If you are running your Informix server on a little-endian
platform (for example Linux) and you query the
sysmaster:sysrawdsk table using the 'where rowid=xxxxx' clause
and the rowid of 'xxxxx' doesn't exist, you will get following
assertion failure:
09/05/14 08:40:00 Assert Failed: No Exception Handler
09/05/14 08:40:00 IBM Informix Dynamic Server Version 12.10.FC3
09/05/14 08:40:00 Who: Session(15530, user@hostname, 2708,
0x48fa8158)
Thread(55011, sqlexec, 48f77a28, 1)
File: mtex.c Line: 516
09/05/14 08:40:00 Results: Exception Caught. Type: MT_EX_OS,
Context: mem
09/05/14 08:40:00 Action: Please notify IBM Informix Technical
Support.
09/05/14 08:40:00 See Also: /tmp/af.dacb5ac0
The stack of the failing thread will look like this:
afstack
mt_ex_throw_sig
afsig_handler
<signal frame>
prrawdsk
pstread
pst_rsread
rsread
fmread
getsinglerow
readidx_new
gettupl
scan_next
getrow
fetchrow
exfetch
sql_nfetch
sq_nfetch
sqmain
spawn_thread
th_init_initgls
startup
If you run similar query on a big-endian platform (AIX, for
example), no AF occurs, but the server always returns the same,
incomplete row, regardless of whether the used rowid exists or
not:
$ echo "select * from sysrawdsk where rowid=13" | dbaccess
sysmaster
Database selected.
pg_chunk 1
pg_offset 0
offset 0
loc 00000001:00000000:0000:
hexdata
ascdata
Another aspect of this defect is that on big-endian platforms,
the rowids returned by the server for the query below are
non-unique, while on the little-endian platforms they are unique
and can be used for accessing the rows:
select rowid, * from sysrawdsk;
big-endian results:
rowid 0
pg_chunk 1
pg_offset 0
offset 0
loc 00000001:00000000:0000:
hexdata 00000000 00013512 00031800 01b00e40
ascdata ......5......0.@
rowid 0
pg_chunk 1
pg_offset 0
offset 16
loc 00000001:00000000:0010:
hexdata 00000000 00000000 49424d20 496e666f
ascdata ........IBM Info
rowid 0
pg_chunk 1
pg_offset 0
offset 32
loc 00000001:00000000:0020:
hexdata 726d6978 2044796e 616d6963 20536572
ascdata rmix Dynamic Ser
....
little-endian results:
rowid 1
pg_chunk 1
pg_offset 0
offset 0
loc 00000001:00000000:0000:
hexdata 00000000 0100341a 03000018 3001c006
ascdata ......4.....0.@.
rowid 16777217
pg_chunk 1
pg_offset 0
offset 16
loc 00000001:00000000:0010:
hexdata 00000000 00000000 49424d20 496e666f
ascdata ........IBM Info
rowid 33554433
pg_chunk 1
pg_offset 0
offset 32
loc 00000001:00000000:0020:
hexdata 726d6978 2044796e 616d6963 20536572
ascdata rmix Dynamic Ser
... |
