ORA-01722: invalid number caused with SQL using bind variable

Question

Hi,
Im am hoping that someone can help me resolve a problem thats only just services and is being experienced on quite a few clients.
our application uses C++ exes and makes OCI calls to the database.
what has happened in the last week or so, there has been quite a few invalid number errors being received on a prod server but strangly enough we cannot reproduct the error on our UAT system.
The sql is using bind variables and the information in the trace file shows that a number is being used for the bind variable, here is an extract from one trace file:
for some schemas, the bind variable value is some currupted value, i think:
oacdty=01 mxl=32(21) mxlc=00 mal=00 scl=00 pre=00
oacflg=03 fl2=1206001 frm=01 csi=178 siz=32 off=0
kxsbbbfp=9a8d62b8 bln=32 avl=03 flg=05
value="Â*d"
but on another schema, the value used is:
Bind#0
oacdty=01 mxl=32(32) mxlc=00 mal=00 scl=00 pre=00
oacflg=03 fl2=1206001 frm=01 csi=178 siz=32 off=0
kxsbbbfp=c5f92718 bln=32 avl=04 flg=05
value="2101"
however both produce invalid number errors.
I am relatively inexperienced as a DBA so would appreciate as much help as i can get.

Answer 1

Could you post your sql statement that is being run.
Also post the query plan from your uat system and the one from your production system (They are likely to be different)
You can export the stats from your production system and run them in your uat system. If you do this, then the execution plans should be the same on both systems(dbms_stats) and if you have the same data you should run into the same problem on uat as in production.
The root cause of this type of problem is having a column in a table which holds values which are of different datatypes. Typically there is a condition in the where clause which indicates that for example only numeric columns should be retrieved from the column which holds multiple data types. However since the optimizer is free to rewrite the query any way it sees fit, (It does not necessarily execute in the order the sql statement is written) it does not filter this data first, and therefore you hit non-numeric data and run into the invalid number error.
You can use little techniques like using an inline view with rownum in the column list, to perform the first filter. This ensures that the inline view is executed on its own, rather than being merged (materialized) with the rest of the query.
A quick temporary solution is to use a comparison like to_char(column_name) = variable
Make sure your comparisons are correct and it doesn't negatively impact on performance of the query