Uninstalling Extensions

Command Syntax

UNINSTALL EXTENSION extension_name [VERSION 'version'];

When VERSION is supplied, the server compares it against the installed extension’s version and aborts if they differ. Omit the clause to uninstall whatever version is currently installed.

You must remove all columns, stored procedure parameters, and DECLARE variables that use types from the extension before uninstalling. The uninstall process will then remove all functions and types provided by the extension.

Prerequisites

Administrative access to VillageSQL
No tables using custom types from the extension
No stored procedures with parameters or DECLARE variables using custom types from the extension
Backup of data if extension stores custom data

Uninstall Steps

1. Attempt Uninstall

Run the uninstall command. If the extension has no dependencies, it will succeed immediately. If columns depend on it, the error message identifies exactly which ones:

UNINSTALL EXTENSION vsql_complex;

If the extension has column dependencies, you will see an error like:

ERROR HY000: Cannot drop extension `vsql_complex` as 1 column(s) depend on it,
e.g. mydb.signals.impedance has type COMPLEX

Drop or alter the identified column(s), then retry:

-- Option 1: Drop the table
DROP TABLE mydb.signals;

-- Option 2: Alter to remove only the custom type column
ALTER TABLE mydb.signals DROP COLUMN impedance;

If a stored procedure uses a custom type from the extension, you will see an error like:

ERROR 3219 (HY000): Cannot uninstall extension 'vsql_complex': stored procedure mydb.transform_signal uses custom type COMPLEX

Drop or alter the stored procedure to remove the typed parameter or variable, then retry:

-- Option 1: Drop the stored procedure
DROP PROCEDURE mydb.transform_signal;

-- Option 2: Recreate the procedure without the custom type parameter
-- (replace the custom type with a compatible built-in type or remove the parameter)

2. Uninstall the Extension

UNINSTALL EXTENSION vsql_complex;

To guard against uninstalling an unexpected version — useful in CI or after a rolling upgrade — include the VERSION clause:

UNINSTALL EXTENSION vsql_complex VERSION '1.2.0';

If 1.2.0 is not the installed version, the server returns an error and leaves the extension in place:

ERROR 3219 (HY000): Cannot uninstall extension 'vsql_complex': installed
version is '0.0.1' but VERSION '1.2.0' was specified

What this removes:

✅ All VDFs (functions) provided by the extension
✅ Custom type definitions registered by the extension
✅ Extension registration record
✅ Custom column metadata for the extension
✅ Persisted system variables (SET PERSIST) for the extension from mysqld-auto.cnf

What this does NOT remove:

❌ The .veb file remains in veb_dir
❌ Expanded directories in {datadir}/.veb_expansion_cache/ remain temporarily
❌ Table data (you must drop tables with custom types first)

Expansion directories in {datadir}/.veb_expansion_cache/{extension}/{sha256}/ are cleaned up automatically on server restart.

UNINSTALL EXTENSION also removes any persisted system variables belonging to the extension from mysqld-auto.cnf. If you previously ran SET PERSIST extensionname.varname = value, that entry is deleted automatically during uninstall. Persisted values are not removed during server shutdown — they survive a restart cycle so the extension can read them on next load.

Uninstalling an extension that has a pending version change (a queued ALTER EXTENSION name VERSION 'x' AT RESTART) discards that pending action along with the extension row — there is no orphaned pending state to clean up, and no error. A later INSTALL EXTENSION starts fresh with no pending action. See Managing Extensions for how pending version changes are tracked and cleared.

3. Verify Uninstall

-- Check extension is gone
SELECT * FROM INFORMATION_SCHEMA.EXTENSIONS WHERE EXTENSION_NAME = 'vsql_complex';
-- Should return no rows

-- Verify functions removed
SELECT complex_abs('(1.0,2.0)');
-- Error: FUNCTION test_db.complex_abs does not exist

Common Errors

Error	Cause	Solution
`Cannot drop extension \`name` as N column(s) depend on it, e.g. db.table.col has type TYPE`	Tables have columns using the extension’s custom types	Drop or alter the identified columns, then retry
`Cannot uninstall extension 'name': stored procedure db.sp uses custom type TYPE`	A stored procedure has a parameter or DECLARE variable using the extension’s custom type	Drop or alter the stored procedure to remove the custom type usage, then retry
`Cannot uninstall extension 'name': installed version is 'X' but VERSION 'Y' was specified`	The `VERSION` clause was specified but doesn’t match the installed version	Re-run without `VERSION`, or use the version shown in `SELECT EXTENSION_VERSION FROM INFORMATION_SCHEMA.EXTENSIONS`
`Extension not found`	Extension not installed	Verify with `SELECT * FROM INFORMATION_SCHEMA.EXTENSIONS`

Optional: Remove .veb File

The .veb file remains after uninstall. To remove completely:

# Find veb_dir
mysql -u root -p -e "SHOW VARIABLES LIKE 'veb_dir';"

# Delete .veb file
sudo rm /path/to/veb_dir/vsql_complex.veb

The .veb file can be kept safely for future reinstallation. Deleting it does not affect server performance.

Reinstalling

To reinstall an extension, use INSTALL EXTENSION again (if .veb file still exists):

INSTALL EXTENSION vsql_complex;

See Installing Extensions for details.

Next Steps

Install Extensions

Add extensions back if needed

Managing Extensions

Monitor and troubleshoot extensions

System Reference

Query system tables

Getting Started

Server Development

Extensions

Using Extensions

Creating Extensions

Command Syntax

Prerequisites

Uninstall Steps

1. Attempt Uninstall

2. Uninstall the Extension

3. Verify Uninstall

Common Errors

Optional: Remove .veb File

Reinstalling

Next Steps

Install Extensions

Managing Extensions

System Reference

​Command Syntax

​Prerequisites

​Uninstall Steps

​1. Attempt Uninstall

​2. Uninstall the Extension

​3. Verify Uninstall

​Common Errors

​Optional: Remove .veb File

​Reinstalling

​Next Steps

Install Extensions

Managing Extensions

System Reference

Command Syntax

Prerequisites

Uninstall Steps

1. Attempt Uninstall

2. Uninstall the Extension

3. Verify Uninstall

Common Errors

Optional: Remove .veb File

Reinstalling

Next Steps