Remove or use unused variables in PostgreSQL producer

[dbsrgits/SQL-Translator.git] / lib / SQL / Translator / Producer / PostgreSQL.pm

package SQL::Translator::Producer::PostgreSQL;

=head1 NAME

SQL::Translator::Producer::PostgreSQL - PostgreSQL producer for SQL::Translator

=head1 SYNOPSIS

  my $t = SQL::Translator->new( parser => '...', producer => 'PostgreSQL' );
  $t->translate;

=head1 DESCRIPTION

Creates a DDL suitable for PostgreSQL.  Very heavily based on the Oracle
producer.

Now handles PostGIS Geometry and Geography data types on table definitions.
Does not yet support PostGIS Views.

=cut

use strict;
use warnings;
our ( $DEBUG, $WARN );
our $VERSION = '1.59';
$DEBUG = 0 unless defined $DEBUG;

use base qw(SQL::Translator::Producer);
use SQL::Translator::Schema::Constants;
use SQL::Translator::Utils qw(debug header_comment parse_dbms_version batch_alter_table_statements normalize_quote_options);
use SQL::Translator::Generator::DDL::PostgreSQL;
use Data::Dumper;

use constant MAX_ID_LENGTH => 62;

{
  my ($quoting_generator, $nonquoting_generator);
  sub _generator {
    my $options = shift;
    return $options->{generator} if exists $options->{generator};

    return normalize_quote_options($options)
      ? $quoting_generator ||= SQL::Translator::Generator::DDL::PostgreSQL->new
      : $nonquoting_generator ||= SQL::Translator::Generator::DDL::PostgreSQL->new(
        quote_chars => [],
      );
  }
}

my ( %translate );

BEGIN {

 %translate  = (
    #
    # MySQL types
    #
    double     => 'double precision',
    decimal    => 'numeric',
    int        => 'integer',
    mediumint  => 'integer',
    tinyint    => 'smallint',
    char       => 'character',
    varchar    => 'character varying',
    longtext   => 'text',
    mediumtext => 'text',
    tinytext   => 'text',
    tinyblob   => 'bytea',
    blob       => 'bytea',
    mediumblob => 'bytea',
    longblob   => 'bytea',
    enum       => 'character varying',
    set        => 'character varying',
    datetime   => 'timestamp',
    year       => 'date',

    #
    # Oracle types
    #
    number     => 'integer',
    varchar2   => 'character varying',
    long       => 'text',
    clob       => 'text',

    #
    # Sybase types
    #
    comment    => 'text',

    #
    # MS Access types
    #
    memo       => 'text',
);
}
my %truncated;

=pod

=head1 PostgreSQL Create Table Syntax

  CREATE [ [ LOCAL ] { TEMPORARY | TEMP } ] TABLE table_name (
      { column_name data_type [ DEFAULT default_expr ] [ column_constraint [, ... ] ]
      | table_constraint }  [, ... ]
  )
  [ INHERITS ( parent_table [, ... ] ) ]
  [ WITH OIDS | WITHOUT OIDS ]

where column_constraint is:

  [ CONSTRAINT constraint_name ]
  { NOT NULL | NULL | UNIQUE | PRIMARY KEY |
    CHECK (expression) |
    REFERENCES reftable [ ( refcolumn ) ] [ MATCH FULL | MATCH PARTIAL ]
      [ ON DELETE action ] [ ON UPDATE action ] }
  [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]

and table_constraint is:

  [ CONSTRAINT constraint_name ]
  { UNIQUE ( column_name [, ... ] ) |
    PRIMARY KEY ( column_name [, ... ] ) |
    CHECK ( expression ) |
    FOREIGN KEY ( column_name [, ... ] ) REFERENCES reftable [ ( refcolumn [, ... ] ) ]
      [ MATCH FULL | MATCH PARTIAL ] [ ON DELETE action ] [ ON UPDATE action ] }
  [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]

=head1 Create Index Syntax

  CREATE [ UNIQUE ] INDEX index_name ON table
      [ USING acc_method ] ( column [ ops_name ] [, ...] )
      [ WHERE predicate ]
  CREATE [ UNIQUE ] INDEX index_name ON table
      [ USING acc_method ] ( func_name( column [, ... ]) [ ops_name ] )
      [ WHERE predicate ]

=cut

sub produce {
    my $translator       = shift;
    local $DEBUG         = $translator->debug;
    local $WARN          = $translator->show_warnings;
    my $no_comments      = $translator->no_comments;
    my $add_drop_table   = $translator->add_drop_table;
    my $schema           = $translator->schema;
    my $pargs            = $translator->producer_args;
    my $postgres_version = parse_dbms_version(
        $pargs->{postgres_version}, 'perl'
    );

    my $generator = _generator({ quote_identifiers => $translator->quote_identifiers });

    my @output;
    push @output, header_comment unless ($no_comments);

    my (@table_defs, @fks);
    my %type_defs;
    for my $table ( $schema->get_tables ) {

        my ($table_def, $fks) = create_table($table, {
            generator         => $generator,
            no_comments       => $no_comments,
            postgres_version  => $postgres_version,
            add_drop_table    => $add_drop_table,
            type_defs         => \%type_defs,
        });

        push @table_defs, $table_def;
        push @fks, @$fks;
    }

    for my $view ( $schema->get_views ) {
        push @table_defs, create_view($view, {
            postgres_version  => $postgres_version,
            add_drop_view     => $add_drop_table,
            generator         => $generator,
            no_comments       => $no_comments,
        });
    }

    for my $trigger ( $schema->get_triggers ) {
      push @table_defs, create_trigger( $trigger, {
          add_drop_trigger => $add_drop_table,
          generator        => $generator,
          no_comments      => $no_comments,
        });
    }

    push @output, map { "$_;\n\n" } values %type_defs;
    push @output, map { "$_;\n\n" } @table_defs;
    if ( @fks ) {
        push @output, "--\n-- Foreign Key Definitions\n--\n\n" unless $no_comments;
        push @output, map { "$_;\n\n" } @fks;
    }

    if ( $WARN ) {
        if ( %truncated ) {
            warn "Truncated " . keys( %truncated ) . " names:\n";
            warn "\t" . join( "\n\t", sort keys %truncated ) . "\n";
        }
    }

    return wantarray
        ? @output
        : join ('', @output);
}

{
    my %global_names;
    sub mk_name {
        my $basename      = shift || '';
        my $type          = shift || '';
        my $scope         = shift || '';
        my $critical      = shift || '';
        my $basename_orig = $basename;

        my $max_name      = $type
                            ? MAX_ID_LENGTH - (length($type) + 1)
                            : MAX_ID_LENGTH;
        $basename         = substr( $basename, 0, $max_name )
                            if length( $basename ) > $max_name;
        my $name          = $type ? "${type}_$basename" : $basename;

        if ( $basename ne $basename_orig and $critical ) {
            my $show_type = $type ? "+'$type'" : "";
            warn "Truncating '$basename_orig'$show_type to ", MAX_ID_LENGTH,
                " character limit to make '$name'\n" if $WARN;
            $truncated{ $basename_orig } = $name;
        }

        $scope ||= \%global_names;
        if ( my $prev = $scope->{ $name } ) {
            my $name_orig = $name;
            $name        .= sprintf( "%02d", ++$prev );
            substr($name, MAX_ID_LENGTH - 3) = "00"
                if length( $name ) > MAX_ID_LENGTH;

            warn "The name '$name_orig' has been changed to ",
                 "'$name' to make it unique.\n" if $WARN;

            $scope->{ $name_orig }++;
        }

        $scope->{ $name }++;
        return $name;
    }
}

sub is_geometry
{
   my $field = shift;
   return 1 if $field->data_type eq 'geometry';
}

sub is_geography
{
    my $field = shift;
    return 1 if $field->data_type eq 'geography';
}

sub create_table
{
    my ($table, $options) = @_;

    my $generator = _generator($options);
    my $no_comments = $options->{no_comments} || 0;
    my $add_drop_table = $options->{add_drop_table} || 0;
    my $postgres_version = $options->{postgres_version} || 0;
    my $type_defs = $options->{type_defs} || {};

    my $table_name = $table->name or next;
    my $table_name_qt = $generator->quote($table_name);

    my ( @comments, @field_defs, @index_defs, @constraint_defs, @fks );

    push @comments, "--\n-- Table: $table_name\n--\n" unless $no_comments;

    if ( !$no_comments and my $comments = $table->comments ) {
        $comments =~ s/^/-- /mg;
        push @comments, "-- Comments:\n$comments\n--\n";
    }

    #
    # Fields
    #
    for my $field ( $table->get_fields ) {
        push @field_defs, create_field($field, {
            generator => $generator,
            postgres_version => $postgres_version,
            type_defs => $type_defs,
            constraint_defs => \@constraint_defs,
        });
    }

    #
    # Index Declarations
    #
    for my $index ( $table->get_indices ) {
        my ($idef, $constraints) = create_index($index, {
            generator => $generator,
        });
        $idef and push @index_defs, $idef;
        push @constraint_defs, @$constraints;
    }

    #
    # Table constraints
    #
    for my $c ( $table->get_constraints ) {
        my ($cdefs, $fks) = create_constraint($c, {
            generator => $generator,
        });
        push @constraint_defs, @$cdefs;
        push @fks, @$fks;
    }


    my $create_statement = join("\n", @comments);
    if ($add_drop_table) {
        if ($postgres_version >= 8.002) {
            $create_statement .= "DROP TABLE IF EXISTS $table_name_qt CASCADE;\n";
        } else {
            $create_statement .= "DROP TABLE $table_name_qt CASCADE;\n";
        }
    }
    my $temporary = $table->extra->{temporary} ? "TEMPORARY " : "";
    $create_statement .= "CREATE ${temporary}TABLE $table_name_qt (\n" .
                            join( ",\n", map { "  $_" } @field_defs, @constraint_defs ).
                            "\n)"
                            ;
    $create_statement .= @index_defs ? ';' : q{};
    $create_statement .= ( $create_statement =~ /;$/ ? "\n" : q{} )
        . join(";\n", @index_defs);

   #
   # Geometry
   #
   if(grep { is_geometry($_) } $table->get_fields){
        $create_statement .= ";";
        my @geometry_columns;
        foreach my $col ($table->get_fields) { push(@geometry_columns,$col) if is_geometry($col); }
      $create_statement .= "\n".join("\n", map{ drop_geometry_column($_) } @geometry_columns) if $options->{add_drop_table};
      $create_statement .= "\n".join("\n", map{ add_geometry_column($_) } @geometry_columns);
   }

    return $create_statement, \@fks;
}

sub create_view {
    my ($view, $options) = @_;
    my $generator = _generator($options);
    my $postgres_version = $options->{postgres_version} || 0;
    my $add_drop_view = $options->{add_drop_view};

    my $view_name = $view->name;
    debug("PKG: Looking at view '${view_name}'\n");

    my $create = '';
    $create .= "--\n-- View: " . $generator->quote($view_name) . "\n--\n"
        unless $options->{no_comments};
    if ($add_drop_view) {
        if ($postgres_version >= 8.002) {
            $create .= "DROP VIEW IF EXISTS " . $generator->quote($view_name) . ";\n";
        } else {
            $create .= "DROP VIEW " . $generator->quote($view_name) . ";\n";
        }
    }
    $create .= 'CREATE';

    my $extra = $view->extra;
    $create .= " TEMPORARY" if exists($extra->{temporary}) && $extra->{temporary};
    $create .= " VIEW " . $generator->quote($view_name);

    if ( my @fields = $view->fields ) {
        my $field_list = join ', ', map { $generator->quote($_) } @fields;
        $create .= " ( ${field_list} )";
    }

    if ( my $sql = $view->sql ) {
        $create .= " AS\n    ${sql}\n";
    }

    if ( $extra->{check_option} ) {
        $create .= ' WITH ' . uc $extra->{check_option} . ' CHECK OPTION';
    }

    return $create;
}

{

    my %field_name_scope;

    sub create_field
    {
        my ($field, $options) = @_;

        my $generator = _generator($options);
        my $table_name = $field->table->name;
        my $constraint_defs = $options->{constraint_defs} || [];
        my $postgres_version = $options->{postgres_version} || 0;
        my $type_defs = $options->{type_defs} || {};

        $field_name_scope{$table_name} ||= {};
        my $field_name    = $field->name;
        my $field_comments = '';
        if (my $comments = $field->comments) {
            $comments =~ s/(?<!\A)^/  -- /mg;
            $field_comments = "-- $comments\n  ";
        }

        my $field_def     = $field_comments . $generator->quote($field_name);

        #
        # Datatype
        #
        my $data_type = lc $field->data_type;
        my %extra     = $field->extra;
        my $list      = $extra{'list'} || [];
        my $commalist = join( ', ', map { __PACKAGE__->_quote_string($_) } @$list );

        if ($postgres_version >= 8.003 && $data_type eq 'enum') {
            my $type_name = $extra{'custom_type_name'} || $field->table->name . '_' . $field->name . '_type';
            $field_def .= ' '. $type_name;
            my $new_type_def = "DROP TYPE IF EXISTS $type_name CASCADE;\n" .
                               "CREATE TYPE $type_name AS ENUM ($commalist)";
            if (! exists $type_defs->{$type_name} ) {
                $type_defs->{$type_name} = $new_type_def;
            } elsif ( $type_defs->{$type_name} ne $new_type_def ) {
                die "Attempted to redefine type name '$type_name' as a different type.\n";
            }
        } else {
            $field_def .= ' '. convert_datatype($field);
        }

        #
        # Default value
        #
        __PACKAGE__->_apply_default_value(
          $field,
          \$field_def,
          [
            'NULL'              => \'NULL',
            'now()'             => 'now()',
            'CURRENT_TIMESTAMP' => 'CURRENT_TIMESTAMP',
          ],
        );

        #
        # Not null constraint
        #
        $field_def .= ' NOT NULL' unless $field->is_nullable;

      #
      # Geometry constraints
      #
      if(is_geometry($field)){
         foreach ( create_geometry_constraints($field) ) {
            my ($cdefs, $fks) = create_constraint($_, {
                generator => $generator,
            });
            push @$constraint_defs, @$cdefs;
            push @$fks, @$fks;
         }
        }

        return $field_def;
    }
}

sub create_geometry_constraints{
   my $field = shift;

   my @constraints;
   push @constraints, SQL::Translator::Schema::Constraint->new(
                     name       => "enforce_dims_".$field->name,
                     expression => "(ST_NDims($field) = ".$field->extra->{dimensions}.")",
                     table       => $field->table,
                     type       => CHECK_C,
                  );

   push @constraints, SQL::Translator::Schema::Constraint->new(
                     name       => "enforce_srid_".$field->name,
                     expression => "(ST_SRID($field) = ".$field->extra->{srid}.")",
                     table       => $field->table,
                     type       => CHECK_C,
                  );
   push @constraints, SQL::Translator::Schema::Constraint->new(
                     name       => "enforce_geotype_".$field->name,
                     expression => "(GeometryType($field) = '".$field->extra->{geometry_type}."'::text OR $field IS NULL)",
                     table       => $field->table,
                     type       => CHECK_C,
                  );

   return @constraints;
}

{
    my %index_name;
    sub create_index
    {
        my ($index, $options) = @_;

        my $generator = _generator($options);
        my $table_name = $index->table->name;

        my ($index_def, @constraint_defs);

        my $name
            = $index->name
            || join('_', $table_name, 'idx', ++$index_name{ $table_name });

        my $type = $index->type || NORMAL;
        my @fields     =  $index->fields;
        return unless @fields;

        my $index_using;
        my $index_where;
        for my $opt ( $index->options ) {
            if ( ref $opt eq 'HASH' ) {
                foreach my $key (keys %$opt) {
                    my $value = $opt->{$key};
                    next unless defined $value;
                    if ( uc($key) eq 'USING' ) {
                        $index_using = "USING $value";
                    }
                    elsif ( uc($key) eq 'WHERE' ) {
                        $index_where = "WHERE $value";
                    }
                }
            }
        }

        my $def_start = 'CONSTRAINT ' . $generator->quote($name) . ' ';
        my $field_names = '(' . join(", ", (map { $_ =~ /\(.*\)/ ? $_ : ( $generator->quote($_) ) } @fields)) . ')';
        if ( $type eq PRIMARY_KEY ) {
            push @constraint_defs, "${def_start}PRIMARY KEY ".$field_names;
        }
        elsif ( $type eq UNIQUE ) {
            push @constraint_defs, "${def_start}UNIQUE " .$field_names;
        }
        elsif ( $type eq NORMAL ) {
            $index_def =
                'CREATE INDEX ' . $generator->quote($name) . ' on ' . $generator->quote($table_name) . ' ' .
                join ' ', grep { defined } $index_using, $field_names, $index_where;
        }
        else {
            warn "Unknown index type ($type) on table $table_name.\n"
                if $WARN;
        }

        return $index_def, \@constraint_defs;
    }
}

sub create_constraint
{
    my ($c, $options) = @_;

    my $generator = _generator($options);
    my $table_name = $c->table->name;
    my (@constraint_defs, @fks);

    my $name = $c->name || '';

    my @fields = grep { defined } $c->fields;

    my @rfields = grep { defined } $c->reference_fields;

    next if !@fields && $c->type ne CHECK_C;
    my $def_start = $name ? 'CONSTRAINT ' . $generator->quote($name) . ' ' : '';
    my $field_names = '(' . join(", ", (map { $_ =~ /\(.*\)/ ? $_ : ( $generator->quote($_) ) } @fields)) . ')';
    if ( $c->type eq PRIMARY_KEY ) {
        push @constraint_defs, "${def_start}PRIMARY KEY ".$field_names;
    }
    elsif ( $c->type eq UNIQUE ) {
        push @constraint_defs, "${def_start}UNIQUE " .$field_names;
    }
    elsif ( $c->type eq CHECK_C ) {
        my $expression = $c->expression;
        push @constraint_defs, "${def_start}CHECK ($expression)";
    }
    elsif ( $c->type eq FOREIGN_KEY ) {
        my $def .= "ALTER TABLE " . $generator->quote($table_name) . " ADD ${def_start}FOREIGN KEY $field_names"
            . "\n  REFERENCES " . $generator->quote($c->reference_table);

        if ( @rfields ) {
            $def .= ' (' . join( ', ', map { $generator->quote($_) } @rfields ) . ')';
        }

        if ( $c->match_type ) {
            $def .= ' MATCH ' .
                ( $c->match_type =~ /full/i ) ? 'FULL' : 'PARTIAL';
        }

        if ( $c->on_delete ) {
            $def .= ' ON DELETE '. $c->on_delete;
        }

        if ( $c->on_update ) {
            $def .= ' ON UPDATE '. $c->on_update;
        }

        if ( $c->deferrable ) {
            $def .= ' DEFERRABLE';
        }

        push @fks, "$def";
    }

    return \@constraint_defs, \@fks;
}

sub create_trigger {
  my ($trigger,$options) = @_;
  my $generator = _generator($options);

  my @statements;

  push @statements, sprintf( 'DROP TRIGGER IF EXISTS %s', $generator->quote($trigger->name) )
    if $options->{add_drop_trigger};

  my $scope = $trigger->scope || '';
  $scope = " FOR EACH $scope" if $scope;

  push @statements, sprintf(
    'CREATE TRIGGER %s %s %s ON %s%s %s',
    $generator->quote($trigger->name),
    $trigger->perform_action_when,
    join( ' OR ', @{ $trigger->database_events } ),
    $generator->quote($trigger->on_table),
    $scope,
    $trigger->action,
  );

  return @statements;
}

sub convert_datatype
{
    my ($field) = @_;

    my @size      = $field->size;
    my $data_type = lc $field->data_type;
    my $array = $data_type =~ s/\[\]$//;

    if ( $data_type eq 'enum' ) {
#        my $len = 0;
#        $len = ($len < length($_)) ? length($_) : $len for (@$list);
#        my $chk_name = mk_name( $table_name.'_'.$field_name, 'chk' );
#        push @$constraint_defs,
#        'CONSTRAINT "$chk_name" CHECK (' . $generator->quote(field_name) .
#           qq[IN ($commalist))];
        $data_type = 'character varying';
    }
    elsif ( $data_type eq 'set' ) {
        $data_type = 'character varying';
    }
    elsif ( $field->is_auto_increment ) {
        if ( defined $size[0] && $size[0] > 11 ) {
            $data_type = 'bigserial';
        }
        else {
            $data_type = 'serial';
        }
        undef @size;
    }
    else {
        $data_type  = defined $translate{ lc $data_type } ?
            $translate{ lc $data_type } :
            $data_type;
    }

    if ( $data_type =~ /^time/i || $data_type =~ /^interval/i ) {
        if ( defined $size[0] && $size[0] > 6 ) {
            $size[0] = 6;
        }
    }

    if ( $data_type eq 'integer' ) {
        if ( defined $size[0] && $size[0] > 0) {
            if ( $size[0] > 10 ) {
                $data_type = 'bigint';
            }
            elsif ( $size[0] < 5 ) {
                $data_type = 'smallint';
            }
            else {
                $data_type = 'integer';
            }
        }
        else {
            $data_type = 'integer';
        }
    }

    my $type_with_size = join('|',
        'bit', 'varbit', 'character', 'bit varying', 'character varying',
        'time', 'timestamp', 'interval', 'numeric', 'float'
    );

    if ( $data_type !~ /$type_with_size/ ) {
        @size = ();
    }

    if (defined $size[0] && $size[0] > 0 && $data_type =~ /^time/i ) {
        $data_type =~ s/^(time.*?)( with.*)?$/$1($size[0])/;
        $data_type .= $2 if(defined $2);
    } elsif ( defined $size[0] && $size[0] > 0 ) {
        $data_type .= '(' . join( ',', @size ) . ')';
    }
    if($array)
    {
        $data_type .= '[]';
    }

    #
    # Geography
    #
    if($data_type eq 'geography'){
        $data_type .= '('.$field->extra->{geography_type}.','. $field->extra->{srid} .')'
    }

    return $data_type;
}


sub alter_field
{
    my ($from_field, $to_field, $options) = @_;

    die "Can't alter field in another table"
        if($from_field->table->name ne $to_field->table->name);

    my $generator = _generator($options);
    my @out;

    # drop geometry column and constraints
    push @out, drop_geometry_column($from_field) if is_geometry($from_field);
    push @out, drop_geometry_constraints($from_field) if is_geometry($from_field);

    # it's necessary to start with rename column cause this would affect
    # all of the following statements which would be broken if do the
    # rename later
    # BUT: drop geometry is done before the rename, cause it work's on the
    # $from_field directly
    push @out, sprintf('ALTER TABLE %s RENAME COLUMN %s TO %s',
                       map($generator->quote($_),
                           $to_field->table->name,
                           $from_field->name,
                           $to_field->name,
                       ),
                   )
        if($from_field->name ne $to_field->name);

    push @out, sprintf('ALTER TABLE %s ALTER COLUMN %s SET NOT NULL',
                       map($generator->quote($_),
                           $to_field->table->name,
                           $to_field->name
                       ),
                   )
        if(!$to_field->is_nullable and $from_field->is_nullable);

    push @out, sprintf('ALTER TABLE %s ALTER COLUMN %s DROP NOT NULL',
                      map($generator->quote($_),
                          $to_field->table->name,
                          $to_field->name
                      ),
                   )
       if (!$from_field->is_nullable and $to_field->is_nullable);


    my $from_dt = convert_datatype($from_field);
    my $to_dt   = convert_datatype($to_field);
    push @out, sprintf('ALTER TABLE %s ALTER COLUMN %s TYPE %s',
                       map($generator->quote($_),
                           $to_field->table->name,
                           $to_field->name
                       ),
                       $to_dt,
                   )
        if($to_dt ne $from_dt);

    my $old_default = $from_field->default_value;
    my $new_default = $to_field->default_value;
    my $default_value = $to_field->default_value;

    # fixes bug where output like this was created:
    # ALTER TABLE users ALTER COLUMN column SET DEFAULT ThisIsUnescaped;
    if(ref $default_value eq "SCALAR" ) {
        $default_value = $$default_value;
    } elsif( defined $default_value && $to_dt =~ /^(character|text)/xsmi ) {
        $default_value = __PACKAGE__->_quote_string($default_value);
    }

    push @out, sprintf('ALTER TABLE %s ALTER COLUMN %s SET DEFAULT %s',
                       map($generator->quote($_),
                           $to_field->table->name,
                           $to_field->name,
                       ),
                       $default_value,
                   )
        if ( defined $new_default &&
             (!defined $old_default || $old_default ne $new_default) );

    # fixes bug where removing the DEFAULT statement of a column
    # would result in no change

    push @out, sprintf('ALTER TABLE %s ALTER COLUMN %s DROP DEFAULT',
                       map($generator->quote($_),
                           $to_field->table->name,
                           $to_field->name,
                       ),
                   )
        if ( !defined $new_default && defined $old_default );

    # add geometry column and constraints
    push @out, add_geometry_column($to_field) if is_geometry($to_field);
    push @out, add_geometry_constraints($to_field) if is_geometry($to_field);

    return wantarray ? @out : join(";\n", @out);
}

sub rename_field { alter_field(@_) }

sub add_field
{
    my ($new_field,$options) = @_;

    my $out = sprintf('ALTER TABLE %s ADD COLUMN %s',
                      _generator($options)->quote($new_field->table->name),
                      create_field($new_field, $options));
    $out .= "\n".add_geometry_column($new_field) if is_geometry($new_field);
    $out .= "\n".add_geometry_constraints($new_field) if is_geometry($new_field);
    return $out;

}

sub drop_field
{
    my ($old_field, $options) = @_;

    my $generator = _generator($options);

    my $out = sprintf('ALTER TABLE %s DROP COLUMN %s',
                      $generator->quote($old_field->table->name),
                      $generator->quote($old_field->name));
        $out .= "\n".drop_geometry_column($old_field) if is_geometry($old_field);
    return $out;
}

sub add_geometry_column{
   my ($field,$options) = @_;

   my $out = sprintf("INSERT INTO geometry_columns VALUES ('%s','%s','%s','%s','%s','%s','%s')",
                  '',
                  $field->table->schema->name,
                  $options->{table} ? $options->{table} : $field->table->name,
                  $field->name,
                  $field->extra->{dimensions},
                  $field->extra->{srid},
                  $field->extra->{geometry_type});
    return $out;
}

sub drop_geometry_column
{
   my $field = shift;

   my $out = sprintf("DELETE FROM geometry_columns WHERE f_table_schema = '%s' AND f_table_name = '%s' AND f_geometry_column = '%s'",
                  $field->table->schema->name,
                  $field->table->name,
                  $field->name);
    return $out;
}

sub add_geometry_constraints{
   my $field = shift;

   my @constraints = create_geometry_constraints($field);

   my $out = join("\n", map { alter_create_constraint($_); } @constraints);

   return $out;
}

sub drop_geometry_constraints{
   my $field = shift;

   my @constraints = create_geometry_constraints($field);

   my $out = join("\n", map { alter_drop_constraint($_); } @constraints);

   return $out;
}

sub alter_table {
    my ($to_table, $options) = @_;
    my $generator = _generator($options);
    my $out = sprintf('ALTER TABLE %s %s',
                      $generator->quote($to_table->name),
                      $options->{alter_table_action});
    $out .= "\n".$options->{geometry_changes} if $options->{geometry_changes};
    return $out;
}

sub rename_table {
    my ($old_table, $new_table, $options) = @_;
    my $generator = _generator($options);
    $options->{alter_table_action} = "RENAME TO " . $generator->quote($new_table);

   my @geometry_changes;
   push @geometry_changes, map { drop_geometry_column($_); } grep { is_geometry($_) } $old_table->get_fields;
   push @geometry_changes, map { add_geometry_column($_, { table => $new_table }); } grep { is_geometry($_) } $old_table->get_fields;

    $options->{geometry_changes} = join ("\n",@geometry_changes) if scalar(@geometry_changes);

    return alter_table($old_table, $options);
}

sub alter_create_index {
    my ($index, $options) = @_;
    my $generator = _generator($options);
    my ($idef, $constraints) = create_index($index, {
        generator => $generator,
    });
    return $index->type eq NORMAL ? $idef
        : sprintf('ALTER TABLE %s ADD %s',
              $generator->quote($index->table->name),
              join(q{}, @$constraints)
          );
}

sub alter_drop_index {
    my ($index, $options) = @_;
    return 'DROP INDEX '. _generator($options)->quote($index->name);
}

sub alter_drop_constraint {
    my ($c, $options) = @_;
    my $generator = _generator($options);

    # attention: Postgres  has a very special naming structure for naming
    # foreign keys and primary keys.  It names them using the name of the
    # table as prefix and fkey or pkey as suffix, concatenated by an underscore
    my $c_name;
    if( $c->name ) {
        # Already has a name, just use it
        $c_name = $c->name;
    } elsif ( $c->type eq FOREIGN_KEY ) {
        # Doesn't have a name, and is foreign key, append '_fkey'
        $c_name = $c->table->name . '_' . ($c->fields)[0] . '_fkey';
    } elsif ( $c->type eq PRIMARY_KEY ) {
        # Doesn't have a name, and is primary key, append '_pkey'
        $c_name = $c->table->name . '_pkey';
    }

    return sprintf(
        'ALTER TABLE %s DROP CONSTRAINT %s',
        map { $generator->quote($_) } $c->table->name, $c_name,
    );
}

sub alter_create_constraint {
    my ($index, $options) = @_;
    my $generator = _generator($options);
    my ($defs, $fks) = create_constraint(@_);

    # return if there are no constraint definitions so we don't run
    # into output like this:
    # ALTER TABLE users ADD ;

    return unless(@{$defs} || @{$fks});
    return $index->type eq FOREIGN_KEY ? join(q{}, @{$fks})
        : join( ' ', 'ALTER TABLE', $generator->quote($index->table->name),
              'ADD', join(q{}, @{$defs}, @{$fks})
          );
}

sub drop_table {
    my ($table, $options) = @_;
    my $generator = _generator($options);
    my $out = "DROP TABLE " . $generator->quote($table) . " CASCADE";

    my @geometry_drops = map { drop_geometry_column($_); } grep { is_geometry($_) } $table->get_fields;

    $out .= "\n".join("\n",@geometry_drops) if scalar(@geometry_drops);
    return $out;
}

sub batch_alter_table {
  my ( $table, $diff_hash, $options ) = @_;

  # as long as we're not renaming the table we don't need to be here
  if ( @{$diff_hash->{rename_table}} == 0 ) {
    return batch_alter_table_statements($diff_hash, $options);
  }

  # first we need to perform drops which are on old table
  my @sql = batch_alter_table_statements($diff_hash, $options, qw(
    alter_drop_constraint
    alter_drop_index
    drop_field
  ));

  # next comes the rename_table
  my $old_table = $diff_hash->{rename_table}[0][0];
  push @sql, rename_table( $old_table, $table, $options );

  # for alter_field (and so also rename_field) we need to make sure old
  # field has table name set to new table otherwise calling alter_field dies
  $diff_hash->{alter_field} =
    [map { $_->[0]->table($table) && $_ } @{$diff_hash->{alter_field}}];
  $diff_hash->{rename_field} =
    [map { $_->[0]->table($table) && $_ } @{$diff_hash->{rename_field}}];

  # now add everything else
  push @sql, batch_alter_table_statements($diff_hash, $options, qw(
    add_field
    alter_field
    rename_field
    alter_create_index
    alter_create_constraint
    alter_table
  ));

  return @sql;
}

1;

# -------------------------------------------------------------------
# Life is full of misery, loneliness, and suffering --
# and it's all over much too soon.
# Woody Allen
# -------------------------------------------------------------------

=pod

=head1 SEE ALSO

SQL::Translator, SQL::Translator::Producer::Oracle.

=head1 AUTHOR

Ken Youens-Clark E<lt>kclark@cpan.orgE<gt>.

=cut