Clone the TiFlash repository

Oct 13, 2025 by magicalceylontours.com 62 views

Bug Report

1. Minimal reproduce step (Required)

To reproduce this bug, follow these steps:

Clone the TiFlash repository: Clone the TiFlash repository from the given GitHub link.
Navigate to the dbms directory: Navigate to the dbms directory within the cloned repository.
Create a new table: Create a new table using the TiDB::Schema::SchemaBuilder class.
Observe the behavior: Observe the behavior of the TiDB::ColumnInfo class when creating a new table.

2. What did you expect to see?

When creating a new table using the TiDB::Schema::SchemaBuilder class, we expect the TiDB::ColumnInfo class to share the DataType instances between different columns.

3. What did you see instead?

However, when creating a new table using the TiDB::Schema::SchemaBuilder class, we see that the TiDB::ColumnInfo class does not share the DataType instances between different columns.

4. What is your TiFlash version? (Required)

Our TiFlash version is nightly.

The Issue with `TiDB::ColumnInfo`

The TiDB::ColumnInfo class is responsible for creating and managing the metadata of columns in a table. However, when creating a new table using the TiDB::Schema::SchemaBuilder class, we see that the TiDB::ColumnInfo class does not share the DataType instances between different columns.

The Code

The code responsible for creating a new table using the TiDB::Schema::SchemaBuilder class is located in the dbms/src/TiDB/Schema/SchemaBuilder.cpp file. The relevant code snippet is as follows:

// Create a new table
TiDB::Schema::SchemaBuilder builder;
builder.CreateTable("my_table", TiDB::ColumnInfo("id", TiDB::DataType::Int64), TiDB::ColumnInfo("name", TiDB::DataType::String));

The Problem

The problem lies in the way the TiDB::ColumnInfo class creates and manages the metadata of columns. When creating a new table, the TiDB::ColumnInfo class creates a new instance of the DataType class for each column. This results in multiple instances of the same DataType class being created, which is not only inefficient but also leads to memory leaks.

The Solution

To solve this issue, we need to modify the TiDB::ColumnInfo class to share the DataType instances between different columns. This can be achieved by creating a single instance of the DataType class and reusing it for all columns.

The Modified Code

The modified code snippet is as follows:

// Create a new table
TiDB::Schema::SchemaBuilder builder;
TiDB::DataType::Int64 int64_type;
TiDB::DataType::String string_type;
builder.CreateTable("my_table", TiDB::ColumnInfo("id", int64_type), TiDB::ColumnInfo("name", string_type));

Conclusion

In conclusion, the TiDB::ColumnInfo class does not share the DataType instances between different columns when creating a new table using the TiDB::Schema::SchemaBuilder class. This results in multiple instances of the same DataType class being created, which is not only inefficient but also leads to memory leaks. To solve this issue, we need to modify the TiDB::ColumnInfo class to share the DataType instances between different columns.

The Impact

The impact of this bug is significant, as it can lead to memory leaks and inefficient use of system resources. Additionally, this bug can also lead to data corruption and inconsistencies in the database.

The Recommendation

Based on our analysis, we recommend modifying the TiDB::ColumnInfo class to share the DataType instances between different columns. This can be achieved by creating a single instance of the DataType class and reusing it for all columns.

The Future Work

In the future, we plan to further investigate and optimize the TiDB::ColumnInfo class to improve its performance and efficiency. We also plan to add more features and functionality to the TiDB::ColumnInfo class to make it more robust and reliable.

The Related Issues

This issue is related to the following issues:

The References

The following references were used to analyze and understand this issue:

TiFlash Documentation
TiDB Documentation
C++ Documentation
Q&A: The DataType instances are not shared when creating by TiDB::ColumnInfo ====================================================================

Q: What is the issue with `TiDB::ColumnInfo`?

A: The issue with TiDB::ColumnInfo is that it does not share the DataType instances between different columns when creating a new table using the TiDB::Schema::SchemaBuilder class.

Q: What are the consequences of this issue?

A: The consequences of this issue are significant, as it can lead to memory leaks and inefficient use of system resources. Additionally, this bug can also lead to data corruption and inconsistencies in the database.

Q: How can this issue be solved?

A: This issue can be solved by modifying the TiDB::ColumnInfo class to share the DataType instances between different columns. This can be achieved by creating a single instance of the DataType class and reusing it for all columns.

Q: What is the impact of this bug on the database?

A: The impact of this bug on the database is significant, as it can lead to data corruption and inconsistencies. This can result in data loss and downtime for the database.

Q: How can this bug be reproduced?

A: This bug can be reproduced by creating a new table using the TiDB::Schema::SchemaBuilder class and observing the behavior of the TiDB::ColumnInfo class.

Q: What is the recommended solution for this issue?

A: The recommended solution for this issue is to modify the TiDB::ColumnInfo class to share the DataType instances between different columns.

Q: What are the benefits of sharing `DataType` instances?

A: The benefits of sharing DataType instances are significant, as it can improve the performance and efficiency of the database. It can also reduce memory usage and prevent data corruption.

Q: How can this issue be prevented in the future?

A: This issue can be prevented in the future by following best practices for coding and testing. It is also essential to have a robust testing framework in place to catch bugs like this before they make it to production.

Q: What are the related issues to this bug?

A: The related issues to this bug are:

Q: What are the references used to analyze and understand this issue?

A: The references used to analyze and understand this issue are:

Q: What is the future work planned for this issue?

A: The future work planned for this issue is to further investigate and optimize the TiDB::ColumnInfo class to improve its performance and efficiency. We also plan to add more features and functionality to the TiDB::ColumnInfo class to make it more robust and reliable.