Which DBMSs offer index-organized tables?

Question

My current knowledge:

• Oracle does offer index-organized tables and defaults to heap-organized.
• I heard that SQL-Server uses only index-organized tables

I am especially interested in answers for MySQL, Informix and DB2.

Answer 1

SQL Server can store table data in either Heap Structures or Clustered Index Structures. If a table doesn't have a clustered index then it is considered a heap. For more details see here Heap Structures and Clustered Index Structures

Answer 2

MySql has clustered indexes but there appears to be limited control on these indexes.

MySql clustered indexes and see this question here

DB2 has MDC (multi-dimension cluster) which can effectively index organise the table in several ways. I've never used them but you can probably just have a single dimension MDC which would be the same as a standard clustered index.

Oracle is a bit of a pain. Last time I checked with its IOT implementation requires you create the table as IOT and you can't change it later, which is annoying when you want to load a load of data with no indexes for speed and then index it after.

Answer 3

As for Informix Dynamic Server (IDS) or Standard Engine (SE), they both support clustered and non-clustered indexes. IDS uses RSAM and SE uses C-ISAM B-Tree indexing. For both, when a cluster index is created, a table's rows are physically ordered in the same order as the index, but as new rows are added to the table, the row is physically placed at EOF (heap).