The Difference Between Table Import and Schema Import

Oct 13, 2025 by wbrum.org 83 views

varchar types inferred on schema import are set to size 1023. 18 occurrences overflow row size limit

Understanding the Issue

When importing a table into a Dolt database, the varchar types are inferred based on the schema of the table. However, in some cases, the inferred varchar types can lead to a table size limit being exceeded, resulting in an error. This issue is particularly problematic when using the table import command, as it can cause the import process to fail.

The Difference Between Table Import and Schema Import

To understand why the table import command failed while the schema import command succeeded, we need to examine the differences between these two commands.

The table import command is used to import a table from a CSV file into a Dolt database. This command infers the data types of the columns based on the schema of the table. However, if the inferred data types are not compatible with the existing table schema, the import process can fail.

On the other hand, the schema import command is used to import the schema of a table from a CSV file into a Dolt database. This command creates a new table with the specified schema, without importing any data. The schema import command is useful for creating a new table with a specific schema, without having to worry about the data types of the columns.

Why Did the Table Import Fail?

In the provided repro, the table import command failed because the inferred varchar types for the columns were too large, causing the table size limit to be exceeded. Specifically, the varchar types for columns such as name, controllers_support, supported_languages, and others were set to a size of 1023, which is larger than the maximum allowed size of 65504.

Why Did the Schema Import Succeed?

In contrast, the schema import command succeeded because it created a new table with the specified schema, without importing any data. The schema import command does not infer the data types of the columns, but instead uses the specified schema to create a new table. As a result, the varchar types for the columns were set to a size of 1023, which is within the allowed limit.

Conclusion

In conclusion, the difference between the table import and schema import commands lies in how they handle the data types of the columns. The table import command infers the data types of the columns based on the schema of the table, while the schema import command uses the specified schema to create a new table. As a result, the table import command can fail if the inferred data types are not compatible with the existing table schema, while the schema import command can succeed even if the inferred data types are too large.

Recommendations

To avoid the issue of the table size limit being exceeded, we recommend using the schema import command to create a new table with the specified schema, and then importing the data into the table using the table import command. This approach allows you to control the data types of the columns and ensure that they are compatible with the existing table schema.

Additional Tips

When using the table import command, make sure to specify the data types of the columns explicitly, rather than relying on the inferred data types.
Use the --continue option with the table import command to ignore errors and continue the import process.
Use the schema import command to create a new table with the specified schema, and then import the data into the table using the table import command.

Code Examples

Here are some code examples that demonstrate how to use the table import and schema import commands:

# Import the schema of a table from a CSV file
dolt schema import -c --pks steam_appid steam_games_released cleaned_released_games_feb_2025.csv

# Import the data into the table using the table import command
dolt table import -u --pk steam_appid steam_games_released cleaned_released_games_feb_2025.csv

# Create a new table with the specified schema using the schema import command
dolt schema import -c --pks steam_appid steam_games_released cleaned_released_games_feb_2025.csv

# Import the data into the table using the table import command
dolt table import -u --pk steam_appid steam_games_released cleaned_released_games_feb_2025.csv

Note that the code examples above assume that the CSV file cleaned_released_games_feb_2025.csv contains the data to be imported into the table.
Q&A: varchar types inferred on schema import are set to size 1023. 18 occurrences overflow row size limit

Q: What is the issue with varchar types inferred on schema import?

A: The issue is that the varchar types inferred on schema import are set to a size of 1023, which can cause the row size limit to be exceeded. This can lead to errors during the import process.

Q: Why does the table import command fail when the varchar types are too large?

A: The table import command fails when the varchar types are too large because the inferred data types are not compatible with the existing table schema. This can cause the import process to fail, resulting in an error.

Q: What is the difference between the table import and schema import commands?

A: The table import command is used to import a table from a CSV file into a Dolt database, while the schema import command is used to import the schema of a table from a CSV file into a Dolt database. The schema import command creates a new table with the specified schema, without importing any data.

Q: Why does the schema import command succeed when the varchar types are too large?

A: The schema import command succeeds when the varchar types are too large because it creates a new table with the specified schema, without importing any data. This means that the varchar types are not inferred, and the table size limit is not exceeded.

Q: How can I avoid the issue of the table size limit being exceeded?

A: To avoid the issue of the table size limit being exceeded, you can use the schema import command to create a new table with the specified schema, and then import the data into the table using the table import command. This approach allows you to control the data types of the columns and ensure that they are compatible with the existing table schema.

Q: What are some additional tips for avoiding the issue of the table size limit being exceeded?

A: Some additional tips for avoiding the issue of the table size limit being exceeded include:

Specifying the data types of the columns explicitly when using the table import command
Using the --continue option with the table import command to ignore errors and continue the import process
Using the schema import command to create a new table with the specified schema, and then importing the data into the table using the table import command

Q: What are some code examples that demonstrate how to use the table import and schema import commands?

A: Here are some code examples that demonstrate how to use the table import and schema import commands:

# Import the schema of a table from a CSV file
dolt schema import -c --pks steam_appid steam_games_released cleaned_released_games_feb_2025.csv

# Import the data into the table using the table import command
dolt table import -u --pk steam_appid steam_games_released cleaned_released_games_feb_2025.csv

# Create a new table with the specified schema using the schema import command
dolt schema import -c --pks steam_appid steam_games_released cleaned_released_games_feb_2025.csv

# Import the data into the table using the table import command
dolt table import -u --pk steam_appid steam_games_released cleaned_released_games_feb_2025.csv

Note that the code examples above assume that the CSV file cleaned_released_games_feb_2025.csv contains the data to be imported into the table.

Q: What are some common mistakes to avoid when using the table import and schema import commands?

A: Some common mistakes to avoid when using the table import and schema import commands include:

Not specifying the data types of the columns explicitly when using the table import command
Not using the --continue option with the table import command to ignore errors and continue the import process
Not using the schema import command to create a new table with the specified schema, and then importing the data into the table using the table import command

By avoiding these common mistakes and following the best practices outlined in this article, you can ensure that your table import and schema import commands run smoothly and efficiently.