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Commit809d9a2

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Refactor page compactifying code.
The logic to compact away removed tuples from page was duplicated withsmall differences in PageRepairFragmentation, PageIndexMultiDelete, andPageIndexDeleteNoCompact. Put it into a common function.Reviewed by Peter Geoghegan.
1 parent507627f commit809d9a2

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1 file changed

+53
-77
lines changed

1 file changed

+53
-77
lines changed

‎src/backend/storage/page/bufpage.c

Lines changed: 53 additions & 77 deletions
Original file line numberDiff line numberDiff line change
@@ -404,10 +404,9 @@ PageRestoreTempPage(Page tempPage, Page oldPage)
404404
*/
405405
typedefstructitemIdSortData
406406
{
407-
intoffsetindex;/* linp array index */
408-
intitemoff;/* page offset of item data */
409-
Sizealignedlen;/* MAXALIGN(item data len) */
410-
ItemIdDataolditemid;/* used only in PageIndexMultiDelete */
407+
uint16offsetindex;/* linp array index */
408+
int16itemoff;/* page offset of item data */
409+
uint16alignedlen;/* MAXALIGN(item data len) */
411410
}itemIdSortData;
412411
typedefitemIdSortData*itemIdSort;
413412

@@ -419,6 +418,38 @@ itemoffcompare(const void *itemidp1, const void *itemidp2)
419418
((itemIdSort)itemidp1)->itemoff;
420419
}
421420

421+
/*
422+
* After removing or marking some line pointers unused, move the tuples to
423+
* remove the gaps caused by the removed items.
424+
*/
425+
staticvoid
426+
compactify_tuples(itemIdSortitemidbase,intnitems,Pagepage)
427+
{
428+
PageHeaderphdr= (PageHeader)page;
429+
Offsetupper;
430+
inti;
431+
432+
/* sort itemIdSortData array into decreasing itemoff order */
433+
qsort((char*)itemidbase,nitems,sizeof(itemIdSortData),
434+
itemoffcompare);
435+
436+
upper=phdr->pd_special;
437+
for (i=0;i<nitems;i++)
438+
{
439+
itemIdSortitemidptr=&itemidbase[i];
440+
ItemIdlp;
441+
442+
lp=PageGetItemId(page,itemidptr->offsetindex+1);
443+
upper-=itemidptr->alignedlen;
444+
memmove((char*)page+upper,
445+
(char*)page+itemidptr->itemoff,
446+
itemidptr->alignedlen);
447+
lp->lp_off=upper;
448+
}
449+
450+
phdr->pd_upper=upper;
451+
}
452+
422453
/*
423454
* PageRepairFragmentation
424455
*
@@ -441,7 +472,6 @@ PageRepairFragmentation(Page page)
441472
nunused;
442473
inti;
443474
Sizetotallen;
444-
Offsetupper;
445475

446476
/*
447477
* It's worth the trouble to be more paranoid here than in most places,
@@ -515,24 +545,7 @@ PageRepairFragmentation(Page page)
515545
errmsg("corrupted item lengths: total %u, available space %u",
516546
(unsignedint)totallen,pd_special-pd_lower)));
517547

518-
/* sort itemIdSortData array into decreasing itemoff order */
519-
qsort((char*)itemidbase,nstorage,sizeof(itemIdSortData),
520-
itemoffcompare);
521-
522-
/* compactify page */
523-
upper=pd_special;
524-
525-
for (i=0,itemidptr=itemidbase;i<nstorage;i++,itemidptr++)
526-
{
527-
lp=PageGetItemId(page,itemidptr->offsetindex+1);
528-
upper-=itemidptr->alignedlen;
529-
memmove((char*)page+upper,
530-
(char*)page+itemidptr->itemoff,
531-
itemidptr->alignedlen);
532-
lp->lp_off=upper;
533-
}
534-
535-
((PageHeader)page)->pd_upper=upper;
548+
compactify_tuples(itemidbase,nstorage,page);
536549
}
537550

538551
/* Set hint bit for PageAddItem */
@@ -782,13 +795,12 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
782795
Offsetpd_upper=phdr->pd_upper;
783796
Offsetpd_special=phdr->pd_special;
784797
itemIdSortDataitemidbase[MaxIndexTuplesPerPage];
798+
ItemIdDatanewitemids[MaxIndexTuplesPerPage];
785799
itemIdSortitemidptr;
786800
ItemIdlp;
787801
intnline,
788802
nused;
789-
inti;
790803
Sizetotallen;
791-
Offsetupper;
792804
Sizesize;
793805
unsignedoffset;
794806
intnextitm;
@@ -857,9 +869,9 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
857869
{
858870
itemidptr->offsetindex=nused;/* where it will go */
859871
itemidptr->itemoff=offset;
860-
itemidptr->olditemid=*lp;
861872
itemidptr->alignedlen=MAXALIGN(size);
862873
totallen+=itemidptr->alignedlen;
874+
newitemids[nused]=*lp;
863875
itemidptr++;
864876
nused++;
865877
}
@@ -875,26 +887,15 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
875887
errmsg("corrupted item lengths: total %u, available space %u",
876888
(unsignedint)totallen,pd_special-pd_lower)));
877889

878-
/* sort itemIdSortData array into decreasing itemoff order */
879-
qsort((char*)itemidbase,nused,sizeof(itemIdSortData),
880-
itemoffcompare);
881-
882-
/* compactify page and install new itemids */
883-
upper=pd_special;
884-
885-
for (i=0,itemidptr=itemidbase;i<nused;i++,itemidptr++)
886-
{
887-
lp=PageGetItemId(page,itemidptr->offsetindex+1);
888-
upper-=itemidptr->alignedlen;
889-
memmove((char*)page+upper,
890-
(char*)page+itemidptr->itemoff,
891-
itemidptr->alignedlen);
892-
*lp=itemidptr->olditemid;
893-
lp->lp_off=upper;
894-
}
895-
890+
/*
891+
* Looks good. Overwrite the line pointers with the copy, from which we've
892+
* removed all the unused items.
893+
*/
894+
memcpy(phdr->pd_linp,newitemids,nused*sizeof(ItemIdData));
896895
phdr->pd_lower=SizeOfPageHeaderData+nused*sizeof(ItemIdData);
897-
phdr->pd_upper=upper;
896+
897+
/* and compactify the tuple data */
898+
compactify_tuples(itemidbase,nused,page);
898899
}
899900

900901
/*
@@ -1000,7 +1001,6 @@ PageIndexDeleteNoCompact(Page page, OffsetNumber *itemnos, int nitems)
10001001
itemIdSortitemidptr;
10011002
inti;
10021003
Sizetotallen;
1003-
Offsetupper;
10041004

10051005
/*
10061006
* Scan the page taking note of each item that we need to preserve.
@@ -1012,7 +1012,8 @@ PageIndexDeleteNoCompact(Page page, OffsetNumber *itemnos, int nitems)
10121012
*/
10131013
itemidptr=itemidbase;
10141014
totallen=0;
1015-
for (i=0;i<nline;i++,itemidptr++)
1015+
PageClearHasFreeLinePointers(page);
1016+
for (i=0;i<nline;i++)
10161017
{
10171018
ItemIdlp;
10181019

@@ -1024,13 +1025,15 @@ PageIndexDeleteNoCompact(Page page, OffsetNumber *itemnos, int nitems)
10241025
itemidptr->itemoff=ItemIdGetOffset(lp);
10251026
itemidptr->alignedlen=MAXALIGN(ItemIdGetLength(lp));
10261027
totallen+=itemidptr->alignedlen;
1028+
itemidptr++;
10271029
}
10281030
else
10291031
{
1030-
itemidptr->itemoff=0;
1031-
itemidptr->alignedlen=0;
1032+
PageSetHasFreeLinePointers(page);
1033+
ItemIdSetUnused(lp);
10321034
}
10331035
}
1036+
nline=itemidptr-itemidbase;
10341037
/* By here, there are exactly nline elements in itemidbase array */
10351038

10361039
if (totallen> (Size) (pd_special-pd_lower))
@@ -1039,38 +1042,11 @@ PageIndexDeleteNoCompact(Page page, OffsetNumber *itemnos, int nitems)
10391042
errmsg("corrupted item lengths: total %u, available space %u",
10401043
(unsignedint)totallen,pd_special-pd_lower)));
10411044

1042-
/* sort itemIdSortData array into decreasing itemoff order */
1043-
qsort((char*)itemidbase,nline,sizeof(itemIdSortData),
1044-
itemoffcompare);
1045-
10461045
/*
10471046
* Defragment the data areas of each tuple, being careful to preserve
10481047
* each item's position in the linp array.
10491048
*/
1050-
upper=pd_special;
1051-
PageClearHasFreeLinePointers(page);
1052-
for (i=0,itemidptr=itemidbase;i<nline;i++,itemidptr++)
1053-
{
1054-
ItemIdlp;
1055-
1056-
lp=PageGetItemId(page,itemidptr->offsetindex+1);
1057-
if (itemidptr->alignedlen==0)
1058-
{
1059-
PageSetHasFreeLinePointers(page);
1060-
ItemIdSetUnused(lp);
1061-
continue;
1062-
}
1063-
upper-=itemidptr->alignedlen;
1064-
memmove((char*)page+upper,
1065-
(char*)page+itemidptr->itemoff,
1066-
itemidptr->alignedlen);
1067-
lp->lp_off=upper;
1068-
/* lp_flags and lp_len remain the same as originally */
1069-
}
1070-
1071-
/* Set the new page limits */
1072-
phdr->pd_upper=upper;
1073-
phdr->pd_lower=SizeOfPageHeaderData+i*sizeof(ItemIdData);
1049+
compactify_tuples(itemidbase,nline,page);
10741050
}
10751051
}
10761052

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