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#pragma once
#include <Core/Block.h>
namespace DB
{
/** Merging consecutive passed blocks to specified minimum size.
*
* (But if one of input blocks has already at least specified size,
* then don't merge it with neighbours, even if neighbours are small.)
*
* Used to prepare blocks to adequate size for INSERT queries,
* because such storages as Memory, StripeLog, Log, TinyLog...
* store or compress data in blocks exactly as passed to it,
* and blocks of small size are not efficient.
*
* Order of data is kept.
*/
class SquashingTransform
{
public:
/// Conditions on rows and bytes are OR-ed. If one of them is zero, then corresponding condition is ignored.
SquashingTransform(size_t min_block_size_rows_, size_t min_block_size_bytes_);
/** Add next block and possibly returns squashed block.
* At end, you need to pass empty block. As the result for last (empty) block, you will get last Result with ready = true.
*/
Block add(Block && block);
Block add(const Block & block);
private:
size_t min_block_size_rows;
size_t min_block_size_bytes;
Block accumulated_block;
template <typename ReferenceType>
Block addImpl(ReferenceType block);
template <typename ReferenceType>
void append(ReferenceType block);
bool isEnoughSize(const Block & block);
bool isEnoughSize(size_t rows, size_t bytes) const;
};
}
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