Ejemplo n.º 1
0
/*
 * __cursor_truncate_fix --
 *	Discard a cursor range from fixed-width column-store tree.
 */
static int
__cursor_truncate_fix(WT_SESSION_IMPL *session,
    WT_CURSOR_BTREE *start, WT_CURSOR_BTREE *stop,
    int (*rmfunc)(WT_SESSION_IMPL *, WT_CURSOR_BTREE *, int))
{
	WT_DECL_RET;
	uint8_t *value;

	/*
	 * Handle fixed-length column-store objects separately: for row-store
	 * and variable-length column-store objects we have "deleted" values
	 * and so returned objects actually exist: fixed-length column-store
	 * objects are filled-in if they don't exist, that is, if you create
	 * record 37, records 1-36 magically appear.  Those records can't be
	 * deleted, which means we have to ignore already "deleted" records.
	 *
	 * First, call the standard cursor remove method to do a full search and
	 * re-position the cursor because we don't have a saved copy of the
	 * page's write generation information, which we need to remove records.
	 * Once that's done, we can delete records without a full search, unless
	 * we encounter a restart error because the page was modified by some
	 * other thread of control; in that case, repeat the full search to
	 * refresh the page's modification information.
	 */
	if (start == NULL) {
		do {
			WT_RET(__wt_btcur_remove(stop));
			for (;;) {
				if ((ret = __wt_btcur_prev(stop, 1)) != 0)
					break;
				stop->compare = 0;	/* Exact match */
				value = (uint8_t *)stop->iface.value.data;
				if (*value != 0 &&
				    (ret = rmfunc(session, stop, 1)) != 0)
					break;
			}
		} while (ret == WT_RESTART);
	} else {
		do {
			WT_RET(__wt_btcur_remove(start));
			for (;;) {
				if (stop != NULL &&
				    __cursor_equals(start, stop))
					break;
				if ((ret = __wt_btcur_next(start, 1)) != 0)
					break;
				start->compare = 0;	/* Exact match */
				value = (uint8_t *)start->iface.value.data;
				if (*value != 0 &&
				    (ret = rmfunc(session, start, 1)) != 0)
					break;
			}
		} while (ret == WT_RESTART);
	}

	WT_RET_NOTFOUND_OK(ret);
	return (0);
}
Ejemplo n.º 2
0
/*
 * __cursor_truncate --
 *	Discard a cursor range from row-store or variable-width column-store
 * tree.
 */
static int
__cursor_truncate(WT_SESSION_IMPL *session,
    WT_CURSOR_BTREE *start, WT_CURSOR_BTREE *stop,
    int (*rmfunc)(WT_SESSION_IMPL *, WT_CURSOR_BTREE *, int))
{
	WT_DECL_RET;

	/*
	 * First, call the standard cursor remove method to do a full search and
	 * re-position the cursor because we don't have a saved copy of the
	 * page's write generation information, which we need to remove records.
	 * Once that's done, we can delete records without a full search, unless
	 * we encounter a restart error because the page was modified by some
	 * other thread of control; in that case, repeat the full search to
	 * refresh the page's modification information.
	 *
	 * If this is a row-store, we delete leaf pages having no overflow items
	 * without reading them; for that to work, we have to ensure we read the
	 * page referenced by the ending cursor, since we may be deleting only a
	 * partial page at the end of the truncation.  Our caller already fully
	 * instantiated the end cursor, so we know that page is pinned in memory
	 * and we can proceed without concern.
	 */
	if (start == NULL) {
		do {
			WT_RET(__wt_btcur_remove(stop));
			for (;;) {
				if ((ret = __wt_btcur_prev(stop, 1)) != 0)
					break;
				stop->compare = 0;	/* Exact match */
				if ((ret = rmfunc(session, stop, 1)) != 0)
					break;
			}
		} while (ret == WT_RESTART);
	} else {
		do {
			WT_RET(__wt_btcur_remove(start));
			/*
			 * Reset ret each time through so that we don't loop
			 * forever in the cursor equals case.
			 */
			for (ret = 0;;) {
				if (stop != NULL &&
				    __cursor_equals(start, stop))
					break;
				if ((ret = __wt_btcur_next(start, 1)) != 0)
					break;
				start->compare = 0;	/* Exact match */
				if ((ret = rmfunc(session, start, 1)) != 0)
					break;
			}
		} while (ret == WT_RESTART);
	}

	WT_RET_NOTFOUND_OK(ret);
	return (0);
}
Ejemplo n.º 3
0
/*
 * __curfile_next --
 *	WT_CURSOR->next method for the btree cursor type.
 */
static int
__curfile_next(WT_CURSOR *cursor)
{
	WT_CURSOR_BTREE *cbt;
	WT_DECL_RET;
	WT_SESSION_IMPL *session;

	cbt = (WT_CURSOR_BTREE *)cursor;
	CURSOR_API_CALL(cursor, session, next, cbt->btree);
	ret = __wt_btcur_next((WT_CURSOR_BTREE *)cursor, 0);
	API_END(session);

	return (ret);
}
Ejemplo n.º 4
0
/*
 * __curfile_next --
 *	WT_CURSOR->next method for the btree cursor type.
 */
static int
__curfile_next(WT_CURSOR *cursor)
{
	WT_CURSOR_BTREE *cbt;
	WT_DECL_RET;
	WT_SESSION_IMPL *session;

	cbt = (WT_CURSOR_BTREE *)cursor;
	CURSOR_API_CALL(cursor, session, next, cbt->btree);

	F_CLR(cursor, WT_CURSTD_KEY_SET | WT_CURSTD_VALUE_SET);
	if ((ret = __wt_btcur_next(cbt, 0)) == 0)
		F_SET(cursor, WT_CURSTD_KEY_INT | WT_CURSTD_VALUE_INT);

err:	API_END_RET(session, ret);
}
Ejemplo n.º 5
0
/*
 * __curfile_next --
 *	WT_CURSOR->next method for the btree cursor type.
 */
static int
__curfile_next(WT_CURSOR *cursor)
{
	WT_CURSOR_BTREE *cbt;
	WT_DECL_RET;
	WT_SESSION_IMPL *session;

	cbt = (WT_CURSOR_BTREE *)cursor;
	CURSOR_API_CALL(cursor, session, next, cbt->btree);

	WT_ERR(__wt_btcur_next(cbt, false));

	/* Next maintains a position, key and value. */
	WT_ASSERT(session,
	    F_MASK(cursor, WT_CURSTD_KEY_SET) == WT_CURSTD_KEY_INT &&
	    F_MASK(cursor, WT_CURSTD_VALUE_SET) == WT_CURSTD_VALUE_INT);

err:	API_END_RET(session, ret);
}
Ejemplo n.º 6
0
/*
 * __wt_btcur_next_random --
 *	Move to a random record in the tree.
 */
int
__wt_btcur_next_random(WT_CURSOR_BTREE *cbt)
{
	WT_BTREE *btree;
	WT_DECL_RET;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	btree = cbt->btree;

	/*
	 * Only supports row-store: applications can trivially select a random
	 * value from a column-store, if there were any reason to do so.
	 */
	if (btree->type != BTREE_ROW)
		WT_RET(ENOTSUP);

	WT_STAT_FAST_CONN_INCR(session, cursor_next);
	WT_STAT_FAST_DATA_INCR(session, cursor_next);

	WT_RET(__cursor_func_init(cbt, 1));

	WT_WITH_PAGE_INDEX(session,
	    ret = __wt_row_random(session, cbt));
	WT_ERR(ret);
	if (__cursor_valid(cbt, &upd))
		WT_ERR(__wt_kv_return(session, cbt, upd));
	else {
		if ((ret = __wt_btcur_next(cbt, 0)) == WT_NOTFOUND)
			ret = __wt_btcur_prev(cbt, 0);
		WT_ERR(ret);
	}

err:	if (ret != 0)
		WT_TRET(__cursor_reset(cbt));
	return (ret);
}
Ejemplo n.º 7
0
/*
 * __wt_btcur_next_random --
 *	Move to a random record in the tree. There are two algorithms, one
 *	where we select a record at random from the whole tree on each
 *	retrieval and one where we first select a record at random from the
 *	whole tree, and then subsequently sample forward from that location.
 *	The sampling approach allows us to select reasonably uniform random
 *	points from unbalanced trees.
 */
int
__wt_btcur_next_random(WT_CURSOR_BTREE *cbt)
{
	WT_BTREE *btree;
	WT_DECL_RET;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;
	wt_off_t size;
	uint64_t skip;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	btree = cbt->btree;

	/*
	 * Only supports row-store: applications can trivially select a random
	 * value from a column-store, if there were any reason to do so.
	 */
	if (btree->type != BTREE_ROW)
		WT_RET_MSG(session, ENOTSUP,
		    "WT_CURSOR.next_random only supported by row-store tables");

	WT_STAT_CONN_INCR(session, cursor_next);
	WT_STAT_DATA_INCR(session, cursor_next);

	/*
	 * If retrieving random values without sampling, or we don't have a
	 * page reference, pick a roughly random leaf page in the tree.
	 */
	if (cbt->ref == NULL || cbt->next_random_sample_size == 0) {
		/*
		 * Skip past the sample size of the leaf pages in the tree
		 * between each random key return to compensate for unbalanced
		 * trees.
		 *
		 * Use the underlying file size divided by its block allocation
		 * size as our guess of leaf pages in the file (this can be
		 * entirely wrong, as it depends on how many pages are in this
		 * particular checkpoint, how large the leaf and internal pages
		 * really are, and other factors). Then, divide that value by
		 * the configured sample size and increment the final result to
		 * make sure tiny files don't leave us with a skip value of 0.
		 *
		 * !!!
		 * Ideally, the number would be prime to avoid restart issues.
		 */
		if (cbt->next_random_sample_size != 0) {
			WT_ERR(btree->bm->size(btree->bm, session, &size));
			cbt->next_random_leaf_skip = (uint64_t)
			    ((size / btree->allocsize) /
			    cbt->next_random_sample_size) + 1;
		}

		/*
		 * Choose a leaf page from the tree.
		 */
		WT_ERR(__cursor_func_init(cbt, true));
		WT_WITH_PAGE_INDEX(
		    session, ret = __wt_row_random_descent(session, cbt));
		WT_ERR(ret);
	} else {
		/*
		 * Read through the tree, skipping leaf pages. Be cautious about
		 * the skip count: if the last leaf page skipped was also the
		 * last leaf page in the tree, it may be set to zero on return
		 * with the end-of-walk condition.
		 *
		 * Pages read for data sampling aren't "useful"; don't update
		 * the read generation of pages already in memory, and if a page
		 * is read, set its generation to a low value so it is evicted
		 * quickly.
		 */
		for (skip =
		    cbt->next_random_leaf_skip; cbt->ref == NULL || skip > 0;)
			WT_ERR(__wt_tree_walk_skip(session, &cbt->ref, &skip,
			    WT_READ_NO_GEN |
			    WT_READ_SKIP_INTL | WT_READ_WONT_NEED));
	}

	/*
	 * Select a random entry from the leaf page. If it's not valid, move to
	 * the next entry, if that doesn't work, move to the previous entry.
	 */
	WT_ERR(__wt_row_random_leaf(session, cbt));
	if (__cursor_valid(cbt, &upd))
		WT_ERR(__wt_kv_return(session, cbt, upd));
	else {
		if ((ret = __wt_btcur_next(cbt, false)) == WT_NOTFOUND)
			ret = __wt_btcur_prev(cbt, false);
		WT_ERR(ret);
	}
	return (0);

err:	WT_TRET(__cursor_reset(cbt));
	return (ret);
}
Ejemplo n.º 8
0
/*
 * __wt_btcur_search_near --
 *	Search for a record in the tree.
 */
int
__wt_btcur_search_near(WT_CURSOR_BTREE *cbt, int *exactp)
{
	WT_BTREE *btree;
	WT_CURSOR *cursor;
	WT_DECL_RET;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;
	int exact;
	bool valid;

	btree = cbt->btree;
	cursor = &cbt->iface;
	session = (WT_SESSION_IMPL *)cursor->session;
	upd = NULL;					/* -Wuninitialized */
	exact = 0;

	WT_STAT_CONN_INCR(session, cursor_search_near);
	WT_STAT_DATA_INCR(session, cursor_search_near);

	/*
	 * If we have a row-store page pinned, search it; if we don't have a
	 * page pinned, or the search of the pinned page doesn't find an exact
	 * match, search from the root. Unlike WT_CURSOR.search, ignore pinned
	 * pages in the case of column-store, search-near isn't an interesting
	 * enough case for column-store to add the complexity needed to avoid
	 * the tree search.
	 *
	 * Set the "insert" flag for the btree row-store search; we may intend
	 * to position the cursor at the end of the tree, rather than match an
	 * existing record.
	 */
	valid = false;
	if (btree->type == BTREE_ROW &&
	    F_ISSET(cbt, WT_CBT_ACTIVE) &&
	    cbt->ref->page->read_gen != WT_READGEN_OLDEST) {
		__wt_txn_cursor_op(session);

		WT_ERR(__cursor_row_search(session, cbt, cbt->ref, true));

		/*
		 * Search-near is trickier than search when searching an already
		 * pinned page. If search returns the first or last page slots,
		 * discard the results and search the full tree as the neighbor
		 * pages might offer better matches. This test is simplistic as
		 * we're ignoring append lists (there may be no page slots or we
		 * might be legitimately positioned after the last page slot).
		 * Ignore those cases, it makes things too complicated.
		 */
		if (cbt->slot != 0 &&
		    cbt->slot != cbt->ref->page->pg_row_entries - 1)
			valid = __cursor_valid(cbt, &upd);
	}
	if (!valid) {
		WT_ERR(__cursor_func_init(cbt, true));
		WT_ERR(btree->type == BTREE_ROW ?
		    __cursor_row_search(session, cbt, NULL, true) :
		    __cursor_col_search(session, cbt, NULL));
		valid = __cursor_valid(cbt, &upd);
	}

	/*
	 * If we find a valid key, return it.
	 *
	 * Else, creating a record past the end of the tree in a fixed-length
	 * column-store implicitly fills the gap with empty records.  In this
	 * case, we instantiate the empty record, it's an exact match.
	 *
	 * Else, move to the next key in the tree (bias for prefix searches).
	 * Cursor next skips invalid rows, so we don't have to test for them
	 * again.
	 *
	 * Else, redo the search and move to the previous key in the tree.
	 * Cursor previous skips invalid rows, so we don't have to test for
	 * them again.
	 *
	 * If that fails, quit, there's no record to return.
	 */
	if (valid) {
		exact = cbt->compare;
		ret = __wt_kv_return(session, cbt, upd);
	} else if (__cursor_fix_implicit(btree, cbt)) {
		cbt->recno = cursor->recno;
		cbt->v = 0;
		cursor->value.data = &cbt->v;
		cursor->value.size = 1;
		exact = 0;
	} else if ((ret = __wt_btcur_next(cbt, false)) != WT_NOTFOUND)
		exact = 1;
	else {
		WT_ERR(__cursor_func_init(cbt, true));
		WT_ERR(btree->type == BTREE_ROW ?
		    __cursor_row_search(session, cbt, NULL, true) :
		    __cursor_col_search(session, cbt, NULL));
		if (__cursor_valid(cbt, &upd)) {
			exact = cbt->compare;
			ret = __wt_kv_return(session, cbt, upd);
		} else if ((ret = __wt_btcur_prev(cbt, false)) != WT_NOTFOUND)
			exact = -1;
	}

#ifdef HAVE_DIAGNOSTIC
	if (ret == 0)
		WT_ERR(__wt_cursor_key_order_init(session, cbt));
#endif

err:	if (ret != 0)
		WT_TRET(__cursor_reset(cbt));
	if (exactp != NULL && (ret == 0 || ret == WT_NOTFOUND))
		*exactp = exact;
	return (ret);
}
Ejemplo n.º 9
0
/*
 * __wt_btcur_search_near --
 *	Search for a record in the tree.
 */
int
__wt_btcur_search_near(WT_CURSOR_BTREE *cbt, int *exactp)
{
	WT_BTREE *btree;
	WT_CURSOR *cursor;
	WT_DECL_RET;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;
	int exact;

	btree = cbt->btree;
	cursor = &cbt->iface;
	session = (WT_SESSION_IMPL *)cursor->session;
	exact = 0;

	WT_STAT_FAST_CONN_INCR(session, cursor_search_near);
	WT_STAT_FAST_DATA_INCR(session, cursor_search_near);

	if (btree->type == BTREE_ROW)
		WT_RET(__cursor_size_chk(session, &cursor->key));

	WT_RET(__cursor_func_init(cbt, 1));

	/*
	 * Set the "insert" flag for the btree row-store search; we may intend
	 * to position our cursor at the end of the tree, rather than match an
	 * existing record.
	 */
	WT_ERR(btree->type == BTREE_ROW ?
	    __cursor_row_search(session, cbt, 1) :
	    __cursor_col_search(session, cbt));

	/*
	 * If we find an valid key, return it.
	 *
	 * Else, creating a record past the end of the tree in a fixed-length
	 * column-store implicitly fills the gap with empty records.  In this
	 * case, we instantiate the empty record, it's an exact match.
	 *
	 * Else, move to the next key in the tree (bias for prefix searches).
	 * Cursor next skips invalid rows, so we don't have to test for them
	 * again.
	 *
	 * Else, redo the search and move to the previous key in the tree.
	 * Cursor previous skips invalid rows, so we don't have to test for
	 * them again.
	 *
	 * If that fails, quit, there's no record to return.
	 */
	if (__cursor_valid(cbt, &upd)) {
		exact = cbt->compare;
		ret = __wt_kv_return(session, cbt, upd);
	} else if (__cursor_fix_implicit(btree, cbt)) {
		cbt->recno = cursor->recno;
		cbt->v = 0;
		cursor->value.data = &cbt->v;
		cursor->value.size = 1;
		exact = 0;
	} else if ((ret = __wt_btcur_next(cbt, 0)) != WT_NOTFOUND)
		exact = 1;
	else {
		WT_ERR(btree->type == BTREE_ROW ?
		    __cursor_row_search(session, cbt, 1) :
		    __cursor_col_search(session, cbt));
		if (__cursor_valid(cbt, &upd)) {
			exact = cbt->compare;
			ret = __wt_kv_return(session, cbt, upd);
		} else if ((ret = __wt_btcur_prev(cbt, 0)) != WT_NOTFOUND)
			exact = -1;
	}

err:	if (ret != 0)
		WT_TRET(__cursor_reset(cbt));
	if (exactp != NULL && (ret == 0 || ret == WT_NOTFOUND))
		*exactp = exact;
	return (ret);
}
Ejemplo n.º 10
0
/*
 * __wt_btcur_search_near --
 *	Search for a record in the tree.
 */
int
__wt_btcur_search_near(WT_CURSOR_BTREE *cbt, int *exact)
{
	WT_BTREE *btree;
	WT_ITEM *val;
	WT_CURSOR *cursor;
	WT_SESSION_IMPL *session;
	int ret;

	btree = cbt->btree;
	cursor = &cbt->iface;
	session = (WT_SESSION_IMPL *)cursor->session;
	WT_BSTAT_INCR(session, cursor_read_near);

	if (btree->type == BTREE_ROW)
		WT_RET(__cursor_size_chk(session, &cursor->key));

	__cursor_func_init(cbt, 1);

	WT_ERR(btree->type == BTREE_ROW ?
	    __wt_row_search(session, cbt, 0) :
	    __wt_col_search(session, cbt, 0));

	/*
	 * Creating a record past the end of the tree in a fixed-length column-
	 * store implicitly fills the gap with empty records.  In this case, we
	 * instantiate the empty record, it's an exact match.
	 *
	 * Else, if we find a valid key (one that wasn't deleted), return it.
	 *
	 * Else, if we found a deleted key, try to move to the next key in the
	 * tree (bias for prefix searches).  Cursor next skips deleted records,
	 * so we don't have to test for them again.
	 *
	 * Else if there's no larger tree key, redo the search and try and find
	 * an earlier record.  If that fails, quit, there's no record to return.
	 */
	if (cbt->compare != 0 && __cursor_fix_implicit(btree, cbt)) {
		cbt->v = 0;
		val = &cbt->iface.value;
		val->data = &cbt->v;
		val->size = 1;
		*exact = 0;
	} else if (!__cursor_invalid(cbt)) {
		*exact = cbt->compare;
		ret = __wt_kv_return(session, cbt, cbt->compare == 0 ? 0 : 1);
	} else if ((ret = __wt_btcur_next(cbt)) != WT_NOTFOUND)
		*exact = 1;
	else {
		WT_ERR(btree->type == BTREE_ROW ?
		    __wt_row_search(session, cbt, 0) :
		    __wt_col_search(session, cbt, 0));
		if (!__cursor_invalid(cbt)) {
			*exact = cbt->compare;
			ret = __wt_kv_return(
			    session, cbt, cbt->compare == 0 ? 0 : 1);
		} else if ((ret = __wt_btcur_prev(cbt)) != WT_NOTFOUND)
			*exact = -1;
	}

err:	__cursor_func_resolve(cbt, ret);
	return (ret);
}