1 files changed, 71 insertions, 0 deletions
diff --git a/challenge-139/luca-ferrari/postgresql/ch-2.sql b/challenge-139/luca-ferrari/postgresql/ch-2.sql
new file mode 100644
index 0000000000..0356250936
--- /dev/null
+++ b/challenge-139/luca-ferrari/postgresql/ch-2.sql
@@ -0,0 +1,71 @@
+CREATE OR REPLACE FUNCTION
+  f_long_primes( l int default 5 )
+  RETURNS SETOF bigint
+AS $CODE$
+  DECLARE
+  current_value numeric;
+  i int;
+  is_prime bool;
+  rational_part text;
+  done int := 0;
+  repeating_part_size int := 0;
+  repeating_part      text;
+  result_as_text      text;
+  text_array          text[];
+
+BEGIN
+
+  for current_value IN 1 .. 99999 LOOP
+    is_prime := true;
+
+    -- check if this is prime
+    for i in 2 .. ( current_value - 1 ) LOOP
+      if current_value % i = 0 THEN
+        is_prime := false;
+        exit; -- terminate this loop
+        END IF;
+    END LOOP;
+
+    -- avoid inspecting this number if it is not prime
+    if is_prime = false THEN
+      continue;
+    END IF;
+
+    result_as_text := ( 1 / current_value::numeric )::text;
+    i := strpos( result_as_text, '.' );
+    rational_part := substr( result_as_text, i + 1 );
+    repeating_part_size :=  current_value - 1;
+    repeating_part      := substr( rational_part, 1, repeating_part_size );
+
+    RAISE DEBUG 'Inspecting % -> % {%} => % ( %, % )',
+      current_value,
+      rational_part,
+      repeating_part_size,
+      repeating_part,
+      i,
+      ( 1 / current_value )::text;
+
+
+    text_array := regexp_split_to_array( rational_part, repeating_part  );
+    is_prime   := true;
+    FOREACH result_as_text IN ARRAY text_array LOOP
+      IF result_as_text <> '' AND substr( repeating_part, 1, length( result_as_text ) ) <> result_as_text THEN
+        is_prime := false;
+        exit;
+      END IF;
+    END LOOP;
+
+    IF is_prime THEN
+      RETURN NEXT current_value;
+      done := done + 1;
+    END IF;
+
+    IF done > l THEN
+      EXIT;
+    END IF;
+  END LOOP;
+
+  RETURN;
+END
+  $CODE$
+  LANGUAGE plpgsql;