# How to Change gc_grace_seconds for a Table

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**Topic: subject**

How to change (reduce) gc_grace_seconds parameter of the table

**Audience: ScyllaDB administrators**

## Issue

When you want to change the `gc_grace_seconds` parameter value for a particular table you should readjust your repairs frequency to have at
least one successful full repair for the table in question every (new) `gc_grace_seconds` window as discussed [here](https://university.scylladb.com/courses/scylla-operations/lessons/repair-tombstones-and-scylla-manager/topic/repair-tombstones-and-scylla-manager/)
in order to avoid data resurrection.

In addition, you should follow the procedure below in order to avoid data resurrection after the changing the `gc_grace_seconds` and before the next repair.

## Resolution

1. Run a [full repair](https://manager.docs.scylladb.com/stable/repair) for the table in question.
2. Change the `gc_grace_seconds` value for the table using the [ALTER table](https://docs.scylladb.com/manual/master/cql/ddl.md#alter-table-statement) command.
3. Verify that the schema is in sync after the change by issuing [nodetool describecluster](https://docs.scylladb.com/manual/master/operating-scylla/nodetool-commands/describecluster.md) command from all nodes.
   Verify that only a single schema version is reported. Read the [Schema Mismatch Troubleshooting Guide](https://docs.scylladb.com/manual/master/troubleshooting/error-messages/schema-mismatch.md) if it’s not the case.
4. Make sure that you run at least one [full repair](https://manager.docs.scylladb.com/stable/repair) for the table in question during the `gc_grace_seconds` time window.
   For example, if the `gc_grace_seconds` is set to 10 days, you should run a full repair on your tables every 8-9 days to make sure your tables are repaired before the `gc_grace_seconds` threshold is reached.

## Additional Notes

You can also avoid data resurrection (and hence the requirement of running the repair every gc_grace_seconds)
if you make sure that tombstones are generated with operations that use Consistency Level: *ALL*

The operations that generate tombstones are:

* DELETE operations
* TTLs
* INSERT/UPDATE operations that overwrite the whole composite type value(s) like *map*, *list* or *UDT*.