Re: rules / triggers on insert. why after? - Mailing list pgsql-sql

From Tom Lane
Subject Re: rules / triggers on insert. why after?
Date
Msg-id 9792.1026486449@sss.pgh.pa.us
Whole thread Raw
In response to rules / triggers on insert. why after?  (Ahti Legonkov <lego@127.0.0.1>)
List pgsql-sql
Ahti Legonkov <lego@127.0.0.1> writes:
> CREATE TABLE reo (
>    "REO_ID" int4 DEFAULT nextval('"REO_ID_seq"'::text) NOT NULL,
>    "TYPE" varchar(64) NOT NULL,
>    CONSTRAINT "REO_ID_reo_ukey" UNIQUE ("REO_ID"),
>    CONSTRAINT reo_pkey PRIMARY KEY ("REO_ID")
> );

> CREATE TABLE lreo (
>    "CITY" varchar(64),
>    "STREET" varchar(64),
>    "PRICE" int4,
>    "REO_ID" int4 DEFAULT currval('"REO_ID_seq"'::text),
>    CONSTRAINT "REO_ID_land_reo_ukey" UNIQUE ("REO_ID"),
>    CONSTRAINT "fk_LREO_REO_ID" FOREIGN KEY ("REO_ID") REFERENCES reo 
> ("REO_ID") ON DELETE NO ACTION ON UPDATE NO ACTION NOT DEFERRABLE 
> INITIALLY IMMEDIATE
> );

That default for reo_id is too fragile to consider using in any case.
You are making way too many assumptions about when defaults will be
evaluated relative to other actions (such as rule/trigger firings).

I'd suggest that you have no default for column reo_id, and instead
have a BEFORE INSERT trigger for lreo that (a) inserts a row into reo
and (b) sets new.reo_id to the inserted key (which you could get from
currval at that point).
        regards, tom lane


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