Function remove_leaf_node

src/jrd/btr.cpp:6596–6730

static contents remove_leaf_node(thread_db* tdbb, index_insertion* insertion, WIN* window)
{
/**************************************
 *
 *	r e m o v e _ l e a f _ n o d e
 *
 **************************************
 *
 * Functional description
 *	Remove an index node from the leaf level.
 *
 **************************************/
	SET_TDBB(tdbb);
	btree_page* page = (btree_page*) window->win_buffer;
	temporary_key* key = insertion->iib_key;

	const index_desc* const idx = insertion->iib_descriptor;
	const bool primary = (idx->idx_flags & idx_primary);
	const bool unique = (idx->idx_flags & idx_unique);
	const bool key_all_nulls = (key->key_nulls == (1 << idx->idx_count) - 1);
	const bool validateDuplicates = (unique && !key_all_nulls) || primary;

	// Look for the first node with the value to be removed.
	UCHAR* pointer;
	USHORT prefix;
	while (!(pointer = find_node_start_point(page, key, 0, &prefix,
			(idx->idx_flags & idx_descending),
			false, false,
			(validateDuplicates ? NO_VALUE : insertion->iib_number))))
	{
		page = (btree_page*) CCH_HANDOFF(tdbb, window, page->btr_sibling, LCK_write, pag_index);
	}

	// Make sure first node looks ok
	IndexNode node;
	pointer = node.readNode(pointer, true);
	if (prefix > node.prefix || key->key_length != node.length + node.prefix)
	{
#ifdef DEBUG_BTR
		CCH_RELEASE(tdbb, window);
		CORRUPT(204);	// msg 204 index inconsistent
#endif
		return contents_above_threshold;
	}

	if (node.length && memcmp(node.data, key->key_data + node.prefix, node.length))
	{
#ifdef DEBUG_BTR
		CCH_RELEASE(tdbb, window);
		CORRUPT(204);	// msg 204 index inconsistent
#endif
		return contents_above_threshold;
	}


	// *****************************************************
	// AB: This becomes a very expensive task if there are
	// many duplicates inside the index (non-unique index)!