Esempio n. 1
0
/*
 * Allocate a new page (either by recycling, or by extending the index file).
 *
 * The returned buffer is already pinned and exclusive-locked.
 * Caller is responsible for initializing the page by calling SpGistInitBuffer.
 */
Buffer
SpGistNewBuffer(Relation index)
{
	Buffer		buffer;
	bool		needLock;

	/* First, try to get a page from FSM */
	for (;;)
	{
		BlockNumber blkno = GetFreeIndexPage(index);

		if (blkno == InvalidBlockNumber)
			break;				/* nothing known to FSM */

		/*
		 * The fixed pages shouldn't ever be listed in FSM, but just in case
		 * one is, ignore it.
		 */
		if (SpGistBlockIsFixed(blkno))
			continue;

		buffer = ReadBuffer(index, blkno);

		/*
		 * We have to guard against the possibility that someone else already
		 * recycled this page; the buffer may be locked if so.
		 */
		if (ConditionalLockBuffer(buffer))
		{
			Page		page = BufferGetPage(buffer);

			if (PageIsNew(page))
				return buffer;	/* OK to use, if never initialized */

			if (SpGistPageIsDeleted(page) || PageIsEmpty(page))
				return buffer;	/* OK to use */

			LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
		}

		/* Can't use it, so release buffer and try again */
		ReleaseBuffer(buffer);
	}

	/* Must extend the file */
	needLock = !RELATION_IS_LOCAL(index);
	if (needLock)
		LockRelationForExtension(index, ExclusiveLock);

	buffer = ReadBuffer(index, P_NEW);
	LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);

	if (needLock)
		UnlockRelationForExtension(index, ExclusiveLock);

	return buffer;
}
Esempio n. 2
0
/*
 * Process the pending-TID list between pages of the main scan
 */
static void
spgprocesspending(spgBulkDeleteState *bds)
{
	Relation	index = bds->info->index;
	spgVacPendingItem *pitem;
	spgVacPendingItem *nitem;
	BlockNumber blkno;
	Buffer		buffer;
	Page		page;

	for (pitem = bds->pendingList; pitem != NULL; pitem = pitem->next)
	{
		if (pitem->done)
			continue;			/* ignore already-done items */

		/* call vacuum_delay_point while not holding any buffer lock */
		vacuum_delay_point();

		/* examine the referenced page */
		blkno = ItemPointerGetBlockNumber(&pitem->tid);
		buffer = ReadBufferExtended(index, MAIN_FORKNUM, blkno,
									RBM_NORMAL, bds->info->strategy);
		LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
		page = (Page) BufferGetPage(buffer);

		if (PageIsNew(page) || SpGistPageIsDeleted(page))
		{
			/* Probably shouldn't happen, but ignore it */
		}
		else if (SpGistPageIsLeaf(page))
		{
			if (SpGistBlockIsRoot(blkno))
			{
				/* this should definitely not happen */
				elog(ERROR, "redirection leads to root page of index \"%s\"",
					 RelationGetRelationName(index));
			}

			/* deal with any deletable tuples */
			vacuumLeafPage(bds, index, buffer, true);
			/* might as well do this while we are here */
			vacuumRedirectAndPlaceholder(index, buffer);

			SpGistSetLastUsedPage(index, buffer);

			/*
			 * We can mark as done not only this item, but any later ones
			 * pointing at the same page, since we vacuumed the whole page.
			 */
			pitem->done = true;
			for (nitem = pitem->next; nitem != NULL; nitem = nitem->next)
			{
				if (ItemPointerGetBlockNumber(&nitem->tid) == blkno)
					nitem->done = true;
			}
		}
		else
		{
			/*
			 * On an inner page, visit the referenced inner tuple and add all
			 * its downlinks to the pending list.  We might have pending items
			 * for more than one inner tuple on the same page (in fact this is
			 * pretty likely given the way space allocation works), so get
			 * them all while we are here.
			 */
			for (nitem = pitem; nitem != NULL; nitem = nitem->next)
			{
				if (nitem->done)
					continue;
				if (ItemPointerGetBlockNumber(&nitem->tid) == blkno)
				{
					OffsetNumber offset;
					SpGistInnerTuple innerTuple;

					offset = ItemPointerGetOffsetNumber(&nitem->tid);
					innerTuple = (SpGistInnerTuple) PageGetItem(page,
												PageGetItemId(page, offset));
					if (innerTuple->tupstate == SPGIST_LIVE)
					{
						SpGistNodeTuple node;
						int			i;

						SGITITERATE(innerTuple, i, node)
						{
							if (ItemPointerIsValid(&node->t_tid))
								spgAddPendingTID(bds, &node->t_tid);
						}
					}
					else if (innerTuple->tupstate == SPGIST_REDIRECT)
					{
						/* transfer attention to redirect point */
						spgAddPendingTID(bds,
								   &((SpGistDeadTuple) innerTuple)->pointer);
					}
					else
						elog(ERROR, "unexpected SPGiST tuple state: %d",
							 innerTuple->tupstate);

					nitem->done = true;
				}
			}
Esempio n. 3
0
/*
 * Process one page during a bulkdelete scan
 */
static void
spgvacuumpage(spgBulkDeleteState *bds, BlockNumber blkno)
{
	Relation	index = bds->info->index;
	Buffer		buffer;
	Page		page;

	/* call vacuum_delay_point while not holding any buffer lock */
	vacuum_delay_point();

	buffer = ReadBufferExtended(index, MAIN_FORKNUM, blkno,
								RBM_NORMAL, bds->info->strategy);
	LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
	page = (Page) BufferGetPage(buffer);

	if (PageIsNew(page))
	{
		/*
		 * We found an all-zero page, which could happen if the database
		 * crashed just after extending the file.  Initialize and recycle it.
		 */
		SpGistInitBuffer(buffer, 0);
		SpGistPageSetDeleted(page);
		/* We don't bother to WAL-log this action; easy to redo */
		MarkBufferDirty(buffer);
	}
	else if (SpGistPageIsDeleted(page))
	{
		/* nothing to do */
	}
	else if (SpGistPageIsLeaf(page))
	{
		if (SpGistBlockIsRoot(blkno))
		{
			vacuumLeafRoot(bds, index, buffer);
			/* no need for vacuumRedirectAndPlaceholder */
		}
		else
		{
			vacuumLeafPage(bds, index, buffer, false);
			vacuumRedirectAndPlaceholder(index, buffer);
		}
	}
	else
	{
		/* inner page */
		vacuumRedirectAndPlaceholder(index, buffer);
	}

	/*
	 * The root pages must never be deleted, nor marked as available in FSM,
	 * because we don't want them ever returned by a search for a place to put
	 * a new tuple.  Otherwise, check for empty/deletable page, and make sure
	 * FSM knows about it.
	 */
	if (!SpGistBlockIsRoot(blkno))
	{
		/* If page is now empty, mark it deleted */
		if (PageIsEmpty(page) && !SpGistPageIsDeleted(page))
		{
			SpGistPageSetDeleted(page);
			/* We don't bother to WAL-log this action; easy to redo */
			MarkBufferDirty(buffer);
		}

		if (SpGistPageIsDeleted(page))
		{
			RecordFreeIndexPage(index, blkno);
			bds->stats->pages_deleted++;
		}
		else
			bds->lastFilledBlock = blkno;
	}

	SpGistSetLastUsedPage(index, buffer);

	UnlockReleaseBuffer(buffer);
}
Esempio n. 4
0
/*
 * Get a buffer of the type and parity specified by flags, having at least
 * as much free space as indicated by needSpace.  We use the lastUsedPages
 * cache to assign the same buffer previously requested when possible.
 * The returned buffer is already pinned and exclusive-locked.
 *
 * *isNew is set true if the page was initialized here, false if it was
 * already valid.
 */
Buffer
SpGistGetBuffer(Relation index, int flags, int needSpace, bool *isNew)
{
	SpGistCache *cache = spgGetCache(index);
	SpGistLastUsedPage *lup;

	/* Bail out if even an empty page wouldn't meet the demand */
	if (needSpace > SPGIST_PAGE_CAPACITY)
		elog(ERROR, "desired SPGiST tuple size is too big");

	/*
	 * If possible, increase the space request to include relation's
	 * fillfactor.	This ensures that when we add unrelated tuples to a page,
	 * we try to keep 100-fillfactor% available for adding tuples that are
	 * related to the ones already on it.  But fillfactor mustn't cause an
	 * error for requests that would otherwise be legal.
	 */
	needSpace += RelationGetTargetPageFreeSpace(index,
												SPGIST_DEFAULT_FILLFACTOR);
	needSpace = Min(needSpace, SPGIST_PAGE_CAPACITY);

	/* Get the cache entry for this flags setting */
	lup = GET_LUP(cache, flags);

	/* If we have nothing cached, just turn it over to allocNewBuffer */
	if (lup->blkno == InvalidBlockNumber)
	{
		*isNew = true;
		return allocNewBuffer(index, flags);
	}

	/* fixed pages should never be in cache */
	Assert(!SpGistBlockIsFixed(lup->blkno));

	/* If cached freeSpace isn't enough, don't bother looking at the page */
	if (lup->freeSpace >= needSpace)
	{
		Buffer		buffer;
		Page		page;

		buffer = ReadBuffer(index, lup->blkno);

		if (!ConditionalLockBuffer(buffer))
		{
			/*
			 * buffer is locked by another process, so return a new buffer
			 */
			ReleaseBuffer(buffer);
			*isNew = true;
			return allocNewBuffer(index, flags);
		}

		page = BufferGetPage(buffer);

		if (PageIsNew(page) || SpGistPageIsDeleted(page) || PageIsEmpty(page))
		{
			/* OK to initialize the page */
			uint16		pageflags = 0;

			if (GBUF_REQ_LEAF(flags))
				pageflags |= SPGIST_LEAF;
			if (GBUF_REQ_NULLS(flags))
				pageflags |= SPGIST_NULLS;
			SpGistInitBuffer(buffer, pageflags);
			lup->freeSpace = PageGetExactFreeSpace(page) - needSpace;
			*isNew = true;
			return buffer;
		}

		/*
		 * Check that page is of right type and has enough space.  We must
		 * recheck this since our cache isn't necessarily up to date.
		 */
		if ((GBUF_REQ_LEAF(flags) ? SpGistPageIsLeaf(page) : !SpGistPageIsLeaf(page)) &&
			(GBUF_REQ_NULLS(flags) ? SpGistPageStoresNulls(page) : !SpGistPageStoresNulls(page)))
		{
			int			freeSpace = PageGetExactFreeSpace(page);

			if (freeSpace >= needSpace)
			{
				/* Success, update freespace info and return the buffer */
				lup->freeSpace = freeSpace - needSpace;
				*isNew = false;
				return buffer;
			}
		}

		/*
		 * fallback to allocation of new buffer
		 */
		UnlockReleaseBuffer(buffer);
	}

	/* No success with cache, so return a new buffer */
	*isNew = true;
	return allocNewBuffer(index, flags);
}