Exemple #1
0
/*
 * Update lastUsedPages cache when done modifying a page.
 *
 * We update the appropriate cache entry if it already contained this page
 * (its freeSpace is likely obsolete), or if this page has more space than
 * whatever we had cached.
 */
void
SpGistSetLastUsedPage(Relation index, Buffer buffer)
{
	SpGistCache *cache = spgGetCache(index);
	SpGistLastUsedPage *lup;
	int			freeSpace;
	Page		page = BufferGetPage(buffer);
	BlockNumber blkno = BufferGetBlockNumber(buffer);
	int			flags;

	/* Never enter fixed pages (root pages) in cache, though */
	if (SpGistBlockIsFixed(blkno))
		return;

	if (SpGistPageIsLeaf(page))
		flags = GBUF_LEAF;
	else
		flags = GBUF_INNER_PARITY(blkno);
	if (SpGistPageStoresNulls(page))
		flags |= GBUF_NULLS;

	lup = GET_LUP(cache, flags);

	freeSpace = PageGetExactFreeSpace(page);
	if (lup->blkno == InvalidBlockNumber || lup->blkno == blkno ||
		lup->freeSpace < freeSpace)
	{
		lup->blkno = blkno;
		lup->freeSpace = freeSpace;
	}
}
Exemple #2
0
/*
 * Update lastUsedPages cache when done modifying a page.
 *
 * We update the appropriate cache entry if it already contained this page
 * (its freeSpace is likely obsolete), or if this page has more space than
 * whatever we had cached.
 */
void
SpGistSetLastUsedPage(Relation index, Buffer buffer)
{
	SpGistCache *cache = spgGetCache(index);
	SpGistLastUsedPage *lup;
	int			freeSpace;
	Page		page = BufferGetPage(buffer);
	BlockNumber blkno = BufferGetBlockNumber(buffer);
	int			flags;

	/* Never enter the root page in cache, though */
	if (blkno == SPGIST_HEAD_BLKNO)
		return;

	if (SpGistPageIsLeaf(page))
		flags = GBUF_LEAF;
	else
		flags = GBUF_INNER_PARITY(blkno);

	lup = GET_LUP(cache, flags);

	freeSpace = PageGetExactFreeSpace(page);
	if (lup->blkno == InvalidBlockNumber || lup->blkno == blkno ||
		lup->freeSpace < freeSpace)
	{
		lup->blkno = blkno;
		lup->freeSpace = freeSpace;
	}
}
Exemple #3
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);
}