Module: ActiveRecord::ConnectionAdapters::PostgreSQL::SchemaStatements

Included in:
ActiveRecord::ConnectionAdapters::PostgreSQLAdapter
Defined in:
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

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 432

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

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

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 486

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 438

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]
  sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quote_column_name(column_name)} TYPE #{sql_type}"
  sql << " USING #{options[:using]}" if options[:using]
  if options[:cast_as]
    sql << " USING CAST(#{quote_column_name(column_name)} AS #{type_to_sql(options[:cast_as], options[:limit], options[:precision], options[:scale])})"
  end
  execute sql

  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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 455

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

  alter_column_query = "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} %s"
  if default.nil?
    # <tt>DEFAULT NULL</tt> results in the same behavior as <tt>DROP DEFAULT</tt>. However, PostgreSQL will
    # cast the default to the columns type, which leaves us with a default like "default NULL::character varying".
    execute alter_column_query % "DROP DEFAULT"
  else
    execute alter_column_query % "SET DEFAULT #{quote_default_value(default, column)}"
  end
end

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



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 470

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_messages ⇒ Object

Returns the current client message level.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 280

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 285

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

#collation ⇒ Object

Returns the current database collation.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 228

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

#columns(table_name) ⇒ Object

Returns the list of all column definitions for a table.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 195

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, type)
    default_value = extract_value_from_default(oid, default)
    default_function = extract_default_function(default_value, default)
    new_column(column_name, default_value, oid, type, notnull == 'f', default_function)
  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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 582

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 54

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

  option_string = options.inject("") do |memo, (key, value)|
    memo += 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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 253

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

#ctype ⇒ Object

Returns the current database ctype.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 235

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_database ⇒ Object

Returns the current database name.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 210

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

#current_schema ⇒ Object

Returns the current schema name.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 215

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

#data_sources ⇒ Object

:nodoc



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 98

def data_sources # :nodoc
  select_values(<<-SQL, 'SCHEMA')
    SELECT c.relname
    FROM pg_class c
    LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
    WHERE c.relkind IN ('r', 'v','m') -- (r)elation/table, (v)iew, (m)aterialized view
    AND n.nspname = ANY (current_schemas(false))
  SQL
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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 290

def default_sequence_name(table_name, pk = nil) #:nodoc:
  result = serial_sequence(table_name, pk || 'id')
  return nil unless result
  Utils.extract_schema_qualified_name(result).to_s
rescue ActiveRecord::StatementInvalid
  PostgreSQL::Name.new(nil, "#{table_name}_#{pk || 'id'}_seq").to_s
end

#drop_database(name) ⇒ Object

Drops a PostgreSQL database.

Example:

drop_database 'matt_development'



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 85

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 258

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

#drop_table(table_name, options = {}) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 126

def drop_table(table_name, options = {})
  execute "DROP TABLE #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :cascade}"
end

#encoding ⇒ Object

Returns the current database encoding format.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 220

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

#extract_foreign_key_action(specifier) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 530

def extract_foreign_key_action(specifier) # :nodoc:
  case specifier
  when 'c'; :cascade
  when 'n'; :nullify
  when 'r'; :restrict
  end
end

#foreign_keys(table_name) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 501

def foreign_keys(table_name)
  fk_info = select_all <<-SQL.strip_heredoc
    SELECT t2.oid::regclass::text AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confupdtype AS on_update, c.confdeltype AS on_delete
    FROM pg_constraint c
    JOIN pg_class t1 ON c.conrelid = t1.oid
    JOIN pg_class t2 ON c.confrelid = t2.oid
    JOIN pg_attribute a1 ON a1.attnum = c.conkey[1] AND a1.attrelid = t1.oid
    JOIN pg_attribute a2 ON a2.attnum = c.confkey[1] AND a2.attrelid = t2.oid
    JOIN pg_namespace t3 ON c.connamespace = t3.oid
    WHERE c.contype = 'f'
      AND t1.relname = #{quote(table_name)}
      AND t3.nspname = ANY (current_schemas(false))
    ORDER BY c.conname
  SQL

  fk_info.map do |row|
    options = {
      column: row['column'],
      name: row['name'],
      primary_key: row['primary_key']
    }

    options[:on_delete] = extract_foreign_key_action(row['on_delete'])
    options[:on_update] = extract_foreign_key_action(row['on_update'])

    ForeignKeyDefinition.new(table_name, row['to_table'], options)
  end
end

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

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 139

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_length ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 538

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 153

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

#new_column(name, default, cast_type, sql_type = nil, null = true, default_function = nil) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 205

def new_column(name, default, cast_type, sql_type = nil, null = true, default_function = nil) # :nodoc:
  PostgreSQLColumn.new(name, default, cast_type, sql_type, null, default_function)
end

#pk_and_sequence_for(table) ⇒ Object

Returns a table’s primary key and belonging sequence.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 345

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, nsp.nspname, seq.relname
    FROM pg_class      seq,
         pg_attribute  attr,
         pg_depend     dep,
         pg_constraint cons,
         pg_namespace  nsp
    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 seq.relnamespace  = nsp.oid
      AND cons.contype      = 'p'
      AND dep.classid       = 'pg_class'::regclass
      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, nsp.nspname,
        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])
      JOIN pg_namespace   nsp  ON (t.relnamespace = nsp.oid)
      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

  pk = result.shift
  if result.last
    [pk, PostgreSQL::Name.new(*result)]
  else
    [pk, nil]
  end
rescue
  nil
end

#primary_key(table) ⇒ Object

Returns just a table’s primary key



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

def primary_key(table)
  pks = exec_query(<<-end_sql, 'SCHEMA').rows
    SELECT attr.attname
    FROM pg_attribute attr
    INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = any(cons.conkey)
    WHERE cons.contype = 'p'
      AND cons.conrelid = '#{quote_table_name(table)}'::regclass
  end_sql
  return nil unless pks.count == 1
  pks[0][0]
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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 41

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

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 480

def rename_column(table_name, column_name, new_column_name) #:nodoc:
  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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 495

def rename_index(table_name, old_name, new_name)
  validate_index_length!(table_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 exists and matches the Active Record default.

Example:

rename_table('octopuses', 'octopi')



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 417

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 && seq.identifier == "#{table_name}_#{pk}_seq"
    new_seq = "#{new_name}_#{pk}_seq"
    idx = "#{table_name}_pkey"
    new_idx = "#{new_name}_pkey"
    execute "ALTER TABLE #{quote_table_name(seq)} RENAME TO #{quote_table_name(new_seq)}"
    execute "ALTER INDEX #{quote_table_name(idx)} RENAME TO #{quote_table_name(new_idx)}"
  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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 323

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 131

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_names ⇒ Object

Returns an array of schema names.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 242

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_path ⇒ Object

Returns the active schema search path.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 275

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 267

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 298

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

#set_pk_sequence!(table, value) ⇒ Object

Sets the sequence of a table’s primary key to the specified value.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 306

def set_pk_sequence!(table, value) #:nodoc:
  pk, sequence = pk_and_sequence_for(table)

  if pk
    if sequence
      quoted_sequence = quote_table_name(sequence)

      select_value <<-end_sql, 'SCHEMA'
      SELECT setval('#{quoted_sequence}', #{value})
      end_sql
    else
      @logger.warn "#{table} has primary key #{pk} with no default sequence" if @logger
    end
  end
end

#table_exists?(name) ⇒ Boolean Also known as: data_source_exists?

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 111

def table_exists?(name)
  name = Utils.extract_schema_qualified_name(name.to_s)
  return false unless name.identifier

  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 ('r','v','m') -- (r)elation/table, (v)iew, (m)aterialized view
      AND c.relname = '#{name.identifier}'
      AND n.nspname = #{name.schema ? "'#{name.schema}'" : 'ANY (current_schemas(false))'}
  SQL
end

#tables(name = nil) ⇒ Object

Returns the list of all tables in the schema search path.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 90

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 543

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 scale 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