Fraud! The variable tidb_enable_tiflash_pipeline_model was deprecated in version 7.4 but re-enabled in version 7.5?

Note:
This topic has been translated from a Chinese forum by GPT and might contain errors.

Original topic: 诈!变量tidb_enable_tiflash_pipeline_model,7.4废弃变量,7.5中又启用?

| username: ShawnYan

[TiDB Usage Environment] Production Environment / Testing / Poc
[TiDB Version]
[Reproduction Path] What operations were performed when the issue occurred
[Encountered Issue: Issue Phenomenon and Impact]
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[Attachments: Screenshots/Logs/Monitoring]

tidb_enable_tiflash_pipeline_model removed

Image

but, in 7.5, this parameter still exists and is ON.

mysql> select version();
+--------------------+
| version()          |
+--------------------+
| 8.0.11-TiDB-v7.5.0 |
+--------------------+
1 row in set (0.01 sec)

mysql> show global variables like '%tidb_enable_tiflash_pipeline_model%';
+------------------------------------+-------+
| Variable_name                      | Value |
+------------------------------------+-------+
| tidb_enable_tiflash_pipeline_model | ON    |
+------------------------------------+-------+
1 row in set (0.00 sec)
| username: yiduoyunQ | Original post link

It might be better to write “deprecated” first.

| username: ShawnYan | Original post link

I also saw this. If it is deprecated, it should be OFF by default.

| username: ShawnYan | Original post link

The original default value was true, and it wasn’t changed when it was deprecated.

It’s not appropriate to write “deleted” in the release notes, but the related parameter description has already been removed…
(related: remove sys var tidb_enable_tiflash_pipeline_model · Issue #47138 · pingcap/tidb · GitHub)

| username: Kongdom | Original post link

:thinking: I’m more concerned about whether the usage of this parameter has been removed from the code. If it has been removed, the impact should not be significant.

| username: ShawnYan | Original post link

I reviewed the code PR, and it has been deleted without any impact, which was surprising. Now, looking at it again, there is a bit of discrepancy between the documentation description and the actual handling. The “deletion” here should be “deprecation.”

| username: Kongdom | Original post link

:rofl: As expected, it was just a feint, hahaha

| username: dba远航 | Original post link

Congratulations to the original poster for discovering a vulnerability.