From: | "Robins Tharakan" <tharakan(at)gmail(dot)com> |
---|---|
To: | Patric <lists(at)p-dw(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Saving result set of SELECT to table column |
Date: | 2008-01-15 03:30:27 |
Message-ID: | 36af4bed0801141930r4bcaf94cqed26557899fc578b@mail.gmail.com |
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Thread: | |
Lists: | pgsql-performance |
Hi Patric,
This doesn't seem to be a question pertaining to the PERFORM queue.
If I understand you correctly, this should solve your problems, without the
need for any RULES / TRIGGERS.
CREATE TABLE y
(
y1 int4 NOT NULL,
y2 varchar,
CONSTRAINT a PRIMARY KEY (y1)
)
CREATE TABLE z
(
z1 int4 NOT NULL,
z2 varchar,
CONSTRAINT zz PRIMARY KEY (z1)
)
CREATE TABLE x
(
x1 int4 NOT NULL,
xy1 int4 NOT NULL,
xz1 int4 NOT NULL,
xy2 varchar,
xz2 varchar,
CONSTRAINT xa PRIMARY KEY (x1),
CONSTRAINT xy1 FOREIGN KEY (xy1)
REFERENCES y (y1) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION,
CONSTRAINT xz1 FOREIGN KEY (xz1)
REFERENCES z (z1) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)
INSERT INTO x (x1, xy1, xz1, xy2, xz2)
SELECT 1, y1, z1, y2, z2
FROM y, z
WHERE y1 = 1
AND z1 = 1;
*Robins*
On Jan 14, 2008 11:49 PM, Patric <lists(at)p-dw(dot)com> wrote:
> Hi,
> There will be some flames i suppose.
> Well I've a normalized database..
> For instance:
>
> create table Y ( pk, data... );
> create table Z ( pk , data... );
>
> create table X ( char, references Y, references Z);
>
> SELECT * from X;
>
> Now I want to make a listing of the result set from X.
> If there are references to Z or Y (not null refs), I want to display
> that data too.
>
> Normally I would SELECT, to get that data, not in my case.
> Nearly all queries will be SELECTs, no UPDATEs or INSERTs, so need to
> optimize that case.
>
> The dirty little denormalization would look like this:
>
> create table X ( char, ref. to Y, ref. to Z, StoreY Y , StoreZ Z);
>
> On insert or update of Z or Y, I would update these two (StoreY,
> StoreZ) columns by RULE or TRIGGER..
> I know this is not nice etc.. Codd would sue for this, but in my case
> performance over beauty is ok.
> I'm looking for something like UPDATE X set StoreY=(SELECT * FROM Y
> WHERE pk=4) WHERE foreignID2Y = 4;
>
> Is there a away to accomplish this straightforward in a single
> statement without doing loops and stuff in a serverside procedure?
>
> Thanks in advance,
> Patric
>
>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: Don't 'kill -9' the postmaster
>
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