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help / color / mirror / Atom feedFrom: Christoph Moench-Tegeder <[email protected]>
To: Ron Johnson <[email protected]>
Cc: pgsql-general <[email protected]>
Subject: Re: Better way to process records in bash?
Date: Thu, 12 Sep 2024 21:30:44 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CANzqJaCaLwc6rOK7O8PkCgVDi_8fg6duzdUrMy0rtn_tQL144g@mail.gmail.com>
References: <CANzqJaCaLwc6rOK7O8PkCgVDi_8fg6duzdUrMy0rtn_tQL144g@mail.gmail.com>
## Ron Johnson ([email protected]):
> I need to process table records in a bash script. Currently, I read them
> using a while loop and redirection. The table isn't that big (30ish
> thousand rows), and performance is adequate, but am always looking for
> "better".
Use python, or any other sane language, and don't do bash in python.
Anything non-trivial is unreasonably hard to get really right when
using shell.
Take this example (even when allowing some fuzz with the variables):
> Here's the current code:
> declare f1 f3 f8
> while IFS='|' read f1 f3 f8; do
> something f8 f3 f1
> done < <(psql -XAt -c "select f1, f3, f8 from some.table_name;")
What happens when f3
a) is NULL?
b) contains a '|' character?
c) contains spaces? (this one depends on how exactly you're handling
the shell variables).
This might be fine if your data is only NOT NULL numbers, but that's
already quite a limitation on your data.
Regards,
Christoph
--
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