Yukang-Lian opened a new pull request, #31461:
URL: https://github.com/apache/doris/pull/31461
Problem:
Inconsistent behavior occurs when executing partial column update `UPDATE`
statements and `INSERT` statements on merge-on-write tables with the Nereids
optimizer enabled. The number of columns passed to BE differs; `UPDATE`
operations incorrectly pass all columns, while `INSERT` operations correctly
pass only the updated columns.
Reason:
The Nereids optimizer does not handle partial column update `UPDATE`
statements properly. The processing logic for `UPDATE` statements rewrites them
as equivalent `INSERT` statements, which are then processed according to the
logic of `INSERT` statements. For example, assuming a MoW table structure with
columns k1, k2, v1, v2, the correct rewrite should be:
* `UPDATE` table t1 set v1 = v1 + 1 where k1 = 1 and k2 = 2
* =>
* `INSERT` into table (v1) select v1 + 1 from table t1 where k1 = 1 and k2
= 2
However, the actual rewriting process does not consider the logic for
partial column updates, leading to all columns being included in the `INSERT`
statement, i.e., the result is:
* `INSERT` into table (k1, k2, v1, v2) select k1, k2, v1 + 1, v2 from table
t1 where k1 = 1 and k2 = 2
This results in `UPDATE` operations incorrectly passing all columns to BE.
Solution:
Having analyzed the cause, the solution is straightforward: when rewriting
partial column update `UPDATE` statements to `INSERT` statements, only retain
the updated columns and all key columns (as partial column updates must include
all key columns). Additionally, this PR includes error injection cases to
verify the number of columns passed to BE is correct.
## Proposed changes
Issue Number: close #xxx
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