Parsing postgres queries

[ea-rus]

Add to support by parser:

• match (~) or not match operators (!~)
• order with column index
• case <col> when <value> then <value> ...
  • at the moment supported is: case when <condition> then <value> ...

Example query:

SELECT n.nspname as "Schema",
  c.relname as "Name",
  CASE c.relkind WHEN 'r' THEN 'table'  WHEN 'I' THEN 'partitioned index' END as "Type",  -- <-------------
  pg_catalog.pg_get_userbyid(c.relowner) as "Owner"
FROM pg_catalog.pg_class c
     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
     LEFT JOIN pg_catalog.pg_am am ON am.oid = c.relam
WHERE c.relkind IN ('r','p','v','m','S','f','')
      AND n.nspname <> 'pg_catalog'
      AND n.nspname !~ '^pg_toast'           -- <-------------
      AND n.nspname <> 'information_schema'
  AND pg_catalog.pg_table_is_visible(c.oid)
ORDER BY 1,2   -- <-------------

[ea-rus]

Order with index is fixed in #400

[ea-rus]

case was fixed in #404