Hello,
I'm trying to do a simple SQL query over Postgresl 9.0 running on Ubuntu.
I have a large table (over 100 million records) with three fields,
id_signal (bigint), time_stamp (timestamp) and var_value (float).
My query looks like this:
select var_value from ism_floatvalues where id_signal = 29660 order by
time_stamp desc limit 1;
So I want to select the last value from a determinated ID (is_signal).
This query runs FOREVER, while if I delete "limit 1" it runs instantly....
Any help?
Regards.
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