Incompatible Results for GREATEST Function

[dwenking]

Bug Report

There is a compatibility issue between TiDB and MySQL 8 when using the GREATEST function.

1. Minimal reproduce step (Required)

Set up the table:

CREATE TABLE t0 (c_0 DOUBLE, c_1 TEXT, c_2 DOUBLE);
INSERT INTO t0 VALUES (8.127934079803597e+27, 633230464, 8.127934079803597e+27);

Execute the following query:

SELECT (GREATEST(t0.c_0, t0.c_1)) FROM t0;

Observed Results:

MySQL8 returns 8.127934079803597e27 and TiDB returns 8127934079803597000000000000

2. What did you expect to see? (Required)

The query returns the same result in both MySQL 8 and TiDB.

3. What did you see instead (Required)

See part 1.

4. What is your TiDB version? (Required)

Release Version: v7.5.1
Edition: Community
Git Commit Hash: 7d16cc7
Git Branch: heads/refs/tags/v7.5.1
UTC Build Time: 2024-02-27 14:30:59
GoVersion: go1.21.6
Race Enabled: false
Check Table Before Drop: false
Store: tikv