From 01557dde29ac3af993da17113c728a58401f6456 Mon Sep 17 00:00:00 2001 From: unknown Date: Mon, 14 Jan 2008 16:16:36 +0100 Subject: Bug#33143: Incorrect ORDER BY for ROUND()/TRUNCATE() result The ROUND(X, D) function would change the Item::decimals field during execution to achieve the effect of a dynamic number of decimal digits. This caused a series of bugs: Bug #30617:Round() function not working under some circumstances in InnoDB Bug #33402:ROUND with decimal and non-constant cannot round to 0 decimal places Bug #30889:filesort and order by with float/numeric crashes server Fixed by never changing the number of shown digits for DECIMAL when used with a nonconstant number of decimal digits. mysql-test/r/type_decimal.result: Bug#33143: Test result mysql-test/t/type_decimal.test: Bug#33143: Test case sql/item_func.cc: Bug#33143: - Moved the DECIMAL_MAX_SCALE limitation to fix_length_and_dec. - Removed resetting of Item::decimals field. - set the frac field of the output value to current scale. strings/decimal.c: Bug#33143: It is necessary to set all digits in the buffer following the rounded one to zero, as they may now be displayed. --- strings/decimal.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'strings') diff --git a/strings/decimal.c b/strings/decimal.c index cbea0e340c6..3176cf6afa7 100644 --- a/strings/decimal.c +++ b/strings/decimal.c @@ -1595,9 +1595,21 @@ decimal_round(decimal_t *from, decimal_t *to, int scale, x+=10; *buf1=powers10[pos]*(x-y); } - if (frac0 < 0) + /* + In case we're rounding e.g. 1.5e9 to 2.0e9, the decimal_digit_t's inside + the buffer are as follows. + + Before <1, 5e8> + After <2, 5e8> + + Hence we need to set the 2nd field to 0. + The same holds if we round 1.5e-9 to 2e-9. + */ + if (frac0 < frac1) { - dec1 *end=to->buf+intg0, *buf=buf1+1; + dec1 *buf= to->buf + ((scale == 0 && intg0 == 0) ? 1 : intg0 + frac0); + dec1 *end= to->buf + len; + while (buf < end) *buf++=0; } -- cgit v1.2.1