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#pragma once
#include <Storages/IStorage.h>
#include <TableFunctions/ITableFunction.h>
#include <QueryPipeline/Pipe.h>
#include <Storages/StorageProxy.h>
#include <Common/CurrentThread.h>
#include <Processors/Transforms/ExpressionTransform.h>
#include <Processors/QueryPlan/QueryPlan.h>
#include <Processors/QueryPlan/ExpressionStep.h>
#include <Interpreters/getHeaderForProcessingStage.h>
#include <Interpreters/Context.h>
namespace DB
{
namespace ErrorCodes
{
extern const int INCOMPATIBLE_COLUMNS;
}
using GetNestedStorageFunc = std::function<StoragePtr()>;
/// Lazily creates underlying storage.
/// Adds ConversionTransform in case of structure mismatch.
class StorageTableFunctionProxy final : public StorageProxy
{
public:
StorageTableFunctionProxy(const StorageID & table_id_, GetNestedStorageFunc get_nested_,
ColumnsDescription cached_columns, bool add_conversion_ = true)
: StorageProxy(table_id_), get_nested(std::move(get_nested_)), add_conversion(add_conversion_)
{
StorageInMemoryMetadata cached_metadata;
cached_metadata.setColumns(std::move(cached_columns));
setInMemoryMetadata(cached_metadata);
}
StoragePtr getNestedImpl() const
{
std::lock_guard lock{nested_mutex};
if (nested)
return nested;
auto nested_storage = get_nested();
nested_storage->startup();
nested_storage->renameInMemory(getStorageID());
nested = nested_storage;
get_nested = {};
return nested;
}
StoragePtr getNested() const override
{
StoragePtr nested_storage = getNestedImpl();
assert(!nested_storage->getStoragePolicy());
assert(!nested_storage->storesDataOnDisk());
return nested_storage;
}
/// Table functions cannot have storage policy and cannot store data on disk.
/// We may check if table is readonly or stores data on disk on DROP TABLE.
/// Avoid loading nested table by returning nullptr/false for all table functions.
StoragePolicyPtr getStoragePolicy() const override { return nullptr; }
bool storesDataOnDisk() const override { return false; }
String getName() const override
{
std::lock_guard lock{nested_mutex};
if (nested)
return nested->getName();
return StorageProxy::getName();
}
void startup() override { }
void shutdown() override
{
std::lock_guard lock{nested_mutex};
if (nested)
nested->shutdown();
}
void flushAndPrepareForShutdown() override
{
std::lock_guard lock{nested_mutex};
if (nested)
nested->flushAndPrepareForShutdown();
}
void drop() override
{
std::lock_guard lock{nested_mutex};
if (nested)
nested->drop();
}
void read(
QueryPlan & query_plan,
const Names & column_names,
const StorageSnapshotPtr & storage_snapshot,
SelectQueryInfo & query_info,
ContextPtr context,
QueryProcessingStage::Enum processed_stage,
size_t max_block_size,
size_t num_streams) override
{
auto storage = getNested();
auto nested_snapshot = storage->getStorageSnapshot(storage->getInMemoryMetadataPtr(), context);
storage->read(query_plan, column_names, nested_snapshot, query_info, context,
processed_stage, max_block_size, num_streams);
if (add_conversion)
{
auto from_header = query_plan.getCurrentDataStream().header;
auto to_header = getHeaderForProcessingStage(column_names, storage_snapshot,
query_info, context, processed_stage);
auto convert_actions_dag = ActionsDAG::makeConvertingActions(
from_header.getColumnsWithTypeAndName(),
to_header.getColumnsWithTypeAndName(),
ActionsDAG::MatchColumnsMode::Name);
auto step = std::make_unique<ExpressionStep>(
query_plan.getCurrentDataStream(),
convert_actions_dag);
step->setStepDescription("Converting columns");
query_plan.addStep(std::move(step));
}
}
SinkToStoragePtr write(
const ASTPtr & query,
const StorageMetadataPtr & metadata_snapshot,
ContextPtr context,
bool async_insert) override
{
auto storage = getNested();
auto cached_structure = metadata_snapshot->getSampleBlock();
auto actual_structure = storage->getInMemoryMetadataPtr()->getSampleBlock();
if (!blocksHaveEqualStructure(actual_structure, cached_structure) && add_conversion)
{
throw Exception(ErrorCodes::INCOMPATIBLE_COLUMNS, "Source storage and table function have different structure");
}
return storage->write(query, metadata_snapshot, context, async_insert);
}
void renameInMemory(const StorageID & new_table_id) override
{
std::lock_guard lock{nested_mutex};
if (nested)
StorageProxy::renameInMemory(new_table_id);
else
IStorage::renameInMemory(new_table_id); /// NOLINT
}
bool isView() const override { return false; }
void checkTableCanBeDropped([[ maybe_unused ]] ContextPtr query_context) const override {}
private:
mutable std::recursive_mutex nested_mutex;
mutable GetNestedStorageFunc get_nested;
mutable StoragePtr nested;
const bool add_conversion;
};
}
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