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From Reid Thompson <reid.thomp...@ateb.com>
Subject Re: Postgress autogenerated keys.
Date Thu, 29 Oct 2009 04:03:25 GMT
Emanuele Maiarelli wrote:
> I'm using cayenne 3 with postgresql 8.2.14, for instance i've a table 
> structured like that
> 
> CREATE TABLE documenti
> (
>  doc_pk bigserial NOT NULL,
>  doc_desc character varying(255),
>  doc_mine character varying(255),
>  doc_prot_fk bigint,
>  doc_self_fk bigint,
>  doc_prot_nr bigint,
>  doc_folder_fk bigint,
>  doc_uid character varying(255),
>  doc_prot_anno bigint,
>  doc_unsubmitted boolean,
>  CONSTRAINT "DOCUMENTI_pkey" PRIMARY KEY (doc_pk),
>  CONSTRAINT "DOCUMENTI_DOC_PROT_FK_fkey" FOREIGN KEY (doc_prot_fk)
>      REFERENCES protocolli (prot_pk) MATCH SIMPLE
>      ON UPDATE NO ACTION ON DELETE NO ACTION,
>  CONSTRAINT documenti_doc_folder_fk_fkey FOREIGN KEY (doc_folder_fk)
>      REFERENCES folders (fold_pk) MATCH SIMPLE
>      ON UPDATE NO ACTION ON DELETE NO ACTION
> )
> WITHOUT OIDS;
> and a sequnce for generating Pks
> 
> CREATE SEQUENCE documenti_doc_pk_seq
>  INCREMENT 1
>  MINVALUE 1
>  MAXVALUE 9223372036854775807
>  START 20
>  CACHE 1;
> 
> My question is what's the best pratice to ensure correts Pks being 
> generated from sequence:
> 
> actually entity is configured as follow
> 
>    <db-entity name="documenti" schema="public">
>        <db-attribute name="doc_desc" type="VARCHAR" length="255"/>
>        <db-attribute name="doc_folder_fk" type="BIGINT" length="8"/>
>        <db-attribute name="doc_mine" type="VARCHAR" length="255"/>
>        <db-attribute name="doc_pk" type="BIGINT" isPrimaryKey="true" 
> isMandatory="true" length="8"/>
>        <db-attribute name="doc_prot_anno" type="BIGINT" length="8"/>
>        <db-attribute name="doc_prot_fk" type="BIGINT" length="8"/>
>        <db-attribute name="doc_prot_nr" type="BIGINT" length="8"/>
>        <db-attribute name="doc_self_fk" type="BIGINT" length="8"/>
>        <db-attribute name="doc_uid" type="VARCHAR" length="255"/>
>        <db-attribute name="doc_unsubmitted" type="BIT" length="1"/>
>        <db-key-generator>
>            <db-generator-type>ORACLE</db-generator-type>
>            <db-generator-name>documenti_doc_pk_seq</db-generator-name>
>            <db-key-cache-size>1</db-key-cache-size>
>        </db-key-generator>
>    </db-entity>
> 
> but since i missed initially to specify 
> <db-key-cache-size>1</db-key-cache-size> i got duplicated keys problems.
> 
> Specifing <db-key-cache-size>1</db-key-cache-size> seems like solve the 
> problem. Is this correct?
> 
> 
> Or should i change postgresql to automatically create the pk i mean, 
> changing doc_pk like that  "doc_pk bigserial NOT NULL DEFAULT 
> nextval('documenti_doc_pk_seq')
> 
> and setting
> <db-attribute name="doc_pk" type="BIGINT" isPrimaryKey="true" 
> isGenerated="true" isMandatory="true" length="8"/>
> 
> 
> 
> 
> 
> 

let the db manage it, that's what it's designed for

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