MemDb::Table Class Reference

#include <table.h>

Detailed Description

A table of columns (attributes) and rows.

A Table in MemDb is a collection of rows with attributes (columns) Tables are organized into Partitions, which help manage memory and improve performance. Each Partition has a fixed capacity and contains column buffers for storing attribute data. The Table maintains a list of all partitions, including free partitions for recycling, and keeps track of active partitions that contain valid rows.

Attributes in a Table are defined by an array of AttributeIds. Each attribute is associated with a specific index in the columns array of each Partition, which is managed by a hash table mapping AttributeId to column index.

The TableSignature of a Table contains a bitfield where each bit represents the presence or absence of an attribute. This allows for quick checks if a table contains a specific set of attributes.

Partitions are linked together in a chain, starting from the first active partition, which helps in efficiently iterating over all partitions that contain entities. Each Partition maintains its own list of free indices for row reuse, as well as bitfields for tracking modified and valid rows.

Classes
class	Partition
	Represents a partition within a Table in MemDb. More...

Public Member Functions
bool	HasAttribute (AttributeId attribute) const
	Check if a column exists in the table.
AttributeId	GetAttributeId (ColumnIndex columnIndex) const
	Returns the attribute located in given column.
ColumnIndex	GetAttributeIndex (AttributeId attribute) const
	Returns the index of the attribute or invalid if attribute is missing from table.
Util::Array< AttributeId > const &	GetAttributes () const
	Get the all descriptors for a table.
TableSignature const &	GetSignature () const
	Get the table signature.
ColumnIndex	AddAttribute (AttributeId attribute, bool updateSignature=true)
	Add an attribute to the table.
RowId	AddRow ()
	Add/Get a free row from the table.
void	RemoveRow (RowId row)
	Deallocate a row from a table. This only frees the row for recycling. See Defragment.
SizeT	GetNumRows () const
	Get total number of rows in a table.
void	SetNumRows (SizeT value)
	set total number of rows in a table. This does not allocate any memory or create instaces, thus should pretty much never be used.
void	SetToDefault (RowId row)
	Set all row values to default.
SizeT	Defragment (std::function< void(Partition *, RowId, RowId)> const &moveCallback)
	Defragment table.
void	Clean ()
	Clean table. Does not deallocate anything; just sets the size of the table to zero.
void	Reset ()
	Reset table. Deallocate all data.
Partition *	GetFirstActivePartition ()
	Get first active partition with entities.
uint16_t	GetNumActivePartitions () const
	Get number of partitions that contain entities.
uint16_t	GetNumPartitions () const
	Get number of partitions in table.
Partition *	GetCurrentPartition ()
	Get current partition.
Partition *	GetPartition (uint16_t partitionId)
void *	GetValuePointer (ColumnIndex cid, RowId row)
	get a buffer. Might be invalidated if rows are allocated or deallocated
void *	GetBuffer (uint16_t partition, ColumnIndex cid)
	get a buffer. Might be invalidated if rows are allocated or deallocated
Util::Blob	SerializeInstance (RowId row) const
	Serialize a row into a blob.
void	DeserializeInstance (Util::Blob const &data, RowId row)
	deserialize a blob into a row
Partition *	NewPartition ()
	Create a new partition for this table. Adds it to the list of partitions and the vacancy list.

Static Public Member Functions
static RowId	MigrateInstance (Table &src, RowId srcRow, Table &dst, bool defragment=true, std::function< void(Partition *, RowId, RowId)> const &moveCallback=nullptr)
	move instance from one table to another.
static RowId	DuplicateInstance (Table const &src, RowId srcRow, Table &dst)
	duplicate instance from one row into destination table.
static void	MigrateInstances (Table &src, Util::Array< RowId > const &srcRows, Table &dst, Util::FixedArray< RowId > &dstRows, bool defragment=true, std::function< void(Partition *, IndexT, IndexT)> const &moveCallback=nullptr)
	move n instances from one table to another.
static void	DuplicateInstances (Table &src, Util::Array< RowId > const &srcRows, Table &dst, Util::FixedArray< RowId > &dstRows)
	duplicate instance from one row into destination table.

Public Attributes
Util::StringAtom	name
	name of the table

Static Public Attributes
static constexpr Memory::HeapType	HEAP_MEMORY_TYPE = Memory::HeapType::DefaultHeap
	allocation heap used for the column buffers

Private Types
using	ColumnBuffer = void*

Private Member Functions
	Table ()=default
	~Table ()

Private Attributes
TableSignature	signature
	the signature of this table. Contains one bit set to true for every attribute that exists in the table.
TableId	tid = TableId::Invalid()
	table identifier
uint32_t	totalNumRows = 0
	sum of all rows in all partitions of this table,
Partition *	currentPartition = nullptr
	Current partition that we'll be using when allocating data.
Util::Array< Partition * >	partitions
	All partitions, even null partitions.
Util::Array< Partition * >	freePartitions
	free partitions for recycling allocated partitions
Util::Array< uint16_t >	nullPartitions
	indices to null partitions
Partition *	firstActivePartition = nullptr
	First partition that has entities. You can use this to iterate over all active partitions with entities by following the chain of partition->next.
uint16_t	numActivePartitions = 0
	number of active partitions
Util::Array< AttributeId >	attributes
	all attributes that this table has
Util::HashTable< AttributeId, IndexT, 32, 1 >	columnRegistry
	maps attr id -> index in columns array

Friends
class	Database

Member Typedef Documentation

ColumnBuffer

using MemDb::Table::ColumnBuffer = void*

private

Constructor & Destructor Documentation

Table()

MemDb::Table::Table ( )

privatedefault

~Table()

MemDb::Table::~Table ( )

private

Member Function Documentation

AddAttribute()

ColumnIndex MemDb::Table::AddAttribute	(	AttributeId	attribute,
		bool	updateSignature = true )

Add an attribute to the table.

AddRow()

RowId MemDb::Table::AddRow

(

)

Add/Get a free row from the table.

Clean()

void MemDb::Table::Clean

(

)

Clean table. Does not deallocate anything; just sets the size of the table to zero.

Defragment()

SizeT MemDb::Table::Defragment

(

std::function< void(Partition *, RowId, RowId)> const &

moveCallback

)

Defragment table.

DeserializeInstance()

void MemDb::Table::DeserializeInstance	(	Util::Blob const &	data,
		RowId	row )

deserialize a blob into a row

DuplicateInstance()

RowId MemDb::Table::DuplicateInstance ( Table const & src, RowId srcRow, Table & dst )

static

duplicate instance from one row into destination table.

Returns

New index/row in destination table

Note

This might be destructive if the destination table is missing some of the source tables columns!

DuplicateInstances()

void MemDb::Table::DuplicateInstances ( Table & src, Util::Array< RowId > const & srcRows, Table & dst, Util::FixedArray< RowId > & dstRows )

static

duplicate instance from one row into destination table.

GetAttributeId()

AttributeId MemDb::Table::GetAttributeId

(

ColumnIndex

columnIndex

)

const

Returns the attribute located in given column.

GetAttributeIndex()

ColumnIndex MemDb::Table::GetAttributeIndex

(

AttributeId

attribute

)

const

Returns the index of the attribute or invalid if attribute is missing from table.

GetAttributes()

Util::Array< AttributeId > const & MemDb::Table::GetAttributes

(

)

const

Get the all descriptors for a table.

GetBuffer()

void * MemDb::Table::GetBuffer	(	uint16_t	partition,
		ColumnIndex	cid )

get a buffer. Might be invalidated if rows are allocated or deallocated

GetCurrentPartition()

Table::Partition * MemDb::Table::GetCurrentPartition

(

)

Get current partition.

GetFirstActivePartition()

Table::Partition * MemDb::Table::GetFirstActivePartition

(

)

Get first active partition with entities.

GetNumActivePartitions()

uint16_t MemDb::Table::GetNumActivePartitions

(

)

const

Get number of partitions that contain entities.

GetNumPartitions()

uint16_t MemDb::Table::GetNumPartitions

(

)

const

Get number of partitions in table.

GetNumRows()

SizeT MemDb::Table::GetNumRows

(

)

const

Get total number of rows in a table.

GetPartition()

Table::Partition * MemDb::Table::GetPartition

(

uint16_t

partitionId

)

GetSignature()

TableSignature const & MemDb::Table::GetSignature

(

)

const

Get the table signature.

GetValuePointer()

void * MemDb::Table::GetValuePointer	(	ColumnIndex	cid,
		RowId	row )

get a buffer. Might be invalidated if rows are allocated or deallocated

HasAttribute()

bool MemDb::Table::HasAttribute

(

AttributeId

attribute

)

const

Check if a column exists in the table.

MigrateInstance()

RowId MemDb::Table::MigrateInstance ( Table & src, RowId srcRow, Table & dst, bool defragment = true, std::function< void(Partition *, RowId, RowId)> const & moveCallback = nullptr )

static

move instance from one table to another.

MigrateInstances()

void MemDb::Table::MigrateInstances ( Table & src, Util::Array< RowId > const & srcRows, Table & dst, Util::FixedArray< RowId > & dstRows, bool defragment = true, std::function< void(Partition *, IndexT, IndexT)> const & moveCallback = nullptr )

static

move n instances from one table to another.

NewPartition()

Table::Partition * MemDb::Table::NewPartition

(

)

Create a new partition for this table. Adds it to the list of partitions and the vacancy list.

RemoveRow()

void MemDb::Table::RemoveRow

(

RowId

row

)

Deallocate a row from a table. This only frees the row for recycling. See Defragment.

Reset()

void MemDb::Table::Reset

(

)

Reset table. Deallocate all data.

SerializeInstance()

Util::Blob MemDb::Table::SerializeInstance

(

RowId

row

)

const

Serialize a row into a blob.

SetNumRows()

void MemDb::Table::SetNumRows

(

SizeT

value

)

set total number of rows in a table. This does not allocate any memory or create instaces, thus should pretty much never be used.

SetToDefault()

void MemDb::Table::SetToDefault

(

RowId

row

)

Set all row values to default.

Friends And Related Symbol Documentation

Database

friend class Database

friend

Member Data Documentation

attributes

Util::Array<AttributeId> MemDb::Table::attributes

private

all attributes that this table has

columnRegistry

Util::HashTable<AttributeId, IndexT, 32, 1> MemDb::Table::columnRegistry

private

maps attr id -> index in columns array

currentPartition

Partition* MemDb::Table::currentPartition = nullptr

private

Current partition that we'll be using when allocating data.

firstActivePartition

Partition* MemDb::Table::firstActivePartition = nullptr

private

First partition that has entities. You can use this to iterate over all active partitions with entities by following the chain of partition->next.

freePartitions

Util::Array<Partition*> MemDb::Table::freePartitions

private

free partitions for recycling allocated partitions

HEAP_MEMORY_TYPE

Memory::HeapType MemDb::Table::HEAP_MEMORY_TYPE = Memory::HeapType::DefaultHeap

staticconstexpr

allocation heap used for the column buffers

name

Util::StringAtom MemDb::Table::name

name of the table

nullPartitions

Util::Array<uint16_t> MemDb::Table::nullPartitions

private

indices to null partitions

numActivePartitions

uint16_t MemDb::Table::numActivePartitions = 0

private

number of active partitions

partitions

Util::Array<Partition*> MemDb::Table::partitions

private

All partitions, even null partitions.

signature

TableSignature MemDb::Table::signature

private

the signature of this table. Contains one bit set to true for every attribute that exists in the table.

tid

TableId MemDb::Table::tid = TableId::Invalid()

private

table identifier

totalNumRows

uint32_t MemDb::Table::totalNumRows = 0

private

sum of all rows in all partitions of this table,

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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