impala::BufferedTupleStream::RowIdx Struct Reference

#include <buffered-tuple-stream.h>

Collaboration diagram for impala::BufferedTupleStream::RowIdx:

Public Member Functions
uint64_t	block () const
uint64_t	offset () const
uint64_t	idx () const
uint64_t	set (uint64_t block, uint64_t offset, uint64_t idx)
std::string	DebugString () const

Public Attributes
uint64_t	data

Static Public Attributes
static const uint64_t	BLOCK_MASK = 0xFFFF
static const uint64_t	BLOCK_SHIFT = 0
static const uint64_t	OFFSET_MASK = 0xFFFFFF0000
static const uint64_t	OFFSET_SHIFT = 16
static const uint64_t	IDX_MASK = 0xFFFFFF0000000000
static const uint64_t	IDX_SHIFT = 40

Detailed Description

Ordinal index into the stream to retrieve a row in O(1) time. This index can only be used if the stream is pinned. To read a row from a stream we need three pieces of information that we squeeze in 64 bits:

• The index of the block. The block id is stored in 16 bits. We can have up to 64K blocks per tuple stream. With 8MB blocks that is 512GB per stream.
• The offset of the start of the row (data) within the block. Since blocks are 8MB we use 24 bits for the offsets. (In theory we could use 23 bits.)
• The idx of the row in the block. We need this for retrieving the null indicators. We use 24 bits for this index as well.

Definition at line 121 of file buffered-tuple-stream.h.

Member Function Documentation

uint64_t impala::BufferedTupleStream::RowIdx::block ( ) const

inline

Definition at line 129 of file buffered-tuple-stream.h.

References BLOCK_MASK, and data.

Referenced by impala::HashTable::DebugStringTuple(), and impala::BufferedTupleStream::GetTupleRow().

string BufferedTupleStream::RowIdx::DebugString

(

)

const

Definition at line 37 of file buffered-tuple-stream.cc.

References gen_ir_descriptions::idx, and offset.

uint64_t impala::BufferedTupleStream::RowIdx::idx ( ) const

inline

Definition at line 137 of file buffered-tuple-stream.h.

References data, IDX_MASK, and IDX_SHIFT.

Referenced by impala::HashTable::DebugStringTuple(), and impala::BufferedTupleStream::GetTupleRow().

uint64_t impala::BufferedTupleStream::RowIdx::offset ( ) const

inline

Definition at line 133 of file buffered-tuple-stream.h.

References data, OFFSET_MASK, and OFFSET_SHIFT.

Referenced by impala::HashTable::DebugStringTuple(), and impala::BufferedTupleStream::GetTupleRow().

uint64_t impala::BufferedTupleStream::RowIdx::set ( uint64_t  block, uint64_t  offset, uint64_t  idx  )

inline

Definition at line 141 of file buffered-tuple-stream.h.

References BLOCK_MASK, data, IDX_MASK, IDX_SHIFT, OFFSET_MASK, and OFFSET_SHIFT.

Member Data Documentation

const uint64_t impala::BufferedTupleStream::RowIdx::BLOCK_MASK = 0xFFFF

static

Definition at line 122 of file buffered-tuple-stream.h.

Referenced by block(), and set().

const uint64_t impala::BufferedTupleStream::RowIdx::BLOCK_SHIFT = 0

static

Definition at line 123 of file buffered-tuple-stream.h.

uint64_t impala::BufferedTupleStream::RowIdx::data

Definition at line 154 of file buffered-tuple-stream.h.

Referenced by block(), idx(), offset(), and set().

const uint64_t impala::BufferedTupleStream::RowIdx::IDX_MASK = 0xFFFFFF0000000000

static

Definition at line 126 of file buffered-tuple-stream.h.

Referenced by idx(), and set().

const uint64_t impala::BufferedTupleStream::RowIdx::IDX_SHIFT = 40

static

Definition at line 127 of file buffered-tuple-stream.h.

Referenced by idx(), and set().

const uint64_t impala::BufferedTupleStream::RowIdx::OFFSET_MASK = 0xFFFFFF0000

static

Definition at line 124 of file buffered-tuple-stream.h.

Referenced by offset(), and set().

const uint64_t impala::BufferedTupleStream::RowIdx::OFFSET_SHIFT = 16

static

Definition at line 125 of file buffered-tuple-stream.h.

Referenced by offset(), and set().

---

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

• be/src/runtime/buffered-tuple-stream.h
• be/src/runtime/buffered-tuple-stream.cc