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Commit123474c

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nbtree: Minor sibling link traversal tweaks.
Tweak some code comments for clarity, and relocate some local variabledeclarations to the scope where they're actually used.Follow-up to recent commit1bd4bc8.
1 parentde5afdd commit123474c

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+8
-11
lines changed

1 file changed

+8
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lines changed

‎src/backend/access/nbtree/nbtsearch.c

Lines changed: 8 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -1580,7 +1580,7 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum,
15801580
so->currPos.currPage);
15811581
}
15821582

1583-
/* initialize remaining currPos fields (before moreLeft/moreright) */
1583+
/* initialize remaining currPos fields (before moreLeft/moreRight) */
15841584
so->currPos.lsn=BufferGetLSNAtomic(so->currPos.buf);
15851585
so->currPos.dir=dir;
15861586
so->currPos.nextTupleOffset=0;
@@ -2154,7 +2154,7 @@ _bt_readfirstpage(IndexScanDesc scan, OffsetNumber offnum, ScanDirection dir)
21542154
so->numKilled=0;/* just paranoia */
21552155
so->markItemIndex=-1;/* ditto */
21562156

2157-
/* Initialize currPos for so->currPos */
2157+
/* Initializeso->currPos forthe first page (page inso->currPos.buf) */
21582158
if (so->needPrimScan)
21592159
{
21602160
Assert(so->numArrayKeys);
@@ -2175,7 +2175,7 @@ _bt_readfirstpage(IndexScanDesc scan, OffsetNumber offnum, ScanDirection dir)
21752175
}
21762176

21772177
/*
2178-
* Attempt to load matching tuples from thepage in so->currPos.buf.
2178+
* Attempt to load matching tuples from thefirst page.
21792179
*
21802180
* Note that _bt_readpage will finish initializing the so->currPos fields.
21812181
* _bt_readpage also releases parallel scan (even when it returns false).
@@ -2208,8 +2208,7 @@ _bt_readfirstpage(IndexScanDesc scan, OffsetNumber offnum, ScanDirection dir)
22082208
* Caller's blkno is the next interesting page's link, taken from either the
22092209
* previously-saved right link or left link. lastcurrblkno is the page that
22102210
* was current at the point where the blkno link was saved, which we use to
2211-
* reason about concurrent page splits/page deletions during backwards scans
2212-
* (_bt_parallel_seize also requires it, regardless of scan direction).
2211+
* reason about concurrent page splits/page deletions during backwards scans.
22132212
*
22142213
* On entry, caller shouldn't hold any locks or pins on any page (we work
22152214
* directly off of blkno and lastcurrblkno instead). Parallel scan callers
@@ -2234,8 +2233,6 @@ _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno,
22342233
{
22352234
Relationrel=scan->indexRelation;
22362235
BTScanOpaqueso= (BTScanOpaque)scan->opaque;
2237-
Pagepage;
2238-
BTPageOpaqueopaque;
22392236

22402237
Assert(so->currPos.currPage==lastcurrblkno||scan->parallel_scan!=NULL);
22412238
Assert(!BTScanPosIsPinned(so->currPos));
@@ -2251,14 +2248,14 @@ _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno,
22512248

22522249
for (;;)
22532250
{
2254-
/*
2255-
* if we're at end of scan, give up and mark parallel scan as done, so
2256-
* that all the workers can finish their scan
2257-
*/
2251+
Pagepage;
2252+
BTPageOpaqueopaque;
2253+
22582254
if (blkno==P_NONE||
22592255
(ScanDirectionIsForward(dir) ?
22602256
!so->currPos.moreRight : !so->currPos.moreLeft))
22612257
{
2258+
/* most recent _bt_readpage call (for lastcurrblkno) ended scan */
22622259
_bt_parallel_done(scan);
22632260
BTScanPosInvalidate(so->currPos);
22642261
return false;

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