RE: fetch across commit
- From: "Goulet, Dick" <DGoulet@xxxxxxxx>
- To: "Oracle List" <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 26 Nov 2004 21:47:03 -0500
Seems you've asked this question twice now, which means you did not
understand the answer the first time. OK; the short answer is yes it
can cause an ORA-1555 error. The reason is that when you opened the
cursor Oracle captured the current SCN, say 100. You've done several
updates/inserts/deletes based on the logic of your program and done a
commit, which changed the SCN to say 105. In doing so you've told
Oracle that you are no longer interested in any rollback segments before
SCN 105, when in fact you are. Immediately that is not a problem, but
sooner or later part of your cursor will need to recreate a data row to
SCN 100 with rollback data. Problem is that you've let it go &
consequently Oracle cannot create a read consistent view as of SCN 100 &
you get ORA-01555.
One trick I've used rather successfully in the past is to put an "order
by" clause on the cursor statement. Order By causes a sort, which means
Oracle has to find all of the data that your cursor will need and sort
it before handing you the first row. Now all of your return rows are
stored in a temp table in the Temp tablespace & no more rollback or read
consistent view activity is needed. It's a hack I'll admit, but one
that appears to work 90% of the time.=20
Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA
-----Original Message-----
From: ryan_gaffuri@xxxxxxxxxxx [mailto:ryan_gaffuri@xxxxxxxxxxx]=20
Sent: Wednesday, November 24, 2004 1:53 PM
To: zimsbait@xxxxxxxxx; Oracle List
Cc: z b
Subject: Re: fetch across commit
yes, because a commit releases the lock on the rollback segments and
orac=3D
le can overwrite them with another process.=3D20
-------------- Original message --------------=3D20
> Listers,=3D20
>=3D20
> I have a question where I need a little clarification about fetching
ac=3D
ross=3D20
> commits. Can this happen if the table being committed to is not the
sam=3D
e=3D20
> as the tables(s) in the cursors?=3D20
>=3D20
> For example, if I had :=3D20
> cursor c1 is select empname form emp where=3D20
> dept =3D3D 100;=3D20
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