mirror of
https://github.com/postgres/postgres.git
synced 2025-06-03 00:02:26 -04:00
bb437f995d
This adds a new executor node named TID Range Scan. The query planner will generate paths for TID Range scans when quals are discovered on base relations which search for ranges on the table's ctid column. These ranges may be open at either end. For example, WHERE ctid >= '(10,0)'; will return all tuples on page 10 and over. To support this, two new optional callback functions have been added to table AM. scan_set_tidrange is used to set the scan range to just the given range of TIDs. scan_getnextslot_tidrange fetches the next tuple in the given range. For AMs were scanning ranges of TIDs would not make sense, these functions can be set to NULL in the TableAmRoutine. The query planner won't generate TID Range Scan Paths in that case. Author: Edmund Horner, David Rowley Reviewed-by: David Rowley, Tomas Vondra, Tom Lane, Andres Freund, Zhihong Yu Discussion: https://postgr.es/m/CAMyN-kB-nFTkF=VA_JPwFNo08S0d-Yk0F741S2B7LDmYAi8eyA@mail.gmail.com
133 lines
3.2 KiB
C
133 lines
3.2 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* itemptr.c
|
|
* POSTGRES disk item pointer code.
|
|
*
|
|
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
*
|
|
* IDENTIFICATION
|
|
* src/backend/storage/page/itemptr.c
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#include "postgres.h"
|
|
|
|
#include "storage/itemptr.h"
|
|
|
|
|
|
/*
|
|
* ItemPointerEquals
|
|
* Returns true if both item pointers point to the same item,
|
|
* otherwise returns false.
|
|
*
|
|
* Note:
|
|
* Asserts that the disk item pointers are both valid!
|
|
*/
|
|
bool
|
|
ItemPointerEquals(ItemPointer pointer1, ItemPointer pointer2)
|
|
{
|
|
/*
|
|
* We really want ItemPointerData to be exactly 6 bytes. This is rather a
|
|
* random place to check, but there is no better place.
|
|
*/
|
|
StaticAssertStmt(sizeof(ItemPointerData) == 3 * sizeof(uint16),
|
|
"ItemPointerData struct is improperly padded");
|
|
|
|
if (ItemPointerGetBlockNumber(pointer1) ==
|
|
ItemPointerGetBlockNumber(pointer2) &&
|
|
ItemPointerGetOffsetNumber(pointer1) ==
|
|
ItemPointerGetOffsetNumber(pointer2))
|
|
return true;
|
|
else
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* ItemPointerCompare
|
|
* Generic btree-style comparison for item pointers.
|
|
*/
|
|
int32
|
|
ItemPointerCompare(ItemPointer arg1, ItemPointer arg2)
|
|
{
|
|
/*
|
|
* Use ItemPointerGet{Offset,Block}NumberNoCheck to avoid asserting
|
|
* ip_posid != 0, which may not be true for a user-supplied TID.
|
|
*/
|
|
BlockNumber b1 = ItemPointerGetBlockNumberNoCheck(arg1);
|
|
BlockNumber b2 = ItemPointerGetBlockNumberNoCheck(arg2);
|
|
|
|
if (b1 < b2)
|
|
return -1;
|
|
else if (b1 > b2)
|
|
return 1;
|
|
else if (ItemPointerGetOffsetNumberNoCheck(arg1) <
|
|
ItemPointerGetOffsetNumberNoCheck(arg2))
|
|
return -1;
|
|
else if (ItemPointerGetOffsetNumberNoCheck(arg1) >
|
|
ItemPointerGetOffsetNumberNoCheck(arg2))
|
|
return 1;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* ItemPointerInc
|
|
* Increment 'pointer' by 1 only paying attention to the ItemPointer's
|
|
* type's range limits and not MaxOffsetNumber and FirstOffsetNumber.
|
|
* This may result in 'pointer' becoming !OffsetNumberIsValid.
|
|
*
|
|
* If the pointer is already the maximum possible values permitted by the
|
|
* range of the ItemPointer's types, then do nothing.
|
|
*/
|
|
void
|
|
ItemPointerInc(ItemPointer pointer)
|
|
{
|
|
BlockNumber blk = ItemPointerGetBlockNumberNoCheck(pointer);
|
|
OffsetNumber off = ItemPointerGetOffsetNumberNoCheck(pointer);
|
|
|
|
if (off == PG_UINT16_MAX)
|
|
{
|
|
if (blk != InvalidBlockNumber)
|
|
{
|
|
off = 0;
|
|
blk++;
|
|
}
|
|
}
|
|
else
|
|
off++;
|
|
|
|
ItemPointerSet(pointer, blk, off);
|
|
}
|
|
|
|
/*
|
|
* ItemPointerDec
|
|
* Decrement 'pointer' by 1 only paying attention to the ItemPointer's
|
|
* type's range limits and not MaxOffsetNumber and FirstOffsetNumber.
|
|
* This may result in 'pointer' becoming !OffsetNumberIsValid.
|
|
*
|
|
* If the pointer is already the minimum possible values permitted by the
|
|
* range of the ItemPointer's types, then do nothing. This does rely on
|
|
* FirstOffsetNumber being 1 rather than 0.
|
|
*/
|
|
void
|
|
ItemPointerDec(ItemPointer pointer)
|
|
{
|
|
BlockNumber blk = ItemPointerGetBlockNumberNoCheck(pointer);
|
|
OffsetNumber off = ItemPointerGetOffsetNumberNoCheck(pointer);
|
|
|
|
if (off == 0)
|
|
{
|
|
if (blk != 0)
|
|
{
|
|
off = PG_UINT16_MAX;
|
|
blk--;
|
|
}
|
|
}
|
|
else
|
|
off--;
|
|
|
|
ItemPointerSet(pointer, blk, off);
|
|
}
|