Re: Time Aggregates

From: Thomas Lockhart <lockhart(at)alumni(dot)caltech(dot)edu>
To: Itai Zukerman <zukerman(at)math-hat(dot)com>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: Time Aggregates
Date: 2000-08-02 15:27:13
Message-ID: 39883DD1.610A0954@alumni.caltech.edu
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-sql

> I'm currently doing this:
> SELECT symbol, date_trunc('minute', posted),
> min(price), max(price), avg(price)
> FROM trade
> GROUP BY symbol, date_trunc('minute', posted);
> to get a list of minute-averages of trade prices. I get the feeling
> that this is bad form, that I should be doing this some other way. Is
> that the case?

Looks OK to me. If you are doing this *a lot* (i.e. many more queries
than inserts), then you might want to set up another column which
contains date_trunc('minute',posted) to avoid the calculation. Something
like

create table trade (
symbol text,
posted timestamp,
price integer,
mpost timestamp
)

then define a rule to update mpost when posted gets set (haven't done
that part).

- Thomas

In response to

Responses

Browse pgsql-sql by date

  From Date Subject
Next Message David Lloyd-Jones 2000-08-02 15:37:44 Re: Time Aggregates
Previous Message Itai Zukerman 2000-08-02 13:41:52 Time Aggregates