void StorageMerge::convertingSourceStream(const Block & header, const Context & context, ASTPtr & query,
BlockInputStreamPtr & source_stream, QueryProcessingStage::Enum processed_stage)
{
Block before_block_header = source_stream->getHeader();
source_stream = std::make_shared<ConvertingBlockInputStream>(context, source_stream, header, ConvertingBlockInputStream::MatchColumnsMode::Name);
ASTPtr where_expression = typeid_cast<ASTSelectQuery *>(query.get())->where_expression;
if (!where_expression)
return;
for (size_t column_index : ext::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 convertingBlockInputStream.
/// So we need to throw exception.
if (!header_column.type->equals(*before_column.type.get()) && processed_stage > QueryProcessingStage::FetchColumns)
{
NamesAndTypesList source_columns = getSampleBlock().getNamesAndTypesList();
NameAndTypePair virtual_column = getColumn("_table");
source_columns.insert(source_columns.end(), virtual_column);
auto syntax_result = SyntaxAnalyzer(context).analyze(where_expression, source_columns);
ExpressionActionsPtr actions = ExpressionAnalyzer{where_expression, syntax_result, 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::BLOCKS_HAVE_DIFFERENT_STRUCTURE);
}
}
}
}
SquashingBlockInputStream::SquashingBlockInputStream(
const BlockInputStreamPtr & src, size_t min_block_size_rows, size_t min_block_size_bytes)
: header(src->getHeader()), transform(min_block_size_rows, min_block_size_bytes)
{
children.emplace_back(src);
}