adding indices to tables improves responsiveness

UPGRADE.md

@@ -2,6 +2,32 @@
 Upgrade documentation for Zeebe Simple Monitor 
 ==================================================
 
+## Upgrading from v2.1.0
+
+In order to improve database lookup performance, a handful of indices was added to the database structure.
+Zeebe Simple Monitor will not alter existing database tables automatically, but if you have a PostgreSQL
+or other DB running, you may want to alter the table structures manually, in order to improve lookup performance.
+Again, this is an optional step - Zeebe Simple Monitor will work as is without it - just a bit slower response times.
+
+Of course, if you use an in-memory DB or do not need to keep prior data, then simply drop all tables and sequences,
+and let Zeebe Simple Monitor create them again for you (automatic creation works).
+
+### Upgrade procedure
+
+1. stop Zeebe Simple Monitor (v2.1.0)
+2. run the SQL script below against your PostgreSQL Database
+3. start up Zeebe Simple Monitor (new version)
+
+```sql
+CREATE INDEX error_processInstanceKeyIndex ON error (process_instance_key_);
+CREATE INDEX incident_processInstanceKeyIndex ON incident (process_instance_key_);
+CREATE INDEX job_processInstanceKeyIndex ON job (process_instance_key_);
+CREATE INDEX message_subscription_processInstanceKeyIndex ON message_subscription (process_instance_key_);
+CREATE INDEX timer_processInstanceKeyIndex ON timer (process_instance_key_);
+```
+(This SQL was developed and tested using a recent PostgreSQL instance.
+You might need to adopt that if you're using another Database)
+
 ## Upgrading from v2.0.0
 
 Due to some issues with storing variables and element instances, the database structure changed.

src/main/java/io/zeebe/monitor/entity/ElementInstanceEntity.java

@@ -19,7 +19,8 @@
 
 @Entity(name = "ELEMENT_INSTANCE")
 @Table(indexes = {
-    // performance reason, because we use it in the ElementInstanceRepository.findByProcessInstanceKey()
+    // performance reason, because we use it in the
+    // {@link io.zeebe.monitor.repository.ElementInstanceRepository#findByProcessInstanceKey(long)}
     @Index(name = "element_instance_processInstanceKeyIndex", columnList = "PROCESS_INSTANCE_KEY_"),
 })
 public class ElementInstanceEntity {

src/main/java/io/zeebe/monitor/entity/ErrorEntity.java

@@ -15,12 +15,14 @@
  */
 package io.zeebe.monitor.entity;
 
-import javax.persistence.Column;
-import javax.persistence.Entity;
-import javax.persistence.Id;
-import javax.persistence.Lob;
+import javax.persistence.*;
 
 @Entity(name = "ERROR")
+@Table(indexes = {
+    // performance reason, because we use it in the
+    // {@link io.zeebe.monitor.repository.ErrorRepository#findByProcessInstanceKey(long)}
+    @Index(name = "error_processInstanceKeyIndex", columnList = "PROCESS_INSTANCE_KEY_"),
+})
 public class ErrorEntity {
 
   @Id

src/main/java/io/zeebe/monitor/entity/IncidentEntity.java

@@ -15,12 +15,14 @@
  */
 package io.zeebe.monitor.entity;
 
-import javax.persistence.Column;
-import javax.persistence.Entity;
-import javax.persistence.Id;
-import javax.persistence.Lob;
+import javax.persistence.*;
 
 @Entity(name = "INCIDENT")
+@Table(indexes = {
+    // performance reason, because we use it in the
+    // {@link io.zeebe.monitor.repository.IncidentRepository#findByProcessInstanceKey(long)}
+    @Index(name = "incident_processInstanceKeyIndex", columnList = "PROCESS_INSTANCE_KEY_"),
+})
 public class IncidentEntity {
 
   @Id

src/main/java/io/zeebe/monitor/entity/JobEntity.java

@@ -15,11 +15,14 @@
  */
 package io.zeebe.monitor.entity;
 
-import javax.persistence.Column;
-import javax.persistence.Entity;
-import javax.persistence.Id;
+import javax.persistence.*;
 
 @Entity(name = "JOB")
+@Table(indexes = {
+    // performance reason, because we use it in the
+    // {@link io.zeebe.monitor.repository.JobRepository#findByProcessInstanceKey(long)}
+    @Index(name = "job_processInstanceKeyIndex", columnList = "PROCESS_INSTANCE_KEY_"),
+})
 public class JobEntity {
 
   @Id

src/main/java/io/zeebe/monitor/entity/MessageSubscriptionEntity.java

@@ -15,11 +15,14 @@
  */
 package io.zeebe.monitor.entity;
 
-import javax.persistence.Column;
-import javax.persistence.Entity;
-import javax.persistence.Id;
+import javax.persistence.*;
 
 @Entity(name = "MESSAGE_SUBSCRIPTION")
+@Table(indexes = {
+    // performance reason, because we use it in the
+    // {@link io.zeebe.monitor.repository.MessageSubscriptionRepository#findByProcessInstanceKey(long)}
+    @Index(name = "message_subscription_processInstanceKeyIndex", columnList = "PROCESS_INSTANCE_KEY_"),
+})
 public class MessageSubscriptionEntity {
 
   @Id

src/main/java/io/zeebe/monitor/entity/TimerEntity.java

@@ -15,11 +15,14 @@
  */
 package io.zeebe.monitor.entity;
 
-import javax.persistence.Column;
-import javax.persistence.Entity;
-import javax.persistence.Id;
+import javax.persistence.*;
 
 @Entity(name = "TIMER")
+@Table(indexes = {
+    // performance reason, because we use it in the
+    // {@link io.zeebe.monitor.repository.TimerRepository#findByProcessInstanceKey(long)}
+    @Index(name = "timer_processInstanceKeyIndex", columnList = "PROCESS_INSTANCE_KEY_"),
+})
 public class TimerEntity {
 
   @Id