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Make rs_cindex and rs_ntuples unsigned

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HeapScanDescData.rs_cindex and rs_ntuples can't be less than 0. All scan
types using the heap scan descriptor expect these values to be >= 0.
Make that expectation clear by making rs_cindex and rs_ntuples unsigned.

Also remove the test in heapam_scan_bitmap_next_tuple() that checks if
rs_cindex < 0. This was never true, but now that rs_cindex is unsigned,
it makes even less sense.

While we are at it, initialize both rs_cindex and rs_ntuples to 0 in
initscan().

Author: Melanie Plageman
Reviewed-by: Dilip Kumar
Discussion: https://postgr.es/m/CAAKRu_ZxF8cDCM_BFi_L-t%3DRjdCZYP1usd1Gd45mjHfZxm0nZw%40mail.gmail.com
This commit is contained in:
Melanie Plageman 2024-12-18 11:47:38 -05:00
parent 1f0de66ea2
commit 68d9662be1
3 changed files with 8 additions and 5 deletions
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7
src/backend/access/heap/heapam.c
View File

@ -378,6 +378,8 @@ initscan(HeapScanDesc scan, ScanKey key, bool keep_startblock)
ItemPointerSetInvalid(&scan->rs_ctup.t_self);
scan->rs_cbuf = InvalidBuffer;
scan->rs_cblock = InvalidBlockNumber;
scan->rs_ntuples = 0;
scan->rs_cindex = 0;
/*
* Initialize to ForwardScanDirection because it is most common and
@ -943,8 +945,8 @@ heapgettup_pagemode(HeapScanDesc scan,
{
HeapTuple tuple = &(scan->rs_ctup);
Page page;
int lineindex;
int linesleft;
uint32 lineindex;
uint32 linesleft;
if (likely(scan->rs_inited))
{
@ -989,6 +991,7 @@ continue_page:
ItemId lpp;
OffsetNumber lineoff;
Assert(lineindex <= scan->rs_ntuples);
lineoff = scan->rs_vistuples[lineindex];
lpp = PageGetItemId(page, lineoff);
Assert(ItemIdIsNormal(lpp));

2
src/backend/access/heap/heapam_handler.c
View File

@ -2303,7 +2303,7 @@ heapam_scan_bitmap_next_tuple(TableScanDesc scan,
/*
* Out of range? If so, nothing more to look at on this page
*/
if (hscan->rs_cindex < 0 || hscan->rs_cindex >= hscan->rs_ntuples)
if (hscan->rs_cindex >= hscan->rs_ntuples)
return false;
targoffset = hscan->rs_vistuples[hscan->rs_cindex];

4
src/include/access/heapam.h
View File

@ -103,8 +103,8 @@ typedef struct HeapScanDescData
int rs_empty_tuples_pending;
/* these fields only used in page-at-a-time mode and for bitmap scans */
int rs_cindex; /* current tuple's index in vistuples */
int rs_ntuples; /* number of visible tuples on page */
uint32 rs_cindex; /* current tuple's index in vistuples */
uint32 rs_ntuples; /* number of visible tuples on page */
OffsetNumber rs_vistuples[MaxHeapTuplesPerPage]; /* their offsets */
} HeapScanDescData;
typedef struct HeapScanDescData *HeapScanDesc;