Method: ActiveRecord::ConnectionAdapters::PostgreSQL::SchemaStatements#pk_and_sequence_for

Defined in:
activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb

#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 315

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("    SELECT attr.attname, nsp.nspname, seq.relname\n    FROM pg_class      seq,\n         pg_attribute  attr,\n         pg_depend     dep,\n         pg_constraint cons,\n         pg_namespace  nsp\n    WHERE seq.oid           = dep.objid\n      AND seq.relkind       = 'S'\n      AND attr.attrelid     = dep.refobjid\n      AND attr.attnum       = dep.refobjsubid\n      AND attr.attrelid     = cons.conrelid\n      AND attr.attnum       = cons.conkey[1]\n      AND seq.relnamespace  = nsp.oid\n      AND cons.contype      = 'p'\n      AND dep.classid       = 'pg_class'::regclass\n      AND dep.refobjid      = \#{quote(quote_table_name(table))}::regclass\n  SQL\n\n  if result.nil? || result.empty?\n    result = query(<<~SQL, \"SCHEMA\")[0]\n      SELECT attr.attname, nsp.nspname,\n        CASE\n          WHEN pg_get_expr(def.adbin, def.adrelid) !~* 'nextval' THEN NULL\n          WHEN split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2) ~ '.' THEN\n            substr(split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2),\n                   strpos(split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2), '.')+1)\n          ELSE split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2)\n        END\n      FROM pg_class       t\n      JOIN pg_attribute   attr ON (t.oid = attrelid)\n      JOIN pg_attrdef     def  ON (adrelid = attrelid AND adnum = attnum)\n      JOIN pg_constraint  cons ON (conrelid = adrelid AND adnum = conkey[1])\n      JOIN pg_namespace   nsp  ON (t.relnamespace = nsp.oid)\n      WHERE t.oid = \#{quote(quote_table_name(table))}::regclass\n        AND cons.contype = 'p'\n        AND pg_get_expr(def.adbin, def.adrelid) ~* 'nextval|uuid_generate|gen_random_uuid'\n    SQL\n  end\n\n  pk = result.shift\n  if result.last\n    [pk, PostgreSQL::Name.new(*result)]\n  else\n    [pk, nil]\n  end\nrescue\n  nil\nend\n", "SCHEMA")[0]