>>>>> "AH" == Alvaro Herrera <alvherre@dcc.uchile.cl> writes:
>> once within a vacuum process. I am fairly certian it would reduce
>> disk bandwidth requirements since at least one necessary page will
>> already be in memory.
AH> There's no way to check for "external references", because said
AH> references are actually the running transactions. So you can't drop a
AH> row until all the transactions that were active during your transaction
How does the backend running vacuum detect that a row has no active
references? Why can't the current backend know that same information?