Documentation of the additional GQL error info in the query log

Author: WilcoNeo

modules/ROOT/pages/monitoring/logging.adoc

@@ -1239,6 +1239,10 @@ Included when xref:configuration/configuration-settings.adoc#config_db.logs.quer
 | Reason for failure.
 Included when applicable.
 
+| errorInfo
+| GQL error information as a JSON object.
+See xref:monitoring/logging.adoc#_gql_error_information[GQL error information] for what is contained in this errorInfo JSON object.
+
 | transactionId
 | The transaction ID of the running query.
 
@@ -1272,3 +1276,47 @@ Either same as `authenticatedUser` or an impersonated user.
 | transactionId
 | ID of the transaction.
 |===
+
+==== GQL error information
+
+The GQL error information is included in the querylog as the field `errorInfo`.
+The JSON object `errorInfo` can contain the following elements:
+
+* `GQLSTATUS:` A 5 character long alpha-numeric code which identifies the error.
+* `statusDescription:` A message describing the error.
+* `classification:` The type of error, representing a division of client errors, transient errors and database errors.
+* `position:` The position (a JSON object containing a field for `column`, `offset` and `line`) in the query where this error occurred.
+* `cause:` This is a JSON object containing the errorInfo JSON object of the cause of the current errorInfo JSON object.
+
+Below are examples of the `errorInfo` JSON object:
+[source%linenums,xml,options="nowrap",highlight=4]
+----
+...
+"errorInfo": {
+    "GQLSTATUS": "51N66",
+    "statusDescription": "error: system configuration or operation exception - resource exhaustion. Insufficient resources to complete the request.",
+    "cause": {
+      "GQLSTATUS": "51N55",
+      "statusDescription": "error: system configuration or operation exception - cannot create additional database. Failed to create the database `db10`. The limit of databases is reached. Either increase the limit using the config setting dbms.max_databases or drop a database.",
+      "classification": "DATABASE_ERROR"
+    },
+    "classification": "DATABASE_ERROR"
+  },
+...
+----
+
+----
+...
+"errorInfo": {
+    "GQLSTATUS": "42N62",
+    "statusDescription": "error: syntax error or access rule violation - variable not defined. Variable `m` not defined.",
+    "position": {
+      "column": 18,
+      "offset": 17,
+      "line": 1
+    },
+    "classification": "CLIENT_ERROR"
+  },
+"query": "MATCH (n) RETURN m",
+...
+----