Re: Why is the comparison between timestamp and date so much slower then between two dates

Tom Lane schrieb am 14.04.2016 um 15:57:
>> So the optimizer _should_ be smart enough to do the conversion only
>> once at the beginning of the statement and then use that converted
>> value during the execution of the statement without the need
>> to re-evaluate it for each row.
>
> It's not; especially not in your originally posted case where the
> up-conversion happens on the variable not the pseudo-constant.

Which variable are you referring to?

The original query only uses a simple between condition where the
comparison value is a "constant" (the value of "now()")