Hi,
just want to share with all of you a wierd thing that i found when i tested it.
i was doing a query that will call a function long2ip to convert bigint to ips.
so the query looks something like this.
select id, long2ip(srcip), long2ip(dstip) from sometable
where timestamp between timestamp '01-10-2005' and timestamp '01-10-2005 23:59' order by id limit 30;
for your info, there are about 300k rows for that timeframe.
it cost me about 57+ secs to get the list.
which is about the same if i query
select id, long2ip(srcip), long2ip(dstip) from sometable
where timestamp between timestamp '01-10-2005' and timestamp '01-10-2005 23:59'
it will cost me about 57+ secs also.
Now if i did this
select id,long2ip(srcip), long2ip(dstip) from (
* from sometable
where timestamp between timestamp '01-10-2005' and timestamp '01-10-2005 23:59' order by id limit 30) as t;
it will cost me about 3+ secs
Anyone knows why this is the case?
Hasnul
---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
