branches/zip:

Fix Bug#43660 SHOW INDEXES/ANALYZE does NOT update cardinality for
indexes of InnoDB table

by replacing the pseudo random number generator with a better one (LCG).

This also fixes Mantis Issue#212.

Approved by:	Heikki (rb://110)

page/page0cur.c

@@ -30,16 +30,49 @@ Created 10/4/1994 Heikki Tuuri
 #include "page0zip.h"
 #include "mtr0log.h"
 #include "log0recv.h"
+#include "ut0ut.h"
 #ifndef UNIV_HOTBACKUP
 #include "rem0cmp.h"
 
-static ulint	page_rnd	= 976722341;
-
 #ifdef PAGE_CUR_ADAPT
 # ifdef UNIV_SEARCH_PERF_STAT
 static ulint	page_cur_short_succ	= 0;
 # endif /* UNIV_SEARCH_PERF_STAT */
 
+/***********************************************************************
+This is a linear congruential generator PRNG. Returns a pseudo random
+number between 0 and 2^64-1 inclusive. The formula and the constants
+being used are:
+X[n+1] = (a * X[n] + c) mod m
+where:
+X[0] = ut_time_us(NULL)
+a = 1103515245 (3^5 * 5 * 7 * 129749)
+c = 12345 (3 * 5 * 823)
+m = 18446744073709551616 (2^64)
+*/
+#define LCG_a	1103515245
+#define LCG_c	12345
+static
+ib_uint64_t
+page_cur_lcg_prng()
+/*===============*/
+			/* out: number between 0 and 2^64-1 */
+{
+	static ib_uint64_t	lcg_current = 0;
+	static ibool		initialized = FALSE;
+
+	if (!initialized) {
+		lcg_current = (ib_uint64_t) ut_time_us(NULL);
+		initialized = TRUE;
+	}
+
+	/* no need to "% 2^64" explicitly because lcg_current is
+	64 bit and this will be done anyway */
+	lcg_current = LCG_a * lcg_current + LCG_c;
+
+	return(lcg_current);
+}
+
 /********************************************************************
 Tries a search shortcut based on the last insert. */
 UNIV_INLINE
@@ -524,9 +557,7 @@ page_cur_open_on_rnd_user_rec(
 		return;
 	}
 
-	page_rnd += 87584577;
-
-	rnd = page_rnd % n_recs;
+	rnd = (ulint) page_cur_lcg_prng() % n_recs;
 
 	do {
 		page_cur_move_to_next(cursor);
@@ -1930,3 +1961,30 @@ page_cur_delete_rec(
 	ut_a(!page_zip || page_zip_validate(page_zip, page));
 #endif /* UNIV_ZIP_DEBUG */
 }
+
+#ifdef UNIV_COMPILE_TEST_FUNCS
+
+/***********************************************************************
+Print the first n numbers, generated by page_cur_lcg_prng() to make sure
+(visually) that it works properly. */
+void
+test_page_cur_lcg_prng(
+/*===================*/
+	int	n)	/* in: print first n numbers */
+{
+	int			i;
+	unsigned long long	rnd;
+
+	for (i = 0; i < n; i++) {
+		rnd = page_cur_lcg_prng();
+		printf("%llu\t%%2=%llu %%3=%llu %%5=%llu %%7=%llu %%11=%llu\n",
+		       rnd,
+		       rnd % 2,
+		       rnd % 3,
+		       rnd % 5,
+		       rnd % 7,
+		       rnd % 11);
+	}
+}
+
+#endif /* UNIV_COMPILE_TEST_FUNCS */