The problem is that I don't know which column is corrupt. But I found a
solution: by simply copying the record into another variable, the values
are parsed and the TOAST errors are thrown.
In case anyone's interested, here's my code, based on an example from
http://www.databasesoup.com/2013/10/de-corrupting-toast-tables.html
DO $f$
DECLARE
rContent1 record;
rContent2 record;
iCounter integer DEFAULT 1;
iValue integer;
pTableName varchar := 'f_gsxws_transaction';
pFieldName varchar := 'gwta_number';
BEGIN
FOR iValue IN EXECUTE 'SELECT ' || pFieldName || ' FROM ' ||
pTableName::regclass || ' ORDER BY ' || pFieldName LOOP
BEGIN
EXECUTE 'SELECT * FROM ' || pTableName::regclass || ' WHERE ' ||
pFieldName || ' = $1'
INTO rContent1
USING iValue;
rContent2 := rContent1;
EXCEPTION WHEN OTHERS THEN
RAISE NOTICE 'data for %.% % is corrupt', pTableName, pFieldName,
iValue;
END;
IF iCounter % 100000 = 0 THEN
RAISE NOTICE '% % records checked', iCounter, pTableName;
END IF;
iCounter := iCounter+1;
END LOOP;
END;
$f$;
Cheers,
Nick
On 14 Feb 2020, at 16:14, Tom Lane wrote:
"Nick Renders" <postgres@xxxxxxxxxx> writes:
I thought I would write a little PL script that would loop through
all
the data and report any inconsistencies. However, I can't get it to
work
properly.
...
1) The function has no problem executing the SELECT statement. It is
only when "rcontents" is returned, that the function fails. This is a
problem, because the ultimate goal is to loop through all records and
only return/alert something in case of an error.
2) The function never enters the EXCEPTION clause. Instead, when it
hits
the RETURN command, it breaks and shows the same message as in
pgAdmin:
missing chunk number 0 for toast value 8289525 in pg_toast_5572299.
I think what's happening there is that the function doesn't try to
dereference the value's TOAST pointer during SELECT INTO. It just
stores
that pointer into a variable, and only sometime later when the actual
content of the value is demanded, do you see the error raised.
The solution to that is to do something that uses the contents of the
busted column right away while still inside the EXCEPTION block,
perhaps
along the lines of "select md5(mycolumn) into local_variable from..."
A close reading of
https://www.postgresql.org/docs/current/storage-toast.html
would probably help you understand what's happening here.
regards, tom lane
