README.md in embulk-output-bigquery-0.4.2 vs README.md in embulk-output-bigquery-0.4.3

- old
+ new

@@ -100,12 +100,12 @@
 |  encoding                         | string   | optional  | "UTF-8" | `UTF-8` or `ISO-8859-1` |
 |  ignore_unknown_values            | boolean  | optional  | false   | |
 |  allow_quoted_newlines            | boolean  | optional  | false   | Set true, if data contains newline characters. It may cause slow procsssing |
 |  time_partitioning                | hash     | optional  | `{"type":"DAY"}` if `table` parameter has a partition decorator, otherwise nil | See [Time Partitioning](#time-partitioning) |
 |  time_partitioning.type           | string   | required  | nil     | The only type supported is DAY, which will generate one partition per day based on data loading time. |
-|  time_partitioning.expiration__ms | int      | optional  | nil     | Number of milliseconds for which to keep the storage for a partition. partition |
-|  schema_update_options            | array    | optional  | nil     | List of `ALLOW_FIELD_ADDITION` or `ALLOW_FIELD_RELAXATION` or both. See [jobs#configuration.load.schemaUpdateOptions](https://cloud.google.com/bigquery/docs/reference/v2/jobs#configuration.load.schemaUpdateOptions) |
+|  time_partitioning.expiration_ms | int      | optional  | nil     | Number of milliseconds for which to keep the storage for a partition. partition |
+|  schema_update_options            | array    | optional  | nil     | (Experimental) List of `ALLOW_FIELD_ADDITION` or `ALLOW_FIELD_RELAXATION` or both. See [jobs#configuration.load.schemaUpdateOptions](https://cloud.google.com/bigquery/docs/reference/v2/jobs#configuration.load.schemaUpdateOptions). NOTE for the current status: `schema_update_options` does not work for `copy` job, that is, is not effective for most of modes such as `append`, `append_direct`, `replace`, `replace_backup` (except `delete_in_advance`) |
 
 ### Example
 
 ```yaml
 out:
@@ -125,28 +125,29 @@
 
 5 modes are provided.
 
 ##### append
 
-1. Load to temporary table.
+1. Load to temporary table (Create and WRITE_APPEND in parallel)
 2. Copy temporary table to destination table (or partition). (WRITE_APPEND)
 
 ##### append_direct
 
-Insert data into existing table (or partition) directly.
+1. Insert data into existing table (or partition) directly. (WRITE_APPEND in parallel)
+
 This is not transactional, i.e., if fails, the target table could have some rows inserted.
 
 ##### replace
 
-1. Load to temporary table.
+1. Load to temporary table (Create and WRITE_APPEND in parallel)
 2. Copy temporary table to destination table (or partition). (WRITE_TRUNCATE)
 
 ```is_skip_job_result_check``` must be false when replace mode
 
 ##### replace_backup
 
-1. Load to temporary table.
+1. Load to temporary table (Create and WRITE_APPEND in parallel)
 2. Copy destination table (or partition) to backup table (or partition). (dataset_old, table_old)
 3. Copy temporary table to destination table (or partition). (WRITE_TRUNCATE)
 
 ```is_skip_job_result_check``` must be false when replace_backup mode.
 
@@ -314,11 +315,11 @@
 
 ```
 filters:
   - type: to_json
     column: {name: payload, type: string}
-    default_format: %Y-%m-%d %H:%M:%S.%6N
+    default_format: "%Y-%m-%d %H:%M:%S.%6N"
 out:
   type: bigquery
   payload_column_index: 0 # or, payload_column: payload
 ```
 
@@ -395,27 +396,15 @@
   time_partitioning:
     type: DAY
     expiration_ms: 259200000
 ```
 
-Use `schema_update_options` to allow the schema of the desitination table to be updated as a side effect of the load job as:
+Use [Tables: patch](https://cloud.google.com/bigquery/docs/reference/v2/tables/patch) API to update the schema of the partitioned table, embulk-output-bigquery itself does not support it, though.
+Note that only adding a new column, and relaxing non-necessary columns to be `NULLABLE` are supported now. Deleting columns, and renaming columns are not supported.
 
-```yaml
-out:
-  type: bigquery
-  table: table_name$20160929
-  auto_create_table: true
-  time_partitioning:
-    type: DAY
-    expiration_ms: 259200000
-  schema_update_options:
-    - ALLOW_FIELD_ADDITION
-    - ALLOW_FIELD_RELAXATION
-```
-
-It seems that only adding a new column, and relaxing non-necessary columns to be `NULLABLE` are supported now.
-Deleting columns, and renaming columns are not supported.
-See [jobs#configuration.load.schemaUpdateOptions](https://cloud.google.com/bigquery/docs/reference/v2/jobs#configuration.load.schemaUpdateOptions) for details.
+MEMO: [jobs#configuration.load.schemaUpdateOptions](https://cloud.google.com/bigquery/docs/reference/v2/jobs#configuration.load.schemaUpdateOptions) is available
+to update the schema of the desitination table as a side effect of the load job, but it is not available for copy job.
+Thus, it was not suitable for embulk-output-bigquery idempotence modes, `append`, `replace`, and `replace_backup`, sigh.
 
 ## Development
 
 ### Run example:
 