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Commit6b8b942

Browse files
author
Artur Zakirov
committed
Added comments to rumget.c
1 parent353ea47 commit6b8b942

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3 files changed

+93
-30
lines changed

3 files changed

+93
-30
lines changed

‎rum.h‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -259,9 +259,9 @@ typedef signed char RumNullCategory;
259259

260260
typedefstruct
261261
{
262-
ItemPointerDataiptr;
263-
OffsetNumberoffsetNumer;
264-
uint16pageOffset;
262+
ItemPointerDataiptr;
263+
OffsetNumberoffsetNumer;
264+
uint16pageOffset;
265265
}RumDataLeafItemIndex;
266266

267267
#defineRumDataLeafIndexCount 32

‎rumbtree.c‎

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -72,6 +72,10 @@ rumPrepareFindLeafPage(RumBtree btree, BlockNumber blkno)
7272
RumBtreeStack*
7373
rumReFindLeafPage(RumBtreebtree,RumBtreeStack*stack)
7474
{
75+
/*
76+
* Traverse the tree upwards until we sure that requested leaf page is
77+
* in this subtree. Or we can stop at root page.
78+
*/
7579
while (stack->parent)
7680
{
7781
RumBtreeStack*ptr;
@@ -90,6 +94,11 @@ rumReFindLeafPage(RumBtree btree, RumBtreeStack *stack)
9094
page=BufferGetPage(stack->buffer);
9195
maxoff=RumPageGetOpaque(page)->maxoff;
9296

97+
/*
98+
* We don't know right bound of rightmost pointer. So, we can be sure
99+
* that requested leaf page is in this subtree only when requested item
100+
* pointer is less than item pointer previous to rightmost.
101+
*/
93102
if (rumCompareItemPointers(
94103
&(((PostingItem*)RumDataPageGetItem(page,maxoff-1))->key),
95104
&btree->items[btree->curitem].iptr) >=0)
@@ -98,6 +107,7 @@ rumReFindLeafPage(RumBtree btree, RumBtreeStack *stack)
98107
}
99108
}
100109

110+
/* Traverse tree downwards. */
101111
stack=rumFindLeafPage(btree,stack);
102112
returnstack;
103113
}

‎rumget.c‎

Lines changed: 80 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -80,14 +80,14 @@ callConsistentFn(RumState *rumstate, RumScanKey key)
8080

8181
if (res&&key->attnum==rumstate->attrnAddToColumn)
8282
{
83-
inti;
83+
uint32i;
8484

8585
/* remember some addinfo value for later ordering by addinfo
8686
from another column */
8787

8888
key->outerAddInfoIsNull= true;
8989

90-
for(i=0;i<key->nuserentries;i++)
90+
for(i=0;i<key->nuserentries;i++)
9191
{
9292
if (key->entryRes[i]&&key->addInfoIsNull[0]== false)
9393
{
@@ -571,6 +571,10 @@ startScanKey(RumState *rumstate, RumScanKey key)
571571
key->isFinished= false;
572572
}
573573

574+
/*
575+
* Compare entries position. At first consider isFinished flag, then compare
576+
* item pointers.
577+
*/
574578
staticint
575579
cmpEntries(RumScanEntrye1,RumScanEntrye2)
576580
{
@@ -670,6 +674,10 @@ startScan(IndexScanDesc scan)
670674

671675
if (useFastScan)
672676
{
677+
/*
678+
* We are going to use fast scan. Do some preliminaries. Start scan
679+
* of each entry and sort entries by descending item pointers.
680+
*/
673681
so->sortedEntries= (RumScanEntry*)palloc(sizeof(RumScanEntry)*
674682
so->totalentries);
675683
memcpy(so->sortedEntries,so->entries,sizeof(RumScanEntry)*
@@ -1237,15 +1245,21 @@ scanGetItemRegular(IndexScanDesc scan, ItemPointer advancePast,
12371245
return TRUE;
12381246
}
12391247

1248+
/*
1249+
* Finds part of page containing requested item using small index at the end
1250+
* of page.
1251+
*/
12401252
staticbool
1241-
scanPage(RumState*rumstate,RumScanEntryentry,ItemPointeritem,Pagepage,boolequalOk)
1253+
scanPage(RumState*rumstate,RumScanEntryentry,ItemPointeritem,Pagepage,
1254+
boolequalOk)
12421255
{
1243-
intj;
1256+
intj;
12441257
RumKeyiter_item;
1245-
Pointerptr;
1246-
OffsetNumberfirst=FirstOffsetNumber,i,maxoff;
1247-
boolfound;
1248-
intcmp;
1258+
Pointerptr;
1259+
OffsetNumberfirst=FirstOffsetNumber,
1260+
i,maxoff;
1261+
boolfound;
1262+
intcmp;
12491263

12501264
ItemPointerSetMin(&iter_item.iptr);
12511265

@@ -1300,6 +1314,9 @@ scanPage(RumState *rumstate, RumScanEntry entry, ItemPointer item, Page page, bo
13001314
return true;
13011315
}
13021316

1317+
/*
1318+
* Find item pointer of entry with is greater or equal to given item pointer.
1319+
*/
13031320
staticvoid
13041321
entryFindItem(RumState*rumstate,RumScanEntryentry,RumKey*item)
13051322
{
@@ -1311,6 +1328,7 @@ entryFindItem(RumState *rumstate, RumScanEntry entry, RumKey *item)
13111328
return;
13121329
}
13131330

1331+
/* Try to find in loaded part of page */
13141332
if (rumCompareItemPointers(&entry->list[entry->nlist-1].iptr,
13151333
&item->iptr) >=0)
13161334
{
@@ -1329,13 +1347,13 @@ entryFindItem(RumState *rumstate, RumScanEntry entry, RumKey *item)
13291347
}
13301348
}
13311349

1332-
13331350
if (!BufferIsValid(entry->buffer))
13341351
{
13351352
entry->isFinished= TRUE;
13361353
return;
13371354
}
13381355

1356+
/* Check rest of page */
13391357
LockBuffer(entry->buffer,RUM_SHARE);
13401358

13411359
if (scanPage(rumstate,entry,&item->iptr,
@@ -1346,6 +1364,7 @@ entryFindItem(RumState *rumstate, RumScanEntry entry, RumKey *item)
13461364
return;
13471365
}
13481366

1367+
/* Try to traverse to another leaf page */
13491368
entry->gdi->btree.items=item;
13501369
entry->gdi->btree.curitem=0;
13511370

@@ -1363,6 +1382,7 @@ entryFindItem(RumState *rumstate, RumScanEntry entry, RumKey *item)
13631382
return;
13641383
}
13651384

1385+
/* At last try to traverse by right links */
13661386
for (;;)
13671387
{
13681388
/*
@@ -1402,17 +1422,20 @@ entryFindItem(RumState *rumstate, RumScanEntry entry, RumKey *item)
14021422
}
14031423
}
14041424

1425+
/*
1426+
* Do preConsistent check for all the key where applicable.
1427+
*/
14051428
staticbool
14061429
preConsistentCheck(RumScanOpaqueso)
14071430
{
1408-
RumState*rumstate=&so->rumstate;
1409-
inti,j;
1410-
boolrecheck;
1431+
RumState*rumstate=&so->rumstate;
1432+
uint32i,j;
1433+
boolrecheck;
14111434

14121435
for (j=0;j<so->nkeys;j++)
14131436
{
1414-
RumScanKeykey=&so->keys[j];
1415-
boolhasFalse= false;
1437+
RumScanKeykey=&so->keys[j];
1438+
boolhasFalse= false;
14161439

14171440
if (key->orderBy)
14181441
continue;
@@ -1448,29 +1471,43 @@ preConsistentCheck(RumScanOpaque so)
14481471
return true;
14491472
}
14501473

1474+
/*
1475+
* Shift value of some entry which index in so->sortedEntries is equal or greater
1476+
* to i.
1477+
*/
14511478
staticvoid
14521479
entryShift(inti,RumScanOpaqueso,boolfind)
14531480
{
1454-
intminIndex=-1,j;
1455-
uint32minPredictNumberResult=0;
1481+
intminIndex=-1,
1482+
j;
1483+
uint32minPredictNumberResult=0;
14561484
RumState*rumstate=&so->rumstate;
14571485

1486+
/*
1487+
* It's more efficient to move entry with smallest posting list/tree. So
1488+
* find one.
1489+
*/
14581490
for (j=i;j<so->totalentries;j++)
14591491
{
1460-
if (minIndex<0||so->sortedEntries[j]->predictNumberResult<minPredictNumberResult)
1492+
if (minIndex<0||
1493+
so->sortedEntries[j]->predictNumberResult<minPredictNumberResult)
14611494
{
14621495
minIndex=j;
14631496
minPredictNumberResult=so->sortedEntries[j]->predictNumberResult;
14641497
}
14651498
}
14661499

1500+
/* Do shift of required type */
14671501
if (find)
1468-
entryFindItem(rumstate,so->sortedEntries[minIndex],&so->sortedEntries[i-1]->curItem);
1502+
entryFindItem(rumstate,so->sortedEntries[minIndex],
1503+
&so->sortedEntries[i-1]->curItem);
14691504
elseif (!so->sortedEntries[minIndex]->isFinished)
14701505
entryGetItem(rumstate,so->sortedEntries[minIndex]);
14711506

1507+
/* Restore order of so->sortedEntries */
14721508
while (minIndex>0&&
1473-
cmpEntries(so->sortedEntries[minIndex],so->sortedEntries[minIndex-1])>0)
1509+
cmpEntries(so->sortedEntries[minIndex],
1510+
so->sortedEntries[minIndex-1])>0)
14741511
{
14751512
RumScanEntrytmp;
14761513
tmp=so->sortedEntries[minIndex];
@@ -1480,13 +1517,16 @@ entryShift(int i, RumScanOpaque so, bool find)
14801517
}
14811518
}
14821519

1520+
/*
1521+
* Get next item pointer using fast scan.
1522+
*/
14831523
staticbool
14841524
scanGetItemFast(IndexScanDescscan,ItemPointeradvancePast,
1485-
ItemPointerData*item,bool*recheck)
1525+
ItemPointerData*item,bool*recheck)
14861526
{
14871527
RumScanOpaqueso= (RumScanOpaque)scan->opaque;
1488-
inti,j,k;
1489-
boolpreConsistentFalse,consistentFalse;
1528+
inti,j,k;
1529+
boolpreConsistentFalse,consistentFalse;
14901530

14911531
if (so->entriesIncrIndex >=0)
14921532
{
@@ -1496,6 +1536,10 @@ scanGetItemFast(IndexScanDesc scan, ItemPointer advancePast,
14961536

14971537
for (;;)
14981538
{
1539+
/*
1540+
* Our entries is ordered by descending of item pointers.
1541+
* The first goal is to find border where preConsistent becomes false.
1542+
*/
14991543
preConsistentFalse= false;
15001544
j=0;
15011545
k=0;
@@ -1517,6 +1561,10 @@ scanGetItemFast(IndexScanDesc scan, ItemPointer advancePast,
15171561
}
15181562
}
15191563

1564+
/*
1565+
* If we found false in preConsistent then we can safely move entries
1566+
* which was true in preConsistent argument.
1567+
*/
15201568
if (so->sortedEntries[i-1]->isFinished== TRUE)
15211569
return false;
15221570

@@ -1526,6 +1574,7 @@ scanGetItemFast(IndexScanDesc scan, ItemPointer advancePast,
15261574
continue;
15271575
}
15281576

1577+
/* Call consistent method */
15291578
consistentFalse= false;
15301579
for (i=0;i<so->nkeys;i++)
15311580
{
@@ -1563,6 +1612,7 @@ scanGetItemFast(IndexScanDesc scan, ItemPointer advancePast,
15631612
if (consistentFalse)
15641613
continue;
15651614

1615+
/* Calculate recheck from each key */
15661616
*recheck= false;
15671617
for (i=0;i<so->nkeys;i++)
15681618
{
@@ -1586,6 +1636,9 @@ scanGetItemFast(IndexScanDesc scan, ItemPointer advancePast,
15861636
return false;
15871637
}
15881638

1639+
/*
1640+
* Get next item whether using regular or fast scan.
1641+
*/
15891642
staticbool
15901643
scanGetItem(IndexScanDescscan,ItemPointeradvancePast,
15911644
ItemPointerData*item,bool*recheck)
@@ -1776,7 +1829,7 @@ collectMatchesForHeapRow(IndexScanDesc scan, pendingPosition *pos)
17761829
OffsetNumberattrnum;
17771830
Pagepage;
17781831
IndexTupleitup;
1779-
inti,
1832+
uint32i,
17801833
j;
17811834

17821835
/*
@@ -1997,7 +2050,7 @@ scanPendingInsert(IndexScanDesc scan)
19972050
MemoryContextoldCtx;
19982051
boolrecheck,
19992052
match;
2000-
inti;
2053+
uint32i;
20012054
pendingPositionpos;
20022055
Buffermetabuffer=ReadBuffer(scan->indexRelation,RUM_METAPAGE_BLKNO);
20032056
BlockNumberblkno;
@@ -2145,7 +2198,7 @@ keyGetOrdering(RumState *rumstate, MemoryContext tempCtx, RumScanKey key,
21452198
ItemPointeriptr)
21462199
{
21472200
RumScanEntryentry;
2148-
inti;
2201+
uint32i;
21492202

21502203
if (key->useAddToColumn)
21512204
{
@@ -2200,7 +2253,7 @@ static void
22002253
insertScanItem(RumScanOpaqueso,boolrecheck)
22012254
{
22022255
RumSortItem*item;
2203-
inti,j;
2256+
uint32i,j;
22042257

22052258
item= (RumSortItem*)
22062259
MemoryContextAlloc(rum_tuplesort_get_memorycontext(so->sortstate),
@@ -2297,7 +2350,7 @@ rumgettuple(IndexScanDesc scan, ScanDirection direction)
22972350
item=rum_tuplesort_getrum(so->sortstate, true,&should_free);
22982351
if (item)
22992352
{
2300-
inti,j=0;
2353+
uint32i,j=0;
23012354

23022355
scan->xs_ctup.t_self=item->iptr;
23032356
scan->xs_recheck=item->recheck;

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