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The following commit(s) were added to refs/heads/master by this push:
new 99b38ddca74 [improve](env) Ensure next majority is met before drop an
alive follower (#28101)
99b38ddca74 is described below
commit 99b38ddca74f1cf7f50292db3f7dc924d546a700
Author: walter <[email protected]>
AuthorDate: Sat Dec 9 01:41:38 2023 +0800
[improve](env) Ensure next majority is met before drop an alive follower
(#28101)
Here is an example:
```
mysql> ALTER SYSTEM DROP FOLLOWER "127.0.0.1:19017";
ERROR 1105 (HY000): errCode = 2, detailMessage = Unable to drop this alive
follower, because the quorum requirements are not met after this command
execution. Current num alive followers 2, num followers 3, majority after
execution 2
```
---
.../main/java/org/apache/doris/catalog/Env.java | 28 ++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/fe/fe-core/src/main/java/org/apache/doris/catalog/Env.java
b/fe/fe-core/src/main/java/org/apache/doris/catalog/Env.java
index b1ecd46956f..b498ccb6a67 100755
--- a/fe/fe-core/src/main/java/org/apache/doris/catalog/Env.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/catalog/Env.java
@@ -2768,6 +2768,10 @@ public class Env {
throw new DdlException(role.toString() + " does not exist[" +
NetUtils
.getHostPortInAccessibleFormat(host, port) + "]");
}
+ if (role == FrontendNodeType.FOLLOWER && fe.isAlive()) {
+ // Try drop an alive follower, check the quorum safety.
+ ensureSafeToDropAliveFollower();
+ }
int targetFollowerCount = getFollowerCount() - 1;
if (fe.getRole() == FrontendNodeType.FOLLOWER || fe.getRole() ==
FrontendNodeType.REPLICA) {
@@ -2796,6 +2800,30 @@ public class Env {
helperNodes.removeIf(node -> node.getHost().equals(host) &&
node.getPort() == port);
}
+ private void ensureSafeToDropAliveFollower() throws DdlException {
+ int numFollower = 0;
+ int numAliveFollower = 0;
+ for (Frontend fe : frontends.values()) {
+ if (fe.getRole() == FrontendNodeType.FOLLOWER) {
+ numFollower += 1;
+ if (fe.isAlive()) {
+ numAliveFollower += 1;
+ }
+ }
+ }
+
+ int nextMajority = ((numFollower - 1) / 2) + 1;
+ if (nextMajority + 1 <= numAliveFollower) {
+ return;
+ }
+
+ LOG.warn("Drop an alive follower is not safety. Current alive
followers {}, followers {}, next majority: {}",
+ numAliveFollower, numFollower, nextMajority);
+ throw new DdlException("Unable to drop this alive follower, because
the quorum requirements "
+ + "are not met after this command execution. Current num alive
followers "
+ + numAliveFollower + ", num followers " + numFollower + ",
majority after execution " + nextMajority);
+ }
+
public Frontend checkFeExist(String host, int port) {
for (Frontend fe : frontends.values()) {
if (fe.getEditLogPort() != port) {
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