Postgres 9.5.4 Window in update trigger function (lag and lead) - ruby-on-rails

Question

Been banging away and would like some help
After running a lot of mathematical functions on rails and finding spurious results I decided to climb down to do it in the DB to find it's all very do-able for me however as soon as I get to the second function I have the following errors:
PG::UndefinedFunction: ERROR: function updown(integer) does not exist
LINE 3: SELECT "updown" (lag(updown) over (order by id)) table_nam...
^ HINT: No function matches the given name and argument types.
Migration:
class CreateSmoothings < ActiveRecord::Migration
def change
create_table :smoothings do |t|
t.decimal :firstsmprice, :precision => 8, :scale => 6
t.decimal :finalsmprice, :precision => 8, :scale => 6
t.decimal :firstsmdelta, :precision => 8, :scale => 6
t.decimal :finalsmdelta, :precision => 8, :scale => 6
t.integer :updown, :null => false, :default => 0
t.integer :posture
t.integer :step
t.references :usdzar, index: true, foreign_key: true
t.references :smoothval, index: true, foreign_key: true
t.timestamps null: false
end
add_index :smoothings, :finalsmprice
end
end
I have an update controller that sets the data in smoothings from another table and this is when the trigger is fired. The first trigger works like a charm. This is the controller action and then the trigger and function.
# POST /smoothings works and does the insert of all data to the smoothings table
def create
# Do the 1st and 2nd SMOOTHINGS
# Get the row with the smoothval_id parameter to use these
sv = Smoothval.find(smoothing_params[:smoothval_id])
fval = sv.fval
sval = sv.sval
svid = sv.id
toremove = Smoothing.where(:smoothval_id => sv.id)
toremove.destroy_all
# For every entry in the table do:
collection = Usdzar.all
collection.each_with_index do |usdzar, i|
# Declare the previous variables required for id = 1 as
# the calculation cannot be done as it has no previous id
# I am sure this can be refactored
if usdzar.id == 1
prevprice = usdzar.price
prevfirstsmprice = usdzar.price
prevfinalsmprice = usdzar.price
else
prevprice = collection[i-1].price
prevfirstsmprice = Smoothing.last.firstsmprice
prevfinalsmprice = Smoothing.last.finalsmprice
end
# Do the smoothing calcs for the first smoothing using fval (first value)
firstsmprice = (((fval * usdzar.delta)/100) + prevprice)
# Find the difference of the current and previous of the first smoothing
firstsmdelta = firstsmprice - prevfirstsmprice
# Do the final smooting with the fval
finalsmprice = ((sval * firstsmdelta)/100) + prevfirstsmprice
# Find the differance of the current and previous of the second smoothing
finalsmdelta = finalsmprice - prevfinalsmprice
# Create the rows at end of iteration
Smoothing.create!(
usdzar_id: usdzar.id,
smoothval_id: sv.id,
firstsmprice: firstsmprice,
firstsmdelta: firstsmdelta,
finalsmprice: finalsmprice,
finalsmdelta: finalsmdelta
)
end
redirect_to smoothings_url, notice: 'Old smoothings removed and new smoothings successfully created.'
The trigger function and trigger that works :-)
CREATE TRIGGER a_smoothings_trigger
AFTER INSERT
ON smoothings
FOR EACH ROW
EXECUTE PROCEDURE make_updowns_trg();
CREATE FUNCTION make_updowns_trg()
RETURNS trigger
LANGUAGE 'plpgsql'
AS $BODY$
BEGIN
update smoothings
set updown = case when (finalsmdelta < 0) then 1
when (finalsmdelta > 0 ) then 0
else 2 end;
RETURN NULL;
END
$BODY$;
This (the above) runs well.
What I am trying to do next is extend the function by another trigger and function (knowing now that they run in alphabetical order
The trigger/function is meant to take the "updown" (being 0, 1 or 2: up, down or same is the enum in rails) and:
If updown and next updown are the same then update as 2 (in between)
If the updown is greater than next "updown" update as 1 (high)
If the updown is less then next "updown" update as 0 (low)
CREATE FUNCTION public.make_high_lows_trg()
RETURNS trigger
LANGUAGE 'plpgsql'
COST 100.0
VOLATILE NOT LEAKPROOF
AS $BODY$
BEGIN
WITH next_updown AS
(SELECT updown (lag(updown) over (order by id)) table_name FROM smoothings
ORDER BY id DESC)
update smoothings
set posture = case when updown < next_updown then 1
when updown > next_updown then 0
else 2 end;
RETURN NULL;
END
$BODY$;
CREATE TRIGGER b_smoothings_trigger
AFTER INSERT
ON public.smoothings
FOR EACH ROW
EXECUTE PROCEDURE public.make_high_lows_trg();
Model for the controller:
class Smoothing < ActiveRecord::Base
enum updown: [:up, :down, :same]
enum posture: [:high, :low, :inbetween]
belongs_to :usdzar
belongs_to :smoothval
end
I had this all running in the controller as my model method coding really sucks and got it all running however after testing found the data to be very unreliable. Thanks in advance for the help. I am really astounded by the number of functions in Postgres and when I came across the window function thought it would be appropriate but can get over the hurdle. I know that (from the psql docs) you cannot put the lag/lead windowing into the update part of the function but have an issue obviously with how to do the sql block correctly
This query runs after running the first but how do I update the table on this:
with myUpdowns as (
Select id, updown, Lag(updown) over (order by id desc) next_updown from smoothings
)
select *
from myUpdowns
where updown < next_updown;
AND now I got one high to update correctly: I am now trying to do the full spread of high. low and inbetween (0, 1 and 2). If you have any suggestions I would love to hear them. The updated trigger that adds the high to the table looks as follows:
CREATE FUNCTION make_high_lows_trg()
RETURNS trigger
LANGUAGE 'plpgsql'
AS $BODY$
BEGIN
UPDATE smoothings
SET posture = 0
FROM (
Select id, updown, Lag(updown) over (order by id desc) next_updown from smoothings
) as highs
WHERE highs.updown < highs.next_updown
AND smoothings.id = highs.id;
RETURN NULL;
END
$BODY$;
The Trigger:
CREATE TRIGGER b_smoothings_trigger
AFTER INSERT
ON smoothings
FOR EACH ROW
EXECUTE PROCEDURE make_high_lows_trg();
Hmm, now how to do low and inbetween, actually just the high and low are good