Duration/scope of SET ISOLATION and SET LOCK MODE TO WAIT

[chr...@ignitemedia.com]

I'm trying to solve a problem in which I'm getting error -107 (failed
to perform physical-order read) when updating a single row in a table.
I have several applications updating the same table, although each
application only updates its own specific rows, so no more than one
application can update a particular row.

What I need to know is the scope or duration of the following SQL
statements:

SET ISOLATION TO DIRTY READ

and

SET LOCK MODE TO WAIT n

Do these statements apply for the duration of an open connection,
within a single transaction, or some other scope of which I am unaware?

thanks,

- chris

chr...@ignitemedia.com

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[Wolfgang Zager]

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The scope is the duration of Your connection.

Wolfgang

[Art S. Kagel]

Scpe is the duration of the connection. You problem is probably that
the table in question has LOCK MODE page set. Change that to row level
locking (ALTER TABLE SET LOCK MODE (row);) and also SET LOCK MODE TO
WAIT n.

Art S. Kagel

[June Tong]

Possibly, although I'd say more likely the applications are not using an
index to get at their "specific rows". Thus the "physical-order read" error,
which implies sequential scan. One application thus blocks another
application, even though they are not going after the same rows. This is
covered in more detail on my unofficial Informix FAQ at
http://ww.geocities.com/SiliconValley/Bridge/4578 .

June

jun...@hotmail.com
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