Module: Gadget

Defined in:
lib/gadget.rb,
lib/gadget/version.rb

Defined Under Namespace

Classes: TsortableHash

Constant Summary collapse

VERSION = 
"0.7.0"

Class Method Summary collapse

Class Method Details

.columns(conn, *args) ⇒ Object

Return a collection enumerating the columns in a table or database.

Usage

columns = Gadget.columns(conn)
columns_in_table = Gadget.columns(conn, "tablename")

Parameters

  • conn - a PG::Connection to the database

  • +tablename - if given, return columns only for the named table

Returns

  • a Hash:

    table name

    a Hash:

    :columns

    an Array of column names



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# File 'lib/gadget.rb', line 82

def self.columns(conn, *args)
  options = args.extract_options!
  tablename = args.shift
  nspname = args.shift || "public"

  sql = <<-END_OF_SQL
SELECT t.tablename, a.attnum, a.attname, ns.nspname
FROM pg_catalog.pg_attribute a
INNER JOIN pg_catalog.pg_class c ON a.attrelid = c.oid
INNER JOIN pg_catalog.pg_tables t ON c.relname = t.tablename
INNER JOIN pg_catalog.pg_namespace ns ON c.relnamespace = ns.oid
WHERE a.attnum >= 0
AND t.schemaname = ns.nspname
AND ns.nspname = $1
  END_OF_SQL
  unless options[:include_dropped]
    sql += " AND a.attisdropped IS FALSE"
  end
  if tablename.nil?
    rs = conn.exec_params(sql, [ nspname ])
  else
    sql += " AND t.tablename = $2"
    rs = conn.exec_params(sql, [ nspname, tablename ])
  end
  tuples = rs.reduce({}) do | h, row |
    h[row["tablename"]] ||= { columns: {} }
    h[row["tablename"]][:columns][row["attnum"]] = row["attname"]
    h
  end
  rs.clear
  tuples
end

.constraints(conn, *args) ⇒ Object

Return a collection enumerating the constraints in a table or database.

Usage

constraints = Gadget.constraints(conn)
constraints_in_table = Gadget.constraints(conn, "tablename")

Parameters

  • conn - a PG::Connection to the database

  • +tablename - if given, return constraints only for the named table

Returns

  • a Hash:

    table name

    a Hash:

    :constraints

    an Array of Hashes:

    :name

    the name of the constraint

    :kind

    the kind of the constraint:

    * +check+
* +exclusion+
* +foreign key+
* +primary key+
* +trigger+
* +unique+



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# File 'lib/gadget.rb', line 196

def self.constraints(conn, *args)
  _ = args.extract_options!
  tablename = args.shift

  sql = <<-END_OF_SQL
SELECT pg_constraint.conname AS name,
     pg_constraint.contype AS constrainttype,
     t.tablename AS tablename
FROM pg_catalog.pg_constraint
INNER JOIN pg_catalog.pg_class c ON pg_constraint.conrelid = c.oid
INNER JOIN pg_catalog.pg_tables t ON c.relname = t.tablename
WHERE t.schemaname = 'public'
  END_OF_SQL
  if tablename.nil?
    rs = conn.exec(sql)
  else
    sql += " AND t.tablename = $1"
    rs = conn.exec_params(sql, [ tablename ])
  end
  tuples = rs.reduce({}) do | h, row |
    name = row["tablename"]
    h[name] ||= { constraints: [] }
    new_constraint = {
      name: row["name"],
      kind: case row["constrainttype"]
            when "c"
              "check"
            when "f"
              "foreign key"
            when "p"
              "primary key"
            when "t"
              "trigger"
            when "u"
              "unique"
            when "x"
              "exclusion"
            else
              %Q(*** unknown: "#{row["constrainttype"]}"")
            end,
    }
    h[name][:constraints] << new_constraint
    h
  end
  rs.clear
  tuples
end

.dependencies(conn, *args) ⇒ Object

Return a collection enumerating the dependencies between tables in a database. A table a is considered to be dependent on a table b if a has a foreign key constraint that refers to b.

Usage

dependencies = Gadget.dependencies(conn)

Parameters

  • conn - a PG::Connection to the database

Returns

  • a Hash:

    table name

    an Array of table names



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# File 'lib/gadget.rb', line 257

def self.dependencies(conn, *args)
  _ = args.extract_options!

  tables = self.tables(conn)
  foreign_keys = self.foreign_keys(conn)
  tables.reduce({}) do | h, (tablename, _) |
    h[tablename] = []
    refs = foreign_keys[tablename]
    unless refs.nil?
      refs[:refs].each { | ref | h[tablename] << ref[:ref_name] }
    end
    h
  end
end

.dependency_graph(conn, *args) ⇒ Object

Print dot (Graphviz data format) describing the dependency graph for a database to stdout.

Usage

Gadget.dependency_graph(conn)

Parameters

  • conn - a PG::Connection to the database



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# File 'lib/gadget.rb', line 296

def self.dependency_graph(conn, *args)
  _ = args.extract_options!

  puts "digraph dependencies {"
  self.dependencies(conn).each do | tablename, deps |
    if deps.empty?
      puts %Q<"#{tablename}">
    else
      deps.each { | dep | puts %Q|"#{tablename}" -> "#{dep}"| }
    end
  end
  puts "}"
end

.foreign_keys(conn, *args) ⇒ Object

Return a collection enumerating the foreign keys in a table or database.

Usage

fks = Gadget.foreign_keys(conn)
fks_in_table = Gadget.foreign_keys(conn, "tablename")

Parameters

  • conn - a PG::Connection to the database

  • +tablename - if given, return foreign keys only for the named table

Returns

  • a Hash:

    table name

    a Hash:

    :refs

    an Array of Hashes:

    :name

    the name of the foreign key

    :cols

    the columns in _this table_ that make up the foreign key

    :ref_name

    the name of the table referred to by this foreign key

    :ref_cols

    the columns in _the other table_ that are referred to by this foreign key



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# File 'lib/gadget.rb', line 133

def self.foreign_keys(conn, *args)
  _ = args.extract_options!
  tablename = args.shift

  sql = <<-END_OF_SQL
SELECT pg_constraint.conname AS name,
     t1.tablename AS tablename, pg_constraint.conkey AS cols,
     t2.tablename AS refname, pg_constraint.confkey AS refcols
FROM pg_catalog.pg_constraint
INNER JOIN pg_catalog.pg_class c1 ON pg_constraint.conrelid = c1.oid
INNER JOIN pg_catalog.pg_tables t1 ON c1.relname = t1.tablename
INNER JOIN pg_catalog.pg_class c2 ON pg_constraint.confrelid = c2.oid
INNER JOIN pg_catalog.pg_tables t2 ON c2.relname = t2.tablename
WHERE t1.schemaname = 'public'
AND t2.schemaname = 'public'
AND pg_constraint.contype = 'f'
  END_OF_SQL
  if tablename.nil?
    rs = conn.exec(sql)
  else
    sql += " AND t1.tablename = $1"
    rs = conn.exec_params(sql, [ tablename ])
  end
  tuples = rs.reduce({}) do | h, row |
    name = row["tablename"]
    h[name] ||= { refs: [] }
    col_names = self.columns(conn, name, include_dropped: true)[name][:columns]
    refcol_names = self.columns(conn, row["refname"], include_dropped: true)[row["refname"]][:columns]
    new_ref = {
      name: row["name"],
      cols: row["cols"].sub(/\A\{|\}\z/, "").split(",").map { | attnum | col_names[attnum] },
      ref_name: row["refname"],
      ref_cols: row["refcols"].sub(/\A\{|\}\z/, "").split(",").map { | attnum | refcol_names[attnum] },
    }
    h[name][:refs] << new_ref
    h
  end
  rs.clear
  tuples
end

.functions(conn, *args) ⇒ Object

Return a collection enumerating the functions in a database.

Usage

functions = Gadget.functions(conn)

Parameters

  • conn - a PG::Connection to the database

Returns

  • a Hash:

    function name

    a Hash:

    :oid

    the function’s OID

    :arg_types

    the type IDs for the arguments to the function



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# File 'lib/gadget.rb', line 323

def self.functions(conn, *args)
  _ = args.extract_options!

  rs = conn.exec(<<-END_OF_SQL)
SELECT p.oid, p.proname, p.proargtypes
FROM pg_catalog.pg_proc p
INNER JOIN pg_catalog.pg_namespace n ON p.pronamespace = n.oid
WHERE n.nspname = 'public'
  END_OF_SQL

  tuples = rs.reduce({}) do | h, row |
    h[row["proname"]] = {
      oid: row["oid"].to_i,
      arg_types: row["proargtypes"].split(/\s+/).map(&:to_i),
    }
    h
  end
  rs.clear
  tuples
end

.sequences(conn, *args) ⇒ Object

Return a collection enumerating the sequences in a database.

Usage

sequences = Gadget.sequences(conn)

Parameters

  • conn - a PG::Connection to the database

Returns

  • a Hash:

    sequence name

    a Hash:

    :oid

    the sequence’s OID



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# File 'lib/gadget.rb', line 356

def self.sequences(conn, *args)
  _ = args.extract_options!

  sql = <<-END_OF_SQL
SELECT c.oid, c.relname
FROM pg_catalog.pg_class c
INNER JOIN pg_catalog.pg_namespace n on c.relnamespace = n.oid
WHERE c.relkind = 'S'
AND n.nspname = 'public'
  END_OF_SQL
  rs = conn.exec(sql)
  tuples = rs.reduce({}) do | h, row |
    h[row["relname"]] = {
      oid: row["oid"].to_i,
    }
    h
  end
  rs.clear
  tuples
end

.tables(conn, *args) ⇒ Object

Return a collection enumerating the tables in a database.

Usage

tables = Gadget.tables(conn)

Parameters

  • conn - a PG::Connection to the database

Returns

  • a Hash:

    table name

    a Hash:

    :oid

    the table’s OID



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# File 'lib/gadget.rb', line 48

def self.tables(conn, *args)
  _ = args.extract_options!

  sql = <<-END_OF_SQL
SELECT c.oid, t.tablename
FROM pg_catalog.pg_tables t
INNER JOIN pg_catalog.pg_class c ON c.relname=t.tablename
WHERE t.schemaname='public'
  END_OF_SQL
  rs = conn.exec(sql)
  tuples = rs.reduce({}) do | h, row |
    h[row["tablename"]] = {
      oid: row["oid"].to_i,
    }
    h
  end
  rs.clear
  tuples
end

.tables_in_dependency_order(conn, *args) ⇒ Object

Return a collection enumerating the tables in a database in dependency order. If a table a is dependent on a table b, then a will appear after b in the collection.

Usage

dependencies = Gadget.dependencies(conn)

Parameters

  • conn - a PG::Connection to the database

Returns

  • a Hash:

    table name

    an Array of table names



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# File 'lib/gadget.rb', line 284

def self.tables_in_dependency_order(conn, *args)
  _ = args.extract_options!
  self.dependencies(conn).reduce(TsortableHash.new) { | h, (k, v) | h[k] = v; h }.tsort
end

.triggers(conn, *args) ⇒ Object

Return a collection enumerating the triggers in a database.

Usage

triggers = Gadget.triggers(conn)

Parameters

  • conn - a PG::Connection to the database

Returns

  • a Hash:

    trigger name

    a Hash:

    :oid

    the trigger’s OID

    :table_name

    the table on which the trigger is defined

    :function_name

    the name of the trigger’s function



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# File 'lib/gadget.rb', line 391

def self.triggers(conn, *args)
  _ = args.extract_options!
  tablename = args.shift

  sql = <<-END_OF_SQL
SELECT tg.oid, tg.tgname, t.tablename, p.proname
FROM pg_catalog.pg_trigger tg
INNER JOIN pg_catalog.pg_class c ON tg.tgrelid = c.oid
INNER JOIN pg_catalog.pg_tables t ON c.relname = t.tablename
INNER JOIN pg_catalog.pg_proc p ON tg.tgfoid = p.oid
WHERE tg.tgconstrrelid = 0
  END_OF_SQL
  if tablename.nil?
    rs = conn.exec(sql)
  else
    sql += " AND t.tablename = $1"
    rs = conn.exec_params(sql, [ tablename ])
  end
  tuples = rs.reduce({}) do | h, row |
    h[row["tgname"]] = {
      oid: row["oid"].to_i,
      table_name: row["tablename"],
      function_name: row["proname"],
    }
    h
  end
  rs.clear
  tuples
end

.types(conn, *args) ⇒ Object

Return a collection enumerating the types in a database.

Usage

types = Gadget.types(conn)

Parameters

  • conn - a PG::Connection to the database

Returns

  • a Hash:

    type name

    a Hash:

    :oid

    the type’s OID



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# File 'lib/gadget.rb', line 433

def self.types(conn, *args)
  _ = args.extract_options!

  rs = conn.exec(<<-END_OF_SQL)
SELECT t.oid, t.typname
FROM pg_catalog.pg_type t
  END_OF_SQL

  tuples = rs.reduce({}) do | h, row |
    h[row["typname"]] = {
      oid: row["oid"].to_i,
    }
    h
  end
  rs.clear
  tuples
end