Module: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::SchemaStatements

Included in:
ActiveRecord::ConnectionAdapters::PostgreSQLAdapter
Defined in:
activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb

Instance Method Summary collapse

Instance Method Details

#add_column(table_name, column_name, type, options = {}) ⇒ Object

Adds a new column to the named table. See TableDefinition#column for details of the options you can use.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 393

def add_column(table_name, column_name, type, options = {})
  clear_cache!
  super
end

#add_index(table_name, column_name, options = {}) ⇒ Object

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 434

def add_index(table_name, column_name, options = {}) #:nodoc:
  index_name, index_type, index_columns, index_options, index_algorithm, index_using = add_index_options(table_name, column_name, options)
  execute "CREATE #{index_type} INDEX #{index_algorithm} #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} #{index_using} (#{index_columns})#{index_options}"
end

#change_column(table_name, column_name, type, options = {}) ⇒ Object

Changes the column of a table.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 399

def change_column(table_name, column_name, type, options = {})
  clear_cache!
  quoted_table_name = quote_table_name(table_name)
  sql_type = type_to_sql(type, options[:limit], options[:precision], options[:scale])
  sql_type << "[]" if options[:array]
  execute "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quote_column_name(column_name)} TYPE #{sql_type}"

  change_column_default(table_name, column_name, options[:default]) if options_include_default?(options)
  change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
end

#change_column_default(table_name, column_name, default) ⇒ Object

Changes the default value of a table column.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 411

def change_column_default(table_name, column_name, default)
  clear_cache!
  column = column_for(table_name, column_name)

  execute "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} SET DEFAULT #{quote_default_value(default, column)}" if column
end

#change_column_null(table_name, column_name, null, default = nil) ⇒ Object


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 418

def change_column_null(table_name, column_name, null, default = nil)
  clear_cache!
  unless null || default.nil?
    column = column_for(table_name, column_name)
    execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote_default_value(default, column)} WHERE #{quote_column_name(column_name)} IS NULL") if column
  end
  execute("ALTER TABLE #{quote_table_name(table_name)} ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL")
end

#client_min_messagesObject

Returns the current client message level.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 268

def client_min_messages
  query('SHOW client_min_messages', 'SCHEMA')[0][0]
end

#client_min_messages=(level) ⇒ Object

Set the client message level.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 273

def client_min_messages=(level)
  execute("SET client_min_messages TO '#{level}'", 'SCHEMA')
end

#collationObject

Returns the current database collation.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 216

def collation
  query(<<-end_sql, 'SCHEMA')[0][0]
    SELECT pg_database.datcollate FROM pg_database WHERE pg_database.datname LIKE '#{current_database}'
  end_sql
end

#column_for(table_name, column_name) ⇒ Object

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 193

def column_for(table_name, column_name) #:nodoc:
  columns(table_name).detect { |c| c.name == column_name.to_s }
end

#columns(table_name) ⇒ Object

Returns the list of all column definitions for a table.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 185

def columns(table_name)
  # Limit, precision, and scale are all handled by the superclass.
  column_definitions(table_name).map do |column_name, type, default, notnull, oid, fmod|
    oid = get_oid_type(oid.to_i, fmod.to_i, column_name)
    PostgreSQLColumn.new(column_name, default, oid, type, notnull == 'f')
  end
end

#columns_for_distinct(columns, orders) ⇒ Object

PostgreSQL requires the ORDER BY columns in the select list for distinct queries, and requires that the ORDER BY include the distinct column.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 491

def columns_for_distinct(columns, orders) #:nodoc:
  order_columns = orders.reject(&:blank?).map{ |s|
      # Convert Arel node to string
      s = s.to_sql unless s.is_a?(String)
      # Remove any ASC/DESC modifiers
      s.gsub(/\s+(?:ASC|DESC)\b/i, '')
       .gsub(/\s+NULLS\s+(?:FIRST|LAST)\b/i, '')
    }.reject(&:blank?).map.with_index { |column, i| "#{column} AS alias_#{i}" }

  [super, *order_columns].join(', ')
end

#create_database(name, options = {}) ⇒ Object

Create a new PostgreSQL database. Options include :owner, :template, :encoding (defaults to utf8), :collation, :ctype, :tablespace, and :connection_limit (note that MySQL uses :charset while PostgreSQL uses :encoding).

Example:

create_database config[:database], config
create_database 'foo_development', encoding: 'unicode'

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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 56

def create_database(name, options = {})
  options = { encoding: 'utf8' }.merge!(options.symbolize_keys)

  option_string = options.sum do |key, value|
    case key
    when :owner
      " OWNER = \"#{value}\""
    when :template
      " TEMPLATE = \"#{value}\""
    when :encoding
      " ENCODING = '#{value}'"
    when :collation
      " LC_COLLATE = '#{value}'"
    when :ctype
      " LC_CTYPE = '#{value}'"
    when :tablespace
      " TABLESPACE = \"#{value}\""
    when :connection_limit
      " CONNECTION LIMIT = #{value}"
    else
      ""
    end
  end

  execute "CREATE DATABASE #{quote_table_name(name)}#{option_string}"
end

#create_schema(schema_name) ⇒ Object

Creates a schema for the given schema name.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 241

def create_schema schema_name
  execute "CREATE SCHEMA #{schema_name}"
end

#ctypeObject

Returns the current database ctype.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 223

def ctype
  query(<<-end_sql, 'SCHEMA')[0][0]
    SELECT pg_database.datctype FROM pg_database WHERE pg_database.datname LIKE '#{current_database}'
  end_sql
end

#current_databaseObject

Returns the current database name.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 198

def current_database
  query('select current_database()', 'SCHEMA')[0][0]
end

#current_schemaObject

Returns the current schema name.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 203

def current_schema
  query('SELECT current_schema', 'SCHEMA')[0][0]
end

#default_sequence_name(table_name, pk = nil) ⇒ Object

Returns the sequence name for a table's primary key or some other specified key.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 278

def default_sequence_name(table_name, pk = nil) #:nodoc:
  result = serial_sequence(table_name, pk || 'id')
  return nil unless result
  result.split('.').last
rescue ActiveRecord::StatementInvalid
  "#{table_name}_#{pk || 'id'}_seq"
end

#drop_database(name) ⇒ Object

Drops a PostgreSQL database.

Example:

drop_database 'matt_development'

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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 87

def drop_database(name) #:nodoc:
  execute "DROP DATABASE IF EXISTS #{quote_table_name(name)}"
end

#drop_schema(schema_name) ⇒ Object

Drops the schema for the given schema name.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 246

def drop_schema schema_name
  execute "DROP SCHEMA #{schema_name} CASCADE"
end

#encodingObject

Returns the current database encoding format.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 208

def encoding
  query(<<-end_sql, 'SCHEMA')[0][0]
    SELECT pg_encoding_to_char(pg_database.encoding) FROM pg_database
    WHERE pg_database.datname LIKE '#{current_database}'
  end_sql
end

#index_name_exists?(table_name, index_name, default) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 129

def index_name_exists?(table_name, index_name, default)
  exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
    SELECT COUNT(*)
    FROM pg_class t
    INNER JOIN pg_index d ON t.oid = d.indrelid
    INNER JOIN pg_class i ON d.indexrelid = i.oid
    WHERE i.relkind = 'i'
      AND i.relname = '#{index_name}'
      AND t.relname = '#{table_name}'
      AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = ANY (current_schemas(false)) )
  SQL
end

#index_name_lengthObject


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 447

def index_name_length
  63
end

#indexes(table_name, name = nil) ⇒ Object

Returns an array of indexes for the given table.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 143

def indexes(table_name, name = nil)
   result = query(<<-SQL, 'SCHEMA')
     SELECT distinct i.relname, d.indisunique, d.indkey, pg_get_indexdef(d.indexrelid), t.oid
     FROM pg_class t
     INNER JOIN pg_index d ON t.oid = d.indrelid
     INNER JOIN pg_class i ON d.indexrelid = i.oid
     WHERE i.relkind = 'i'
       AND d.indisprimary = 'f'
       AND t.relname = '#{table_name}'
       AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = ANY (current_schemas(false)) )
    ORDER BY i.relname
  SQL

  result.map do |row|
    index_name = row[0]
    unique = row[1] == 't'
    indkey = row[2].split(" ")
    inddef = row[3]
    oid = row[4]

    columns = Hash[query(<<-SQL, "SCHEMA")]
    SELECT a.attnum, a.attname
    FROM pg_attribute a
    WHERE a.attrelid = #{oid}
    AND a.attnum IN (#{indkey.join(",")})
    SQL

    column_names = columns.values_at(*indkey).compact

    unless column_names.empty?
      # add info on sort order for columns (only desc order is explicitly specified, asc is the default)
      desc_order_columns = inddef.scan(/(\w+) DESC/).flatten
      orders = desc_order_columns.any? ? Hash[desc_order_columns.map {|order_column| [order_column, :desc]}] : {}
      where = inddef.scan(/WHERE (.+)$/).flatten[0]
      using = inddef.scan(/USING (.+?) /).flatten[0].to_sym

      IndexDefinition.new(table_name, index_name, unique, column_names, [], orders, where, nil, using)
    end
  end.compact
end

#pk_and_sequence_for(table) ⇒ Object

Returns a table's primary key and belonging sequence.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 316

def pk_and_sequence_for(table) #:nodoc:
  # First try looking for a sequence with a dependency on the
  # given table's primary key.
  result = query(<<-end_sql, 'SCHEMA')[0]
    SELECT attr.attname, seq.relname
    FROM pg_class      seq,
         pg_attribute  attr,
         pg_depend     dep,
         pg_constraint cons
    WHERE seq.oid           = dep.objid
      AND seq.relkind       = 'S'
      AND attr.attrelid     = dep.refobjid
      AND attr.attnum       = dep.refobjsubid
      AND attr.attrelid     = cons.conrelid
      AND attr.attnum       = cons.conkey[1]
      AND cons.contype      = 'p'
      AND dep.refobjid      = '#{quote_table_name(table)}'::regclass
  end_sql

  if result.nil? or result.empty?
    result = query(<<-end_sql, 'SCHEMA')[0]
      SELECT attr.attname,
        CASE
          WHEN pg_get_expr(def.adbin, def.adrelid) !~* 'nextval' THEN NULL
          WHEN split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2) ~ '.' THEN
            substr(split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2),
                   strpos(split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2), '.')+1)
          ELSE split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2)
        END
      FROM pg_class       t
      JOIN pg_attribute   attr ON (t.oid = attrelid)
      JOIN pg_attrdef     def  ON (adrelid = attrelid AND adnum = attnum)
      JOIN pg_constraint  cons ON (conrelid = adrelid AND adnum = conkey[1])
      WHERE t.oid = '#{quote_table_name(table)}'::regclass
        AND cons.contype = 'p'
        AND pg_get_expr(def.adbin, def.adrelid) ~* 'nextval|uuid_generate'
    end_sql
  end

  [result.first, result.last]
rescue
  nil
end

#primary_key(table) ⇒ Object

Returns just a table's primary key


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 361

def primary_key(table)
  row = exec_query(<<-end_sql, 'SCHEMA').rows.first
    SELECT attr.attname
    FROM pg_attribute attr
    INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]
    WHERE cons.contype = 'p'
      AND cons.conrelid = '#{quote_table_name(table)}'::regclass
  end_sql

  row && row.first
end

#recreate_database(name, options = {}) ⇒ Object

Drops the database specified on the name attribute and creates it again using the provided options.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 43

def recreate_database(name, options = {}) #:nodoc:
  drop_database(name)
  create_database(name, options)
end

#remove_index!(table_name, index_name) ⇒ Object

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 439

def remove_index!(table_name, index_name) #:nodoc:
  execute "DROP INDEX #{quote_table_name(index_name)}"
end

#rename_column(table_name, column_name, new_column_name) ⇒ Object

Renames a column in a table.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 428

def rename_column(table_name, column_name, new_column_name)
  clear_cache!
  execute "ALTER TABLE #{quote_table_name(table_name)} RENAME COLUMN #{quote_column_name(column_name)} TO #{quote_column_name(new_column_name)}"
  rename_column_indexes(table_name, column_name, new_column_name)
end

#rename_index(table_name, old_name, new_name) ⇒ Object


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 443

def rename_index(table_name, old_name, new_name)
  execute "ALTER INDEX #{quote_column_name(old_name)} RENAME TO #{quote_table_name(new_name)}"
end

#rename_table(table_name, new_name) ⇒ Object

Renames a table. Also renames a table's primary key sequence if the sequence name matches the Active Record default.

Example:

rename_table('octopuses', 'octopi')

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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 379

def rename_table(table_name, new_name)
  clear_cache!
  execute "ALTER TABLE #{quote_table_name(table_name)} RENAME TO #{quote_table_name(new_name)}"
  pk, seq = pk_and_sequence_for(new_name)
  if seq == "#{table_name}_#{pk}_seq"
    new_seq = "#{new_name}_#{pk}_seq"
    execute "ALTER TABLE #{quote_table_name(seq)} RENAME TO #{quote_table_name(new_seq)}"
  end

  rename_table_indexes(table_name, new_name)
end

#reset_pk_sequence!(table, pk = nil, sequence = nil) ⇒ Object

Resets the sequence of a table's primary key to the maximum value.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 294

def reset_pk_sequence!(table, pk = nil, sequence = nil) #:nodoc:
  unless pk and sequence
    default_pk, default_sequence = pk_and_sequence_for(table)

    pk ||= default_pk
    sequence ||= default_sequence
  end

  if @logger && pk && !sequence
    @logger.warn "#{table} has primary key #{pk} with no default sequence"
  end

  if pk && sequence
    quoted_sequence = quote_table_name(sequence)

    select_value <<-end_sql, 'SCHEMA'
      SELECT setval('#{quoted_sequence}', (SELECT COALESCE(MAX(#{quote_column_name pk})+(SELECT increment_by FROM #{quoted_sequence}), (SELECT min_value FROM #{quoted_sequence})) FROM #{quote_table_name(table)}), false)
    end_sql
  end
end

#schema_exists?(name) ⇒ Boolean

Returns true if schema exists.

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 121

def schema_exists?(name)
  exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
    SELECT COUNT(*)
    FROM pg_namespace
    WHERE nspname = '#{name}'
  SQL
end

#schema_namesObject

Returns an array of schema names.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 230

def schema_names
  query(<<-SQL, 'SCHEMA').flatten
    SELECT nspname
      FROM pg_namespace
     WHERE nspname !~ '^pg_.*'
       AND nspname NOT IN ('information_schema')
     ORDER by nspname;
  SQL
end

#schema_search_pathObject

Returns the active schema search path.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 263

def schema_search_path
  @schema_search_path ||= query('SHOW search_path', 'SCHEMA')[0][0]
end

#schema_search_path=(schema_csv) ⇒ Object

Sets the schema search path to a string of comma-separated schema names. Names beginning with $ have to be quoted (e.g. $user => '$user'). See: www.postgresql.org/docs/current/static/ddl-schemas.html

This should be not be called manually but set in database.yml.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 255

def schema_search_path=(schema_csv)
  if schema_csv
    execute("SET search_path TO #{schema_csv}", 'SCHEMA')
    @schema_search_path = schema_csv
  end
end

#serial_sequence(table, column) ⇒ Object


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 286

def serial_sequence(table, column)
  result = exec_query(<<-eosql, 'SCHEMA')
    SELECT pg_get_serial_sequence('#{table}', '#{column}')
  eosql
  result.rows.first.first
end

#table_exists?(name) ⇒ Boolean

Returns true if table exists. If the schema is not specified as part of name then it will only find tables within the current schema search path (regardless of permissions to access tables in other schemas)

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 103

def table_exists?(name)
  schema, table = Utils.extract_schema_and_table(name.to_s)
  return false unless table

  binds = [[nil, table]]
  binds << [nil, schema] if schema

  exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
      SELECT COUNT(*)
      FROM pg_class c
      LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
      WHERE c.relkind in ('v','r')
      AND c.relname = '#{table.gsub(/(^"|"$)/,'')}'
      AND n.nspname = #{schema ? "'#{schema}'" : 'ANY (current_schemas(false))'}
  SQL
end

#tables(name = nil) ⇒ Object

Returns the list of all tables in the schema search path or a specified schema.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 92

def tables(name = nil)
  query(<<-SQL, 'SCHEMA').map { |row| row[0] }
    SELECT tablename
    FROM pg_tables
    WHERE schemaname = ANY (current_schemas(false))
  SQL
end

#type_to_sql(type, limit = nil, precision = nil, scale = nil) ⇒ Object

Maps logical Rails types to PostgreSQL-specific data types.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 452

def type_to_sql(type, limit = nil, precision = nil, scale = nil)
  case type.to_s
  when 'binary'
    # PostgreSQL doesn't support limits on binary (bytea) columns.
    # The hard limit is 1Gb, because of a 32-bit size field, and TOAST.
    case limit
    when nil, 0..0x3fffffff; super(type)
    else raise(ActiveRecordError, "No binary type has byte size #{limit}.")
    end
  when 'text'
    # PostgreSQL doesn't support limits on text columns.
    # The hard limit is 1Gb, according to section 8.3 in the manual.
    case limit
    when nil, 0..0x3fffffff; super(type)
    else raise(ActiveRecordError, "The limit on text can be at most 1GB - 1byte.")
    end
  when 'integer'
    return 'integer' unless limit

    case limit
      when 1, 2; 'smallint'
      when 3, 4; 'integer'
      when 5..8; 'bigint'
      else raise(ActiveRecordError, "No integer type has byte size #{limit}. Use a numeric with precision 0 instead.")
    end
  when 'datetime'
    return super unless precision

    case precision
      when 0..6; "timestamp(#{precision})"
      else raise(ActiveRecordError, "No timestamp type has precision of #{precision}. The allowed range of precision is from 0 to 6")
    end
  else
    super
  end
end