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ClickHouse/src/Storages/StorageMerge.cpp
Alexey Milovidov ab4db2d0c4 Fix 5/6 of trash
2022-09-19 08:50:53 +02:00

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#include <QueryPipeline/narrowPipe.h>
#include <QueryPipeline/QueryPipelineBuilder.h>
#include <Storages/StorageMerge.h>
#include <Storages/StorageFactory.h>
#include <Storages/StorageView.h>
#include <Storages/VirtualColumnUtils.h>
#include <Storages/AlterCommands.h>
#include <Storages/checkAndGetLiteralArgument.h>
#include <Interpreters/Context.h>
#include <Interpreters/TreeRewriter.h>
#include <Interpreters/ExpressionActions.h>
#include <Interpreters/evaluateConstantExpression.h>
#include <Interpreters/InterpreterSelectQuery.h>
#include <Interpreters/IdentifierSemantic.h>
#include <Interpreters/getHeaderForProcessingStage.h>
#include <Interpreters/addTypeConversionToAST.h>
#include <Interpreters/replaceAliasColumnsInQuery.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTSelectQuery.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTExpressionList.h>
#include <DataTypes/DataTypeString.h>
#include <Columns/ColumnString.h>
#include <Common/typeid_cast.h>
#include <Common/checkStackSize.h>
#include <Processors/QueryPlan/ReadFromMergeTree.h>
#include <Processors/Sources/NullSource.h>
#include <Processors/QueryPlan/BuildQueryPipelineSettings.h>
#include <Processors/QueryPlan/Optimizations/QueryPlanOptimizationSettings.h>
#include <Processors/Transforms/MaterializingTransform.h>
#include <Processors/ConcatProcessor.h>
#include <Processors/Transforms/ExpressionTransform.h>
#include <Processors/QueryPlan/QueryPlan.h>
#include <Processors/Sources/SourceFromSingleChunk.h>
#include <Databases/IDatabase.h>
#include <base/range.h>
#include <algorithm>
namespace DB
{
namespace ErrorCodes
{
extern const int BAD_ARGUMENTS;
extern const int LOGICAL_ERROR;
extern const int NOT_IMPLEMENTED;
extern const int ILLEGAL_PREWHERE;
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int SAMPLING_NOT_SUPPORTED;
extern const int ALTER_OF_COLUMN_IS_FORBIDDEN;
extern const int CANNOT_EXTRACT_TABLE_STRUCTURE;
}
StorageMerge::StorageMerge(
const StorageID & table_id_,
const ColumnsDescription & columns_,
const String & comment,
const String & source_database_name_or_regexp_,
bool database_is_regexp_,
const DBToTableSetMap & source_databases_and_tables_,
ContextPtr context_)
: IStorage(table_id_)
, WithContext(context_->getGlobalContext())
, source_database_regexp(source_database_name_or_regexp_)
, source_databases_and_tables(source_databases_and_tables_)
, source_database_name_or_regexp(source_database_name_or_regexp_)
, database_is_regexp(database_is_regexp_)
{
StorageInMemoryMetadata storage_metadata;
storage_metadata.setColumns(columns_.empty() ? getColumnsDescriptionFromSourceTables() : columns_);
storage_metadata.setComment(comment);
setInMemoryMetadata(storage_metadata);
}
StorageMerge::StorageMerge(
const StorageID & table_id_,
const ColumnsDescription & columns_,
const String & comment,
const String & source_database_name_or_regexp_,
bool database_is_regexp_,
const String & source_table_regexp_,
ContextPtr context_)
: IStorage(table_id_)
, WithContext(context_->getGlobalContext())
, source_database_regexp(source_database_name_or_regexp_)
, source_table_regexp(source_table_regexp_)
, source_database_name_or_regexp(source_database_name_or_regexp_)
, database_is_regexp(database_is_regexp_)
{
StorageInMemoryMetadata storage_metadata;
storage_metadata.setColumns(columns_.empty() ? getColumnsDescriptionFromSourceTables() : columns_);
storage_metadata.setComment(comment);
setInMemoryMetadata(storage_metadata);
}
ColumnsDescription StorageMerge::getColumnsDescriptionFromSourceTables() const
{
auto table = getFirstTable([](auto && t) { return t; });
if (!table)
throw Exception{ErrorCodes::CANNOT_EXTRACT_TABLE_STRUCTURE, "There are no tables satisfied provided regexp, you must specify table structure manually"};
return table->getInMemoryMetadataPtr()->getColumns();
}
template <typename F>
StoragePtr StorageMerge::getFirstTable(F && predicate) const
{
auto database_table_iterators = getDatabaseIterators(getContext());
for (auto & iterator : database_table_iterators)
{
while (iterator->isValid())
{
const auto & table = iterator->table();
if (table.get() != this && predicate(table))
return table;
iterator->next();
}
}
return {};
}
template <typename F>
void StorageMerge::forEachTable(F && func) const
{
getFirstTable([&func](const auto & table)
{
func(table);
return false;
});
}
bool StorageMerge::isRemote() const
{
auto first_remote_table = getFirstTable([](const StoragePtr & table) { return table && table->isRemote(); });
return first_remote_table != nullptr;
}
bool StorageMerge::canMoveConditionsToPrewhere() const
{
/// NOTE: This check is used during query analysis as condition for applying
/// "move to PREWHERE" optimization. However, it contains a logical race:
/// If new table that matches regexp for current storage and doesn't support PREWHERE
/// will appear after this check and before calling "read" method, the optimized query may fail.
/// Since it's quite rare case, we just ignore this possibility.
return getFirstTable([](const auto & table) { return !table->canMoveConditionsToPrewhere(); }) == nullptr;
}
bool StorageMerge::mayBenefitFromIndexForIn(const ASTPtr & left_in_operand, ContextPtr query_context, const StorageMetadataPtr & /*metadata_snapshot*/) const
{
/// It's beneficial if it is true for at least one table.
StorageListWithLocks selected_tables = getSelectedTables(query_context);
size_t i = 0;
for (const auto & table : selected_tables)
{
const auto & storage_ptr = std::get<1>(table);
auto metadata_snapshot = storage_ptr->getInMemoryMetadataPtr();
if (storage_ptr->mayBenefitFromIndexForIn(left_in_operand, query_context, metadata_snapshot))
return true;
++i;
/// For simplicity reasons, check only first ten tables.
if (i > 10)
break;
}
return false;
}
QueryProcessingStage::Enum StorageMerge::getQueryProcessingStage(
ContextPtr local_context,
QueryProcessingStage::Enum to_stage,
const StorageSnapshotPtr &,
SelectQueryInfo & query_info) const
{
/// In case of JOIN the first stage (which includes JOIN)
/// should be done on the initiator always.
///
/// Since in case of JOIN query on shards will receive query without JOIN (and their columns).
/// (see removeJoin())
///
/// And for this we need to return FetchColumns.
if (const auto * select = query_info.query->as<ASTSelectQuery>(); select && hasJoin(*select))
return QueryProcessingStage::FetchColumns;
auto stage_in_source_tables = QueryProcessingStage::FetchColumns;
DatabaseTablesIterators database_table_iterators = getDatabaseIterators(local_context);
size_t selected_table_size = 0;
/// TODO: Find a way to support projections for StorageMerge
query_info.ignore_projections = true;
for (const auto & iterator : database_table_iterators)
{
while (iterator->isValid())
{
const auto & table = iterator->table();
if (table && table.get() != this)
{
++selected_table_size;
stage_in_source_tables = std::max(
stage_in_source_tables,
table->getQueryProcessingStage(local_context, to_stage,
table->getStorageSnapshot(table->getInMemoryMetadataPtr(), local_context), query_info));
}
iterator->next();
}
}
return selected_table_size == 1 ? stage_in_source_tables : std::min(stage_in_source_tables, QueryProcessingStage::WithMergeableState);
}
SelectQueryInfo getModifiedQueryInfo(
const SelectQueryInfo & query_info, ContextPtr modified_context, const StorageID & current_storage_id, bool is_merge_engine)
{
SelectQueryInfo modified_query_info = query_info;
modified_query_info.query = query_info.query->clone();
/// Original query could contain JOIN but we need only the first joined table and its columns.
auto & modified_select = modified_query_info.query->as<ASTSelectQuery &>();
TreeRewriterResult new_analyzer_res = *modified_query_info.syntax_analyzer_result;
removeJoin(modified_select, new_analyzer_res, modified_context);
modified_query_info.syntax_analyzer_result = std::make_shared<TreeRewriterResult>(std::move(new_analyzer_res));
if (!is_merge_engine)
{
VirtualColumnUtils::rewriteEntityInAst(modified_query_info.query, "_table", current_storage_id.table_name);
VirtualColumnUtils::rewriteEntityInAst(modified_query_info.query, "_database", current_storage_id.database_name);
}
return modified_query_info;
}
void StorageMerge::read(
QueryPlan & query_plan,
const Names & column_names,
const StorageSnapshotPtr & storage_snapshot,
SelectQueryInfo & query_info,
ContextPtr local_context,
QueryProcessingStage::Enum processed_stage,
const size_t max_block_size,
unsigned num_streams)
{
/** Just in case, turn off optimization "transfer to PREWHERE",
* since there is no certainty that it works when one of table is MergeTree and other is not.
*/
auto modified_context = Context::createCopy(local_context);
modified_context->setSetting("optimize_move_to_prewhere", false);
bool has_database_virtual_column = false;
bool has_table_virtual_column = false;
Names real_column_names;
real_column_names.reserve(column_names.size());
for (const auto & column_name : column_names)
{
if (column_name == "_database" && isVirtualColumn(column_name, storage_snapshot->metadata))
has_database_virtual_column = true;
else if (column_name == "_table" && isVirtualColumn(column_name, storage_snapshot->metadata))
has_table_virtual_column = true;
else
real_column_names.push_back(column_name);
}
StorageListWithLocks selected_tables
= getSelectedTables(modified_context, query_info.query, has_database_virtual_column, has_table_virtual_column);
InputOrderInfoPtr input_sorting_info;
if (query_info.order_optimizer)
{
for (auto it = selected_tables.begin(); it != selected_tables.end(); ++it)
{
auto storage_ptr = std::get<1>(*it);
auto storage_metadata_snapshot = storage_ptr->getInMemoryMetadataPtr();
auto current_info = query_info.order_optimizer->getInputOrder(storage_metadata_snapshot, modified_context);
if (it == selected_tables.begin())
input_sorting_info = current_info;
else if (!current_info || (input_sorting_info && *current_info != *input_sorting_info))
input_sorting_info.reset();
if (!input_sorting_info)
break;
}
query_info.input_order_info = input_sorting_info;
}
query_plan.addInterpreterContext(modified_context);
/// What will be result structure depending on query processed stage in source tables?
Block common_header = getHeaderForProcessingStage(column_names, storage_snapshot, query_info, local_context, processed_stage);
auto step = std::make_unique<ReadFromMerge>(
common_header,
std::move(selected_tables),
real_column_names,
has_database_virtual_column,
has_table_virtual_column,
max_block_size,
num_streams,
shared_from_this(),
storage_snapshot,
query_info,
std::move(modified_context),
processed_stage);
query_plan.addStep(std::move(step));
}
ReadFromMerge::ReadFromMerge(
Block common_header_,
StorageListWithLocks selected_tables_,
Names column_names_,
bool has_database_virtual_column_,
bool has_table_virtual_column_,
size_t max_block_size,
size_t num_streams,
StoragePtr storage,
StorageSnapshotPtr storage_snapshot,
const SelectQueryInfo & query_info_,
ContextMutablePtr context_,
QueryProcessingStage::Enum processed_stage)
: ISourceStep(DataStream{.header = common_header_})
, required_max_block_size(max_block_size)
, requested_num_streams(num_streams)
, common_header(std::move(common_header_))
, selected_tables(std::move(selected_tables_))
, column_names(std::move(column_names_))
, has_database_virtual_column(has_database_virtual_column_)
, has_table_virtual_column(has_table_virtual_column_)
, storage_merge(std::move(storage))
, merge_storage_snapshot(std::move(storage_snapshot))
, query_info(query_info_)
, context(std::move(context_))
, common_processed_stage(processed_stage)
{
}
void ReadFromMerge::initializePipeline(QueryPipelineBuilder & pipeline, const BuildQueryPipelineSettings &)
{
if (selected_tables.empty())
{
pipeline.init(Pipe(std::make_shared<NullSource>(output_stream->header)));
return;
}
size_t tables_count = selected_tables.size();
Float64 num_streams_multiplier
= std::min(static_cast<unsigned>(tables_count), std::max(1U, static_cast<unsigned>(context->getSettingsRef().max_streams_multiplier_for_merge_tables)));
size_t num_streams = static_cast<size_t>(requested_num_streams * num_streams_multiplier);
size_t remaining_streams = num_streams;
InputOrderInfoPtr input_sorting_info;
if (query_info.order_optimizer)
{
for (auto it = selected_tables.begin(); it != selected_tables.end(); ++it)
{
auto storage_ptr = std::get<1>(*it);
auto storage_metadata_snapshot = storage_ptr->getInMemoryMetadataPtr();
auto current_info = query_info.order_optimizer->getInputOrder(storage_metadata_snapshot, context);
if (it == selected_tables.begin())
input_sorting_info = current_info;
else if (!current_info || (input_sorting_info && *current_info != *input_sorting_info))
input_sorting_info.reset();
if (!input_sorting_info)
break;
}
query_info.input_order_info = input_sorting_info;
}
auto sample_block = merge_storage_snapshot->getMetadataForQuery()->getSampleBlock();
std::vector<std::unique_ptr<QueryPipelineBuilder>> pipelines;
QueryPlanResourceHolder resources;
for (const auto & table : selected_tables)
{
size_t current_need_streams = tables_count >= num_streams ? 1 : (num_streams / tables_count);
size_t current_streams = std::min(current_need_streams, remaining_streams);
remaining_streams -= current_streams;
current_streams = std::max(static_cast<size_t>(1), current_streams);
const auto & storage = std::get<1>(table);
/// If sampling requested, then check that table supports it.
if (query_info.query->as<ASTSelectQuery>()->sampleSize() && !storage->supportsSampling())
throw Exception("Illegal SAMPLE: table doesn't support sampling", ErrorCodes::SAMPLING_NOT_SUPPORTED);
Aliases aliases;
auto storage_metadata_snapshot = storage->getInMemoryMetadataPtr();
auto storage_columns = storage_metadata_snapshot->getColumns();
auto nested_storage_snaphsot = storage->getStorageSnapshot(storage_metadata_snapshot, context);
auto modified_query_info = getModifiedQueryInfo(query_info, context, storage->getStorageID(), storage->as<StorageMerge>());
auto syntax_result = TreeRewriter(context).analyzeSelect(
modified_query_info.query, TreeRewriterResult({}, storage, nested_storage_snaphsot));
Names column_names_as_aliases;
bool with_aliases = common_processed_stage == QueryProcessingStage::FetchColumns && !storage_columns.getAliases().empty();
if (with_aliases)
{
ASTPtr required_columns_expr_list = std::make_shared<ASTExpressionList>();
ASTPtr column_expr;
for (const auto & column : column_names)
{
const auto column_default = storage_columns.getDefault(column);
bool is_alias = column_default && column_default->kind == ColumnDefaultKind::Alias;
if (is_alias)
{
column_expr = column_default->expression->clone();
replaceAliasColumnsInQuery(column_expr, storage_metadata_snapshot->getColumns(),
syntax_result->array_join_result_to_source, context);
auto column_description = storage_columns.get(column);
column_expr = addTypeConversionToAST(std::move(column_expr), column_description.type->getName(),
storage_metadata_snapshot->getColumns().getAll(), context);
column_expr = setAlias(column_expr, column);
auto type = sample_block.getByName(column).type;
aliases.push_back({ .name = column, .type = type, .expression = column_expr->clone() });
}
else
column_expr = std::make_shared<ASTIdentifier>(column);
required_columns_expr_list->children.emplace_back(std::move(column_expr));
}
syntax_result = TreeRewriter(context).analyze(
required_columns_expr_list, storage_columns.getAllPhysical(), storage, storage->getStorageSnapshot(storage_metadata_snapshot, context));
auto alias_actions = ExpressionAnalyzer(required_columns_expr_list, syntax_result, context).getActionsDAG(true);
column_names_as_aliases = alias_actions->getRequiredColumns().getNames();
if (column_names_as_aliases.empty())
column_names_as_aliases.push_back(ExpressionActions::getSmallestColumn(storage_metadata_snapshot->getColumns().getAllPhysical()));
}
auto source_pipeline = createSources(
nested_storage_snaphsot,
modified_query_info,
common_processed_stage,
required_max_block_size,
common_header,
aliases,
table,
column_names_as_aliases.empty() ? column_names : column_names_as_aliases,
context,
current_streams);
if (source_pipeline && source_pipeline->initialized())
{
resources.storage_holders.push_back(std::get<1>(table));
resources.table_locks.push_back(std::get<2>(table));
pipelines.emplace_back(std::move(source_pipeline));
}
}
if (pipelines.empty())
{
pipeline.init(Pipe(std::make_shared<NullSource>(output_stream->header)));
return;
}
pipeline = QueryPipelineBuilder::unitePipelines(std::move(pipelines));
if (!query_info.input_order_info)
// It's possible to have many tables read from merge, resize(num_streams) might open too many files at the same time.
// Using narrowPipe instead. But in case of reading in order of primary key, we cannot do it,
// because narrowPipe doesn't preserve order.
pipeline.narrow(num_streams);
pipeline.addResources(std::move(resources));
}
QueryPipelineBuilderPtr ReadFromMerge::createSources(
const StorageSnapshotPtr & storage_snapshot,
SelectQueryInfo & modified_query_info,
const QueryProcessingStage::Enum & processed_stage,
const UInt64 max_block_size,
const Block & header,
const Aliases & aliases,
const StorageWithLockAndName & storage_with_lock,
Names & real_column_names,
ContextMutablePtr modified_context,
size_t streams_num,
bool concat_streams)
{
const auto & [database_name, storage, _, table_name] = storage_with_lock;
auto & modified_select = modified_query_info.query->as<ASTSelectQuery &>();
QueryPipelineBuilderPtr builder;
if (!storage)
{
return std::make_unique<QueryPipelineBuilder>(InterpreterSelectQuery(
modified_query_info.query, modified_context,
Pipe(std::make_shared<SourceFromSingleChunk>(header)),
SelectQueryOptions(processed_stage).analyze()).buildQueryPipeline());
}
if (!modified_select.final() && storage->needRewriteQueryWithFinal(real_column_names))
{
/// NOTE: It may not work correctly in some cases, because query was analyzed without final.
/// However, it's needed for MaterializedMySQL and it's unlikely that someone will use it with Merge tables.
modified_select.setFinal();
}
auto storage_stage
= storage->getQueryProcessingStage(modified_context, QueryProcessingStage::Complete, storage_snapshot, modified_query_info);
if (processed_stage <= storage_stage)
{
/// If there are only virtual columns in query, you must request at least one other column.
if (real_column_names.empty())
real_column_names.push_back(ExpressionActions::getSmallestColumn(storage_snapshot->metadata->getColumns().getAllPhysical()));
QueryPlan plan;
if (StorageView * view = dynamic_cast<StorageView *>(storage.get()))
{
/// For view storage, we need to rewrite the `modified_query_info.view_query` to optimize read.
/// The most intuitive way is to use InterpreterSelectQuery.
/// Intercept the settings
modified_context->setSetting("max_threads", streams_num);
modified_context->setSetting("max_streams_to_max_threads_ratio", 1);
modified_context->setSetting("max_block_size", max_block_size);
InterpreterSelectQuery(
modified_query_info.query, modified_context, storage, view->getInMemoryMetadataPtr(), SelectQueryOptions(processed_stage))
.buildQueryPlan(plan);
}
else
{
storage->read(
plan,
real_column_names,
storage_snapshot,
modified_query_info,
modified_context,
processed_stage,
max_block_size,
UInt32(streams_num));
}
if (!plan.isInitialized())
return {};
if (auto * read_from_merge_tree = typeid_cast<ReadFromMergeTree *>(plan.getRootNode()->step.get()))
read_from_merge_tree->addFilterNodes(added_filter_nodes);
builder = plan.buildQueryPipeline(
QueryPlanOptimizationSettings::fromContext(modified_context),
BuildQueryPipelineSettings::fromContext(modified_context));
}
else if (processed_stage > storage_stage)
{
modified_select.replaceDatabaseAndTable(database_name, table_name);
/// Maximum permissible parallelism is streams_num
modified_context->setSetting("max_threads", streams_num);
modified_context->setSetting("max_streams_to_max_threads_ratio", 1);
/// TODO: Find a way to support projections for StorageMerge
InterpreterSelectQuery interpreter{
modified_query_info.query, modified_context, SelectQueryOptions(processed_stage).ignoreProjections()};
builder = std::make_unique<QueryPipelineBuilder>(interpreter.buildQueryPipeline());
/** Materialization is needed, since from distributed storage the constants come materialized.
* If you do not do this, different types (Const and non-Const) columns will be produced in different threads,
* And this is not allowed, since all code is based on the assumption that in the block stream all types are the same.
*/
builder->addSimpleTransform([](const Block & stream_header) { return std::make_shared<MaterializingTransform>(stream_header); });
}
if (builder->initialized())
{
if (concat_streams && builder->getNumStreams() > 1)
{
// It's possible to have many tables read from merge, resize(1) might open too many files at the same time.
// Using concat instead.
builder->addTransform(std::make_shared<ConcatProcessor>(builder->getHeader(), builder->getNumStreams()));
}
/// Add virtual columns if we don't already have them.
Block pipe_header = builder->getHeader();
if (has_database_virtual_column && !pipe_header.has("_database"))
{
ColumnWithTypeAndName column;
column.name = "_database";
column.type = std::make_shared<DataTypeString>();
column.column = column.type->createColumnConst(0, Field(database_name));
auto adding_column_dag = ActionsDAG::makeAddingColumnActions(std::move(column));
auto adding_column_actions = std::make_shared<ExpressionActions>(
std::move(adding_column_dag),
ExpressionActionsSettings::fromContext(modified_context, CompileExpressions::yes));
builder->addSimpleTransform([&](const Block & stream_header)
{
return std::make_shared<ExpressionTransform>(stream_header, adding_column_actions);
});
}
if (has_table_virtual_column && !pipe_header.has("_table"))
{
ColumnWithTypeAndName column;
column.name = "_table";
column.type = std::make_shared<DataTypeString>();
column.column = column.type->createColumnConst(0, Field(table_name));
auto adding_column_dag = ActionsDAG::makeAddingColumnActions(std::move(column));
auto adding_column_actions = std::make_shared<ExpressionActions>(
std::move(adding_column_dag),
ExpressionActionsSettings::fromContext(modified_context, CompileExpressions::yes));
builder->addSimpleTransform([&](const Block & stream_header)
{
return std::make_shared<ExpressionTransform>(stream_header, adding_column_actions);
});
}
/// Subordinary tables could have different but convertible types, like numeric types of different width.
/// We must return streams with structure equals to structure of Merge table.
convertingSourceStream(header, storage_snapshot->metadata, aliases, modified_context, modified_query_info.query, *builder, processed_stage);
}
return builder;
}
StorageMerge::StorageListWithLocks StorageMerge::getSelectedTables(
ContextPtr query_context,
const ASTPtr & query /* = nullptr */,
bool filter_by_database_virtual_column /* = false */,
bool filter_by_table_virtual_column /* = false */) const
{
assert(!filter_by_database_virtual_column || !filter_by_table_virtual_column || query);
const Settings & settings = query_context->getSettingsRef();
StorageListWithLocks selected_tables;
DatabaseTablesIterators database_table_iterators = getDatabaseIterators(getContext());
MutableColumnPtr database_name_virtual_column;
MutableColumnPtr table_name_virtual_column;
if (filter_by_database_virtual_column)
{
database_name_virtual_column = ColumnString::create();
}
if (filter_by_table_virtual_column)
{
table_name_virtual_column = ColumnString::create();
}
for (const auto & iterator : database_table_iterators)
{
if (filter_by_database_virtual_column)
database_name_virtual_column->insert(iterator->databaseName());
while (iterator->isValid())
{
StoragePtr storage = iterator->table();
if (!storage)
continue;
if (query && query->as<ASTSelectQuery>()->prewhere() && !storage->supportsPrewhere())
throw Exception("Storage " + storage->getName() + " doesn't support PREWHERE.", ErrorCodes::ILLEGAL_PREWHERE);
if (storage.get() != this)
{
auto table_lock = storage->lockForShare(query_context->getCurrentQueryId(), settings.lock_acquire_timeout);
selected_tables.emplace_back(iterator->databaseName(), storage, std::move(table_lock), iterator->name());
if (filter_by_table_virtual_column)
table_name_virtual_column->insert(iterator->name());
}
iterator->next();
}
}
if (filter_by_database_virtual_column)
{
/// Filter names of selected tables if there is a condition on "_database" virtual column in WHERE clause
Block virtual_columns_block
= Block{ColumnWithTypeAndName(std::move(database_name_virtual_column), std::make_shared<DataTypeString>(), "_database")};
VirtualColumnUtils::filterBlockWithQuery(query, virtual_columns_block, query_context);
auto values = VirtualColumnUtils::extractSingleValueFromBlock<String>(virtual_columns_block, "_database");
/// Remove unused databases from the list
selected_tables.remove_if([&](const auto & elem) { return values.find(std::get<0>(elem)) == values.end(); });
}
if (filter_by_table_virtual_column)
{
/// Filter names of selected tables if there is a condition on "_table" virtual column in WHERE clause
Block virtual_columns_block = Block{ColumnWithTypeAndName(std::move(table_name_virtual_column), std::make_shared<DataTypeString>(), "_table")};
VirtualColumnUtils::filterBlockWithQuery(query, virtual_columns_block, query_context);
auto values = VirtualColumnUtils::extractSingleValueFromBlock<String>(virtual_columns_block, "_table");
/// Remove unused tables from the list
selected_tables.remove_if([&](const auto & elem) { return values.find(std::get<3>(elem)) == values.end(); });
}
return selected_tables;
}
DatabaseTablesIteratorPtr StorageMerge::getDatabaseIterator(const String & database_name, ContextPtr local_context) const
{
auto database = DatabaseCatalog::instance().getDatabase(database_name);
auto table_name_match = [this, database_name](const String & table_name_) -> bool
{
if (source_databases_and_tables)
{
if (auto it = source_databases_and_tables->find(database_name); it != source_databases_and_tables->end())
return it->second.contains(table_name_);
else
return false;
}
else
return source_table_regexp->match(table_name_);
};
return database->getTablesIterator(local_context, table_name_match);
}
StorageMerge::DatabaseTablesIterators StorageMerge::getDatabaseIterators(ContextPtr local_context) const
{
try
{
checkStackSize();
}
catch (Exception & e)
{
e.addMessage("while getting table iterator of Merge table. Maybe caused by two Merge tables that will endlessly try to read each other's data");
throw;
}
DatabaseTablesIterators database_table_iterators;
/// database_name argument is not a regexp
if (!database_is_regexp)
database_table_iterators.emplace_back(getDatabaseIterator(source_database_name_or_regexp, local_context));
/// database_name argument is a regexp
else
{
auto databases = DatabaseCatalog::instance().getDatabases();
for (const auto & db : databases)
{
if (source_database_regexp->match(db.first))
database_table_iterators.emplace_back(getDatabaseIterator(db.first, local_context));
}
}
return database_table_iterators;
}
void StorageMerge::checkAlterIsPossible(const AlterCommands & commands, ContextPtr local_context) const
{
auto name_deps = getDependentViewsByColumn(local_context);
for (const auto & command : commands)
{
if (command.type != AlterCommand::Type::ADD_COLUMN && command.type != AlterCommand::Type::MODIFY_COLUMN
&& command.type != AlterCommand::Type::DROP_COLUMN && command.type != AlterCommand::Type::COMMENT_COLUMN
&& command.type != AlterCommand::Type::COMMENT_TABLE)
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Alter of type '{}' is not supported by storage {}",
command.type, getName());
if (command.type == AlterCommand::Type::DROP_COLUMN && !command.clear)
{
const auto & deps_mv = name_deps[command.column_name];
if (!deps_mv.empty())
{
throw Exception(
"Trying to ALTER DROP column " + backQuoteIfNeed(command.column_name) + " which is referenced by materialized view "
+ toString(deps_mv),
ErrorCodes::ALTER_OF_COLUMN_IS_FORBIDDEN);
}
}
}
}
void StorageMerge::alter(
const AlterCommands & params, ContextPtr local_context, AlterLockHolder &)
{
auto table_id = getStorageID();
StorageInMemoryMetadata storage_metadata = getInMemoryMetadata();
params.apply(storage_metadata, local_context);
DatabaseCatalog::instance().getDatabase(table_id.database_name)->alterTable(local_context, table_id, storage_metadata);
setInMemoryMetadata(storage_metadata);
}
void ReadFromMerge::convertingSourceStream(
const Block & header,
const StorageMetadataPtr & metadata_snapshot,
const Aliases & aliases,
ContextPtr local_context,
ASTPtr & query,
QueryPipelineBuilder & builder,
QueryProcessingStage::Enum processed_stage)
{
Block before_block_header = builder.getHeader();
auto storage_sample_block = metadata_snapshot->getSampleBlock();
auto pipe_columns = builder.getHeader().getNamesAndTypesList();
for (const auto & alias : aliases)
{
pipe_columns.emplace_back(NameAndTypePair(alias.name, alias.type));
ASTPtr expr = alias.expression;
auto syntax_result = TreeRewriter(local_context).analyze(expr, pipe_columns);
auto expression_analyzer = ExpressionAnalyzer{alias.expression, syntax_result, local_context};
auto dag = std::make_shared<ActionsDAG>(pipe_columns);
auto actions_dag = expression_analyzer.getActionsDAG(true, false);
auto actions = std::make_shared<ExpressionActions>(actions_dag, ExpressionActionsSettings::fromContext(local_context, CompileExpressions::yes));
builder.addSimpleTransform([&](const Block & stream_header)
{
return std::make_shared<ExpressionTransform>(stream_header, actions);
});
}
{
auto convert_actions_dag = ActionsDAG::makeConvertingActions(builder.getHeader().getColumnsWithTypeAndName(),
header.getColumnsWithTypeAndName(),
ActionsDAG::MatchColumnsMode::Name);
auto actions = std::make_shared<ExpressionActions>(
convert_actions_dag,
ExpressionActionsSettings::fromContext(local_context, CompileExpressions::yes));
builder.addSimpleTransform([&](const Block & stream_header)
{
return std::make_shared<ExpressionTransform>(stream_header, actions);
});
}
auto where_expression = query->as<ASTSelectQuery>()->where();
if (!where_expression)
return;
if (processed_stage > QueryProcessingStage::FetchColumns)
{
for (size_t column_index : collections::range(0, header.columns()))
{
ColumnWithTypeAndName header_column = header.getByPosition(column_index);
ColumnWithTypeAndName before_column = before_block_header.getByName(header_column.name);
/// If the processed_stage greater than FetchColumns and the block structure between streams is different.
/// the where expression maybe invalid because of ConvertingTransform.
/// So we need to throw exception.
if (!header_column.type->equals(*before_column.type.get()))
{
NamesAndTypesList source_columns = metadata_snapshot->getSampleBlock().getNamesAndTypesList();
auto virtual_column = *storage_merge->getVirtuals().tryGetByName("_table");
source_columns.emplace_back(NameAndTypePair{virtual_column.name, virtual_column.type});
auto syntax_result = TreeRewriter(local_context).analyze(where_expression, source_columns);
ExpressionActionsPtr actions = ExpressionAnalyzer{where_expression, syntax_result, local_context}.getActions(false, false);
Names required_columns = actions->getRequiredColumns();
for (const auto & required_column : required_columns)
{
if (required_column == header_column.name)
throw Exception("Block structure mismatch in Merge Storage: different types:\n" + before_block_header.dumpStructure()
+ "\n" + header.dumpStructure(), ErrorCodes::LOGICAL_ERROR);
}
}
}
}
}
IStorage::ColumnSizeByName StorageMerge::getColumnSizes() const
{
ColumnSizeByName column_sizes;
forEachTable([&](const auto & table)
{
for (const auto & [name, size] : table->getColumnSizes())
column_sizes[name].add(size);
});
return column_sizes;
}
std::tuple<bool /* is_regexp */, ASTPtr> StorageMerge::evaluateDatabaseName(const ASTPtr & node, ContextPtr context_)
{
if (const auto * func = node->as<ASTFunction>(); func && func->name == "REGEXP")
{
if (func->arguments->children.size() != 1)
throw Exception("REGEXP in Merge ENGINE takes only one argument", ErrorCodes::BAD_ARGUMENTS);
auto * literal = func->arguments->children[0]->as<ASTLiteral>();
if (!literal || literal->value.getType() != Field::Types::Which::String || literal->value.safeGet<String>().empty())
throw Exception("Argument for REGEXP in Merge ENGINE should be a non empty String Literal", ErrorCodes::BAD_ARGUMENTS);
return {true, func->arguments->children[0]};
}
auto ast = evaluateConstantExpressionForDatabaseName(node, context_);
return {false, ast};
}
void registerStorageMerge(StorageFactory & factory)
{
factory.registerStorage("Merge", [](const StorageFactory::Arguments & args)
{
/** In query, the name of database is specified as table engine argument which contains source tables,
* as well as regex for source-table names.
*/
ASTs & engine_args = args.engine_args;
if (engine_args.size() != 2)
throw Exception("Storage Merge requires exactly 2 parameters"
" - name of source database and regexp for table names.",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
auto [is_regexp, database_ast] = StorageMerge::evaluateDatabaseName(engine_args[0], args.getLocalContext());
if (!is_regexp)
engine_args[0] = database_ast;
String source_database_name_or_regexp = checkAndGetLiteralArgument<String>(database_ast, "database_name");
engine_args[1] = evaluateConstantExpressionAsLiteral(engine_args[1], args.getLocalContext());
String table_name_regexp = checkAndGetLiteralArgument<String>(engine_args[1], "table_name_regexp");
return std::make_shared<StorageMerge>(
args.table_id, args.columns, args.comment, source_database_name_or_regexp, is_regexp, table_name_regexp, args.getContext());
},
{
.supports_schema_inference = true
});
}
NamesAndTypesList StorageMerge::getVirtuals() const
{
NamesAndTypesList virtuals{{"_database", std::make_shared<DataTypeString>()}, {"_table", std::make_shared<DataTypeString>()}};
auto first_table = getFirstTable([](auto && table) { return table; });
if (first_table)
{
auto table_virtuals = first_table->getVirtuals();
virtuals.insert(virtuals.end(), table_virtuals.begin(), table_virtuals.end());
}
return virtuals;
}
}
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