Skip to main content

inserted value too large for column - in a delete?

One of the well know error everyone meets in Oracle is the ORA-01041: inserted value too large for column (while s/he is cursing Oracle why it did not returned ORA-12899: value too large for column ... with the details).
The error is usualy right - you tried to insert a value too large for the column definition, so Oracle rejects the statement. Although it mentions insert, one can understand such error for updates, too.

But recently I got this issue for a delete statement. And no, there was not any trigger nor other advanced feature doing an insert in the background. So why on Earth, why?

The application (apply process of Dbvisit Replicate) was using OCI and the error indeed came from the OCIStmtExecute call. As it turns out, however, the devil is somewhere else.

One of the confusing topic in OCI is string handling - there are four ways how to pass a string to Oracle, depending on whether it's null-terminated or length-specified and whether it should be space-padded (think about CHAR/VARCHAR2 semantics):
  • SQLT_CHR: varchar2-style, length-specified
  • SQLT_STR: varchar2-style, null-terminated
  • SQLT_AFC: char-style, length-specified
  • SQLT_AFV: char-stype, null-terminated
  • (and a few more for LONGs, RAWs and a different API for LOBs)
The application uses SQLT_AFC, as the data it gets are fed directly from the source database, so no padding magic is required (even worse, the values do not match for some data combinations with SQLT_CHR due to the padding). However, for some strange historical reason, the CHAR() datatype is limited to 2000 bytes - and this carries over to SQLT_AFC, although this is not mentioned in the OCI documentation. What's even more interesting, this happened only when the value was specified as UTF16.

And yes, this is exactly the reason for the ORA-01041 - binding a 4000 bytes string to SQLT_AFC and setting OCI_ATTR_CHARSET_ID to OCI_UTF16ID did result in "inserted value too large for column" when the statement was executed...

Versions: Linux 64-bit, Oracle 10.2 and 11.2, using Oracle Instant Client 11.1.0.7.

Comments

Popular posts from this blog

ORA-27048: skgfifi: file header information is invalid

I was asked to analyze a situation, when an attempt to recover a 11g (standby) database resulted in bunch of "ORA-27048: skgfifi: file header information is invalid" errors.

I tried to reproduce the error on my test system, using different versions (EE, SE, 11.1.0.6, 11.1.0.7), but to no avail. Fortunately, I finally got to the failing system:

SQL> recover standby database;
ORA-00279: change 9614132 generated at 11/27/2009 17:59:06 needed for thread 1
ORA-00289: suggestion :
/u01/flash_recovery_area/T1/archivelog/2009_11_27/o1_mf_1_208_%u_.arc
ORA-27048: skgfifi: file header information is invalid
ORA-27048: skgfifi: file header information is invalid
ORA-27048: skgfifi: file header information is invalid
ORA-27048: skgfifi: file header information is invalid
ORA-27048: skgfifi: file header information is invalid
ORA-27048: skgfifi: file header information is invalid
ORA-00280: change 9614132 for thread 1 is in sequence #208


Interestingly, nothing interesting is written to alert.log n…

Reading data from PGA and SGA

Overview For our investigation of execution plan as it is stored in memory, we need in the first place to be able to read the memory.

We have the options of
x$ksmmem, reading SGA using SQL. Personally I don't like it, it's cumbersome and slow.direct SGA read: obviously reading SGA only; it's fast and easy to doread process memory: can read PGA, process stack - and since the processes do map the SGA, too, you can read it as well. Unfortunately ptrace sends signals to the processes and the process is paused when reading it, but so far all my reads were short and fast and the processes did not notice. Some OS configurations can prevent you from using ptrace (e.g. docker by default), google for CAP_SYS_PTRACE.gdb: using your favorite debugger, you can read memory as well. Useful when investigating. Direct SGA read I always considered direct SGA read of some dark magic, but the fundamentals are actually very easy. It still looks like sorcery when actually reading the Oracle in…

Filter and access predicates

More than just column projections When we look around for further pointers in the tree nodes, we find more pieces resembling the column projections we have seen so far. With some experimenting, we will find out that these are access predicates and filters.

First of all, the location of these pointers is not always the same, it seems that the value at 0x34 is some kind of flag, indicating whether filters and/or access predicates are present, and where. Or whether there is just one, or more of them.  It probably also indicates what other info is present, but I have no idea what info that would be or what each value means.
Resembling, but different The data we see as predicates are not columns; after all, a predicate is a condition, not a single column. But the structure is similar to what we have seen with columns, and if we follow pointers further, we eventually build a tree, and some of the leaves are indeed just column projections.
After some contemplation, we realize it's all t…