Hello,
We encountered that if our ESQL/C written servers see on SELECT or FETCH
in a row a NULL value, it will raise correctly the error -213 as written
and explained in https://www.postgresql.org/docs/11/ecpg-variables.html#ECPG-INDICATORS
We catch this error -213 and deal with in.
What we did not knew and discovered today is something very fatal: In
such a situation on a FETCH of a row of some 55 columns, the transfer of
the column elements into their hostvariables stops on first NULL value,
as here to be seen in the log:
[29217] [17.06.2020 15:49:16:499]: ecpg_execute on line 69: query: select * from acq_ffleit where bnr = $1 ; with 1
parameter(s)on connection sisis
[29217] [17.06.2020 15:49:16:500]: ecpg_execute on line 69: using PQexecParams
[29217] [17.06.2020 15:49:16:500]: ecpg_free_params on line 69: parameter 1 = 742
[29217] [17.06.2020 15:49:16:500]: ecpg_process_output on line 69: correctly got 1 tuples with 55 fields
[29217] [17.06.2020 15:49:16:500]: ecpg_get_data on line 69: RESULT: 742 offset: 752; array: no
...
[29217] [17.06.2020 15:49:16:500]: ecpg_get_data on line 69: RESULT: 49 offset: 752; array: no
[29217] [17.06.2020 15:49:16:500]: ecpg_get_data on line 69: RESULT: offset: 752; array: no
[29217] [17.06.2020 15:49:16:500]: raising sqlcode -213 on line 69: null value without indicator on line 69
In the above examples the transfer stopped after 47 RESULTs; the
hostvariables after this have been untouched in our program, i.e. only
part of the row has been read.
One could say, "so what, you have error -213 and you deserve it". But at
least this behaviour should be documented clearly in the above mentioned page.
I would expect, that NULL values would not be transfered in such case
but all other hostvariables yes, i.e. for me this is perhaps a bug in the
ESQL/C implementation.
Comments?
Thanks
matthias
--
Matthias Apitz, ✉ guru@unixarea.de, http://www.unixarea.de/ +49-176-38902045
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