On Wed, Oct 27, 2010 at 12:49:01PM +0200, HACKER Nora wrote:
> Hi,
>
> Since I do not believe that my computer suddenly has lost the ability to
> compare numbers correctly, I suppose there must be some mistake in my
> following code. To cut a long story short, the below sub
> 1. connects to a db,
> 2. gets the number of datafiles used by this db,
> 3. gets the names of these datafiles,
> 4. gets the number of datafiles for this db from the filesystem,
> 5. checks whether all the db's datafiles' pathes are within the $dbdir
> (from another function)
> 6. and finally compares whether the numbers of datafiles in the db and on
> the filesystem equal.
>
> And this is exactly the point: They equal for one database that I run a test
> against, but the logic says they differ!
>
> CODE:
> ### 2 ###
> # Anzahl der Datafiles in der DB (View DBA_DATA_FILES)
> my $sql = "select count(*) from dba_data_files"; # SQL-Statement
> my $sth = $dbh->prepare($sql); # Ausführung vorbereiten
> my $anz_dbf_db = $dbh->selectcol_arrayref($sth); # holt alle Inhalte der
> 1. Spalte in eine Array-REFERNZ!!!
> $sth->finish();
> if ( ! @$anz_dbf_db ) { # Array-REFERENZ!!!, Error, wenn DB nicht gelesen
> werden kann
> LOGWARN("$fnc - Datenbank konnte nicht gelesen werden:
> $DBI::errstr\n");
> $rcs { "$fnc" } = (1);
> }
> DEBUG("$fnc - Anzahl Datafiles aus DB: @$anz_dbf_db\n");
> ### 6 ###
> if ( @$anz_dbf_db != $anz_dbf_fs ) { # wenn Anzahl der Datafiles ungleich
> <-- ERROR HERE!
> DEBUG("$fnc - vgl. @$anz_dbf_db != $anz_dbf_fs\n");
> my @dbfs_diff;
> if ( @$anz_dbf_db > $anz_dbf_fs ) { # mehr Datafiles in der DB als im
> FS
> LOGWARN("$fnc - ACHTUNG! Mehr Datafiles in der Datenbank
> (@$anz_dbf_db) als im Filesystem ($anz_dbf_fs)!\n");
> @dbfs_diff = grep 'MISSING', @$names_dbf_db;
> } elsif ( @$anz_dbf_db < $anz_dbf_fs ) { # mehr Datafiles im FS als
> in der DB
> DEBUG("$fnc - vgl. @$anz_dbf_db < $anz_dbf_fs\n");
> LOGWARN("$fnc - ACHTUNG! Mehr Datafiles im Filesystem
> ($anz_dbf_fs) als in der Datenbank (@$anz_dbf_db)!\n");
> foreach my $dbf_fs ( @dbfs_fs ) {
> if ( ! grep /$dbf_fs/, @$names_dbf_db ) {
> DEBUG("$fnc - DBF $dbf_fs matcht nicht mit DB.\n");
> push @dbfs_diff, $dbf_fs;
> }
> }
> } else {
> INFO("$fnc - Anzahl Datafiles in Datenbank und Filesystem
> ident.\n");
> }
> if ( @dbfs_diff ) {
> LOGWARN("$fnc - Fehlende(s) Datafile(s): @dbfs_diff\n");
> }
> $rcs { "$fnc" } = (1);
> }
> }
>
> OUTPUT:
>
> 2010/10/27 12:29:15 main::checkDatafiles - Anzahl Datafiles aus DB: 141
> 2010/10/27 12:29:15 main::checkDatafiles - Anzahl Datafiles im Filesystem: 141
> 2010/10/27 12:29:15 main::checkDatafiles - vgl. 141 != 141
> 2010/10/27 12:29:15 main::checkDatafiles - vgl. 141 < 141
> 2010/10/27 12:29:15 main::checkDatafiles - ACHTUNG! Mehr Datafiles im
> Filesystem (141) als in der Datenbank (141)!
The problem here is to do with $anz_dbf_db.
You have correctly noted that this is an array reference. To print in out you
have used "@$anz_dbf_db", which has printed the elements of the array,
separated by spaces. This has shown you that there is one element of the
array, 141.
However, when using the array in a comparison, you have used @$anz_dbf_db
again, but this time in scalar context. Here, you have asked for the number
of elements in the array, which is one. You can test this by adding
DEBUG(scalar @$anz_dbf_db); This is why the comparison is failing - 1 != 141.
So you should really be testing against $anz_dbf_db->[0] in your comparison.
Or better yet, in section two you should make $anz_dbf_db the actual number
you are looking for, rather than the array ref you are getting back.
> I hope that the sense of my output can be understood, even if it is not in
> English...
Ich glaube dass alle verstehen Perl.
--
Paul Johnson - [email protected]
http://www.pjcj.net
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