Function executeQueryImpl

src/Interpreters/executeQuery.cpp:1092–1996

static BlockIO executeQueryImpl(
    const char * begin,
    const char * end,
    ContextMutablePtr context,
    QueryFlags flags,
    QueryProcessingStage::Enum stage,
    ReadBufferUniquePtr & istr,
    ASTPtr & out_ast,
    ImplicitTransactionControlExecutorPtr implicit_tcl_executor,
    HTTPContinueCallback http_continue_callback,
    QueryResultDetails & result_details)
{
    const bool internal = flags.internal;

    /// query_span is a special span, when this function exits, it's lifetime is not ended, but ends when the query finishes.
    /// Some internal queries might call this function recursively by setting 'internal' parameter to 'true',
    /// to make sure SpanHolders in current stack ends in correct order, we disable this span for these internal queries
    ///
    /// This does not have impact on the final span logs, because these internal queries are issued by external queries,
    /// we still have enough span logs for the execution of external queries.
    std::shared_ptr<OpenTelemetry::SpanHolder> query_span = internal ? nullptr : std::make_shared<OpenTelemetry::SpanHolder>("query");
    if (query_span && query_span->trace_id != UUID{})
        LOG_TRACE(getLogger("executeQuery"), "Query span trace_id for opentelemetry log: {}", query_span->trace_id);

    /// Used for logging query start time in system.query_log
    auto query_start_time = std::chrono::system_clock::now();

    /// Used for:
    /// * Setting the watch in QueryStatus (controls timeouts and progress) and the output formats
    /// * Logging query duration (system.query_log)
    Stopwatch start_watch{CLOCK_MONOTONIC};

    const auto & client_info = context->getClientInfo();

    if (client_info.initial_query_start_time == 0)
    {
        // If we don't see an initial_query_start_time yet, initialize it to current time.
        // It's possible to have unset initial_query_start_time for non-initial queries. For
        // example, the query is from an initiator that is running an old version of clickhouse.
        // On the other hand, if it's initialized then take it as the start of the query
        context->setInitialQueryStartTime(query_start_time);
    }

    chassert(internal || CurrentThread::get().tryGetQueryContext());
    chassert(internal || CurrentThread::get().tryGetQueryContext()->getCurrentQueryId() == CurrentThread::getQueryId());

    const Settings & settings = context->getSettingsRef();

    size_t max_query_size = settings[Setting::max_query_size];
    /// Don't limit the size of internal queries or distributed subquery.
    if (internal || client_info.query_kind == ClientInfo::QueryKind::SECONDARY_QUERY)
        max_query_size = 0;

    String query;
    String query_for_logging;
    UInt64 normalized_query_hash = 0;
    size_t log_queries_cut_to_length = settings[Setting::log_queries_cut_to_length];