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 401

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 474

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 407

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)
  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)
    sql << " USING CAST(#{quoted_column_name} AS #{cast_as_type})"
  end
  execute sql

  change_column_default(table_name, column_name, options[:default]) if options.key?(:default)
  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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 456

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 430

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 446

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 462

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_messages ⇒ Object

Returns the current client message level.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 251

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 256

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 203

def collation
  select_value("SELECT datcollate FROM pg_database WHERE datname LIKE '#{current_database}'", "SCHEMA")
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 586

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 22

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 224

def create_schema(schema_name)
  execute "CREATE SCHEMA #{quote_schema_name(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 208

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

#current_database ⇒ Object

Returns the current database name.



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 188

def current_database
  select_value("SELECT current_database()", "SCHEMA")
end

#current_schema ⇒ Object

Returns the current schema name.



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

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

#default_sequence_name(table_name, pk = "id") ⇒ 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 261

def default_sequence_name(table_name, pk = "id") #:nodoc:
  result = serial_sequence(table_name, pk)
  return nil unless result
  Utils.extract_schema_qualified_name(result).to_s
rescue ActiveRecord::StatementInvalid
  PostgreSQL::Name.new(nil, "#{table_name}_#{pk}_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 53

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 229

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 57

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

#encoding ⇒ Object

Returns the current database encoding format.



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

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

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 598

def fetch_type_metadata(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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 513

def foreign_keys(table_name)
  scope = quoted_scope(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 = #{scope[:name]}
      AND t3.nspname = #{scope[:schema]}
    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 = nil) ⇒ Boolean

Verifies existence of an index with a given name.

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 67

def index_name_exists?(table_name, index_name, default = nil)
  unless default.nil?
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
      Passing default to #index_name_exists? is deprecated without replacement.
    MSG
  end
  table = quoted_scope(table_name)
  index = quoted_scope(index_name)

  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[:name]}
      AND t.relname = #{table[:name]}
      AND n.nspname = #{index[:schema]}
  SQL
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 90

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

  scope = quoted_scope(table_name)

  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 = #{scope[:name]}
      AND n.nspname = #{scope[:schema]}
    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_from_field(table_name, field) ⇒ Object

:nondoc:



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 147

def new_column_from_field(table_name, field) # :nondoc:
  column_name, type, default, notnull, oid, fmod, collation, comment = field
  oid = oid.to_i
  fmod = fmod.to_i
  type_metadata = fetch_type_metadata(column_name, type, oid, fmod)
  default_value = extract_value_from_default(default)
  default_function = extract_default_function(default_value, default)
  PostgreSQLColumn.new(
    column_name,
    default_value,
    type_metadata,
    !notnull,
    table_name,
    default_function,
    collation,
    comment: comment.presence
  )
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 311

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? || 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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 364

def primary_keys(table_name) # :nodoc:
  select_values(<<-SQL.strip_heredoc, "SCHEMA")
    SELECT a.attname
      FROM (
             SELECT indrelid, indkey, generate_subscripts(indkey, 1) idx
               FROM pg_index
              WHERE indrelid = #{quote(quote_table_name(table_name))}::regclass
                AND indisprimary
           ) i
      JOIN pg_attribute a
        ON a.attrelid = i.indrelid
       AND a.attnum = i.indkey[i.idx]
     ORDER BY i.idx
  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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 9

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

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 468

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 507

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 386

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 289

def reset_pk_sequence!(table, pk = nil, sequence = nil) #:nodoc:
  unless pk && 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 62

def schema_exists?(name)
  select_value("SELECT COUNT(*) FROM pg_namespace WHERE nspname = #{quote(name)}", "SCHEMA").to_i > 0
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 213

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_path ⇒ Object

Returns the active schema search path.



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

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 238

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 269

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 274

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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 173

def table_comment(table_name) # :nodoc:
  scope = quoted_scope(table_name, type: "BASE TABLE")
  if scope[:name]
    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 = #{scope[:name]}
        AND c.relkind IN (#{scope[:type]})
        AND n.nspname = #{scope[:schema]}
    SQL
  end
end

#table_options(table_name) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 166

def table_options(table_name) # :nodoc:
  if comment = table_comment(table_name)
    { comment: comment }
  end
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 'lib/active_record/connection_adapters/postgresql/schema_statements.rb', line 552

def type_to_sql(type, limit: nil, precision: nil, scale: nil, array: nil, **) # :nodoc:
  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
    end

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