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Remove BTScanOpaqueData.firstPage 

It's not necessary to keep the firstPage flag as a field of BTScanOpaqueData.
This commit makes it an argument of the _bt_readpage() function.  We can easily
distinguish first-time and repeated calls (within the scan) of this function.

Reported-by: Peter Geoghegan
Discussion: https://postgr.es/m/CAH2-Wzk4SOsw%2BtHuTFiz8U9Jqj-R77rYPkhWKODCBb1mdHACXA%40mail.gmail.com
Reviewed-by: Pavel Borisov
This commit is contained in:
Alexander Korotkov 2023-12-27 14:21:49 +02:00
parent 3e527aeeed
commit 06b10f80ba
3 changed files with 8 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
src/backend/access/nbtree/nbtree.c
View File

@ -409,7 +409,6 @@ btrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
so->markItemIndex = -1;
so->arrayKeyCount = 0;
so->firstPage = false;
BTScanPosUnpinIfPinned(so->markPos);
BTScanPosInvalidate(so->markPos);

18
src/backend/access/nbtree/nbtsearch.c
View File

@ -30,7 +30,7 @@ static OffsetNumber _bt_binsrch(Relation rel, BTScanInsert key, Buffer buf);
static int _bt_binsrch_posting(BTScanInsert key, Page page,
OffsetNumber offnum);
static bool _bt_readpage(IndexScanDesc scan, ScanDirection dir,
OffsetNumber offnum);
OffsetNumber offnum, bool firstPage);
static void _bt_saveitem(BTScanOpaque so, int itemIndex,
OffsetNumber offnum, IndexTuple itup);
static int _bt_setuppostingitems(BTScanOpaque so, int itemIndex,
@ -1395,7 +1395,6 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
offnum = _bt_binsrch(rel, &inskey, buf);
Assert(!BTScanPosIsValid(so->currPos));
so->currPos.buf = buf;
so->firstPage = true;
/*
* Now load data from the first page of the scan.
@ -1416,7 +1415,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
* for the page. For example, when inskey is both < the leaf page's high
* key and > all of its non-pivot tuples, offnum will be "maxoff + 1".
*/
if (!_bt_readpage(scan, dir, offnum))
if (!_bt_readpage(scan, dir, offnum, true))
{
/*
* There's no actually-matching data on this page. Try to advance to
@ -1520,7 +1519,8 @@ _bt_next(IndexScanDesc scan, ScanDirection dir)
* Returns true if any matching items found on the page, false if none.
*/
static bool
_bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
_bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum,
bool firstPage)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
Page page;
@ -1601,7 +1601,7 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
* We skip this for the first page in the scan to evade the possible
* slowdown of the point queries.
*/
if (!so->firstPage && minoff < maxoff)
if (!firstPage && minoff < maxoff)
{
ItemId iid;
IndexTuple itup;
@ -1620,7 +1620,6 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
}
else
{
so->firstPage = false;
requiredMatchedByPrecheck = false;
}
@ -2079,7 +2078,7 @@ _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno, ScanDirection dir)
PredicateLockPage(rel, blkno, scan->xs_snapshot);
/* see if there are any matches on this page */
/* note that this will clear moreRight if we can stop */
if (_bt_readpage(scan, dir, P_FIRSTDATAKEY(opaque)))
if (_bt_readpage(scan, dir, P_FIRSTDATAKEY(opaque), false))
break;
}
else if (scan->parallel_scan != NULL)
@ -2170,7 +2169,7 @@ _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno, ScanDirection dir)
PredicateLockPage(rel, BufferGetBlockNumber(so->currPos.buf), scan->xs_snapshot);
/* see if there are any matches on this page */
/* note that this will clear moreLeft if we can stop */
if (_bt_readpage(scan, dir, PageGetMaxOffsetNumber(page)))
if (_bt_readpage(scan, dir, PageGetMaxOffsetNumber(page), false))
break;
}
else if (scan->parallel_scan != NULL)
@ -2487,14 +2486,13 @@ _bt_endpoint(IndexScanDesc scan, ScanDirection dir)
/* remember which buffer we have pinned */
so->currPos.buf = buf;
so->firstPage = true;
_bt_initialize_more_data(so, dir);
/*
* Now load data from the first page of the scan.
*/
if (!_bt_readpage(scan, dir, start))
if (!_bt_readpage(scan, dir, start, false))
{
/*
* There's no actually-matching data on this page. Try to advance to

3
src/include/access/nbtree.h
View File

@ -1051,9 +1051,6 @@ typedef struct BTScanOpaqueData
int *killedItems; /* currPos.items indexes of killed items */
int numKilled; /* number of currently stored items */
/* flag indicating the first page in the scan */
bool firstPage;
/*
* If we are doing an index-only scan, these are the tuple storage
* workspaces for the currPos and markPos respectively. Each is of size