/*----------
* Add an item to a disk page from the sort output.
*
* We must be careful to observe the page layout conventions of nbtsearch.c:
* - rightmost pages start data items at P_HIKEY instead of at P_FIRSTKEY.
* - on non-leaf pages, the key portion of the first item need not be
* stored, we should store only the link.
*
* A leaf page being built looks like:
*
* +----------------+---------------------------------+
* | PageHeaderData | linp0 linp1 linp2 ... |
* +-----------+----+---------------------------------+
* | ... linpN | |
* +-----------+--------------------------------------+
* | ^ last |
* | |
* +-------------+------------------------------------+
* | | itemN ... |
* +-------------+------------------+-----------------+
* | ... item3 item2 item1 | "special space" |
* +--------------------------------+-----------------+
*
* Contrast this with the diagram in bufpage.h; note the mismatch
* between linps and items. This is because we reserve linp0 as a
* placeholder for the pointer to the "high key" item; when we have
* filled up the page, we will set linp0 to point to itemN and clear
* linpN. On the other hand, if we find this is the last (rightmost)
* page, we leave the items alone and slide the linp array over.
*
* 'last' pointer indicates the last offset added to the page.
*----------
*/
static void
_bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup)
{
Page npage;
BlockNumber nblkno;
OffsetNumber last_off;
Size pgspc;
Size itupsz;
/*
* This is a handy place to check for cancel interrupts during the btree
* load phase of index creation.
*/
CHECK_FOR_INTERRUPTS();
npage = state->btps_page;
nblkno = state->btps_blkno;
last_off = state->btps_lastoff;
pgspc = PageGetFreeSpace(npage);
itupsz = IndexTupleDSize(*itup);
itupsz = MAXALIGN(itupsz);
/*
* Check whether the item can fit on a btree page at all. (Eventually, we
* ought to try to apply TOAST methods if not.) We actually need to be
* able to fit three items on every page, so restrict any one item to 1/3
* the per-page available space. Note that at this point, itupsz doesn't
* include the ItemId.
*
* NOTE: similar code appears in _bt_insertonpg() to defend against
* oversize items being inserted into an already-existing index. But
* during creation of an index, we don't go through there.
*/
if (itupsz > BTMaxItemSize(npage))
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("index row size %zu exceeds maximum %zu for index \"%s\"",
itupsz, BTMaxItemSize(npage),
RelationGetRelationName(wstate->index)),
errhint("Values larger than 1/3 of a buffer page cannot be indexed.\n"
"Consider a function index of an MD5 hash of the value, "
"or use full text indexing."),
errtableconstraint(wstate->heap,
RelationGetRelationName(wstate->index))));
/*
* Check to see if page is "full". It's definitely full if the item won't
* fit. Otherwise, compare to the target freespace derived from the
* fillfactor. However, we must put at least two items on each page, so
* disregard fillfactor if we don't have that many.
*/
if (pgspc < itupsz || (pgspc < state->btps_full && last_off > P_FIRSTKEY))
{
/*
* Finish off the page and write it out.
*/
Page opage = npage;
BlockNumber oblkno = nblkno;
ItemId ii;
ItemId hii;
IndexTuple oitup;
/* Create new page of same level */
npage = _bt_blnewpage(state->btps_level);
/* and assign it a page position */
nblkno = wstate->btws_pages_alloced++;
/*
* We copy the last item on the page into the new page, and then
* rearrange the old page so that the 'last item' becomes its high key
* rather than a true data item. There had better be at least two
* items on the page already, else the page would be empty of useful
* data.
*/
Assert(last_off > P_FIRSTKEY);
ii = PageGetItemId(opage, last_off);
oitup = (IndexTuple) PageGetItem(opage, ii);
_bt_sortaddtup(npage, ItemIdGetLength(ii), oitup, P_FIRSTKEY);
/*
* Move 'last' into the high key position on opage
*/
hii = PageGetItemId(opage, P_HIKEY);
*hii = *ii;
ItemIdSetUnused(ii); /* redundant */
((PageHeader) opage)->pd_lower -= sizeof(ItemIdData);
/*
* Link the old page into its parent, using its minimum key. If we
* don't have a parent, we have to create one; this adds a new btree
* level.
*/
if (state->btps_next == NULL)
state->btps_next = _bt_pagestate(wstate, state->btps_level + 1);
Assert(state->btps_minkey != NULL);
ItemPointerSet(&(state->btps_minkey->t_tid), oblkno, P_HIKEY);
_bt_buildadd(wstate, state->btps_next, state->btps_minkey);
pfree(state->btps_minkey);
/*
* Save a copy of the minimum key for the new page. We have to copy
* it off the old page, not the new one, in case we are not at leaf
* level.
*/
state->btps_minkey = CopyIndexTuple(oitup);
/*
* Set the sibling links for both pages.
*/
{
BTPageOpaque oopaque = (BTPageOpaque) PageGetSpecialPointer(opage);
BTPageOpaque nopaque = (BTPageOpaque) PageGetSpecialPointer(npage);
oopaque->btpo_next = nblkno;
nopaque->btpo_prev = oblkno;
nopaque->btpo_next = P_NONE; /* redundant */
}
/*
* Write out the old page. We never need to touch it again, so we can
* free the opage workspace too.
*/
_bt_blwritepage(wstate, opage, oblkno);
/*
* Reset last_off to point to new page
*/
last_off = P_FIRSTKEY;
}
/*
* If the new item is the first for its page, stash a copy for later. Note
* this will only happen for the first item on a level; on later pages,
* the first item for a page is copied from the prior page in the code
* above.
*/
if (last_off == P_HIKEY)
{
Assert(state->btps_minkey == NULL);
state->btps_minkey = CopyIndexTuple(itup);
}
/*
* Add the new item into the current page.
*/
last_off = OffsetNumberNext(last_off);
_bt_sortaddtup(npage, itupsz, itup, last_off);
state->btps_page = npage;
state->btps_blkno = nblkno;
state->btps_lastoff = last_off;
}
/*
* Insert an entry and perhaps return the top element of the heap in *e
*
* Comparison happens from the specified level to the end of levels, as needed:
* Return < 0 if smaller than heap top; *e is unchanged
* Return = 0 if eq to heap top ; *e is unchanged (but will have value equal to the heap top)
* Return > 0 if successfully inserted; *e is populated with the removed heap top
*
* If 0 would be returned but the heap is marked as needing uniqueness enforcement, error is generated instead
*/
static int
mkheap_putAndGet_impl(MKHeap *mkheap, MKEntry *e)
{
int c = 0;
int toplv;
MKEntry tmp;
/* can't put+get from an empty heap */
Assert(mkheap->count > 0);
if (mkheap->mkctxt->enforceUnique &&
mke_has_duplicates_with_root(mkheap))
{
/**
* See NOTE ON UNIQUENESS CHECKING in the comment at the top of the file
* for information about why we check for duplicates here
*/
Datum values[INDEX_MAX_KEYS];
bool isnull[INDEX_MAX_KEYS];
index_deform_tuple((IndexTuple) mkheap->p->ptr, mkheap->mkctxt->tupdesc, values, isnull);
ereport(ERROR,
(errcode(ERRCODE_UNIQUE_VIOLATION),
errmsg("could not create unique index \"%s\"",
RelationGetRelationName(mkheap->mkctxt->indexRel)),
errdetail("Key %s is duplicated.",
BuildIndexValueDescription(mkheap->mkctxt->indexRel,
values, isnull)),
errtableconstraint(mkheap->mkctxt->heapRel,
RelationGetRelationName(mkheap->mkctxt->indexRel))));
}
if (mke_is_empty(e))
{
/*
* adding an empty (sentinel): just remove from count and fallthrough
* to where top is removed
*/
--mkheap->count;
}
else if (mke_get_run(e) != mke_get_run(mkheap->p))
{
/*
* this code assumes that the new one, with lower run, is LARGER than
* the top -- so it must be larger run
*/
Assert(mke_get_run(e) > mke_get_run(mkheap->p));
/*
* when the runs differ it is because we attempted once with the runs
* equal. So if level is zero then: the level was zero AND validly
* prepared for the previous run -- and there is no need to prep again
*/
if (mke_get_lv(e) != 0)
{
/* Not same run, at least prepare lv 0 */
if (mkheap->mkctxt->fetchForPrep)
tupsort_prepare(e, mkheap->mkctxt, 0);
mke_set_lv(e, 0);
}
/*
* now fall through and let top be returned, new one is also inserted
* so no change to count
*/
}
else
{
/* same run so figure out where it fits in relation to the heap top */
int lv = 0;
toplv = mke_get_lv(mkheap->p);
mke_set_lv(e, lv);
/* populate level until we differ from the top element of the heap */
while (lv < toplv)
{
if (mkheap->mkctxt->fetchForPrep)
tupsort_prepare(e, mkheap->mkctxt, lv);
c = mkheap_compare(mkheap, e, mkheap->lvtops + lv);
if (c != 0)
break;
mke_set_lv(e, ++lv);
}
/* smaller than top */
if (c < 0)
return -1;
/*
* we have not done e->lv == toplv yet since we increment at the end
* of the previous loop. Do it now.
*/
Assert(mke_get_lv(e) == lv);
if (lv == toplv)
{
if (mkheap->mkctxt->fetchForPrep)
tupsort_prepare(e, mkheap->mkctxt, lv);
c = mkheap_compare(mkheap, e, mkheap->p);
if (c < 0)
return -1;
}
if (c == 0)
{
/*
* Equal and at top level.
*
* This means that e is less-than/equal to all entries except the
* heap top.
*/
Assert(mke_get_lv(e) == lv);
Assert(lv == mke_get_lv(mkheap->p));
/*
* Expand more levels of lvtop in the current top and the new one
* until we detect a difference.
*/
while (lv < mkheap->mkctxt->total_lv - 1)
{
mkheap_save_lvtop(mkheap);
++lv;
/* expand top */
if (mkheap->mkctxt->fetchForPrep)
tupsort_prepare(mkheap->p, mkheap->mkctxt, lv);
/* expand new element */
if (mkheap->mkctxt->fetchForPrep)
tupsort_prepare(e, mkheap->mkctxt, lv);
mke_set_lv(mkheap->p, lv);
mke_set_lv(e, lv);
c = mkheap_compare(mkheap, e, mkheap->p);
if (c != 0)
break;
}
if (c <= 0)
{
/*
* if new one is less than current top then we just return
* that negative comparison
*/
/*
* if new one equals the current top then we could do an
* insert and immediate removal -- but it won't matter so we
* simply return right away, leaving *e untouched
*/
/* enforce uniqueness first */
if (c == 0 && mkheap->mkctxt->enforceUnique)
{
Datum values[INDEX_MAX_KEYS];
bool isnull[INDEX_MAX_KEYS];
index_deform_tuple((IndexTuple) mkheap->p->ptr, mkheap->mkctxt->tupdesc, values, isnull);
ereport(ERROR,
(errcode(ERRCODE_UNIQUE_VIOLATION),
errmsg("could not create unique index \"%s\"",
RelationGetRelationName(mkheap->mkctxt->indexRel)),
errdetail("Key %s is duplicated.",
BuildIndexValueDescription(mkheap->mkctxt->indexRel,
values, isnull))));
}
return c;
}
}
}
/*
* Now, I am bigger than top but not definitely smaller/equal to all other
* entries
*
* So we will: return top as *e do heap shuffling to restore heap ordering
*/
tmp = *e;
*e = mkheap->p[0];
/* Sift down a hole to bottom of (current or next) run, depends on tmp.run */
mkheap_siftdown(mkheap, 0, &tmp);
if (mkheap_need_heapify(mkheap))
mkheap_heapify(mkheap, false);
if (mkheap->count > 0)
{
mkheap_update_lvtops(mkheap);
}
#ifdef USE_ASSERT_CHECKING
if (gp_mk_sort_check)
mkheap_verify_heap(mkheap, 0);
#endif
return 1;
}