Thread: Insert into VIEW using RULE. Not possible to use nextval()?
I am having the same problem that is documented elsewhere in the archives. Namely when you have a INSERT RULE on a VIEW the nextval() function doesn't behave properly (or it doesn't behave how I'd like it to). http://archives.postgresql.org/pgsql-sql/2003-07/msg00333.php I'm wondering if anything has changed for this in regards to best practices? Suggested solutions are to change to a trigger or use currval() for your secondary INSERTS inside the RULE. A trigger does not apply to my case as I am basically using this as a shortcut to manually doing two INSERTs. Is there any problems with using the currval() approach? If I use that within the same call is there any chance of that not returning the correct value? (e.g. if this INSERT RULE is being called a 1000 times at once, is it guaranteed to be correct? Another option I see is to place the INSERT inside a LOOP. For example instead of: INSERT INTO user_activity_single(user_activity_id, activity_date, user_activity_type_id, user_activity_action_id, user_id, div1) SELECT nextval('user_activity_user_activity_id_seq'), etc.... have: FOR mviews IN SELECT nextval('user_activity_user_activity_id_seq') as id, CURRENT_DATE, 1, 2, 27, 'foo' LOOP INSERT INTO user_activity_single(mviews.id, etc...) END LOOP; Performance wise this doesn't seem as good. In my case the SELECT statement would be around 4000 records. Any tips for me? Regards, Collin Peters
--- Collin Peters <cadiolis@gmail.com> wrote: > I am having the same problem that is documented elsewhere in the > archives. Namely when you have a INSERT RULE on a VIEW the nextval() > function doesn't behave properly (or it doesn't behave how I'd like it > to). > > http://archives.postgresql.org/pgsql-sql/2003-07/msg00333.php > Is your problem that you can't insert more than one record at a time into your INSERTable VIEW?
The exact problem is that you can't use nextval() with an INSERTable VIEW Problem is the same as that in this post: http://archives.postgresql.org/pgsql-sql/2003-07/msg00333.php On 5/3/07, Richard Broersma Jr <rabroersma@yahoo.com> wrote: > > --- Collin Peters <cadiolis@gmail.com> wrote: > > > I am having the same problem that is documented elsewhere in the > > archives. Namely when you have a INSERT RULE on a VIEW the nextval() > > function doesn't behave properly (or it doesn't behave how I'd like it > > to). > > > > http://archives.postgresql.org/pgsql-sql/2003-07/msg00333.php > > > > Is your problem that you can't insert more than one record at a time into your INSERTable VIEW? >
--- Collin Peters <cadiolis@gmail.com> wrote:
> The exact problem is that you can't use nextval() with an INSERTable VIEW
I apoligize if I am not understanding your problem correctly. I am unsure as to intent behind
using nextval() as opposed to currval().
I do not know if the following DDL will help but I can show you how I preform inserts across
multiple tables using the rule system:
CREATE RULE Vschematic_insert AS ON INSERT TO Docs.Vschematic
DO INSTEAD (INSERT INTO Docs.Document ( did, doccode, docnum, docdisc) VALUES ( DEFAULT, 'schematic', New.docnum,
New.docdisc);
INSERT INTO Docs.Drawing ( did, doccode, title1, title2, title3)VALUES ( Currval('Docs.Document_did_seq'), 'schematic',
New.title1,New.title2, New.title3);
INSERT INTO Docs.Schematic ( did, doccode)VALUES ( Currval('Docs.Document_did_seq'), 'schematic') );
For reference the table DDL follows:
CREATE TABLE docs.document (did serial PRIMARY KEY,doccode varchar(30) not null, docnum
varchar(30) unique not null,docdisc text not null default '',
constraint document_doccode_chk check ( doccode in ( 'cpf', 'logicsystem', 'processdetail', 'electricaldetail',
'locationplan','logicdiagram', 'loopdiagram', 'schematic', 'wiringdiagram', 'pid', 'isometric',
'airsupplydetail','mountingdetail', 'pnuematicdetail', 'functionaldiscription', 'datasheet',
'processmaterialspec', 'loopfoldermiscellaneous', 'loopfolderorficeplate', 'loopfolderinstallation',
'loopfolderswitch', 'loopfolderxmtrctrlind', 'loopfoldercontrolvalve', 'loopfolderanalyzer',
'loopfolderworkscope', 'loopfolderdocumentation')));
CREATE TABLE docs.drawing
(did integer primary key references docs.document(did) on delete cascade,doccode
varchar(30) not null,title1 varchar(50) not null,title2 varchar(50) not null,title3
varchar(50) not null,
constraintdrawing_doccode_chkcheck ( doccode in ( 'processdetail', 'electricaldetail', 'locationplan',
'logicdiagram','loopdiagram', 'schematic', 'pid', 'isometric', 'airsupplydetail', 'mountingdetail',
'pnuematicdetail'))) ;
CREATE TABLE docs.schematic
(did integer primary key references docs.drawing(did) on delete cascade,doccode
varchar(30) not null,cid integer references equ.lcp(cid),
constraintschematic_doccode_chkcheck ( doccode = 'schematic')) ;
Regards,
Richard Broersma Jr.
Hi Richard,
Your situation is the same as mine. The only difference is that I
actually had a call to nextval() in the actual call to the VIEW. In
your case this would be something like "INSERT INTO
Vschematic_insert(...". So if you were to try "INSERT INTO
Vschematic_insert(nextval('foo_sql'), ..." and then try to use that
value inside the RULE it will fail.
Your solution works great assuming two things:
1. You don't need to use the ID for anything else (which is true in
your case and actually in mine as well)
2. currval() is guaranteed to be correct within the RULE. This was my
second question. If I call "INSERT INTO Vschematic_insert(..."
simultaneously 1000 times is it guaranteed to be correct?
On 5/3/07, Richard Broersma Jr <rabroersma@yahoo.com> wrote:
>
> --- Collin Peters <cadiolis@gmail.com> wrote:
>
> > The exact problem is that you can't use nextval() with an INSERTable VIEW
>
> I apoligize if I am not understanding your problem correctly. I am unsure as to intent behind
> using nextval() as opposed to currval().
>
> I do not know if the following DDL will help but I can show you how I preform inserts across
> multiple tables using the rule system:
>
> CREATE RULE Vschematic_insert AS ON INSERT TO Docs.Vschematic
> DO INSTEAD (
> INSERT INTO Docs.Document ( did, doccode, docnum, docdisc)
> VALUES ( DEFAULT, 'schematic', New.docnum, New.docdisc);
>
> INSERT INTO Docs.Drawing ( did, doccode, title1, title2, title3)
> VALUES ( Currval('Docs.Document_did_seq'), 'schematic', New.title1, New.title2, New.title3);
>
> INSERT INTO Docs.Schematic ( did, doccode)
> VALUES ( Currval('Docs.Document_did_seq'), 'schematic')
> );
>
> For reference the table DDL follows:
>
> CREATE TABLE docs.document (
> did serial PRIMARY KEY,
> doccode varchar(30) not null,
> docnum varchar(30) unique not null,
> docdisc text not null default '',
>
> constraint
> document_doccode_chk
> check ( doccode in ( 'cpf', 'logicsystem', 'processdetail',
> 'electricaldetail', 'locationplan', 'logicdiagram',
> 'loopdiagram', 'schematic', 'wiringdiagram', 'pid',
> 'isometric', 'airsupplydetail', 'mountingdetail',
> 'pnuematicdetail', 'functionaldiscription',
> 'datasheet', 'processmaterialspec',
> 'loopfoldermiscellaneous', 'loopfolderorficeplate',
> 'loopfolderinstallation', 'loopfolderswitch',
> 'loopfolderxmtrctrlind', 'loopfoldercontrolvalve',
> 'loopfolderanalyzer', 'loopfolderworkscope',
> 'loopfolderdocumentation')));
>
> CREATE TABLE docs.drawing
> (
> did integer primary key references
> docs.document(did) on delete cascade,
> doccode varchar(30) not null,
> title1 varchar(50) not null,
> title2 varchar(50) not null,
> title3 varchar(50) not null,
>
> constraint
> drawing_doccode_chk
> check ( doccode in ( 'processdetail', 'electricaldetail', 'locationplan',
> 'logicdiagram', 'loopdiagram', 'schematic', 'pid',
> 'isometric', 'airsupplydetail', 'mountingdetail',
> 'pnuematicdetail'))) ;
>
> CREATE TABLE docs.schematic
> (
> did integer primary key references
> docs.drawing(did) on delete cascade,
> doccode varchar(30) not null,
> cid integer references equ.lcp(cid),
>
> constraint
> schematic_doccode_chk
> check ( doccode = 'schematic')) ;
>
> Regards,
> Richard Broersma Jr.
>
--- Collin Peters <cadiolis@gmail.com> wrote: > 2. currval() is guaranteed to be correct within the RULE. This was my > second question. If I call "INSERT INTO Vschematic_insert(..." > simultaneously 1000 times is it guaranteed to be correct? To illistrate using psudo code: //This will always work: For i = 1 to 1000 doINSERT INTO Vschematic VALUES ( .. some unique values .. ); Next i //These will always fail: INSERT INTO Vschematic SELECT * FROM A_TABLE LIMIT 1000; or INSERT INTO Vschematic VALUES ( unique vals 1),(unique vals 2), ..., (unique vals n); Regards, Richard Broersma Jr.