X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBI%2FSybase.pm;h=9851303d6a384d024080e48651600a51e7700fad;hb=689819e14e9e6245000c64ece46ddd1bc8293bf5;hp=41b0c81bb297e2557717b25f779ed064c3832335;hpb=ef131d82b1a6cad5ef079a341912b0c6d8b7b990;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/Storage/DBI/Sybase.pm b/lib/DBIx/Class/Storage/DBI/Sybase.pm
index 41b0c81..9851303 100644
--- a/lib/DBIx/Class/Storage/DBI/Sybase.pm
+++ b/lib/DBIx/Class/Storage/DBI/Sybase.pm
@@ -4,63 +4,855 @@ use strict;
 use warnings;
 
 use base qw/
-    DBIx::Class::Storage::DBI::Sybase::Base
-    DBIx::Class::Storage::DBI::NoBindVars
+    DBIx::Class::Storage::DBI::Sybase::Common
+    DBIx::Class::Storage::DBI::AutoCast
 /;
 use mro 'c3';
+use Carp::Clan qw/^DBIx::Class/;
+use List::Util ();
+use Sub::Name ();
+
+__PACKAGE__->mk_group_accessors('simple' =>
+    qw/_identity _blob_log_on_update _writer_storage _is_writer_storage
+       _identity_method/
+);
+
+my @also_proxy_to_writer_storage = qw/
+  connect_call_set_auto_cast auto_cast connect_call_blob_setup
+  connect_call_datetime_setup
+
+  disconnect _connect_info _sql_maker _sql_maker_opts disable_sth_caching
+  auto_savepoint unsafe cursor_class debug debugobj schema
+/;
+
+=head1 NAME
+
+DBIx::Class::Storage::DBI::Sybase - Sybase support for DBIx::Class
+
+=head1 SYNOPSIS
+
+This subclass supports L<DBD::Sybase> for real Sybase databases.  If you are
+using an MSSQL database via L<DBD::Sybase>, your storage will be reblessed to
+L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>.
+
+=head1 DESCRIPTION
+
+If your version of Sybase does not support placeholders, then your storage
+will be reblessed to L<DBIx::Class::Storage::DBI::Sybase::NoBindVars>. You can
+also enable that driver explicitly, see the documentation for more details.
+
+With this driver there is unfortunately no way to get the C<last_insert_id>
+without doing a C<SELECT MAX(col)>. This is done safely in a transaction
+(locking the table.) See L</INSERTS WITH PLACEHOLDERS>.
+
+A recommended L<DBIx::Class::Storage::DBI/connect_info> setting:
+
+  on_connect_call => [['datetime_setup'], ['blob_setup', log_on_update => 0]]
+
+=head1 METHODS
+
+=cut
 
 sub _rebless {
-    my $self = shift;
+  my $self = shift;
 
+  if (ref($self) eq 'DBIx::Class::Storage::DBI::Sybase') {
     my $dbtype = eval {
-      @{$self->_get_dbh
-        ->selectrow_arrayref(qq{sp_server_info \@attribute_id=1})
-      }[2]
-    };
-    unless ( $@ ) {
-        $dbtype =~ s/\W/_/gi;
-        my $subclass = "DBIx::Class::Storage::DBI::Sybase::${dbtype}";
-        if ($self->load_optional_class($subclass) && !$self->isa($subclass)) {
-            bless $self, $subclass;
+      @{$self->_get_dbh->selectrow_arrayref(qq{sp_server_info \@attribute_id=1})}[2]
+    } || '';
+
+    my $exception = $@;
+    $dbtype =~ s/\W/_/gi;
+    my $subclass = "DBIx::Class::Storage::DBI::Sybase::${dbtype}";
+
+    if (!$exception && $dbtype && $self->load_optional_class($subclass)) {
+      bless $self, $subclass;
+      $self->_rebless;
+    } else { # real Sybase
+      my $no_bind_vars = 'DBIx::Class::Storage::DBI::Sybase::NoBindVars';
+
+      if ($self->using_freetds) {
+        carp <<'EOF' unless $ENV{DBIC_SYBASE_FREETDS_NOWARN};
+
+You are using FreeTDS with Sybase.
+
+We will do our best to support this configuration, but please consider this
+support experimental.
+
+TEXT/IMAGE columns will definitely not work.
+
+You are encouraged to recompile DBD::Sybase with the Sybase Open Client libraries
+instead.
+
+See perldoc DBIx::Class::Storage::DBI::Sybase for more details.
+
+To turn off this warning set the DBIC_SYBASE_FREETDS_NOWARN environment
+variable.
+EOF
+        if (not $self->_typeless_placeholders_supported) {
+          if ($self->_placeholders_supported) {
+            $self->auto_cast(1);
+          } else {
+            $self->ensure_class_loaded($no_bind_vars);
+            bless $self, $no_bind_vars;
             $self->_rebless;
+          }
         }
+      }
+      elsif (not $self->_get_dbh->{syb_dynamic_supported}) {
+        # not necessarily FreeTDS, but no placeholders nevertheless
+        $self->ensure_class_loaded($no_bind_vars);
+        bless $self, $no_bind_vars;
+        $self->_rebless;
+      } elsif (not $self->_typeless_placeholders_supported) {
+# this is highly unlikely, but we check just in case
+        $self->auto_cast(1);
+      }
+    }
+  }
+}
+
+sub _init {
+  my $self = shift;
+  $self->_set_max_connect(256);
+
+  # based on LongReadLen in connect_info
+  $self->set_textsize if $self->using_freetds;
+
+# create storage for insert/(update blob) transactions,
+# unless this is that storage
+  return if $self->_is_writer_storage;
+
+  my $writer_storage = (ref $self)->new;
+
+  $writer_storage->_is_writer_storage(1);
+  $writer_storage->connect_info($self->connect_info);
+  $writer_storage->auto_cast($self->auto_cast);
+
+  $self->_writer_storage($writer_storage);
+}
+
+for my $method (@also_proxy_to_writer_storage) {
+  no strict 'refs';
+  no warnings 'redefine';
+
+  my $replaced = __PACKAGE__->can($method);
+
+  *{$method} = Sub::Name::subname __PACKAGE__."::$method" => sub {
+    my $self = shift;
+    $self->_writer_storage->$replaced(@_) if $self->_writer_storage;
+    return $self->$replaced(@_);
+  };
+}
+
+# Make sure we have CHAINED mode turned on if AutoCommit is off in non-FreeTDS
+# DBD::Sybase (since we don't know how DBD::Sybase was compiled.) If however
+# we're using FreeTDS, CHAINED mode turns on an implicit transaction which we
+# only want when AutoCommit is off.
+sub _populate_dbh {
+  my $self = shift;
+
+  $self->next::method(@_);
+
+  if (not $self->using_freetds) {
+    $self->_dbh->{syb_chained_txn} = 1;
+  } else {
+    if ($self->_dbh_autocommit) {
+      $self->_dbh->do('SET CHAINED OFF');
+    } else {
+      $self->_dbh->do('SET CHAINED ON');
+    }
+  }
+}
+
+=head2 connect_call_blob_setup
+
+Used as:
+
+  on_connect_call => [ [ 'blob_setup', log_on_update => 0 ] ]
+
+Does C<< $dbh->{syb_binary_images} = 1; >> to return C<IMAGE> data as raw binary
+instead of as a hex string.
+
+Recommended.
+
+Also sets the C<log_on_update> value for blob write operations. The default is
+C<1>, but C<0> is better if your database is configured for it.
+
+See
+L<DBD::Sybase/Handling_IMAGE/TEXT_data_with_syb_ct_get_data()/syb_ct_send_data()>.
+
+=cut
+
+sub connect_call_blob_setup {
+  my $self = shift;
+  my %args = @_;
+  my $dbh = $self->_dbh;
+  $dbh->{syb_binary_images} = 1;
+
+  $self->_blob_log_on_update($args{log_on_update})
+    if exists $args{log_on_update};
+}
+
+sub _is_lob_type {
+  my $self = shift;
+  my $type = shift;
+  $type && $type =~ /(?:text|image|lob|bytea|binary|memo)/i;
+}
+
+sub _is_lob_column {
+  my ($self, $source, $column) = @_;
+
+  return $self->_is_lob_type($source->column_info($column)->{data_type});
+}
+
+sub _prep_for_execute {
+  my $self = shift;
+  my ($op, $extra_bind, $ident, $args) = @_;
+
+  my ($sql, $bind) = $self->next::method (@_);
+
+  if ($op eq 'insert') {
+    my $table = $ident->from;
+
+    my $bind_info = $self->_resolve_column_info(
+      $ident, [map $_->[0], @{$bind}]
+    );
+    my $identity_col = List::Util::first
+      { $bind_info->{$_}{is_auto_increment} }
+      (keys %$bind_info)
+    ;
+
+    if ($identity_col) {
+      $sql = join ("\n",
+        "SET IDENTITY_INSERT $table ON",
+        $sql,
+        "SET IDENTITY_INSERT $table OFF",
+      );
+    }
+    else {
+      $identity_col = List::Util::first
+        { $ident->column_info($_)->{is_auto_increment} }
+        $ident->columns
+      ;
+    }
+
+    if ($identity_col) {
+      $sql =
+        "$sql\n" .
+        $self->_fetch_identity_sql($ident, $identity_col);
+    }
+  }
+
+  return ($sql, $bind);
+}
+
+# Stolen from SQLT, with some modifications. This is a makeshift
+# solution before a sane type-mapping library is available, thus
+# the 'our' for easy overrides.
+our %TYPE_MAPPING  = (
+    number    => 'numeric',
+    money     => 'money',
+    varchar   => 'varchar',
+    varchar2  => 'varchar',
+    timestamp => 'datetime',
+    text      => 'varchar',
+    real      => 'double precision',
+    comment   => 'text',
+    bit       => 'bit',
+    tinyint   => 'smallint',
+    float     => 'double precision',
+    serial    => 'numeric',
+    bigserial => 'numeric',
+    boolean   => 'varchar',
+    long      => 'varchar',
+);
+
+sub _native_data_type {
+  my ($self, $type) = @_;
+
+  $type = lc $type;
+  $type =~ s/\s* identity//x;
+
+  return uc($TYPE_MAPPING{$type} || $type);
+}
+
+sub _fetch_identity_sql {
+  my ($self, $source, $col) = @_;
+
+  return sprintf ("SELECT MAX(%s) FROM %s",
+    map { $self->sql_maker->_quote ($_) } ($col, $source->from)
+  );
+}
+
+sub _execute {
+  my $self = shift;
+  my ($op) = @_;
+
+  my ($rv, $sth, @bind) = $self->dbh_do($self->can('_dbh_execute'), @_);
+
+  if ($op eq 'insert') {
+    $self->_identity($sth->fetchrow_array);
+    $sth->finish;
+  }
+
+  return wantarray ? ($rv, $sth, @bind) : $rv;
+}
+
+sub last_insert_id { shift->_identity }
+
+# handles TEXT/IMAGE and transaction for last_insert_id
+sub insert {
+  my $self = shift;
+  my ($source, $to_insert) = @_;
+
+  my $blob_cols = $self->_remove_blob_cols($source, $to_insert);
+
+  my $identity_col = List::Util::first
+    { $source->column_info($_)->{is_auto_increment} }
+    $source->columns;
+
+  # do we need the horrific SELECT MAX(COL) hack?
+  my $dumb_last_insert_id =
+       $identity_col
+    && (not exists $to_insert->{$identity_col})
+    && ($self->_identity_method||'') ne '@@IDENTITY';
+
+  my $next = $self->next::can;
+
+  # we are already in a transaction, or there are no blobs
+  # and we don't need the PK - just (try to) do it
+  if ($self->{transaction_depth}
+        || (!$blob_cols && !$dumb_last_insert_id) 
+  ) {
+    return $self->_insert (
+      $next, $source, $to_insert, $blob_cols, $identity_col
+    );
+  }
+
+  # otherwise use the _writer_storage to do the insert+transaction on another
+  # connection
+  my $guard = $self->_writer_storage->txn_scope_guard;
+
+  my $updated_cols = $self->_writer_storage->_insert (
+    $next, $source, $to_insert, $blob_cols, $identity_col
+  );
+
+  $self->_identity($self->_writer_storage->_identity);
+
+  $guard->commit;
+
+  return $updated_cols;
+}
+
+sub _insert {
+  my ($self, $next, $source, $to_insert, $blob_cols, $identity_col) = @_;
+
+  my $updated_cols = $self->$next ($source, $to_insert);
+
+  my $final_row = {
+    $identity_col => $self->last_insert_id($source, $identity_col),
+    %$to_insert,
+    %$updated_cols,
+  };
+
+  $self->_insert_blobs ($source, $blob_cols, $final_row) if $blob_cols;
+
+  return $updated_cols;
+}
+
+sub update {
+  my $self = shift;
+  my ($source, $fields, $where, @rest) = @_;
+
+  my $wantarray = wantarray;
+
+  my $blob_cols = $self->_remove_blob_cols($source, $fields);
+
+  my $table = $source->name;
+
+  my $identity_col = List::Util::first
+    { $source->column_info($_)->{is_auto_increment} }
+    $source->columns;
+
+  my $is_identity_update = $identity_col && defined $fields->{$identity_col};
+
+  if (not $blob_cols) {
+    $self->_set_identity_insert($table, 'update')   if $is_identity_update;
+    return $self->next::method(@_);
+    $self->_unset_identity_insert($table, 'update') if $is_identity_update;
+  }
+
+# check that we're not updating a blob column that's also in $where
+  for my $blob (grep $self->_is_lob_column($source, $_), $source->columns) {
+    if (exists $where->{$blob} && exists $fields->{$blob}) {
+      croak
+'Update of TEXT/IMAGE column that is also in search condition impossible';
+    }
+  }
+
+# update+blob update(s) done atomically on separate connection
+  $self = $self->_writer_storage;
+
+  my $guard = $self->txn_scope_guard;
+
+# First update the blob columns to be updated to '' (taken from $fields, where
+# it is originally put by _remove_blob_cols .)
+  my %blobs_to_empty = map { ($_ => delete $fields->{$_}) } keys %$blob_cols;
+
+  $self->next::method($source, \%blobs_to_empty, $where, @rest);
+
+# Now update the blobs before the other columns in case the update of other
+# columns makes the search condition invalid.
+  $self->_update_blobs($source, $blob_cols, $where);
+
+  my @res;
+  if (%$fields) {
+    $self->_set_identity_insert($table, 'update')   if $is_identity_update;
+
+    if ($wantarray) {
+      @res    = $self->next::method(@_);
+    }
+    elsif (defined $wantarray) {
+      $res[0] = $self->next::method(@_);
+    }
+    else {
+      $self->next::method(@_);
+    }
+
+    $self->_unset_identity_insert($table, 'update') if $is_identity_update;
+  }
+
+  $guard->commit;
+
+  return $wantarray ? @res : $res[0];
+}
+
+### the insert_bulk stuff stolen from DBI/MSSQL.pm
+
+sub _set_identity_insert {
+  my ($self, $table, $op) = @_;
+
+  my $sql = sprintf (
+    'SET IDENTITY_%s %s ON',
+    (uc($op) || 'INSERT'),
+    $self->sql_maker->_quote ($table),
+  );
+
+  $self->_query_start($sql);
+
+  my $dbh = $self->_get_dbh;
+  eval { $dbh->do ($sql) };
+  my $exception = $@;
+
+  $self->_query_end($sql);
+
+  if ($exception) {
+    $self->throw_exception (sprintf "Error executing '%s': %s",
+      $sql,
+      $dbh->errstr,
+    );
+  }
+}
+
+sub _unset_identity_insert {
+  my ($self, $table, $op) = @_;
+
+  my $sql = sprintf (
+    'SET IDENTITY_%s %s OFF',
+    (uc($op) || 'INSERT'),
+    $self->sql_maker->_quote ($table),
+  );
+
+  $self->_query_start($sql);
+
+  my $dbh = $self->_get_dbh;
+  $dbh->do ($sql);
+
+  $self->_query_end($sql);
+}
+
+# for tests
+sub _can_insert_bulk { 1 }
+
+# XXX this should use the DBD::Sybase bulk API, where possible
+sub insert_bulk {
+  my $self = shift;
+  my ($source, $cols, $data) = @_;
+
+  my $is_identity_insert = (List::Util::first
+      { $source->column_info ($_)->{is_auto_increment} }
+      (@{$cols})
+  )
+     ? 1
+     : 0;
+
+  if ($is_identity_insert) {
+     $self->_set_identity_insert ($source->name);
+  }
+
+  $self->next::method(@_);
+
+  if ($is_identity_insert) {
+     $self->_unset_identity_insert ($source->name);
+  }
+}
+
+### end of stolen insert_bulk section
+
+# Make sure blobs are not bound as placeholders, and return any non-empty ones
+# as a hash.
+sub _remove_blob_cols {
+  my ($self, $source, $fields) = @_;
+
+  my %blob_cols;
+
+  for my $col (keys %$fields) {
+    if ($self->_is_lob_type($source->column_info($col)->{data_type})) {
+      my $blob_val = delete $fields->{$col};
+      if (not defined $blob_val) {
+        $fields->{$col} = \'NULL';
+      }
+      else {
+        $fields->{$col} = \"''";
+        $blob_cols{$col} = $blob_val unless $blob_val eq '';
+      }
     }
+  }
+
+  return keys %blob_cols ? \%blob_cols : undef;
+}
+
+sub _update_blobs {
+  my ($self, $source, $blob_cols, $where) = @_;
+
+  my (@primary_cols) = $source->primary_columns;
+
+  $self->throw_exception('Cannot update TEXT/IMAGE column(s) without a primary key')
+    unless @primary_cols;
+
+# check if we're updating a single row by PK
+  my $pk_cols_in_where = 0;
+  for my $col (@primary_cols) {
+    $pk_cols_in_where++ if defined $where->{$col};
+  }
+  my @rows;
+
+  if ($pk_cols_in_where == @primary_cols) {
+    my %row_to_update;
+    @row_to_update{@primary_cols} = @{$where}{@primary_cols};
+    @rows = \%row_to_update;
+  } else {
+    my $cursor = $self->select ($source, \@primary_cols, $where, {});
+    @rows = map {
+      my %row; @row{@primary_cols} = @$_; \%row
+    } $cursor->all;
+  }
+
+  for my $row (@rows) {
+    $self->_insert_blobs($source, $blob_cols, $row);
+  }
 }
 
-sub _dbh_last_insert_id {
-    my ($self, $dbh, $source, $col) = @_;
-    return ($dbh->selectrow_array('select @@identity'))[0];
+sub _insert_blobs {
+  my ($self, $source, $blob_cols, $row) = @_;
+  my $dbh = $self->_get_dbh;
+
+  my $table = $source->name;
+
+  my %row = %$row;
+  my (@primary_cols) = $source->primary_columns;
+
+  $self->throw_exception('Cannot update TEXT/IMAGE column(s) without a primary key')
+    unless @primary_cols;
+
+  $self->throw_exception('Cannot update TEXT/IMAGE column(s) without primary key values')
+    if ((grep { defined $row{$_} } @primary_cols) != @primary_cols);
+
+  for my $col (keys %$blob_cols) {
+    my $blob = $blob_cols->{$col};
+
+    my %where = map { ($_, $row{$_}) } @primary_cols;
+
+    my $cursor = $self->select ($source, [$col], \%where, {});
+    $cursor->next;
+    my $sth = $cursor->sth;
+
+    if (not $sth) {
+
+      $self->throw_exception(
+          "Could not find row in table '$table' for blob update:\n"
+        . $self->_pretty_print (\%where)
+      );
+    }
+
+    eval {
+      do {
+        $sth->func('CS_GET', 1, 'ct_data_info') or die $sth->errstr;
+      } while $sth->fetch;
+
+      $sth->func('ct_prepare_send') or die $sth->errstr;
+
+      my $log_on_update = $self->_blob_log_on_update;
+      $log_on_update    = 1 if not defined $log_on_update;
+
+      $sth->func('CS_SET', 1, {
+        total_txtlen => length($blob),
+        log_on_update => $log_on_update
+      }, 'ct_data_info') or die $sth->errstr;
+
+      $sth->func($blob, length($blob), 'ct_send_data') or die $sth->errstr;
+
+      $sth->func('ct_finish_send') or die $sth->errstr;
+    };
+    my $exception = $@;
+    $sth->finish if $sth;
+    if ($exception) {
+      if ($self->using_freetds) {
+        $self->throw_exception (
+          'TEXT/IMAGE operation failed, probably because you are using FreeTDS: '
+          . $exception
+        );
+      } else {
+        $self->throw_exception($exception);
+      }
+    }
+  }
+}
+
+=head2 connect_call_datetime_setup
+
+Used as:
+
+  on_connect_call => 'datetime_setup'
+
+In L<DBIx::Class::Storage::DBI/connect_info> to set:
+
+  $dbh->syb_date_fmt('ISO_strict'); # output fmt: 2004-08-21T14:36:48.080Z
+  $dbh->do('set dateformat mdy');   # input fmt:  08/13/1979 18:08:55.080
+
+On connection for use with L<DBIx::Class::InflateColumn::DateTime>, using
+L<DateTime::Format::Sybase>, which you will need to install.
+
+This works for both C<DATETIME> and C<SMALLDATETIME> columns, although
+C<SMALLDATETIME> columns only have minute precision.
+
+=cut
+
+{
+  my $old_dbd_warned = 0;
+
+  sub connect_call_datetime_setup {
+    my $self = shift;
+    my $dbh = $self->_dbh;
+
+    if ($dbh->can('syb_date_fmt')) {
+      # amazingly, this works with FreeTDS
+      $dbh->syb_date_fmt('ISO_strict');
+    } elsif (not $old_dbd_warned) {
+      carp "Your DBD::Sybase is too old to support ".
+      "DBIx::Class::InflateColumn::DateTime, please upgrade!";
+      $old_dbd_warned = 1;
+    }
+
+    $dbh->do('SET DATEFORMAT mdy');
+
+    1;
+  }
+}
+
+sub datetime_parser_type { "DateTime::Format::Sybase" }
+
+# ->begin_work and such have no effect with FreeTDS but we run them anyway to
+# let the DBD keep any state it needs to.
+#
+# If they ever do start working, the extra statements will do no harm (because
+# Sybase supports nested transactions.)
+
+sub _dbh_begin_work {
+  my $self = shift;
+  $self->next::method(@_);
+  if ($self->using_freetds) {
+    $self->_get_dbh->do('BEGIN TRAN');
+  }
+}
+
+sub _dbh_commit {
+  my $self = shift;
+  if ($self->using_freetds) {
+    $self->_dbh->do('COMMIT');
+  }
+  return $self->next::method(@_);
+}
+
+sub _dbh_rollback {
+  my $self = shift;
+  if ($self->using_freetds) {
+    $self->_dbh->do('ROLLBACK');
+  }
+  return $self->next::method(@_);
+}
+
+# savepoint support using ASE syntax
+
+sub _svp_begin {
+  my ($self, $name) = @_;
+
+  $self->_get_dbh->do("SAVE TRANSACTION $name");
+}
+
+# A new SAVE TRANSACTION with the same name releases the previous one.
+sub _svp_release { 1 }
+
+sub _svp_rollback {
+  my ($self, $name) = @_;
+
+  $self->_get_dbh->do("ROLLBACK TRANSACTION $name");
 }
 
 1;
 
-=head1 NAME
+=head1 Schema::Loader Support
 
-DBIx::Class::Storage::DBI::Sybase - Storage::DBI subclass for Sybase
+There is an experimental branch of L<DBIx::Class::Schema::Loader> that will
+allow you to dump a schema from most (if not all) versions of Sybase.
 
-=head1 SYNOPSIS
+It is available via subversion from:
+
+  http://dev.catalyst.perl.org/repos/bast/branches/DBIx-Class-Schema-Loader/current/
+
+=head1 FreeTDS
+
+This driver supports L<DBD::Sybase> compiled against FreeTDS
+(L<http://www.freetds.org/>) to the best of our ability, however it is
+recommended that you recompile L<DBD::Sybase> against the Sybase Open Client
+libraries. They are a part of the Sybase ASE distribution:
+
+The Open Client FAQ is here:
+L<http://www.isug.com/Sybase_FAQ/ASE/section7.html>.
+
+Sybase ASE for Linux (which comes with the Open Client libraries) may be
+downloaded here: L<http://response.sybase.com/forms/ASE_Linux_Download>.
+
+To see if you're using FreeTDS check C<< $schema->storage->using_freetds >>, or run:
+
+  perl -MDBI -le 'my $dbh = DBI->connect($dsn, $user, $pass); print $dbh->{syb_oc_version}'
+
+Some versions of the libraries involved will not support placeholders, in which
+case the storage will be reblessed to
+L<DBIx::Class::Storage::DBI::Sybase::NoBindVars>.
+
+In some configurations, placeholders will work but will throw implicit type
+conversion errors for anything that's not expecting a string. In such a case,
+the C<auto_cast> option from L<DBIx::Class::Storage::DBI::AutoCast> is
+automatically set, which you may enable on connection with
+L<DBIx::Class::Storage::DBI::AutoCast/connect_call_set_auto_cast>. The type info
+for the C<CAST>s is taken from the L<DBIx::Class::ResultSource/data_type>
+definitions in your Result classes, and are mapped to a Sybase type (if it isn't
+already) using a mapping based on L<SQL::Translator>.
+
+In other configurations, placeholers will work just as they do with the Sybase
+Open Client libraries.
+
+Inserts or updates of TEXT/IMAGE columns will B<NOT> work with FreeTDS.
+
+=head1 INSERTS WITH PLACEHOLDERS
+
+With placeholders enabled, inserts are done in a transaction so that there are
+no concurrency issues with getting the inserted identity value using
+C<SELECT MAX(col)>, which is the only way to get the C<IDENTITY> value in this
+mode.
+
+In addition, they are done on a separate connection so that it's possible to
+have active cursors when doing an insert.
+
+When using C<DBIx::Class::Storage::DBI::Sybase::NoBindVars> transactions are
+disabled, as there are no concurrency issues with C<SELECT @@IDENTITY> as it's a
+session variable.
+
+=head1 TRANSACTIONS
+
+Due to limitations of the TDS protocol, L<DBD::Sybase>, or both; you cannot
+begin a transaction while there are active cursors. An active cursor is, for
+example, a L<ResultSet|DBIx::Class::ResultSet> that has been executed using
+C<next> or C<first> but has not been exhausted or
+L<reset|DBIx::Class::ResultSet/reset>.
+
+For example, this will not work:
+
+  $schema->txn_do(sub {
+    my $rs = $schema->resultset('Book');
+    while (my $row = $rs->next) {
+      $schema->resultset('MetaData')->create({
+        book_id => $row->id,
+        ...
+      });
+    }
+  });
+
+Transactions done for inserts in C<AutoCommit> mode when placeholders are in use
+are not affected, as they are done on an extra database handle.
+
+Some workarounds:
+
+=over 4
+
+=item * use L<DBIx::Class::Storage::DBI::Replicated>
+
+=item * L<connect|DBIx::Class::Schema/connect> another L<Schema|DBIx::Class::Schema>
+
+=item * load the data from your cursor with L<DBIx::Class::ResultSet/all>
+
+=back
+
+=head1 MAXIMUM CONNECTIONS
+
+The TDS protocol makes separate connections to the server for active statements
+in the background. By default the number of such connections is limited to 25,
+on both the client side and the server side.
+
+This is a bit too low for a complex L<DBIx::Class> application, so on connection
+the client side setting is set to C<256> (see L<DBD::Sybase/maxConnect>.) You
+can override it to whatever setting you like in the DSN.
+
+See
+L<http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.help.ase_15.0.sag1/html/sag1/sag1272.htm>
+for information on changing the setting on the server side.
+
+=head1 DATES
+
+See L</connect_call_datetime_setup> to setup date formats
+for L<DBIx::Class::InflateColumn::DateTime>.
+
+=head1 TEXT/IMAGE COLUMNS
+
+L<DBD::Sybase> compiled with FreeTDS will B<NOT> allow you to insert or update
+C<TEXT/IMAGE> columns.
+
+Setting C<< $dbh->{LongReadLen} >> will also not work with FreeTDS use either:
+
+  $schema->storage->dbh->do("SET TEXTSIZE $bytes");
 
-This subclass supports L<DBD::Sybase> for real Sybase databases.  If
-you are using an MSSQL database via L<DBD::Sybase>, see
-L<DBIx::Class::Storage::DBI::Sybase::MSSQL>.
+or
 
-=head1 CAVEATS
+  $schema->storage->set_textsize($bytes);
 
-This storage driver uses L<DBIx::Class::Storage::DBI::NoBindVars> as a base.
-This means that bind variables will be interpolated (properly quoted of course)
-into the SQL query itself, without using bind placeholders.
+instead.
 
-More importantly this means that caching of prepared statements is explicitly
-disabled, as the interpolation renders it useless.
+However, the C<LongReadLen> you pass in
+L<DBIx::Class::Storage::DBI/connect_info> is used to execute the equivalent
+C<SET TEXTSIZE> command on connection.
 
-=head1 AUTHORS
+See L</connect_call_blob_setup> for a L<DBIx::Class::Storage::DBI/connect_info>
+setting you need to work with C<IMAGE> columns.
 
-Brandon L Black <blblack@gmail.com>
+=head1 AUTHOR
 
-Justin Hunter <justin.d.hunter@gmail.com>
+See L<DBIx::Class/CONTRIBUTORS>.
 
 =head1 LICENSE
 
 You may distribute this code under the same terms as Perl itself.
 
 =cut
+# vim:sts=2 sw=2: