How can I use the crosstab() function?

On 25 February 2014 23:30, Rob Richardson <RDRichardson@rad-con.com> wrote:

Hello!

I am trying to use the crosstab() function in PostgreSQL 9.0 under Windows
7. My table has three columns: a timestamp, a tag name and a tag value. I
am trying to generate a table that has one column for every distinct value
in the tag name field. Each row of the crosstab table will have the
timestamp, plus values for every tag name that had a value recorded at that
time. Of course, many of the fields in each row will be null.

It seems to me that the crosstab() function will do exactly what I want,
but I can't get it to work. If I try:

select * from

crosstab('select recorded_date, tag_name, value from plc_values')

as ct(recorded_date timestamp with time zone, tag_name text, tag_value
text);

I get "function crosstab(unknown) does not exist".

According to documentation, I think I need to add the tablefunc extension
first. But when I run

create extension tablefunc;

I get a syntax error pointing to the word "extension".

What haven't I done?

Hi Rob,

Extensions weren't introduced until PostgreSQL 9.1, so you'll have to
install it the old-fashioned way. See the bottom of 9.0's page on contrib
modules for what the method is:

http://www.postgresql.org/docs/9.0/static/contrib.html

--
Thom