Set the length of event#parameters to 2000 (#8615)

CHANGES.md

@@ -79,6 +79,7 @@ Release Notes.
 * Add a new sampler (`possibility`) in LAL.
 * Unify module name `receiver_zipkin` to `receiver-zipkin`, remove `receiver_jaeger` from `application.yaml`. 
 * Introduce the entity of Process type.
+* Set the length of event#parameters to 2000.
 
 #### UI
 

oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/source/Event.java

@@ -99,7 +99,7 @@ public class Event extends Metrics implements ISource, WithMetadata, LongValueHo
     @Column(columnName = MESSAGE)
     private String message;
 
-    @Column(columnName = PARAMETERS, storageOnly = true, length = 1024)
+    @Column(columnName = PARAMETERS, storageOnly = true, length = 20000)
     private String parameters;
 
     @Column(columnName = START_TIME)