plan));
    }

    if (!delayed_pipes.empty())
    {
        auto plan = std::make_unique<QueryPlan>();
        auto read_from_remote = std::make_unique<ReadFromPreparedSource>(Pipe::unitePipes(std::move(delayed_pipes)));
        read_from_remote->setStepDescription("Read from delayed local replica");
        plan->addStep(std::move(read_from_remote));
        plans.emplace_back(std::move(plan));
    }

    if (plans.empty())
        return;

    if (plans.size() == 1)
    {
        query_plan = std::move(*plans.front());
        return;
    }

    DataStreams input_streams;
    input_streams.reserve(plans.size());
    for (auto & plan : plans)
        input_streams.emplace_back(plan->getCurrentDataStream());

    auto header = input_streams.front().header;
    auto union_step = std::make_unique<UnionStep>(std::move(input_streams), header);
    query_plan.unitePlans(std::move(union_step), std::move(plans));
}

}

}