Exemple #1
0
/*
 * Collect visibility data about a relation.
 */
static vbits *
collect_visibility_data(Oid relid, bool include_pd)
{
	Relation	rel;
	BlockNumber	nblocks;
	vbits	   *info;
	BlockNumber	blkno;
	Buffer		vmbuffer = InvalidBuffer;
	BufferAccessStrategy	bstrategy = GetAccessStrategy(BAS_BULKREAD);

	rel = relation_open(relid, AccessShareLock);

	nblocks = RelationGetNumberOfBlocks(rel);
	info = palloc0(offsetof(vbits, bits) + nblocks);
	info->next = 0;
	info->count = nblocks;

	for (blkno = 0; blkno < nblocks; ++blkno)
	{
		int32		mapbits;

		/* Make sure we are interruptible. */
		CHECK_FOR_INTERRUPTS();

		/* Get map info. */
		mapbits = (int32) visibilitymap_get_status(rel, blkno, &vmbuffer);
		if ((mapbits & VISIBILITYMAP_ALL_VISIBLE) != 0)
			info->bits[blkno] |= (1 << 0);
		if ((mapbits & VISIBILITYMAP_ALL_FROZEN) != 0)
			info->bits[blkno] |= (1 << 1);

		/*
		 * Page-level data requires reading every block, so only get it if
		 * the caller needs it.  Use a buffer access strategy, too, to prevent
		 * cache-trashing.
		 */
		if (include_pd)
		{
			Buffer		buffer;
			Page		page;

			buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
										bstrategy);
			LockBuffer(buffer, BUFFER_LOCK_SHARE);

			page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
			if (PageIsAllVisible(page))
				info->bits[blkno] |= (1 << 2);

			UnlockReleaseBuffer(buffer);
		}
	}

	/* Clean up. */
	if (vmbuffer != InvalidBuffer)
		ReleaseBuffer(vmbuffer);
	relation_close(rel, AccessShareLock);

	return info;
}
Exemple #2
0
/*
 * pgstat_index -- returns live/dead tuples info in a generic index
 */
static Datum
pgstat_index(Relation rel, BlockNumber start, pgstat_page pagefn,
			 FunctionCallInfo fcinfo)
{
	BlockNumber nblocks;
	BlockNumber blkno;
	BufferAccessStrategy bstrategy;
	pgstattuple_type stat = {0};

	/* prepare access strategy for this index */
	bstrategy = GetAccessStrategy(BAS_BULKREAD);

	blkno = start;
	for (;;)
	{
		/* Get the current relation length */
		LockRelationForExtension(rel, ExclusiveLock);
		nblocks = RelationGetNumberOfBlocks(rel);
		UnlockRelationForExtension(rel, ExclusiveLock);

		/* Quit if we've scanned the whole relation */
		if (blkno >= nblocks)
		{
			stat.table_len = (uint64) nblocks *BLCKSZ;

			break;
		}

		for (; blkno < nblocks; blkno++)
		{
			CHECK_FOR_INTERRUPTS();

			pagefn(&stat, rel, blkno, bstrategy);
		}
	}

	relation_close(rel, AccessShareLock);

	return build_pgstattuple_type(&stat, fcinfo);
}
Exemple #3
0
static Datum
pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
{
	Datum		result;
	BlockNumber nblocks;
	BlockNumber blkno;
	BTIndexStat indexStat;
	BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);

	if (!IS_INDEX(rel) || !IS_BTREE(rel))
		elog(ERROR, "relation \"%s\" is not a btree index",
			 RelationGetRelationName(rel));

	/*
	 * Reject attempts to read non-local temporary relations; we would be
	 * likely to get wrong data since we have no visibility into the owning
	 * session's local buffers.
	 */
	if (RELATION_IS_OTHER_TEMP(rel))
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("cannot access temporary tables of other sessions")));

	/*
	 * Read metapage
	 */
	{
		Buffer		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, 0, RBM_NORMAL, bstrategy);
		Page		page = BufferGetPage(buffer);
		BTMetaPageData *metad = BTPageGetMeta(page);

		indexStat.version = metad->btm_version;
		indexStat.level = metad->btm_level;
		indexStat.root_blkno = metad->btm_root;

		ReleaseBuffer(buffer);
	}

	/* -- init counters -- */
	indexStat.internal_pages = 0;
	indexStat.leaf_pages = 0;
	indexStat.empty_pages = 0;
	indexStat.deleted_pages = 0;

	indexStat.max_avail = 0;
	indexStat.free_space = 0;

	indexStat.fragments = 0;

	/*
	 * Scan all blocks except the metapage
	 */
	nblocks = RelationGetNumberOfBlocks(rel);

	for (blkno = 1; blkno < nblocks; blkno++)
	{
		Buffer		buffer;
		Page		page;
		BTPageOpaque opaque;

		CHECK_FOR_INTERRUPTS();

		/* Read and lock buffer */
		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
		LockBuffer(buffer, BUFFER_LOCK_SHARE);

		page = BufferGetPage(buffer);
		opaque = (BTPageOpaque) PageGetSpecialPointer(page);

		/* Determine page type, and update totals */

		if (P_ISDELETED(opaque))
			indexStat.deleted_pages++;
		else if (P_IGNORE(opaque))
			indexStat.empty_pages++;	/* this is the "half dead" state */
		else if (P_ISLEAF(opaque))
		{
			int			max_avail;

			max_avail = BLCKSZ - (BLCKSZ - ((PageHeader) page)->pd_special + SizeOfPageHeaderData);
			indexStat.max_avail += max_avail;
			indexStat.free_space += PageGetFreeSpace(page);

			indexStat.leaf_pages++;

			/*
			 * If the next leaf is on an earlier block, it means a
			 * fragmentation.
			 */
			if (opaque->btpo_next != P_NONE && opaque->btpo_next < blkno)
				indexStat.fragments++;
		}
		else
			indexStat.internal_pages++;

		/* Unlock and release buffer */
		LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
		ReleaseBuffer(buffer);
	}

	relation_close(rel, AccessShareLock);

	/*----------------------------
	 * Build a result tuple
	 *----------------------------
	 */
	{
		TupleDesc	tupleDesc;
		int			j;
		char	   *values[10];
		HeapTuple	tuple;

		/* Build a tuple descriptor for our result type */
		if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
			elog(ERROR, "return type must be a row type");

		j = 0;
		values[j++] = psprintf("%d", indexStat.version);
		values[j++] = psprintf("%d", indexStat.level);
		values[j++] = psprintf(INT64_FORMAT,
							   (1 +		/* include the metapage in index_size */
								indexStat.leaf_pages +
								indexStat.internal_pages +
								indexStat.deleted_pages +
								indexStat.empty_pages) * BLCKSZ);
		values[j++] = psprintf("%u", indexStat.root_blkno);
		values[j++] = psprintf(INT64_FORMAT, indexStat.internal_pages);
		values[j++] = psprintf(INT64_FORMAT, indexStat.leaf_pages);
		values[j++] = psprintf(INT64_FORMAT, indexStat.empty_pages);
		values[j++] = psprintf(INT64_FORMAT, indexStat.deleted_pages);
		if (indexStat.max_avail > 0)
			values[j++] = psprintf("%.2f",
								   100.0 - (double) indexStat.free_space / (double) indexStat.max_avail * 100.0);
		else
			values[j++] = pstrdup("NaN");
		if (indexStat.leaf_pages > 0)
			values[j++] = psprintf("%.2f",
								   (double) indexStat.fragments / (double) indexStat.leaf_pages * 100.0);
		else
			values[j++] = pstrdup("NaN");

		tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
									   values);

		result = HeapTupleGetDatum(tuple);
	}

	return result;
}
Exemple #4
0
/* ------------------------------------------------------
 * pgstathashindex()
 *
 * Usage: SELECT * FROM pgstathashindex('hashindex');
 * ------------------------------------------------------
 */
Datum
pgstathashindex(PG_FUNCTION_ARGS)
{
	Oid			relid = PG_GETARG_OID(0);
	BlockNumber	nblocks;
	BlockNumber	blkno;
	Relation	rel;
	HashIndexStat stats;
	BufferAccessStrategy bstrategy;
	HeapTuple	tuple;
	TupleDesc	tupleDesc;
	Datum		values[8];
	bool		nulls[8];
	Buffer		metabuf;
	HashMetaPage	metap;
	float8		free_percent;
	uint64		total_space;

	rel = index_open(relid, AccessShareLock);

	/* index_open() checks that it's an index */
	if (!IS_HASH(rel))
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("relation \"%s\" is not a HASH index",
						RelationGetRelationName(rel))));


	/*
	 * Reject attempts to read non-local temporary relations; we would be
	 * likely to get wrong data since we have no visibility into the owning
	 * session's local buffers.
	 */
	if (RELATION_IS_OTHER_TEMP(rel))
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
			   errmsg("cannot access temporary indexes of other sessions")));

	/* Get the information we need from the metapage. */
	memset(&stats, 0, sizeof(stats));
	metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE);
	metap = HashPageGetMeta(BufferGetPage(metabuf));
	stats.version = metap->hashm_version;
	stats.space_per_page = metap->hashm_bsize;
	_hash_relbuf(rel, metabuf);

	/* Get the current relation length */
	nblocks = RelationGetNumberOfBlocks(rel);

	/* prepare access strategy for this index */
	bstrategy = GetAccessStrategy(BAS_BULKREAD);

	/* Start from blkno 1 as 0th block is metapage */
	for (blkno = 1; blkno < nblocks; blkno++)
	{
		Buffer		buf;
		Page		page;

		CHECK_FOR_INTERRUPTS();

		buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
								 bstrategy);
		LockBuffer(buf, BUFFER_LOCK_SHARE);
		page = (Page) BufferGetPage(buf);

		if (PageIsNew(page))
			stats.unused_pages++;
		else if (PageGetSpecialSize(page) !=
				 MAXALIGN(sizeof(HashPageOpaqueData)))
			ereport(ERROR,
					(errcode(ERRCODE_INDEX_CORRUPTED),
					 errmsg("index \"%s\" contains corrupted page at block %u",
							RelationGetRelationName(rel),
							BufferGetBlockNumber(buf))));
		else
		{
			HashPageOpaque	opaque;
			int		pagetype;

			opaque = (HashPageOpaque) PageGetSpecialPointer(page);
			pagetype = opaque->hasho_flag & LH_PAGE_TYPE;

			if (pagetype == LH_BUCKET_PAGE)
			{
				stats.bucket_pages++;
				GetHashPageStats(page, &stats);
			}
			else if (pagetype == LH_OVERFLOW_PAGE)
			{
				stats.overflow_pages++;
				GetHashPageStats(page, &stats);
			}
			else if (pagetype == LH_BITMAP_PAGE)
				stats.bitmap_pages++;
			else if (pagetype == LH_UNUSED_PAGE)
				stats.unused_pages++;
			else
				ereport(ERROR,
						(errcode(ERRCODE_INDEX_CORRUPTED),
					errmsg("unexpected page type 0x%04X in HASH index \"%s\" block %u",
							opaque->hasho_flag, RelationGetRelationName(rel),
							BufferGetBlockNumber(buf))));
		}
		UnlockReleaseBuffer(buf);
	}

	/* Done accessing the index */
	index_close(rel, AccessShareLock);

	/* Count unused pages as free space. */
	stats.free_space += stats.unused_pages * stats.space_per_page;

	/*
	 * Total space available for tuples excludes the metapage and the bitmap
	 * pages.
	 */
	total_space = (nblocks - (stats.bitmap_pages + 1)) * stats.space_per_page;

	if (total_space == 0)
		free_percent = 0.0;
	else
		free_percent = 100.0 * stats.free_space / total_space;

	/*
	 * Build a tuple descriptor for our result type
	 */
	if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
		elog(ERROR, "return type must be a row type");

	tupleDesc = BlessTupleDesc(tupleDesc);

	/*
	 * Build and return the tuple
	 */
	MemSet(nulls, 0, sizeof(nulls));
	values[0] = Int32GetDatum(stats.version);
	values[1] = Int64GetDatum((int64) stats.bucket_pages);
	values[2] = Int64GetDatum((int64) stats.overflow_pages);
	values[3] = Int64GetDatum((int64) stats.bitmap_pages);
	values[4] = Int64GetDatum((int64) stats.unused_pages);
	values[5] = Int64GetDatum(stats.live_items);
	values[6] = Int64GetDatum(stats.dead_items);
	values[7] = Float8GetDatum(free_percent);
	tuple = heap_form_tuple(tupleDesc, values, nulls);

	PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
}
/*
 * This function takes an already open relation and scans its pages,
 * skipping those that have the corresponding visibility map bit set.
 * For pages we skip, we find the free space from the free space map
 * and approximate tuple_len on that basis. For the others, we count
 * the exact number of dead tuples etc.
 *
 * This scan is loosely based on vacuumlazy.c:lazy_scan_heap(), but
 * we do not try to avoid skipping single pages.
 */
static void
statapprox_heap(Relation rel, output_type *stat)
{
	BlockNumber scanned,
				nblocks,
				blkno;
	Buffer		vmbuffer = InvalidBuffer;
	BufferAccessStrategy bstrategy;
	TransactionId OldestXmin;
	uint64		misc_count = 0;

	OldestXmin = GetOldestXmin(rel, PROCARRAY_FLAGS_VACUUM);
	bstrategy = GetAccessStrategy(BAS_BULKREAD);

	nblocks = RelationGetNumberOfBlocks(rel);
	scanned = 0;

	for (blkno = 0; blkno < nblocks; blkno++)
	{
		Buffer		buf;
		Page		page;
		OffsetNumber offnum,
					maxoff;
		Size		freespace;

		CHECK_FOR_INTERRUPTS();

		/*
		 * If the page has only visible tuples, then we can find out the free
		 * space from the FSM and move on.
		 */
		if (VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
		{
			freespace = GetRecordedFreeSpace(rel, blkno);
			stat->tuple_len += BLCKSZ - freespace;
			stat->free_space += freespace;
			continue;
		}

		buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno,
								 RBM_NORMAL, bstrategy);

		LockBuffer(buf, BUFFER_LOCK_SHARE);

		page = BufferGetPage(buf);

		/*
		 * It's not safe to call PageGetHeapFreeSpace() on new pages, so we
		 * treat them as being free space for our purposes.
		 */
		if (!PageIsNew(page))
			stat->free_space += PageGetHeapFreeSpace(page);
		else
			stat->free_space += BLCKSZ - SizeOfPageHeaderData;

		if (PageIsNew(page) || PageIsEmpty(page))
		{
			UnlockReleaseBuffer(buf);
			continue;
		}

		scanned++;

		/*
		 * Look at each tuple on the page and decide whether it's live or
		 * dead, then count it and its size. Unlike lazy_scan_heap, we can
		 * afford to ignore problems and special cases.
		 */
		maxoff = PageGetMaxOffsetNumber(page);

		for (offnum = FirstOffsetNumber;
			 offnum <= maxoff;
			 offnum = OffsetNumberNext(offnum))
		{
			ItemId		itemid;
			HeapTupleData tuple;

			itemid = PageGetItemId(page, offnum);

			if (!ItemIdIsUsed(itemid) || ItemIdIsRedirected(itemid) ||
				ItemIdIsDead(itemid))
			{
				continue;
			}

			Assert(ItemIdIsNormal(itemid));

			ItemPointerSet(&(tuple.t_self), blkno, offnum);

			tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
			tuple.t_len = ItemIdGetLength(itemid);
			tuple.t_tableOid = RelationGetRelid(rel);

			/*
			 * We count live and dead tuples, but we also need to add up
			 * others in order to feed vac_estimate_reltuples.
			 */
			switch (HeapTupleSatisfiesVacuum(&tuple, OldestXmin, buf))
			{
				case HEAPTUPLE_RECENTLY_DEAD:
					misc_count++;
					/* Fall through */
				case HEAPTUPLE_DEAD:
					stat->dead_tuple_len += tuple.t_len;
					stat->dead_tuple_count++;
					break;
				case HEAPTUPLE_LIVE:
					stat->tuple_len += tuple.t_len;
					stat->tuple_count++;
					break;
				case HEAPTUPLE_INSERT_IN_PROGRESS:
				case HEAPTUPLE_DELETE_IN_PROGRESS:
					misc_count++;
					break;
				default:
					elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
					break;
			}
		}

		UnlockReleaseBuffer(buf);
	}

	stat->table_len = (uint64) nblocks *BLCKSZ;

	stat->tuple_count = vac_estimate_reltuples(rel, false, nblocks, scanned,
											 stat->tuple_count + misc_count);

	/*
	 * Calculate percentages if the relation has one or more pages.
	 */
	if (nblocks != 0)
	{
		stat->scanned_percent = 100 * scanned / nblocks;
		stat->tuple_percent = 100.0 * stat->tuple_len / stat->table_len;
		stat->dead_tuple_percent = 100.0 * stat->dead_tuple_len / stat->table_len;
		stat->free_percent = 100.0 * stat->free_space / stat->table_len;
	}

	if (BufferIsValid(vmbuffer))
	{
		ReleaseBuffer(vmbuffer);
		vmbuffer = InvalidBuffer;
	}
}
Exemple #6
0
/*
 * Insert all matching tuples into to a bitmap.
 */
int64
blgetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
{
	int64		ntids = 0;
	BlockNumber blkno = BLOOM_HEAD_BLKNO,
				npages;
	int			i;
	BufferAccessStrategy bas;
	BloomScanOpaque so = (BloomScanOpaque) scan->opaque;

	if (so->sign == NULL)
	{
		/* New search: have to calculate search signature */
		ScanKey		skey = scan->keyData;

		so->sign = palloc0(sizeof(SignType) * so->state.opts.bloomLength);

		for (i = 0; i < scan->numberOfKeys; i++)
		{
			/*
			 * Assume bloom-indexable operators to be strict, so nothing could
			 * be found for NULL key.
			 */
			if (skey->sk_flags & SK_ISNULL)
			{
				pfree(so->sign);
				so->sign = NULL;
				return 0;
			}

			/* Add next value to the signature */
			signValue(&so->state, so->sign, skey->sk_argument,
					  skey->sk_attno - 1);

			skey++;
		}
	}

	/*
	 * We're going to read the whole index. This is why we use appropriate
	 * buffer access strategy.
	 */
	bas = GetAccessStrategy(BAS_BULKREAD);
	npages = RelationGetNumberOfBlocks(scan->indexRelation);

	for (blkno = BLOOM_HEAD_BLKNO; blkno < npages; blkno++)
	{
		Buffer		buffer;
		Page		page;

		buffer = ReadBufferExtended(scan->indexRelation, MAIN_FORKNUM,
									blkno, RBM_NORMAL, bas);

		LockBuffer(buffer, BUFFER_LOCK_SHARE);
		page = BufferGetPage(buffer);
		TestForOldSnapshot(scan->xs_snapshot, scan->indexRelation, page);

		if (!BloomPageIsDeleted(page))
		{
			OffsetNumber offset,
						maxOffset = BloomPageGetMaxOffset(page);

			for (offset = 1; offset <= maxOffset; offset++)
			{
				BloomTuple *itup = BloomPageGetTuple(&so->state, page, offset);
				bool		res = true;

				/* Check index signature with scan signature */
				for (i = 0; i < so->state.opts.bloomLength; i++)
				{
					if ((itup->sign[i] & so->sign[i]) != so->sign[i])
					{
						res = false;
						break;
					}
				}

				/* Add matching tuples to bitmap */
				if (res)
				{
					tbm_add_tuples(tbm, &itup->heapPtr, 1, true);
					ntids++;
				}
			}
		}

		UnlockReleaseBuffer(buffer);
		CHECK_FOR_INTERRUPTS();
	}
	FreeAccessStrategy(bas);

	return ntids;
}
Exemple #7
0
/*
 * Returns a list of items whose visibility map information does not match
 * the status of the tuples on the page.
 *
 * If all_visible is passed as true, this will include all items which are
 * on pages marked as all-visible in the visibility map but which do not
 * seem to in fact be all-visible.
 *
 * If all_frozen is passed as true, this will include all items which are
 * on pages marked as all-frozen but which do not seem to in fact be frozen.
 */
static corrupt_items *
collect_corrupt_items(Oid relid, bool all_visible, bool all_frozen)
{
    Relation	rel;
    BlockNumber nblocks;
    corrupt_items *items;
    BlockNumber blkno;
    Buffer		vmbuffer = InvalidBuffer;
    BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
    TransactionId OldestXmin = InvalidTransactionId;

    if (all_visible)
    {
        /* Don't pass rel; that will fail in recovery. */
        OldestXmin = GetOldestXmin(NULL, true);
    }

    rel = relation_open(relid, AccessShareLock);

    if (rel->rd_rel->relkind != RELKIND_RELATION &&
            rel->rd_rel->relkind != RELKIND_MATVIEW &&
            rel->rd_rel->relkind != RELKIND_TOASTVALUE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a table, materialized view, or TOAST table",
                        RelationGetRelationName(rel))));

    nblocks = RelationGetNumberOfBlocks(rel);

    /*
     * Guess an initial array size. We don't expect many corrupted tuples, so
     * start with a small array.  This function uses the "next" field to track
     * the next offset where we can store an item (which is the same thing as
     * the number of items found so far) and the "count" field to track the
     * number of entries allocated.  We'll repurpose these fields before
     * returning.
     */
    items = palloc0(sizeof(corrupt_items));
    items->next = 0;
    items->count = 64;
    items->tids = palloc(items->count * sizeof(ItemPointerData));

    /* Loop over every block in the relation. */
    for (blkno = 0; blkno < nblocks; ++blkno)
    {
        bool		check_frozen = false;
        bool		check_visible = false;
        Buffer		buffer;
        Page		page;
        OffsetNumber offnum,
                     maxoff;

        /* Make sure we are interruptible. */
        CHECK_FOR_INTERRUPTS();

        /* Use the visibility map to decide whether to check this page. */
        if (all_frozen && VM_ALL_FROZEN(rel, blkno, &vmbuffer))
            check_frozen = true;
        if (all_visible && VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
            check_visible = true;
        if (!check_visible && !check_frozen)
            continue;

        /* Read and lock the page. */
        buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
                                    bstrategy);
        LockBuffer(buffer, BUFFER_LOCK_SHARE);

        page = BufferGetPage(buffer);
        maxoff = PageGetMaxOffsetNumber(page);

        /*
         * The visibility map bits might have changed while we were acquiring
         * the page lock.  Recheck to avoid returning spurious results.
         */
        if (check_frozen && !VM_ALL_FROZEN(rel, blkno, &vmbuffer))
            check_frozen = false;
        if (check_visible && !VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
            check_visible = false;
        if (!check_visible && !check_frozen)
        {
            UnlockReleaseBuffer(buffer);
            continue;
        }

        /* Iterate over each tuple on the page. */
        for (offnum = FirstOffsetNumber;
                offnum <= maxoff;
                offnum = OffsetNumberNext(offnum))
        {
            HeapTupleData tuple;
            ItemId		itemid;

            itemid = PageGetItemId(page, offnum);

            /* Unused or redirect line pointers are of no interest. */
            if (!ItemIdIsUsed(itemid) || ItemIdIsRedirected(itemid))
                continue;

            /* Dead line pointers are neither all-visible nor frozen. */
            if (ItemIdIsDead(itemid))
            {
                ItemPointerSet(&(tuple.t_self), blkno, offnum);
                record_corrupt_item(items, &tuple.t_self);
                continue;
            }

            /* Initialize a HeapTupleData structure for checks below. */
            ItemPointerSet(&(tuple.t_self), blkno, offnum);
            tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
            tuple.t_len = ItemIdGetLength(itemid);
            tuple.t_tableOid = relid;

            /*
             * If we're checking whether the page is all-visible, we expect
             * the tuple to be all-visible.
             */
            if (check_visible &&
                    !tuple_all_visible(&tuple, OldestXmin, buffer))
            {
                TransactionId RecomputedOldestXmin;

                /*
                 * Time has passed since we computed OldestXmin, so it's
                 * possible that this tuple is all-visible in reality even
                 * though it doesn't appear so based on our
                 * previously-computed value.  Let's compute a new value so we
                 * can be certain whether there is a problem.
                 *
                 * From a concurrency point of view, it sort of sucks to
                 * retake ProcArrayLock here while we're holding the buffer
                 * exclusively locked, but it should be safe against
                 * deadlocks, because surely GetOldestXmin() should never take
                 * a buffer lock. And this shouldn't happen often, so it's
                 * worth being careful so as to avoid false positives.
                 */
                RecomputedOldestXmin = GetOldestXmin(NULL, true);

                if (!TransactionIdPrecedes(OldestXmin, RecomputedOldestXmin))
                    record_corrupt_item(items, &tuple.t_self);
                else
                {
                    OldestXmin = RecomputedOldestXmin;
                    if (!tuple_all_visible(&tuple, OldestXmin, buffer))
                        record_corrupt_item(items, &tuple.t_self);
                }
            }

            /*
             * If we're checking whether the page is all-frozen, we expect the
             * tuple to be in a state where it will never need freezing.
             */
            if (check_frozen)
            {
                if (heap_tuple_needs_eventual_freeze(tuple.t_data))
                    record_corrupt_item(items, &tuple.t_self);
            }
        }

        UnlockReleaseBuffer(buffer);
    }

    /* Clean up. */
    if (vmbuffer != InvalidBuffer)
        ReleaseBuffer(vmbuffer);
    relation_close(rel, AccessShareLock);

    /*
     * Before returning, repurpose the fields to match caller's expectations.
     * next is now the next item that should be read (rather than written) and
     * count is now the number of items we wrote (rather than the number we
     * allocated).
     */
    items->count = items->next;
    items->next = 0;

    return items;
}
Exemple #8
0
/*
 * Primary entry point for VACUUM and ANALYZE commands.
 *
 * relid is normally InvalidOid; if it is not, then it provides the relation
 * OID to be processed, and vacstmt->relation is ignored.  (The non-invalid
 * case is currently only used by autovacuum.)
 *
 * do_toast is passed as FALSE by autovacuum, because it processes TOAST
 * tables separately.
 *
 * for_wraparound is used by autovacuum to let us know when it's forcing
 * a vacuum for wraparound, which should not be auto-cancelled.
 *
 * bstrategy is normally given as NULL, but in autovacuum it can be passed
 * in to use the same buffer strategy object across multiple vacuum() calls.
 *
 * isTopLevel should be passed down from ProcessUtility.
 *
 * It is the caller's responsibility that vacstmt and bstrategy
 * (if given) be allocated in a memory context that won't disappear
 * at transaction commit.
 */
void
vacuum(VacuumStmt *vacstmt, Oid relid, bool do_toast,
	   BufferAccessStrategy bstrategy, bool for_wraparound, bool isTopLevel)
{
	const char *stmttype;
	volatile bool all_rels,
				in_outer_xact,
				use_own_xacts;
	List	   *relations;

	/* sanity checks on options */
	Assert(vacstmt->options & (VACOPT_VACUUM | VACOPT_ANALYZE));
	Assert((vacstmt->options & VACOPT_VACUUM) ||
		   !(vacstmt->options & (VACOPT_FULL | VACOPT_FREEZE)));
	Assert((vacstmt->options & VACOPT_ANALYZE) || vacstmt->va_cols == NIL);

	stmttype = (vacstmt->options & VACOPT_VACUUM) ? "VACUUM" : "ANALYZE";

	/*
	 * We cannot run VACUUM inside a user transaction block; if we were inside
	 * a transaction, then our commit- and start-transaction-command calls
	 * would not have the intended effect!	There are numerous other subtle
	 * dependencies on this, too.
	 *
	 * ANALYZE (without VACUUM) can run either way.
	 */
	if (vacstmt->options & VACOPT_VACUUM)
	{
		PreventTransactionChain(isTopLevel, stmttype);
		in_outer_xact = false;
	}
	else
		in_outer_xact = IsInTransactionChain(isTopLevel);

	/*
	 * Send info about dead objects to the statistics collector, unless we are
	 * in autovacuum --- autovacuum.c does this for itself.
	 */
	if ((vacstmt->options & VACOPT_VACUUM) && !IsAutoVacuumWorkerProcess())
		pgstat_vacuum_stat();

	/*
	 * Create special memory context for cross-transaction storage.
	 *
	 * Since it is a child of PortalContext, it will go away eventually even
	 * if we suffer an error; there's no need for special abort cleanup logic.
	 */
	vac_context = AllocSetContextCreate(PortalContext,
										"Vacuum",
										ALLOCSET_DEFAULT_MINSIZE,
										ALLOCSET_DEFAULT_INITSIZE,
										ALLOCSET_DEFAULT_MAXSIZE);

	/*
	 * If caller didn't give us a buffer strategy object, make one in the
	 * cross-transaction memory context.
	 */
	if (bstrategy == NULL)
	{
		MemoryContext old_context = MemoryContextSwitchTo(vac_context);

		bstrategy = GetAccessStrategy(BAS_VACUUM);
		MemoryContextSwitchTo(old_context);
	}
	vac_strategy = bstrategy;

	/* Remember whether we are processing everything in the DB */
	all_rels = (!OidIsValid(relid) && vacstmt->relation == NULL);

	/*
	 * Build list of relations to process, unless caller gave us one. (If we
	 * build one, we put it in vac_context for safekeeping.)
	 */
	relations = get_rel_oids(relid, vacstmt->relation);

	/*
	 * Decide whether we need to start/commit our own transactions.
	 *
	 * For VACUUM (with or without ANALYZE): always do so, so that we can
	 * release locks as soon as possible.  (We could possibly use the outer
	 * transaction for a one-table VACUUM, but handling TOAST tables would be
	 * problematic.)
	 *
	 * For ANALYZE (no VACUUM): if inside a transaction block, we cannot
	 * start/commit our own transactions.  Also, there's no need to do so if
	 * only processing one relation.  For multiple relations when not within a
	 * transaction block, and also in an autovacuum worker, use own
	 * transactions so we can release locks sooner.
	 */
	if (vacstmt->options & VACOPT_VACUUM)
		use_own_xacts = true;
	else
	{
		Assert(vacstmt->options & VACOPT_ANALYZE);
		if (IsAutoVacuumWorkerProcess())
			use_own_xacts = true;
		else if (in_outer_xact)
			use_own_xacts = false;
		else if (list_length(relations) > 1)
			use_own_xacts = true;
		else
			use_own_xacts = false;
	}

	/*
	 * vacuum_rel expects to be entered with no transaction active; it will
	 * start and commit its own transaction.  But we are called by an SQL
	 * command, and so we are executing inside a transaction already. We
	 * commit the transaction started in PostgresMain() here, and start
	 * another one before exiting to match the commit waiting for us back in
	 * PostgresMain().
	 */
	if (use_own_xacts)
	{
		/* ActiveSnapshot is not set by autovacuum */
		if (ActiveSnapshotSet())
			PopActiveSnapshot();

		/* matches the StartTransaction in PostgresMain() */
		CommitTransactionCommand();
	}

	/* Turn vacuum cost accounting on or off */
	PG_TRY();
	{
		ListCell   *cur;

		VacuumCostActive = (VacuumCostDelay > 0);
		VacuumCostBalance = 0;

		/*
		 * Loop to process each selected relation.
		 */
		foreach(cur, relations)
		{
			Oid			relid = lfirst_oid(cur);
			bool		scanned_all = false;

			if (vacstmt->options & VACOPT_VACUUM)
				vacuum_rel(relid, vacstmt, do_toast, for_wraparound,
						   &scanned_all);

			if (vacstmt->options & VACOPT_ANALYZE)
			{
				/*
				 * If using separate xacts, start one for analyze. Otherwise,
				 * we can use the outer transaction.
				 */
				if (use_own_xacts)
				{
					StartTransactionCommand();
					/* functions in indexes may want a snapshot set */
					PushActiveSnapshot(GetTransactionSnapshot());
				}

				analyze_rel(relid, vacstmt, vac_strategy, !scanned_all);

				if (use_own_xacts)
				{
					PopActiveSnapshot();
					CommitTransactionCommand();
				}
			}
		}
	}
/*
 * Primary entry point for VACUUM and ANALYZE commands.
 *
 * options is a bitmask of VacuumOption flags, indicating what to do.
 *
 * relid, if not InvalidOid, indicate the relation to process; otherwise,
 * the RangeVar is used.  (The latter must always be passed, because it's
 * used for error messages.)
 *
 * params contains a set of parameters that can be used to customize the
 * behavior.
 *
 * va_cols is a list of columns to analyze, or NIL to process them all.
 *
 * bstrategy is normally given as NULL, but in autovacuum it can be passed
 * in to use the same buffer strategy object across multiple vacuum() calls.
 *
 * isTopLevel should be passed down from ProcessUtility.
 *
 * It is the caller's responsibility that all parameters are allocated in a
 * memory context that will not disappear at transaction commit.
 */
void
vacuum(int options, RangeVar *relation, Oid relid, VacuumParams *params,
	   List *va_cols, BufferAccessStrategy bstrategy, bool isTopLevel)
{
	const char *stmttype;
	volatile bool in_outer_xact,
				use_own_xacts;
	List	   *relations;
	static bool in_vacuum = false;

	Assert(params != NULL);

	stmttype = (options & VACOPT_VACUUM) ? "VACUUM" : "ANALYZE";

	/*
	 * We cannot run VACUUM inside a user transaction block; if we were inside
	 * a transaction, then our commit- and start-transaction-command calls
	 * would not have the intended effect!	There are numerous other subtle
	 * dependencies on this, too.
	 *
	 * ANALYZE (without VACUUM) can run either way.
	 */
	if (options & VACOPT_VACUUM)
	{
		PreventTransactionChain(isTopLevel, stmttype);
		in_outer_xact = false;
	}
	else
		in_outer_xact = IsInTransactionChain(isTopLevel);

	/*
	 * Due to static variables vac_context, anl_context and vac_strategy,
	 * vacuum() is not reentrant.  This matters when VACUUM FULL or ANALYZE
	 * calls a hostile index expression that itself calls ANALYZE.
	 */
	if (in_vacuum)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("%s cannot be executed from VACUUM or ANALYZE",
						stmttype)));

	/*
	 * Sanity check DISABLE_PAGE_SKIPPING option.
	 */
	if ((options & VACOPT_FULL) != 0 &&
		(options & VACOPT_DISABLE_PAGE_SKIPPING) != 0)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("VACUUM option DISABLE_PAGE_SKIPPING cannot be used with FULL")));

	/*
	 * Send info about dead objects to the statistics collector, unless we are
	 * in autovacuum --- autovacuum.c does this for itself.
	 */
	if ((options & VACOPT_VACUUM) && !IsAutoVacuumWorkerProcess())
		pgstat_vacuum_stat();

	/*
	 * Create special memory context for cross-transaction storage.
	 *
	 * Since it is a child of PortalContext, it will go away eventually even
	 * if we suffer an error; there's no need for special abort cleanup logic.
	 */
	vac_context = AllocSetContextCreate(PortalContext,
										"Vacuum",
										ALLOCSET_DEFAULT_SIZES);

	/*
	 * If caller didn't give us a buffer strategy object, make one in the
	 * cross-transaction memory context.
	 */
	if (bstrategy == NULL)
	{
		MemoryContext old_context = MemoryContextSwitchTo(vac_context);

		bstrategy = GetAccessStrategy(BAS_VACUUM);
		MemoryContextSwitchTo(old_context);
	}
	vac_strategy = bstrategy;

	/*
	 * Build list of relations to process, unless caller gave us one. (If we
	 * build one, we put it in vac_context for safekeeping.)
	 */
	relations = get_rel_oids(relid, relation);

	/*
	 * Decide whether we need to start/commit our own transactions.
	 *
	 * For VACUUM (with or without ANALYZE): always do so, so that we can
	 * release locks as soon as possible.  (We could possibly use the outer
	 * transaction for a one-table VACUUM, but handling TOAST tables would be
	 * problematic.)
	 *
	 * For ANALYZE (no VACUUM): if inside a transaction block, we cannot
	 * start/commit our own transactions.  Also, there's no need to do so if
	 * only processing one relation.  For multiple relations when not within a
	 * transaction block, and also in an autovacuum worker, use own
	 * transactions so we can release locks sooner.
	 */
	if (options & VACOPT_VACUUM)
		use_own_xacts = true;
	else
	{
		Assert(options & VACOPT_ANALYZE);
		if (IsAutoVacuumWorkerProcess())
			use_own_xacts = true;
		else if (in_outer_xact)
			use_own_xacts = false;
		else if (list_length(relations) > 1)
			use_own_xacts = true;
		else
			use_own_xacts = false;
	}

	/*
	 * vacuum_rel expects to be entered with no transaction active; it will
	 * start and commit its own transaction.  But we are called by an SQL
	 * command, and so we are executing inside a transaction already. We
	 * commit the transaction started in PostgresMain() here, and start
	 * another one before exiting to match the commit waiting for us back in
	 * PostgresMain().
	 */
	if (use_own_xacts)
	{
		Assert(!in_outer_xact);

		/* ActiveSnapshot is not set by autovacuum */
		if (ActiveSnapshotSet())
			PopActiveSnapshot();

		/* matches the StartTransaction in PostgresMain() */
		CommitTransactionCommand();
	}

	/* Turn vacuum cost accounting on or off */
	PG_TRY();
	{
		ListCell   *cur;

		in_vacuum = true;
		VacuumCostActive = (VacuumCostDelay > 0);
		VacuumCostBalance = 0;
		VacuumPageHit = 0;
		VacuumPageMiss = 0;
		VacuumPageDirty = 0;

		/*
		 * Loop to process each selected relation.
		 */
		foreach(cur, relations)
		{
			Oid			relid = lfirst_oid(cur);

			if (options & VACOPT_VACUUM)
			{
				if (!vacuum_rel(relid, relation, options, params))
					continue;
			}

			if (options & VACOPT_ANALYZE)
			{
				/*
				 * If using separate xacts, start one for analyze. Otherwise,
				 * we can use the outer transaction.
				 */
				if (use_own_xacts)
				{
					StartTransactionCommand();
					/* functions in indexes may want a snapshot set */
					PushActiveSnapshot(GetTransactionSnapshot());
				}

				analyze_rel(relid, relation, options, params,
							va_cols, in_outer_xact, vac_strategy);

				if (use_own_xacts)
				{
					PopActiveSnapshot();
					CommitTransactionCommand();
				}
			}
		}
	}