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154 lines
5.9 KiB
C++
154 lines
5.9 KiB
C++
#include <Storages/ReadInOrderOptimizer.h>
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#include <Interpreters/ExpressionActions.h>
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#include <Interpreters/ExpressionAnalyzer.h>
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#include <Interpreters/TreeRewriter.h>
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#include <Interpreters/replaceAliasColumnsInQuery.h>
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#include <Functions/IFunction.h>
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#include <Interpreters/TableJoin.h>
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#include <Storages/MergeTree/MergeTreeData.h>
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#include <Storages/MergeTree/StorageFromMergeTreeDataPart.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int LOGICAL_ERROR;
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}
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ReadInOrderOptimizer::ReadInOrderOptimizer(
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const ManyExpressionActions & elements_actions_,
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const SortDescription & required_sort_description_,
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const TreeRewriterResultPtr & syntax_result)
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: elements_actions(elements_actions_)
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, required_sort_description(required_sort_description_)
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{
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if (elements_actions.size() != required_sort_description.size())
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throw Exception("Sizes of sort description and actions are mismatched", ErrorCodes::LOGICAL_ERROR);
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/// Do not analyze joined columns.
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/// They may have aliases and come to description as is.
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/// We can mismatch them with order key columns at stage of fetching columns.
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forbidden_columns = syntax_result->getArrayJoinSourceNameSet();
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}
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InputOrderInfoPtr ReadInOrderOptimizer::getInputOrder(const StorageMetadataPtr & metadata_snapshot, const Context & context) const
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{
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Names sorting_key_columns = metadata_snapshot->getSortingKeyColumns();
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if (!metadata_snapshot->hasSortingKey())
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return {};
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SortDescription order_key_prefix_descr;
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int read_direction = required_sort_description.at(0).direction;
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size_t prefix_size = std::min(required_sort_description.size(), sorting_key_columns.size());
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auto aliase_columns = metadata_snapshot->getColumns().getAliases();
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for (size_t i = 0; i < prefix_size; ++i)
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{
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if (forbidden_columns.count(required_sort_description[i].column_name))
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break;
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/// Optimize in case of exact match with order key element
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/// or in some simple cases when order key element is wrapped into monotonic function.
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auto apply_order_judge = [&] (const ExpressionActions::Actions & actions, const String & sort_column)
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{
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int current_direction = required_sort_description[i].direction;
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/// For the path: order by (sort_column, ...)
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if (sort_column == sorting_key_columns[i] && current_direction == read_direction)
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{
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return true;
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}
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/// For the path: order by (function(sort_column), ...)
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/// Allow only one simple monotonic functions with one argument
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/// Why not allow multi monotonic functions?
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else
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{
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bool found_function = false;
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for (const auto & action : actions)
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{
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if (action.node->type != ActionsDAG::ActionType::FUNCTION)
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{
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continue;
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}
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if (found_function)
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{
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current_direction = 0;
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break;
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}
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else
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found_function = true;
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if (action.node->children.size() != 1 || action.node->children.at(0)->result_name != sorting_key_columns[i])
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{
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current_direction = 0;
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break;
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}
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const auto & func = *action.node->function_base;
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if (!func.hasInformationAboutMonotonicity())
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{
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current_direction = 0;
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break;
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}
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auto monotonicity = func.getMonotonicityForRange(*func.getArgumentTypes().at(0), {}, {});
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if (!monotonicity.is_monotonic)
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{
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current_direction = 0;
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break;
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}
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else if (!monotonicity.is_positive)
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current_direction *= -1;
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}
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if (!found_function)
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current_direction = 0;
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if (!current_direction || (i > 0 && current_direction != read_direction))
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return false;
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if (i == 0)
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read_direction = current_direction;
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return true;
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}
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};
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const auto & actions = elements_actions[i]->getActions();
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bool ok;
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/// check if it's alias column
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/// currently we only support alias column without any function wrapper
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/// ie: `order by aliased_column` can have this optimization, but `order by function(aliased_column)` can not.
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/// This suits most cases.
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if (context.getSettingsRef().optimize_respect_aliases && aliase_columns.contains(required_sort_description[i].column_name))
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{
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auto column_expr = metadata_snapshot->getColumns().get(required_sort_description[i].column_name).default_desc.expression->clone();
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replaceAliasColumnsInQuery(column_expr, metadata_snapshot->getColumns(), forbidden_columns, context);
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auto syntax_analyzer_result = TreeRewriter(context).analyze(column_expr, metadata_snapshot->getColumns().getAll());
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const auto expression_analyzer = ExpressionAnalyzer(column_expr, syntax_analyzer_result, context).getActions(true);
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const auto & alias_actions = expression_analyzer->getActions();
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ok = apply_order_judge(alias_actions, column_expr->getColumnName());
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}
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else
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ok = apply_order_judge(actions, required_sort_description[i].column_name);
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if (ok)
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order_key_prefix_descr.push_back(required_sort_description[i]);
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else
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break;
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}
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if (order_key_prefix_descr.empty())
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return {};
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return std::make_shared<InputOrderInfo>(std::move(order_key_prefix_descr), read_direction);
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}
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}
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