I have just came across interesting Postgres behaviour with OR-conditions. Are there any chances that the optimizer will handle this situation in the future?
select * from commons.financial_documents fd where fd.creation_time <= '2011-11-07 10:39:07.285022+08' order by fd.creation_time desc limit 200
select * from commons.financial_documents fd where fd.creation_time = '2011-11-07 10:39:07.285022+08' or fd.creation_time < '2011-11-07 10:39:07.285022+08' order by fd.creation_time desc limit 200
It would certainly be possible, providing the constants compare equally, but... Question: Would you really want to pay a, say 1% increase in planning time for ALL queries, so that you could have this unique case of queries perform better at execution time?
Is there a valid reason why you don't just write the query with the <= operator?
