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| author | unknown <serg@serg.mysql.com> | 2003-02-11 23:19:47 +0100 |
|---|---|---|
| committer | unknown <serg@serg.mysql.com> | 2003-02-11 23:19:47 +0100 |
| commit | 02132f55c29f15dcc1fe0b52158c31e11c21ae5b (patch) | |
| tree | 20bae0512d5ab08a128169b5e91127f801d6b709 /sql | |
| parent | 556bb7bb3d98188d2243fd39b09e7cd4cfc7bfd2 (diff) | |
| download | mariadb-git-02132f55c29f15dcc1fe0b52158c31e11c21ae5b.tar.gz | |
backporting Peter's fix for better RAND() initialization from 4.0
sql/sql_class.cc:
backporting Peter's fix for better RAND() initialization from 4.0
to see what it does try
perl -e 'while($N=shift) { printf "N=%-10d",$N; @b=@c=(); for (1..$N) { @a=split(" ",`mysql -BNe "select rand(), rand(), rand(), rand()"`); for(0..3) { $b[$_]+=$a[$_]; $c[$_]+=$a[$_]*$a[$_]; }} for (0..3) { printf "%15.14f ",($c[$_]-$b[$_]*$b[$_]/$N)/$N } print "\n" }' 10 10 10 100 100 10 100 1000
before and after the fix
Diffstat (limited to 'sql')
| -rw-r--r-- | sql/sql_class.cc | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sql/sql_class.cc b/sql/sql_class.cc index eada94e3d40..319bc87ad8d 100644 --- a/sql/sql_class.cc +++ b/sql/sql_class.cc @@ -156,7 +156,7 @@ THD::THD():user_time(0),fatal_error(0),last_insert_id_used(0), */ { pthread_mutex_lock(&LOCK_thread_count); - ulong tmp=(ulong) (rnd(&sql_rand) * 3000000); + ulong tmp=(ulong) (rnd(&sql_rand) * ((ulong)~0L)); randominit(&rand, tmp + (ulong) start_time, tmp + (ulong) thread_id); pthread_mutex_unlock(&LOCK_thread_count); |