Module: ActiveRecord::ConnectionAdapters::PostgreSQL::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

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 475

def add_column(table_name, column_name, type, options = {}) #:nodoc:
  clear_cache!
  super
  change_column_comment(table_name, column_name, options[:comment]) if options.key?(:comment)
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 548

def add_index(table_name, column_name, options = {}) #:nodoc:
  index_name, index_type, index_columns, index_options, index_algorithm, index_using, comment = 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}").tap do
    execute "COMMENT ON INDEX #{quote_column_name(index_name)} IS #{quote(comment)}" if comment
  end
end

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

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 481

def change_column(table_name, column_name, type, options = {}) #:nodoc:
  clear_cache!
  quoted_table_name = quote_table_name(table_name)
  quoted_column_name = quote_column_name(column_name)
  sql_type = type_to_sql(type, options[:limit], options[:precision], options[:scale], options[:array])
  sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}"
  if options[:collation]
    sql << " COLLATE \"#{options[:collation]}\""
  end
  if options[:using]
    sql << " USING #{options[:using]}"
  elsif options[:cast_as]
    cast_as_type = type_to_sql(options[:cast_as], options[:limit], options[:precision], options[:scale], options[:array])
    sql << " USING CAST(#{quoted_column_name} AS #{cast_as_type})"
  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)
  change_column_comment(table_name, column_name, options[:comment]) if options.key?(:comment)
end

#change_column_comment(table_name, column_name, comment) ⇒ Object

Adds comment for given table column or drops it if comment is a nil


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

def change_column_comment(table_name, column_name, comment) # :nodoc:
  clear_cache!
  execute "COMMENT ON COLUMN #{quote_table_name(table_name)}.#{quote_column_name(column_name)} IS #{quote(comment)}"
end

#change_column_default(table_name, column_name, default_or_changes) ⇒ 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 504

def change_column_default(table_name, column_name, default_or_changes) # :nodoc:
  clear_cache!
  column = column_for(table_name, column_name)
  return unless column

  default = extract_new_default_value(default_or_changes)
  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_expression(default, column)}"
  end
end

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

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 520

def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
  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_expression(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

#change_table_comment(table_name, comment) ⇒ Object

Adds comment for given table or drops it if comment is a nil


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 536

def change_table_comment(table_name, comment) # :nodoc:
  clear_cache!
  execute "COMMENT ON TABLE #{quote_table_name(table_name)} IS #{quote(comment)}"
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 326

def client_min_messages
  select_value('SHOW client_min_messages', 'SCHEMA')
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 331

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 278

def collation
  select_value("SELECT datcollate FROM pg_database WHERE datname LIKE '#{current_database}'", 'SCHEMA')
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 225

def columns(table_name) # :nodoc:
  table_name = table_name.to_s
  column_definitions(table_name).map do |column_name, type, default, notnull, oid, fmod, collation, comment|
    oid = oid.to_i
    fmod = fmod.to_i
     = (column_name, type, oid, fmod)
    default_value = extract_value_from_default(default)
    default_function = extract_default_function(default_value, default)
    new_column(column_name, default_value, , !notnull, table_name, default_function, collation, comment: comment.presence)
  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 662

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 38

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 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 299

def create_schema schema_name
  execute "CREATE SCHEMA #{quote_schema_name(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 283

def ctype
  select_value("SELECT datctype FROM pg_database WHERE datname LIKE '#{current_database}'", 'SCHEMA')
end

#current_databaseObject

Returns the current database name.


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

def current_database
  select_value('select current_database()', 'SCHEMA')
end

#current_schemaObject

Returns the current schema name.


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

def current_schema
  select_value('SELECT current_schema', 'SCHEMA')
end

#data_source_exists?(name) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 107

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

  select_value(<<-SQL, 'SCHEMA').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

#data_sourcesObject

:nodoc


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 84

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 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 336

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 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 69

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

#drop_schema(schema_name, options = {}) ⇒ 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 304

def drop_schema(schema_name, options = {})
  execute "DROP SCHEMA#{' IF EXISTS' if options[:if_exists]} #{quote_schema_name(schema_name)} CASCADE"
end

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

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 145

def drop_table(table_name, options = {}) # :nodoc:
  execute "DROP TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :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 273

def encoding
  select_value("SELECT pg_encoding_to_char(encoding) FROM pg_database WHERE datname LIKE '#{current_database}'", 'SCHEMA')
end

#extract_foreign_key_action(specifier) ⇒ Object

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 616

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

#fetch_type_metadata(column_name, sql_type, oid, fmod) ⇒ Object


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 674

def (column_name, sql_type, oid, fmod)
  cast_type = get_oid_type(oid, fmod, column_name, sql_type)
  simple_type = SqlTypeMetadata.new(
    sql_type: sql_type,
    type: cast_type.type,
    limit: cast_type.limit,
    precision: cast_type.precision,
    scale: cast_type.scale,
  )
  PostgreSQLTypeMetadata.new(simple_type, oid: oid, fmod: fmod)
end

#foreign_keys(table_name) ⇒ Object


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 587

def foreign_keys(table_name)
  fk_info = select_all(<<-SQL.strip_heredoc, 'SCHEMA')
    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

Verifies existence of an index with a given name.

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 155

def index_name_exists?(table_name, index_name, default)
  table = Utils.extract_schema_qualified_name(table_name.to_s)
  index = Utils.extract_schema_qualified_name(index_name.to_s)

  select_value(<<-SQL, 'SCHEMA').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
    LEFT JOIN pg_namespace n ON n.oid = i.relnamespace
    WHERE i.relkind = 'i'
      AND i.relname = '#{index.identifier}'
      AND t.relname = '#{table.identifier}'
      AND n.nspname = #{index.schema ? "'#{index.schema}'" : '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 624

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 173

def indexes(table_name, name = nil)
  table = Utils.extract_schema_qualified_name(table_name.to_s)

  result = query(<<-SQL, 'SCHEMA')
    SELECT distinct i.relname, d.indisunique, d.indkey, pg_get_indexdef(d.indexrelid), t.oid,
                    pg_catalog.obj_description(i.oid, 'pg_class') AS comment,
    (SELECT COUNT(*) FROM pg_opclass o
       JOIN (SELECT unnest(string_to_array(d.indclass::text, ' '))::int oid) c
         ON o.oid = c.oid WHERE o.opcdefault = 'f')
    FROM pg_class t
    INNER JOIN pg_index d ON t.oid = d.indrelid
    INNER JOIN pg_class i ON d.indexrelid = i.oid
    LEFT JOIN pg_namespace n ON n.oid = i.relnamespace
    WHERE i.relkind = 'i'
      AND d.indisprimary = 'f'
      AND t.relname = '#{table.identifier}'
      AND n.nspname = #{table.schema ? "'#{table.schema}'" : 'ANY (current_schemas(false))'}
    ORDER BY i.relname
  SQL

  result.map do |row|
    index_name = row[0]
    unique = row[1]
    indkey = row[2].split(" ").map(&:to_i)
    inddef = row[3]
    oid = row[4]
    comment = row[5]
    opclass = row[6]

    using, expressions, where = inddef.scan(/ USING (\w+?) \((.+?)\)(?: WHERE (.+))?\z/).flatten

    if indkey.include?(0) || opclass > 0
      columns = expressions
    else
      columns = Hash[query(<<-SQL.strip_heredoc, "SCHEMA")].values_at(*indkey).compact
        SELECT a.attnum, a.attname
        FROM pg_attribute a
        WHERE a.attrelid = #{oid}
        AND a.attnum IN (#{indkey.join(",")})
      SQL

      # add info on sort order for columns (only desc order is explicitly specified, asc is the default)
      orders = Hash[
        expressions.scan(/(\w+) DESC/).flatten.map { |order_column| [order_column, :desc] }
      ]
    end

    IndexDefinition.new(table_name, index_name, unique, columns, [], orders, where, nil, using.to_sym, comment.presence)
  end.compact
end

#new_column(*args) ⇒ Object

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 237

def new_column(*args) # :nodoc:
  PostgreSQLColumn.new(*args)
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 386

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_keys(table_name) ⇒ Object

:nodoc:


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

def primary_keys(table_name) # :nodoc:
  select_values(<<-SQL.strip_heredoc, 'SCHEMA')
    WITH pk_constraint AS (
      SELECT conrelid, unnest(conkey) AS connum FROM pg_constraint
      WHERE contype = 'p'
        AND conrelid = '#{quote_table_name(table_name)}'::regclass
    ), cons AS (
      SELECT conrelid, connum, row_number() OVER() AS rownum FROM pk_constraint
    )
    SELECT attr.attname FROM pg_attribute attr
    INNER JOIN cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.connum
    ORDER BY cons.rownum
  SQL
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 25

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

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

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 555

def remove_index(table_name, options = {}) #:nodoc:
  table = Utils.extract_schema_qualified_name(table_name.to_s)

  if options.is_a?(Hash) && options.key?(:name)
    provided_index = Utils.extract_schema_qualified_name(options[:name].to_s)

    options[:name] = provided_index.identifier
    table = PostgreSQL::Name.new(provided_index.schema, table.identifier) unless table.schema.present?

    if provided_index.schema.present? && table.schema != provided_index.schema
      raise ArgumentError.new("Index schema '#{provided_index.schema}' does not match table schema '#{table.schema}'")
    end
  end

  index_to_remove = PostgreSQL::Name.new(table.schema, index_name_for_remove(table.to_s, options))
  algorithm =
    if options.is_a?(Hash) && options.key?(:algorithm)
      index_algorithms.fetch(options[:algorithm]) do
        raise ArgumentError.new("Algorithm must be one of the following: #{index_algorithms.keys.map(&:inspect).join(', ')}")
      end
    end
  execute "DROP INDEX #{algorithm} #{quote_table_name(index_to_remove)}"
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 542

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

Renames an index of a table. Raises error if length of new index name is greater than allowed limit.


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 581

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 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 460

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 #{seq.quoted} 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 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 364

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 150

def schema_exists?(name)
  select_value("SELECT COUNT(*) FROM pg_namespace WHERE nspname = '#{name}'", 'SCHEMA').to_i > 0
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 288

def schema_names
  select_values(<<-SQL, 'SCHEMA')
    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 321

def schema_search_path
  @schema_search_path ||= select_value('SHOW search_path', 'SCHEMA')
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 313

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 344

def serial_sequence(table, column)
  select_value("SELECT pg_get_serial_sequence('#{table}', '#{column}')", 'SCHEMA')
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 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 349

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

#table_comment(table_name) ⇒ Object

Returns a comment stored in database for given table


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 248

def table_comment(table_name) # :nodoc:
  name = Utils.extract_schema_qualified_name(table_name.to_s)
  if name.identifier
    select_value(<<-SQL.strip_heredoc, 'SCHEMA')
      SELECT pg_catalog.obj_description(c.oid, 'pg_class')
      FROM pg_catalog.pg_class c
        LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
      WHERE c.relname = #{quote(name.identifier)}
        AND c.relkind IN ('r') -- (r)elation/table
        AND n.nspname = #{name.schema ? quote(name.schema) : 'ANY (current_schemas(false))'}
    SQL
  end
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 97

def table_exists?(name)
  ActiveSupport::Deprecation.warn(<<-MSG.squish)
    #table_exists? currently checks both tables and views.
    This behavior is deprecated and will be changed with Rails 5.1 to only check tables.
    Use #data_source_exists? instead.
  MSG

  data_source_exists?(name)
end

#table_options(table_name) ⇒ Object

:nodoc:


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

def table_options(table_name) # :nodoc:
  if comment = table_comment(table_name)
    { comment: comment }
  end
end

#tables(name = nil) ⇒ Object

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


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# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 74

def tables(name = nil)
  if name
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
      Passing arguments to #tables is deprecated without replacement.
    MSG
  end

  select_values("SELECT tablename FROM pg_tables WHERE schemaname = ANY(current_schemas(false))", 'SCHEMA')
end

#type_to_sql(type, limit = nil, precision = nil, scale = nil, array = 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 629

def type_to_sql(type, limit = nil, precision = nil, scale = nil, array = nil)
  sql = 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'
    case limit
    when 1, 2; 'smallint'
    when nil, 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
  else
    super(type, limit, precision, scale)
  end

  sql << '[]' if array && type != :primary_key
  sql
end

#view_exists?(view_name) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean)

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

def view_exists?(view_name) # :nodoc:
  name = Utils.extract_schema_qualified_name(view_name.to_s)
  return false unless name.identifier

  select_values(<<-SQL, 'SCHEMA').any?
    SELECT c.relname
    FROM pg_class c
    LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
    WHERE c.relkind IN ('v','m') -- (v)iew, (m)aterialized view
    AND c.relname = '#{name.identifier}'
    AND n.nspname = #{name.schema ? "'#{name.schema}'" : 'ANY (current_schemas(false))'}
  SQL
end

#viewsObject

:nodoc:


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

def views # :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 ('v','m') -- (v)iew, (m)aterialized view
    AND n.nspname = ANY (current_schemas(false))
  SQL
end