feiniaofeiafei opened a new pull request, #67809:
URL: https://github.com/apache/doris/pull/67809
### What problem does this PR solve?
Problem Summary:
CREATE TABLE LIKE reconstructs generated columns from SQL using the caller's
session settings, losing the expression settings saved in the source columns.
For a generated expression `a * b` over `DECIMAL(20,5)` and `DECIMAL(21,6)`, a
source created with `enable_decimal256=true` produces `1.26212529751`, but a
clone created with the option disabled produces `1.26212530000` for the same
input. SQL mode also affects parsing: a source expression `a || 'x'` created
with `PIPES_AS_CONCAT` produces `ax`, while its clone can produce NULL under a
different SQL mode.
Snapshot each generated column's session settings under the source table's
read lock and carry them through `GeneratedColumnDesc`. Restore these settings
temporarily when parsing and analyzing the cloned expression, then persist them
in the new `Column`. The caller's session is restored after analysis, including
on exceptions. Ordinary CREATE TABLE retains its existing session behavior.
Existing incorrectly created clones and stored data are not automatically
repaired.
### Release note
Fix CREATE TABLE LIKE changing generated column results when the caller's
expression-related session settings differ from the source table's settings.
### Check List (For Author)
- Test
- [x] Regression test
- Passed `test_generated_column_like_session`,
`test_generated_column`, and `test_generated_column_fault_tolerance_nereids` on
the final branch's FE.
- New coverage includes both decimal256 setting directions, repeated
LIKE, SQL mode, NULL values, and preservation of the caller's session. Expected
output was generated by `run-regression-test.sh` and verified in subsequent
runs.
- [x] Unit Test
- All 11 `CreateTableLikeTest` tests passed via `run-fe-ut.sh` on
the initial validation baseline with the same repair and test files.
- The final upstream baseline has an unrelated test-compilation
error in `IvmNormalizeMTMVJoinTest` (an outdated `IvmRewriteContext`
constructor call). Final FE packaging therefore used `DISABLE_BUILD_UI=ON
MVN_OPT=-Dmaven.test.skip=true ./build.sh --fe`. No unrelated test code was
changed. Checkstyle passed.
- [x] Manual test (add detailed scripts or steps below)
- Reproduced both precision and SQL mode differences before
replacing FE libraries; verified correct results after replacement.
- Restarted the final FE and cloned previously created fixed tables
again, verifying persisted session settings and unchanged caller settings.
- The test FE used `be_exec_version=13` to match its existing BE.
- [ ] No need to test or manual test. Explain why:
- Behavior changed:
- [ ] No.
- [x] Yes. Generated columns created through LIKE preserve the source
columns' expression semantics.
- Does this need documentation?
- [x] No.
- [ ] Yes.
### Check List (For Reviewer who merge this PR)
- [ ] Confirm the release note
- [ ] Confirm test cases
- [ ] Confirm document
- [ ] Add branch pick label
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