On 01.06.2013 11:22, Simon Riggs wrote:
What is the benefit?
Merging xmin/xmax would save 4 bytes per row. On servers with 8 byte
word length, that means that we'd save 8 bytes per row for tables that
have between 9 and 40 columns. Which is the majority of tables.

Hmm, it would probably be much easier to squeeze, say, one byte from the tuple header, than full four bytes. Then you could store store a null bitmap for upto 16 columns, without crossing the 24 byte mark. That would already get you much of the benefit.

- Heikki


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