Heaps, Deletes, and Optimistic Isolation Levels

Erik shows that heaps have even more drawbacks under optimistic concurrency.

DELETE Operation in SQL Server HEAPs

You should stick to using tables in SQL Server, rather than heaps that have no clustered index, unless you have well-considered reasons to choose heaps. However, there are uses for heaps in special circumstances, and it is useful to know what these uses are, and when you should avoid heaps. Uwe Ricken explains, and demonstrates why you'd be unwise to use heaps rather than tables when the data is liable to change.

SQL Server Heaps, and Their Fragmentation

In SQL Server, heaps are rightly treated with suspicion. Although there are rare cases where they perform well, they are likely to be the cause of poor performance. If a table is likely to have a large number of changes, then it can become fragmented due to way that space is allocated and forward pointers used. How does one detect this problem? Is it significant? How does one deal with it, if necessary? Neeraj Tripathi explains.

Heaps rebuild

Forwarding Pointers in Heaps

When no clustered index is defined on a table, that table is said to be a Heap. Heaps are not ideal when it comes to performance but there are lots of instances where you have heaps.