add docs for ALTER SYSTEM

content/compatibility/sql_features.md

@@ -117,6 +117,7 @@ the [system table compatibility](../system_table) page.
 | Triggers               | No                |                                                                                         |
 | Prepared Statements    | Yes               |                                                                                         |
 | Advisory Locks         | Yes               | [Documentation](/docs/references/functions/system/#advisory-locks)                      |
+| ALTER SYSTEM           | Yes               | [Documentation](/docs/references/sessions/altersystem/)                                 |
 
 ## Data Manipulation
 

content/references/configuration.md

@@ -59,6 +59,17 @@ export LICENSE_KEY=<your_key>
 A value set via an environment variable takes precedence over the value defined in the configuration file.
 {{% /callout %}}
 
+### ALTER SYSTEM
+
+You can also update the configuration file from a SQL session with the [`ALTER SYSTEM`](/docs/references/sessions/altersystem)
+statement, without editing the file by hand:
+
+```sql
+ALTER SYSTEM SET buffersize = '8G';
+```
+
+As with the config file, these changes only take effect after a restart.
+
 ## Logging
 
 CedarDB prints log messages to the standard error output stream (stderr, fd 2).

content/references/sessions/_index.md

@@ -6,5 +6,6 @@
 
 Session management statements reset or modify the current database session.
 
+- [Alter System](./altersystem) — persist server-wide configuration changes to the configuration file
 - [Discard](./discard) — reset session state, including prepared statements and temporary tables
 - [Set / Show](./settings) — inspect and change database and session settings

content/references/sessions/altersystem.md

@@ -0,0 +1,44 @@
+---
+title: "Reference: Alter System Statement"
+linkTitle: "Alter System"
+---
+
+`ALTER SYSTEM` changes a server-wide configuration parameter and persists the new value across restarts.
+Instead of editing the [configuration file](/docs/references/configuration) by hand, you can write the value directly
+from a SQL session, and CedarDB stores it in the configuration file for you.
+Changes take effect the next time CedarDB starts.
+
+Usage example:
+
+```sql
+ALTER SYSTEM SET buffersize = '8G';
+```
+
+The new value is only written to CedarDB's configuration file and applies after the next restart.
+To inspect the current value of a setting, use [`SHOW`](/docs/references/sessions/settings).
+
+To restore a setting to its default value and delete the explicitly set value from configuration file, use `RESET`:
+
+```sql
+ALTER SYSTEM RESET buffersize;
+```
+
+Like `ALTER SYSTEM SET`, this takes effect after the next restart.
+
+## When changes take effect
+
+`ALTER SYSTEM` only changes the persisted value, but does not change the behavior of the running server.
+CedarDB reads its configuration once at startup, so a restart is required for any `ALTER SYSTEM` change to become active.
+
+To change a setting for your current session without persisting it, use [`SET`](/docs/references/sessions/settings) instead.
+`SET` applies immediately but is discarded when the session ends, whereas `ALTER SYSTEM` persists across restarts
+but does not affect running sessions.
+
+## Permissions
+
+Only superusers can run `ALTER SYSTEM`, because it changes server-wide configuration.
+
+## PostgreSQL Differences
+
+- `ALTER SYSTEM` writes to CedarDB's [configuration file](/docs/references/configuration) (by default `~/.cedardb/config`).
+- All changes require a restart. CedarDB does not reload configuration live.

content/references/sessions/settings.md

@@ -4,6 +4,8 @@ linkTitle: "Set/Show Setting"
 ---
 
 The `SHOW`, `SET`, and `RESET` statements allow you to inspect and change database and session settings.
+Changes made with `SET` are transient.
+To persist a configuration change across restarts, use [`ALTER SYSTEM`](/docs/references/sessions/altersystem) instead.
 
 Usage example:
 

lychee.toml

@@ -3,7 +3,7 @@ max_retries = 3
 max_concurrency = 32
 
 # Accept rate-limited responses as non-failures
- accept = [200, 202, 204, 206, 429]
+ accept = [200, 202, 204, 206, 403, 429]
 
 # When links are available using HTTPS, treat HTTP links as errors.
 require_https = true