Ivan

mysqlcompat-0.0.7是网上开源的postgresql兼容包；

以下是写sql兼容的方式，兼容mysql函数，此种方式效率会是瓶颈；

因此尽量改成postgresql原生的函数或者底层源码兼容；

1 -- INET_ATON()

-- Credit: Michael Fuhr

CREATE OR REPLACE FUNCTION inet_aton(text)

RETURNS bigint AS $$

  DECLARE

      a text[];

      b text[4];

      up int;

      family int;

      i int;

  BEGIN

      IF position(':' in $1) > 0 THEN

        family = 6;

      ELSE

        family = 4;

      END IF;

      -- mysql doesn't support IPv6 yet, it seems

      IF family = 6 THEN

        RETURN NULL;

      END IF;

      a = pg_catalog.string_to_array($1, '.');

      up = array_upper(a, 1);

      IF up = 4 THEN

        -- nothing to do

        b = a;

      ELSIF up = 3 THEN

        -- 127.1.2 = 127.1.0.2

        b = array[a[1], a[2], '0', a[3]];

      ELSIF up = 2 THEN

        -- 127.1 = 127.0.0.1

        b = array[a[1], '0', '0', a[2]];

      ELSIF up = 1 THEN

        -- 127 = 0.0.0.127

        b = array['0', '0', '0', a[1]];

      END IF;

      i = 1;

      -- handle 127..1

      WHILE i <= 4 LOOP

        IF length(b[i]) = 0 THEN

          b[i] = '0';

        END IF;

        i = i + 1;

      END LOOP;

      RETURN (b[1]::bigint << 24) | (b[2]::bigint << 16) |

              (b[3]::bigint << 8) | b[4]::bigint;

  END

$$ IMMUTABLE STRICT LANGUAGE PLPGSQL;

2 -- INET_NTOA()

-- done in SQL to take advantage of inlining

CREATE OR REPLACE FUNCTION inet_ntoa(bigint)

RETURNS text AS $$

SELECT CASE WHEN $1 > 4294967295 THEN NULL ELSE

    ((($1::bigint >> 24) % 256) + 256) % 256 operator(pg_catalog.||) '.' operator(pg_catalog.||)

    ((($1::bigint >> 16) % 256) + 256) % 256 operator(pg_catalog.||) '.' operator(pg_catalog.||)

    ((($1::bigint >>  8) % 256) + 256) % 256 operator(pg_catalog.||) '.' operator(pg_catalog.||)

    ((($1::bigint      ) % 256) + 256) % 256 END;

$$ IMMUTABLE STRICT LANGUAGE SQL;

3 -- SLEEP()

CREATE OR REPLACE FUNCTION sleep(float)

RETURNS integer AS $$

  BEGIN

    IF $1 > 0 THEN

      WHILE pg_catalog.timeofday()::timestamp < (current_timestamp + interval '1 second' * $1) LOOP

      -- Do nothing

      END LOOP;

    END IF;

    RETURN 0;

  END

$$ STRICT VOLATILE LANGUAGE PLPGSQL;