Added the last_insert_rowid API function. Improved documentation of

the random ROWID algorithm. (CVS 349)

FossilOrigin-Name: f74d61aaf3fec06cde2c4a6f1465f86ac9058ad2

src/random.c

@@ -15,14 +15,24 @@
 ** Random numbers are used by some of the database backends in order
 ** to generate random integer keys for tables or random filenames.
 **
-** $Id: random.c,v 1.8 2001/10/09 04:19:47 drh Exp $
+** $Id: random.c,v 1.9 2002/01/16 21:00:27 drh Exp $
 */
 #include "sqliteInt.h"
 #include "os.h"
 
+
 /*
 ** Get a single 8-bit random value from the RC4 PRNG.  The Mutex
 ** must be held while executing this routine.
+**
+** Why not just use a library random generator like lrand48() for this?
+** Because the OP_NewRecno opcode in the VDBE depends on having a very
+** good source of random numbers.  The lrand48() library function may
+** well be good enough.  But maybe not.  Or maybe lrand48() has some
+** subtle problems on some systems that could cause problems.  It is hard
+** to know.  To minimize the risk of problems due to bad lrand48()
+** implementations, SQLite uses is this random number generator based
+** on RC4, which we know works very well.
 */
 static int randomByte(){
   int t;