Another question is, what should cmin and cmax system columns return? If we overlay cmin and cmax, cmin and cmax on-disk will always be the same value. And with phantom cids, it wouldn't be meaningful outside the inserting/deleting transaction.

The options that I can think of are:

1. Only return cmin and cmax when they mean something, that is within the inserting / deleting transaction. This is not good if you want to use them for debugging (and what other use do they have?)

2. Cmin and cmax return the value that's stored on disk, whether or not they make sense.

3. Remove cmin and cmax system columns to avoid confusion, and replace them with cminmax, that returns what's on disk.

 Heikki Linnakangas

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