From: Hannu Krosing <hannu@trust.ee>
To: Bruce Momjian <maillist@candle.pha.pa.us>
Cc: Hannu Krosing <hannu@trust.ee>
Cc: byronn@insightdist.com
Cc: pgsql-hackers@postgreSQL.org
Cc: pgsql-interfaces@postgreSQL.org
Subject: Re: [HACKERS] Re: [INTERFACES] retrieving varchar size
Date: Thu, 23 Apr 1998 20:28:39 +0300
Message-ID: <353F7A47.3C8D677F@sid.trust.ee> (raw)
References: <199804231645.MAA26157@candle.pha.pa.us>
Bruce Momjian wrote:
>
> >
> > Byron Nikolaidis wrote:
> > >
> > > Hello,
> > >
> > > I was wondering if it would be possible, in the Postgres backend, to
> > > send back the defined column size for the varchar data type (and
> > > possibly the char() type, i.e., bpchar) on a query? Currently, it just
> > > sends back -1 for the size, which makes it difficult in the frontend
> > > (i.e., odbc driver) to determine what the size of the column is.
>
> This is kind of tough to do.
What makes it tough?
Is this info not available where needed, or is changing the protocol
tough.
In the latter case, I would suggest an additional SQL command for open
cursors,
or a pseudo table for open cursor where you could do a simple select
statement:
DECLARE CURSOR FOO_CURSOR FOR SELECT * FROM MYTABLE;
SELECT _FIELD_NAME,_FIELD_TYPE,_FIELD_SIZE FROM
FOO_CURSOR_INFO_PSEUTOTABLE;
> > While the right solution to this is of course getting the size from
> > backend, there exists a workaround now (assuming that the query is not
> > too expensive). While ASCII cursors always hide the varchar sizes,
> > binary ones return the size in actual data (by zero-padding the
> > returned data to max size), so one can determine the actual max
> > sizes by opening the query in binary cursor and then examining
> > enough records to get one non-null field for each varchar field.
>
> As of 6.3, this is only true of char() fields. Varchar() is now
> variable length.
As knowing field size is quite essential for Borland applications some
solution should be found for this.
Hannu
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To: pgsql-interfaces@postgresql.org
Cc: hannu@trust.ee, maillist@candle.pha.pa.us, byronn@insightdist.com, pgsql-hackers@postgreSQL.org
Subject: Re: [HACKERS] Re: [INTERFACES] retrieving varchar size
In-Reply-To: <353F7A47.3C8D677F@sid.trust.ee>
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