--- In firebird-support@yahoogroups.com, "Ann W. Harrison" <aharrison@...> wrote:

>
> Bert_Herngreen wrote:
> >>> Why is the Timestamp field value padded with 'zero' when it is combined
> >>> with (var)char fields?
> > --- In firebird-support@yahoogroups.com, Dimitry Sibiryakov <sd@> wrote:
> >> Every value in external tables is aligned. And this alignment depends
> >> on data type. Timestamps are aligned to 8 bytes.
> >> For details you can search for thread with subject "Alignment of
> >> ISC_TIMESTAMP" in firebird-devel list.
> >>
> >
> > Maybe I misunderstood your answer, but the Timestamp IS 8 bytes
> > (30 D7 00 00 70 12 EB 14). My question was about the 7 'zero'
> > bytes that are inserted before the TimeStamp field, after the
> > 20's from the char(21). These appear in case 3 only, not in case 1
> > or case 2.
> >
>
> Ah, was Dimitry said was not that the timestamp had to be eight bytes
> long, but that it had to be *aligned* on an eight byte boundary. The
> first byte of the timestamp field must be on a byte with an address that
> is evenly divisible by eight.
>
> As a general rule, data stored in external tables should be stored as
> char(n) to avoid problems with alignment and file systems that assume
> that some byte combinations have special semantics.
>
> Good luck,
>
> Ann
>

Ok, now I understand.
Thank you for the information Dimitry and Ann.

Bert