Marc Munro <[EMAIL PROTECTED]> writes:
> Am I right in thinking that altering a column from varchar(n) to
> varchar(n+m) requires each tuple to be visited?
Yes. Doing otherwise would require an unreasonable amount of
data-type-specific knowledge hardwired into ALTER COLUMN TYPE.
regards, tom lane
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
