The view pg_settings provides access to
   run-time parameters of the server.  It is essentially an alternative
   interface to the SHOW and SET commands.
   It also provides access to some facts about each parameter that are
   not directly available from SHOW, such as minimum and
   maximum values.
  
Table 43-44. pg_settings Columns
| Name | Type | Description |  | 
|---|
| name | text | Run-time configuration parameter name |  | 
| setting | text | Current value of the parameter |  | 
| unit | text | Implicit unit of the parameter |  | 
| category | text | Logical group of the parameter |  | 
| short_desc | text | A brief description of the parameter |  | 
| extra_desc | text | Additional, more detailed, information about the parameter |  | 
| context | text | Context required to set the parameter's value |  | 
| vartype | text | Parameter type (bool, integer,
       real, or string) |  | 
| source | text | Source of the current parameter value |  | 
| min_val | text | Minimum allowed value of the parameter (NULL for non-numeric
      values) |  | 
| max_val | text | Maximum allowed value of the parameter (NULL for non-numeric
      values) |  | 
   The pg_settings view cannot be inserted into or
   deleted from, but it can be updated.  An UPDATE applied
   to a row of pg_settings is equivalent to executing
   the SET command on that named
   parameter. The change only affects the value used by the current
   session. If an UPDATE is issued within a transaction
   that is later aborted, the effects of the UPDATE command
   disappear when the transaction is rolled back. Once the surrounding
   transaction is committed, the effects will persist until the end of the
   session, unless overridden by another UPDATE or
   SET.