[rwultsch]

You missed the point of my post. You are going to have one of the two issues, either looking through two index or indexes including the a large PK. At least with InnoDB you can make the choice. The strategy I suggested gets you the desired outcome of not including a large PK in all secondary indexes.

[ngrilly]

> The strategy I suggested gets you the desired outcome of not including a large PK in all secondary indexes.

For an application in which most queries need a secondary index lookup, using heap organized tables is more efficient because the database needs to traverse only one B-tree (for the secondary index) that gives the physical position of the row in the heap. When using index organized tables, the database needs to traverse 2 B-trees (the secondary index first, then the primary index). Making the primary key short by using an auto incrementing integer helps, but doesn't remove this overhead.

[joshberkus]

The other part of the tradeoff is that inserts and many other write operations are less expensive in heap tables. A Big Table in InnoDB, measured in "when do I start having to spend a lot of time troubleshooting this table's performance" is about 1% the size of a Big Table in Postgres. TokuDB was introduced for MySQL for a reason.

Heap vs. Index organization is a classic tradeoff of database design.

Now, if you're saying "it would be really nice if Postgres had the option of index-organized tables" I'd agree with you. I'd love to have that, as an option.