MemDb::Table::Partition Class Reference

#include <table.h>

Detailed Description

Represents a partition within a Table in MemDb.

A Partition is a segment of a Table that contains a fixed number of rows and manages memory for attribute data through column buffers. Each Partition has a unique partition ID and maintains metadata about its contents, such as the number of rows it currently holds.

Partitions are linked together in a chain within a Table, starting from the first active partition, which allows efficient iteration over all partitions that contain valid rows. Each Partition keeps track of free indices using an array, enabling reuse of memory for deleted rows.

Column buffers in a Partition store data for each attribute defined in the Table. The columns array contains these buffers, and a bitfield tracks whether each row is valid (i.e., not deleted) or modified. This information is used for operations like defragmentation and garbage collection within the partition.

Public Attributes
Table *	table = nullptr
Partition *	next = nullptr
Partition *	previous = nullptr
uint16_t	partitionId = 0xFFFF
uint32_t	numRows = 0
	number of rows
uint64_t	version = 0
Util::Array< uint16_t >	freeIds
Util::Array< ColumnBuffer >	columns
	holds all the column buffers. This excludes non-typed attributes
Util::BitField< CAPACITY >	modifiedRows
	check a bit if the row has been modified, and you need to track it.
Util::BitField< CAPACITY >	validRows
	bits are set if the row is occupied.

Static Public Attributes
static constexpr uint	CAPACITY = 256

Private Member Functions
	Partition ()=default
	~Partition ()
uint16_t	AllocateRowIndex ()
	recycle free row or allocate new row
void	FreeIndex (uint16_t instance)
	Free an index.
void	EraseSwapIndex (uint16_t instance)
	erase row by swapping with last row and reducing number of rows in table

Private Attributes
friend	Table

Constructor & Destructor Documentation

Partition()

MemDb::Table::Partition::Partition ( )

privatedefault

~Partition()

MemDb::Table::Partition::~Partition ( )

private

Member Function Documentation

AllocateRowIndex()

uint16_t MemDb::Table::Partition::AllocateRowIndex ( )

private

recycle free row or allocate new row

EraseSwapIndex()

void MemDb::Table::Partition::EraseSwapIndex ( uint16_t instance )

private

erase row by swapping with last row and reducing number of rows in table

FreeIndex()

void MemDb::Table::Partition::FreeIndex ( uint16_t instance )

private

Free an index.

Member Data Documentation

CAPACITY

uint MemDb::Table::Partition::CAPACITY = 256

staticconstexpr

columns

Util::Array<ColumnBuffer> MemDb::Table::Partition::columns

holds all the column buffers. This excludes non-typed attributes

freeIds

Util::Array<uint16_t> MemDb::Table::Partition::freeIds

modifiedRows

Util::BitField<CAPACITY> MemDb::Table::Partition::modifiedRows

check a bit if the row has been modified, and you need to track it.

bits are reset when partition is defragged

next

Partition* MemDb::Table::Partition::next = nullptr

numRows

uint32_t MemDb::Table::Partition::numRows = 0

number of rows

partitionId

uint16_t MemDb::Table::Partition::partitionId = 0xFFFF

previous

Partition* MemDb::Table::Partition::previous = nullptr

Table

friend MemDb::Table::Partition::Table

private

table

Table* MemDb::Table::Partition::table = nullptr

validRows

Util::BitField<CAPACITY> MemDb::Table::Partition::validRows

bits are set if the row is occupied.

If the row is removed, the bit is set to zero. this is kept up to date if defragging the partition.

version

uint64_t MemDb::Table::Partition::version = 0

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The documentation for this class was generated from the following files:

• /github/workspace/code/addons/memdb/table.h
• /github/workspace/code/addons/memdb/table.cc