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Add more sanity-checking to PageAddItem and PageIndexTupleDelete,
to prevent spreading of corruption when page header pointers are bad. Merge PageZero into PageInit, since it was never used separately, and remove separate memset calls used at most other PageInit call points. Remove IndexPageCleanup, which wasn't used at all.
This commit is contained in:
Tom Lane
@@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/storage/page/bufpage.c,v 1.41 2001/11/08 04:05:13 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/storage/page/bufpage.c,v 1.42 2002/01/15 22:14:17 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@@ -20,10 +20,6 @@
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#include "storage/bufpage.h"
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static void PageIndexTupleDeleteAdjustLinePointers(PageHeader phdr,
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char *location, Size size);
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/* ----------------------------------------------------------------
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* Page support functions
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* ----------------------------------------------------------------
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@@ -44,24 +40,15 @@ PageInit(Page page, Size pageSize, Size specialSize)
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Assert(pageSize >
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specialSize + sizeof(PageHeaderData) - sizeof(ItemIdData));
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/* Make sure all fields of page are zero, as well as unused space */
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MemSet(p, 0, pageSize);
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p->pd_lower = sizeof(PageHeaderData) - sizeof(ItemIdData);
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p->pd_upper = pageSize - specialSize;
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p->pd_special = pageSize - specialSize;
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PageSetPageSize(page, pageSize);
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p->pd_lsn.xlogid = p->pd_lsn.xrecoff = 0;
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p->pd_sui = 0;
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}
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/*
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* WAL needs in zero-ed page data content
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*/
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void
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PageZero(Page page)
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{
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MemSet((char *) page + ((PageHeader) page)->pd_lower, 0,
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((PageHeader) page)->pd_special - ((PageHeader) page)->pd_lower);
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}
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/* ----------------
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* PageAddItem
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@@ -86,10 +73,11 @@ PageAddItem(Page page,
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OffsetNumber offsetNumber,
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ItemIdFlags flags)
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{
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PageHeader phdr = (PageHeader) page;
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int i;
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Size alignedSize;
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Offset lower;
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Offset upper;
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int lower;
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int upper;
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ItemId itemId;
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OffsetNumber limit;
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bool needshuffle = false;
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@@ -97,6 +85,16 @@ PageAddItem(Page page,
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flags &= ~OverwritePageMode;
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/*
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* Be wary about corrupted page pointers
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*/
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if (phdr->pd_lower < (sizeof(PageHeaderData) - sizeof(ItemIdData)) ||
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phdr->pd_lower > phdr->pd_upper ||
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phdr->pd_upper > phdr->pd_special ||
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phdr->pd_special > BLCKSZ)
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elog(ERROR, "PageAddItem: corrupted page pointers: lower = %u, upper = %u, special = %u",
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phdr->pd_lower, phdr->pd_upper, phdr->pd_special);
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/*
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* Find first unallocated offsetNumber
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*/
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@@ -114,7 +112,7 @@ PageAddItem(Page page,
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}
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if (offsetNumber < limit)
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{
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itemId = &((PageHeader) page)->pd_linp[offsetNumber - 1];
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itemId = &phdr->pd_linp[offsetNumber - 1];
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if (((*itemId).lp_flags & LP_USED) ||
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((*itemId).lp_len != 0))
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{
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@@ -138,7 +136,7 @@ PageAddItem(Page page,
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/* look for "recyclable" (unused & deallocated) ItemId */
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for (offsetNumber = 1; offsetNumber < limit; offsetNumber++)
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{
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itemId = &((PageHeader) page)->pd_linp[offsetNumber - 1];
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itemId = &phdr->pd_linp[offsetNumber - 1];
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if ((((*itemId).lp_flags & LP_USED) == 0) &&
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((*itemId).lp_len == 0))
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break;
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@@ -146,18 +144,21 @@ PageAddItem(Page page,
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}
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/*
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* Compute new lower and upper pointers for page, see if it'll fit
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* Compute new lower and upper pointers for page, see if it'll fit.
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*
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* Note: do arithmetic as signed ints, to avoid mistakes if, say,
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* alignedSize > pd_upper.
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*/
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if (offsetNumber > limit)
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lower = (Offset) (((char *) (&((PageHeader) page)->pd_linp[offsetNumber])) - ((char *) page));
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lower = (char *) (&phdr->pd_linp[offsetNumber]) - (char *) page;
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else if (offsetNumber == limit || needshuffle)
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lower = ((PageHeader) page)->pd_lower + sizeof(ItemIdData);
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lower = phdr->pd_lower + sizeof(ItemIdData);
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else
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lower = ((PageHeader) page)->pd_lower;
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lower = phdr->pd_lower;
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alignedSize = MAXALIGN(size);
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upper = ((PageHeader) page)->pd_upper - alignedSize;
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upper = (int) phdr->pd_upper - (int) alignedSize;
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if (lower > upper)
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return InvalidOffsetNumber;
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@@ -169,24 +170,26 @@ PageAddItem(Page page,
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if (needshuffle)
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{
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/* shuffle ItemId's (Do the PageManager Shuffle...) */
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for (i = (limit - 1); i >= offsetNumber; i--)
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for (i = (int) limit - 1; i >= (int) offsetNumber; i--)
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{
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ItemId fromitemId,
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toitemId;
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fromitemId = &((PageHeader) page)->pd_linp[i - 1];
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toitemId = &((PageHeader) page)->pd_linp[i];
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fromitemId = &phdr->pd_linp[i - 1];
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toitemId = &phdr->pd_linp[i];
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*toitemId = *fromitemId;
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}
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}
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itemId = &((PageHeader) page)->pd_linp[offsetNumber - 1];
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itemId = &phdr->pd_linp[offsetNumber - 1];
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(*itemId).lp_off = upper;
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(*itemId).lp_len = size;
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(*itemId).lp_flags = flags;
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memmove((char *) page + upper, item, size);
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((PageHeader) page)->pd_lower = lower;
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((PageHeader) page)->pd_upper = upper;
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phdr->pd_lower = (LocationIndex) lower;
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phdr->pd_upper = (LocationIndex) upper;
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return offsetNumber;
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}
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@@ -383,79 +386,76 @@ PageRepairFragmentation(Page page, OffsetNumber *unused)
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Size
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PageGetFreeSpace(Page page)
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{
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Size space;
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int space;
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space = ((PageHeader) page)->pd_upper - ((PageHeader) page)->pd_lower;
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/*
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* Use signed arithmetic here so that we behave sensibly if
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* pd_lower > pd_upper.
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*/
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space = (int) ((PageHeader) page)->pd_upper -
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(int) ((PageHeader) page)->pd_lower;
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if (space < sizeof(ItemIdData))
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if (space < (int) sizeof(ItemIdData))
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return 0;
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space -= sizeof(ItemIdData); /* XXX not always appropriate */
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return space;
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return (Size) space;
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}
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/*
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* PageRepairFragmentation un-useful for index page cleanup because
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* of it doesn't remove line pointers. This routine could be more
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* effective but ... no time -:)
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*/
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void
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IndexPageCleanup(Buffer buffer)
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{
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Page page = (Page) BufferGetPage(buffer);
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ItemId lp;
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OffsetNumber maxoff;
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OffsetNumber i;
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maxoff = PageGetMaxOffsetNumber(page);
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for (i = 0; i < maxoff; i++)
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{
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lp = ((PageHeader) page)->pd_linp + i;
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if ((*lp).lp_flags & LP_DELETE) /* marked for deletion */
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{
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PageIndexTupleDelete(page, i + 1);
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maxoff--;
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}
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}
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}
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/*
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*----------------------------------------------------------------
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* PageIndexTupleDelete
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*----------------------------------------------------------------
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*
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* This routine does the work of removing a tuple from an index page.
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* This routine does the work of removing a tuple from an index page.
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*
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* Unlike heap pages, we compact out the line pointer for the removed tuple.
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*/
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void
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PageIndexTupleDelete(Page page, OffsetNumber offnum)
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{
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PageHeader phdr;
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PageHeader phdr = (PageHeader) page;
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char *addr;
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ItemId tup;
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Size size;
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char *locn;
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unsigned offset;
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int nbytes;
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int offidx;
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int nline,
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i;
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phdr = (PageHeader) page;
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/*
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* As with PageRepairFragmentation, paranoia seems justified.
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*/
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if (phdr->pd_lower < (sizeof(PageHeaderData) - sizeof(ItemIdData)) ||
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phdr->pd_lower > phdr->pd_upper ||
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phdr->pd_upper > phdr->pd_special ||
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phdr->pd_special > BLCKSZ)
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elog(ERROR, "PageIndexTupleDelete: corrupted page pointers: lower = %u, upper = %u, special = %u",
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phdr->pd_lower, phdr->pd_upper, phdr->pd_special);
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nline = PageGetMaxOffsetNumber(page);
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if ((int) offnum <= 0 || (int) offnum > nline)
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elog(ERROR, "PageIndexTupleDelete: bad offnum %u", offnum);
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/* change offset number to offset index */
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offidx = offnum - 1;
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tup = PageGetItemId(page, offnum);
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size = ItemIdGetLength(tup);
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size = MAXALIGN(size);
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offset = ItemIdGetOffset(tup);
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/* location of deleted tuple data */
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locn = (char *) (page + ItemIdGetOffset(tup));
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if (offset < phdr->pd_upper || (offset + size) > phdr->pd_special ||
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offset != MAXALIGN(offset) || size != MAXALIGN(size))
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elog(ERROR, "PageIndexTupleDelete: corrupted item pointer: offset = %u size = %u",
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offset, size);
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/*
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* First, we want to get rid of the pd_linp entry for the index tuple.
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* We copy all subsequent linp's back one slot in the array.
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*/
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nbytes = phdr->pd_lower -
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((char *) &phdr->pd_linp[offidx + 1] - (char *) phdr);
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memmove((char *) &(phdr->pd_linp[offidx]),
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(char *) &(phdr->pd_linp[offidx + 1]),
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nbytes);
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@@ -470,52 +470,28 @@ PageIndexTupleDelete(Page page, OffsetNumber offnum)
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*/
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/* beginning of tuple space */
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addr = (char *) (page + phdr->pd_upper);
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addr = (char *) page + phdr->pd_upper;
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if (locn != addr)
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memmove(addr + size, addr, (int) (locn - addr));
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if (offset > phdr->pd_upper)
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memmove(addr + size, addr, (int) (offset - phdr->pd_upper));
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/* adjust free space boundary pointers */
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phdr->pd_upper += size;
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phdr->pd_lower -= sizeof(ItemIdData);
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/* finally, we need to adjust the linp entries that remain */
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/*
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* Finally, we need to adjust the linp entries that remain.
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*
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* Anything that used to be before the deleted tuple's data was moved
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* forward by the size of the deleted tuple.
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*/
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if (!PageIsEmpty(page))
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PageIndexTupleDeleteAdjustLinePointers(phdr, locn, size);
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}
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/*
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*----------------------------------------------------------------
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* PageIndexTupleDeleteAdjustLinePointers
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*----------------------------------------------------------------
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*
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* Once the line pointers and tuple data have been shifted around
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* on the page, we need to go down the line pointer vector and
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* adjust pointers to reflect new locations. Anything that used
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* to be before the deleted tuple's data was moved forward by the
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* size of the deleted tuple.
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*
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* This routine does the work of adjusting the line pointers.
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* Location is where the tuple data used to lie; size is how
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* much space it occupied. We assume that size has been aligned
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* as required by the time we get here.
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*
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* This routine should never be called on an empty page.
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*/
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static void
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PageIndexTupleDeleteAdjustLinePointers(PageHeader phdr,
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char *location,
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Size size)
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{
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int i;
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unsigned offset;
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/* location is an index into the page... */
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offset = (unsigned) (location - (char *) phdr);
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for (i = PageGetMaxOffsetNumber((Page) phdr) - 1; i >= 0; i--)
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{
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if (phdr->pd_linp[i].lp_off <= offset)
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phdr->pd_linp[i].lp_off += size;
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nline--; /* there's one less than when we started */
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for (i = nline; --i >= 0; )
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{
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if (phdr->pd_linp[i].lp_off <= offset)
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phdr->pd_linp[i].lp_off += size;
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}
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}
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}
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