Hi, Alexey! On Oct 24, Alexey Botchkov wrote:

revision-id: c29706f7560148488791acca3c92dde1b188334e (mariadb-5.5.61-32-gc29706f) parent(s): e31e697f17f79ffa6913499e7e2d29866f24b475 committer: Alexey Botchkov timestamp: 2018-10-24 01:26:49 +0400 message:

MDEV-17286 Decimal field multiplication bug.

We should clear trailing zeroes in frac part. Otherwise that tail is growing quickly and forces unnecessary truncating of arguments.

This looks good, thanks. Please add a test for create select, as discussed. And fix the bug number in the commit comment. See one question below.

@@ -2109,6 +2104,14 @@ int decimal_mul(const decimal_t *from1, const decimal_t *from2, decimal_t *to) for (; d_to_move--; cur_d++, buf1++) *cur_d= *buf1; } + + /* Now we have to check for -0.000 case */ + if (to->sign && to->intg <= DIG_PER_DEC1 && to->frac == 0 && + to->buf[0] == 0)

What if both arguments will be zeros, but have intg=DIG_PER_DEC1-1. Won't the result have more that DIG_PER_DEC1 zeros?

+ { + /* We got decimal zero */ + decimal_make_zero(to); + } return error; }

Regards, Sergei Chief Architect MariaDB and security@mariadb.org