README.md in embulk-output-redshift-0.5.0 vs README.md in embulk-output-redshift-0.5.1

@@ -3,12 +3,12 @@
 Redshift output plugins for Embulk loads records to Redshift.
 
 ## Overview
 
 * **Plugin type**: output
-* **Load all or nothing**: depnds on the mode. see bellow.
-* **Resume supported**: depnds on the mode. see bellow.
+* **Load all or nothing**: depnds on the mode. see below.
+* **Resume supported**: depnds on the mode. see below.
 
 ## Configuration
 
 - **host**: database host name (string, required)
 - **port**: database port number (integer, default: 5439)
@@ -17,23 +17,24 @@
 - **database**: destination database name (string, required)
 - **schema**: destination schema name (string, default: "public")
 - **table**: destination table name (string, required)
 - **access_key_id**: access key id for AWS
 - **secret_access_key**: secret access key for AWS
-- **iam_user_name**: IAM user name for uploading temporary files to S3. The user should have permissions of `s3:GetObject`, `s3:PutObject`, `s3:ListBucket` and `sts:GetFederationToken`.
+- **iam_user_name**: IAM user name for uploading temporary files to S3. The user should have permissions of `s3:GetObject`, `s3:PutObject`, `s3:DeleteObject`, , `s3:ListBucket` and `sts:GetFederationToken`. (string, default: "", but we strongly recommend that you use IAM user for security reasons. see below.)
 - **s3_bucket**: S3 bucket name for temporary files
 - **s3_key_prefix**: S3 key prefix for temporary files (string, default:"")
 - **options**: extra connection properties (hash, default: {})
-- **mode**: "replace" or "insert" (string, required)
+- **mode**: "insert", "insert_direct", "truncate_insert", or "replace". See below. (string, required)
 - **batch_size**: size of a single batch insert (integer, default: 16777216)
 - **default_timezone**: If input column type (embulk type) is timestamp, this plugin needs to format the timestamp into a SQL string. This default_timezone option is used to control the timezone. You can overwrite timezone for each columns using column_options option. (string, default: `UTC`)
 - **column_options**: advanced: a key-value pairs where key is a column name and value is options for the column.
   - **type**: type of a column when this plugin creates new tables (e.g. `VARCHAR(255)`, `INTEGER NOT NULL UNIQUE`). This used when this plugin creates intermediate tables (insert, truncate_insert and merge modes), when it creates the target table (insert_direct and replace modes), and when it creates nonexistent target table automatically. (string, default: depends on input column type. `BIGINT` if input column type is long, `BOOLEAN` if boolean, `DOUBLE PRECISION` if double, `CLOB` if string, `TIMESTAMP` if timestamp)
   - **value_type**: This plugin converts input column type (embulk type) into a database type to build a INSERT statement. This value_type option controls the type of the value in a INSERT statement. (string, default: depends on input column type. Available values options are: `byte`, `short`, `int`, `long`, `double`, `float`, `boolean`, `string`, `nstring`, `date`, `time`, `timestamp`, `decimal`, `null`, `pass`)
   - **timestamp_format**: If input column type (embulk type) is timestamp and value_type is `string` or `nstring`, this plugin needs to format the timestamp value into a string. This timestamp_format option is used to control the format of the timestamp. (string, default: `%Y-%m-%d %H:%M:%S.%6N`)
   - **timezone**: If input column type (embulk type) is timestamp, this plugin needs to format the timestamp value into a SQL string. In this cases, this timezone option is used to control the timezone. (string, value of default_timezone option is used by default)
 
+
 ### Modes
 
 * **insert**:
   * Behavior: This mode writes rows to some intermediate tables first. If all those tasks run correctly, runs `INSERT INTO <target_table> SELECT * FROM <intermediate_table_1> UNION ALL SELECT * FROM <intermediate_table_2> UNION ALL ...` query. If the target table doesn't exist, it is created automatically.
   * Transactional: Yes. This mode successfully writes all rows, or fails with writing zero rows.
@@ -96,5 +97,10 @@
 ### Build
 
 ```
 $ ./gradlew gem
 ```
+
+### Security
+This plugin requires AWS access credentials so that it may write temporary files to S3. There are two security options, Standard and Federated.
+To use Standard security, give **aws_key_id** and **secret_access_key**. To use Federated mode, also give the **iam_user_name** field.
+Federated mode really means temporary credentials, so that a man-in-the-middle attack will see AWS credentials that are only valid for 1 calendar day after the transaction.
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