Method getCreateTableQuery

src/Interpreters/SystemLog.cpp:881–967

template <typename LogElement>
ASTPtr SystemLog<LogElement>::getCreateTableQuery()
{
    auto create = make_intrusive<ASTCreateQuery>();

    create->setDatabase(table_id.database_name);
    create->setTable(table_id.table_name);

    auto new_columns_list = make_intrusive<ASTColumns>();
    auto ordinary_columns = LogElement::getColumnsDescription();
    auto alias_columns = LogElement::getNamesAndAliases();
    /// S3-backed engines do not support alias columns; `shouldSkipAliasColumns` returns
    /// `true` for `SharedSystemLogFlushPolicy` and for `DefaultSystemLogFlushPolicy` when
    /// `default_system_log_flush_policy.skip_alias_columns` is set to `true` in config.
    if (!flush_policy->shouldSkipAliasColumns())
        ordinary_columns.setAliases(alias_columns);

    new_columns_list->set(new_columns_list->columns, InterpreterCreateQuery::formatColumns(ordinary_columns));

    ParserStorageWithComment storage_parser;

    ASTPtr storage_with_comment_ast = parseQuery(
        storage_parser, storage_def.data(), storage_def.data() + storage_def.size(),
        "Storage to create table for " + LogElement::name(), 0, DBMS_DEFAULT_MAX_PARSER_DEPTH, DBMS_DEFAULT_MAX_PARSER_BACKTRACKS);

    StorageWithComment & storage_with_comment = storage_with_comment_ast->as<StorageWithComment &>();

    /// The default engine string wraps `PARTITION BY` / `ORDER BY` / `PRIMARY KEY` /
    /// `SAMPLE BY` arguments in artificial parentheses so the parser accepts both
    /// single-expression and tuple forms. Clear the `parenthesized` flag so the formatter
    /// does not emit those artificial wrapping parens in `system.tables.engine_full`.
    if (auto * storage = storage_with_comment.storage->as<ASTStorage>())
    {
        if (storage->partition_by)
            storage->partition_by->setParenthesized(false);
        if (storage->order_by)
            storage->order_by->setParenthesized(false);
        if (storage->primary_key)
            storage->primary_key->setParenthesized(false);
        if (storage->sample_by)
            storage->sample_by->setParenthesized(false);
    }

    create->set(create->storage, storage_with_comment.storage);
    create->set(create->comment, storage_with_comment.comment);

    const auto & engine = create->storage->engine->as<ASTFunction &>();

    /// Add secondary indexes (minmax on time columns) for MergeTree engines only,
    /// since other engines (e.g. Null) do not support skipping indices.
    if (endsWith(engine.name, "MergeTree"))
    {
        auto indices = make_intrusive<ASTExpressionList>();

        auto add_index = [&](const char * definition)
        {
            ParserIndexDeclaration parser;
            ASTPtr ast = parseQuery(parser, definition, definition + strlen(definition),
                "index declaration for " + LogElement::name(), 0, DBMS_DEFAULT_MAX_PARSER_DEPTH, DBMS_DEFAULT_MAX_PARSER_BACKTRACKS);