Re: Strange results when casting string to double

On Wed, Feb 16, 2022 at 05:46 PM Adrian Klaver wrote
> On 2/16/22 05:27, Carsten Klein wrote:
>> Hi there,
>>
>> I'm using several (now unsupported) PostgreSQL 9.3.24 servers on 
>> different (ancient) Ubuntu 14.04 LTS machines. On only one of those 
>> servers, I get strange/wrong results when converting a string into a 
>> double value:
>>
> 
>> Has anyone an idea of what's going on here? I know, this version is 
>> far from still being supported, however, there's not much real changes 
>> in file float.c between these versions (in other words, this may 
>> happen with recent versions as well?). The database instances on all 
>> servers are configured quite the same (more or less). 


> What is the more or less for the problem server?

What? Didn't get that...


> Are the hardware(CPU) architectures the same for all the servers?

The problem server is a virtual machine (VMware). I've tested this on 
two other servers and do receive probably correct results. One of these 
is also a virtual machine (same VMware, running on different hardware), 
the other one is a physical box with an AMD Athlon(tm) II X4 640 64-bit 
processor.

Customer site:

Production System:  VMware (ESX Host A)   works as expected

Testing System:     VMware (ESX Host B)   DOES NOT WORK as expected


Our site:

Development System: AMD Athlon(tm) II     works as expected


However, since the strtod function works correctly from my tiny C 
program on all these machines, I don't believe that this problem has to 
do with hardware or architecture. I guess, PostgreSQL dynamically links 
to these C library functions, right?


> If not how does the problem server differ?

I certainly have no idea. Actually, I don't see any more relevant 
differences.


> Was Postgres installed from the same source/same way on all the server?

PostgreSQL was installed from Ubuntu's official repositories (14.04 LTS) 
on all servers.

-- 
Carsten Klein
c(dot)klein(@)datagis(dot)com