fix cast to decimal wrong sign (#9300) (#9356)

close #9301 Signed-off-by: guo-shaoge <[email protected]> Co-authored-by: guo-shaoge <[email protected]> Co-authored-by: ti-chi-bot[bot] <108142056+ti-chi-bot[bot]@users.noreply.github.com>
pingcap · Sep 27, 2024 · 08595f4 · 08595f4
1 parent aa9c596
commit 08595f4
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Showing 2 changed files with 28 additions and 2 deletions.
diff --git a/dbms/src/Functions/FunctionsTiDBConversion.h b/dbms/src/Functions/FunctionsTiDBConversion.h
@@ -1012,12 +1012,13 @@ struct TiDBConvertToDecimal
         }
         else if (v_scale > scale)
         {
-            const bool need_to_round = ((value < 0 ? -value : value) % scale_mul) >= (scale_mul / 2);
+            const bool neg = (value < 0);
+            const bool need_to_round = ((neg ? -value : value) % scale_mul) >= (scale_mul / 2);
             auto old_value = value;
             value /= scale_mul;
             if (need_to_round)
             {
-                if (value < 0)
+                if (neg)
                     --value;
                 else
                     ++value;

diff --git a/tests/fullstack-test/expr/cast_as_decimal.test b/tests/fullstack-test/expr/cast_as_decimal.test
@@ -35,3 +35,28 @@ mysql> set @@tidb_isolation_read_engines='tiflash'; set @@tidb_enforce_mpp = 1;
 +------------------------------------+
 |                 20221010101010.123 |
 +------------------------------------+
+
+mysql> drop table if exists test.t2;
+mysql> create table test.t2(d decimal(11, 4));
+mysql> alter table test.t2 set tiflash replica 1;
+mysql> insert into test.t2 values(-0.741);
+mysql> alter table test.t2 set tiflash replica 1;
+func> wait_table test t2
+mysql> set @@tidb_isolation_read_engines='tiflash'; set @@tidb_enforce_mpp = 1; SELECT cast(d as decimal) from test.t2;
++--------------------+
+| cast(d as decimal) |
++--------------------+
+|                 -1 |
++--------------------+
+
+mysql> drop table if exists test.t2;
+mysql> create table test.t2 (c1 int not null, c2 int not null, primary key(c1) CLUSTERED);
+mysql> alter table test.t2 set tiflash replica 1;
+mysql> insert into test.t2 (c1,c2) values (1486109909, -1113200806);
+func> wait_table test t2
+mysql> set @@tidb_isolation_read_engines='tiflash'; set @@tidb_enforce_mpp = 1; select c2, c1, cast( (c2 / cast(c1 as signed)) as decimal) as c2 from test.t2;
++-------------+------------+------+
+| c2          | c1         | c2   |
++-------------+------------+------+
+| -1113200806 | 1486109909 |   -1 |
++-------------+------------+------+