diff --git a/system-variables.md b/system-variables.md
index 9d7449ada4245..ec785b4367488 100644
--- a/system-variables.md
+++ b/system-variables.md
@@ -320,6 +320,22 @@ This variable is an alias for `last_insert_id`.
 - Range: `[0, 65535]`
 - The port that the `tidb-server` is listening on when speaking the MySQL protocol.
 
+### rand_seed1
+
+- Scope: SESSION
+- Default value: `0`
+- Range: `[0, 2147483647]`
+- This variable is used to seed the random value generator used in the `RAND()` SQL function.
+- The behavior of this variable is MySQL compatible.
+
+### rand_seed2
+
+- Scope: SESSION
+- Default value: `0`
+- Range: `[0, 2147483647]`
+- This variable is used to seed the random value generator used in the `RAND()` SQL function.
+- The behavior of this variable is MySQL compatible.
+
 ### skip_name_resolve <span class="version-mark">New in v5.2.0</span>
 
 - Scope: GLOBAL
@@ -463,7 +479,7 @@ MPP is a distributed computing framework provided by the TiFlash engine, which a
 ### tidb_backoff_lock_fast
 
 - Scope: SESSION | GLOBAL
-- Default value: `100`
+- Default value: `10`
 - Range: `[1, 2147483647]`
 - This variable is used to set the `backoff` time when the read request meets a lock.
 
@@ -1542,7 +1558,7 @@ SET tidb_slow_log_threshold = 200;
 
 ### tidb_store_limit <span class="version-mark">New in v3.0.4 and v4.0</span>
 
-- Scope: INSTANCE | GLOBAL
+- Scope: GLOBAL
 - Default value: `0`
 - Range: `[0, 9223372036854775807]`
 - This variable is used to limit the maximum number of requests TiDB can send to TiKV at the same time. 0 means no limit.