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Refactor page compactifying code.
The logic to compact away removed tuples from page was duplicated with small differences in PageRepairFragmentation, PageIndexMultiDelete, and PageIndexDeleteNoCompact. Put it into a common function. Reviewed by Peter Geoghegan.
This commit is contained in:
Heikki Linnakangas
parent
507627f5b5
commit
809d9a260b
@ -404,10 +404,9 @@ PageRestoreTempPage(Page tempPage, Page oldPage)
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*/
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typedef struct itemIdSortData
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{
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int offsetindex; /* linp array index */
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int itemoff; /* page offset of item data */
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Size alignedlen; /* MAXALIGN(item data len) */
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ItemIdData olditemid; /* used only in PageIndexMultiDelete */
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uint16 offsetindex; /* linp array index */
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int16 itemoff; /* page offset of item data */
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uint16 alignedlen; /* MAXALIGN(item data len) */
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} itemIdSortData;
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typedef itemIdSortData *itemIdSort;
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@ -419,6 +418,38 @@ itemoffcompare(const void *itemidp1, const void *itemidp2)
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((itemIdSort) itemidp1)->itemoff;
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}
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/*
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* After removing or marking some line pointers unused, move the tuples to
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* remove the gaps caused by the removed items.
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*/
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static void
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compactify_tuples(itemIdSort itemidbase, int nitems, Page page)
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{
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PageHeader phdr = (PageHeader) page;
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Offset upper;
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int i;
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/* sort itemIdSortData array into decreasing itemoff order */
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qsort((char *) itemidbase, nitems, sizeof(itemIdSortData),
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itemoffcompare);
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upper = phdr->pd_special;
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for (i = 0; i < nitems; i++)
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{
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itemIdSort itemidptr = &itemidbase[i];
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ItemId lp;
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lp = PageGetItemId(page, itemidptr->offsetindex + 1);
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upper -= itemidptr->alignedlen;
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memmove((char *) page + upper,
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(char *) page + itemidptr->itemoff,
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itemidptr->alignedlen);
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lp->lp_off = upper;
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}
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phdr->pd_upper = upper;
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}
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/*
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* PageRepairFragmentation
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*
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@ -441,7 +472,6 @@ PageRepairFragmentation(Page page)
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nunused;
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int i;
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Size totallen;
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Offset upper;
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/*
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* It's worth the trouble to be more paranoid here than in most places,
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@ -515,24 +545,7 @@ PageRepairFragmentation(Page page)
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errmsg("corrupted item lengths: total %u, available space %u",
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(unsigned int) totallen, pd_special - pd_lower)));
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/* sort itemIdSortData array into decreasing itemoff order */
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qsort((char *) itemidbase, nstorage, sizeof(itemIdSortData),
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itemoffcompare);
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/* compactify page */
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upper = pd_special;
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for (i = 0, itemidptr = itemidbase; i < nstorage; i++, itemidptr++)
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{
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lp = PageGetItemId(page, itemidptr->offsetindex + 1);
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upper -= itemidptr->alignedlen;
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memmove((char *) page + upper,
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(char *) page + itemidptr->itemoff,
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itemidptr->alignedlen);
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lp->lp_off = upper;
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}
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((PageHeader) page)->pd_upper = upper;
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compactify_tuples(itemidbase, nstorage, page);
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}
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/* Set hint bit for PageAddItem */
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@ -782,13 +795,12 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
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Offset pd_upper = phdr->pd_upper;
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Offset pd_special = phdr->pd_special;
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itemIdSortData itemidbase[MaxIndexTuplesPerPage];
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ItemIdData newitemids[MaxIndexTuplesPerPage];
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itemIdSort itemidptr;
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ItemId lp;
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int nline,
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nused;
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int i;
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Size totallen;
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Offset upper;
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Size size;
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unsigned offset;
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int nextitm;
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@ -857,9 +869,9 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
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{
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itemidptr->offsetindex = nused; /* where it will go */
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itemidptr->itemoff = offset;
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itemidptr->olditemid = *lp;
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itemidptr->alignedlen = MAXALIGN(size);
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totallen += itemidptr->alignedlen;
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newitemids[nused] = *lp;
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itemidptr++;
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nused++;
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}
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@ -875,26 +887,15 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
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errmsg("corrupted item lengths: total %u, available space %u",
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(unsigned int) totallen, pd_special - pd_lower)));
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/* sort itemIdSortData array into decreasing itemoff order */
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qsort((char *) itemidbase, nused, sizeof(itemIdSortData),
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itemoffcompare);
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/* compactify page and install new itemids */
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upper = pd_special;
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for (i = 0, itemidptr = itemidbase; i < nused; i++, itemidptr++)
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{
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lp = PageGetItemId(page, itemidptr->offsetindex + 1);
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upper -= itemidptr->alignedlen;
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memmove((char *) page + upper,
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(char *) page + itemidptr->itemoff,
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itemidptr->alignedlen);
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*lp = itemidptr->olditemid;
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lp->lp_off = upper;
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}
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/*
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* Looks good. Overwrite the line pointers with the copy, from which we've
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* removed all the unused items.
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*/
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memcpy(phdr->pd_linp, newitemids, nused * sizeof(ItemIdData));
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phdr->pd_lower = SizeOfPageHeaderData + nused * sizeof(ItemIdData);
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phdr->pd_upper = upper;
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/* and compactify the tuple data */
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compactify_tuples(itemidbase, nused, page);
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}
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/*
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@ -1000,7 +1001,6 @@ PageIndexDeleteNoCompact(Page page, OffsetNumber *itemnos, int nitems)
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itemIdSort itemidptr;
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int i;
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Size totallen;
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Offset upper;
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/*
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* Scan the page taking note of each item that we need to preserve.
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@ -1012,7 +1012,8 @@ PageIndexDeleteNoCompact(Page page, OffsetNumber *itemnos, int nitems)
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*/
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itemidptr = itemidbase;
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totallen = 0;
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for (i = 0; i < nline; i++, itemidptr++)
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PageClearHasFreeLinePointers(page);
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for (i = 0; i < nline; i++)
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{
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ItemId lp;
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@ -1024,13 +1025,15 @@ PageIndexDeleteNoCompact(Page page, OffsetNumber *itemnos, int nitems)
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itemidptr->itemoff = ItemIdGetOffset(lp);
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itemidptr->alignedlen = MAXALIGN(ItemIdGetLength(lp));
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totallen += itemidptr->alignedlen;
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itemidptr++;
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}
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else
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{
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itemidptr->itemoff = 0;
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itemidptr->alignedlen = 0;
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PageSetHasFreeLinePointers(page);
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ItemIdSetUnused(lp);
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}
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}
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nline = itemidptr - itemidbase;
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/* By here, there are exactly nline elements in itemidbase array */
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if (totallen > (Size) (pd_special - pd_lower))
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@ -1039,38 +1042,11 @@ PageIndexDeleteNoCompact(Page page, OffsetNumber *itemnos, int nitems)
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errmsg("corrupted item lengths: total %u, available space %u",
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(unsigned int) totallen, pd_special - pd_lower)));
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/* sort itemIdSortData array into decreasing itemoff order */
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qsort((char *) itemidbase, nline, sizeof(itemIdSortData),
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itemoffcompare);
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/*
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* Defragment the data areas of each tuple, being careful to preserve
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* each item's position in the linp array.
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*/
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upper = pd_special;
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PageClearHasFreeLinePointers(page);
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for (i = 0, itemidptr = itemidbase; i < nline; i++, itemidptr++)
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{
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ItemId lp;
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lp = PageGetItemId(page, itemidptr->offsetindex + 1);
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if (itemidptr->alignedlen == 0)
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{
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PageSetHasFreeLinePointers(page);
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ItemIdSetUnused(lp);
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continue;
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}
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upper -= itemidptr->alignedlen;
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memmove((char *) page + upper,
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(char *) page + itemidptr->itemoff,
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itemidptr->alignedlen);
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lp->lp_off = upper;
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/* lp_flags and lp_len remain the same as originally */
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}
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/* Set the new page limits */
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phdr->pd_upper = upper;
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phdr->pd_lower = SizeOfPageHeaderData + i * sizeof(ItemIdData);
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compactify_tuples(itemidbase, nline, page);
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}
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}
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