update doc

Signed-off-by: Peng Huo <[email protected]>

docs/index.md

@@ -506,9 +506,9 @@ In the index mapping, the `_meta` and `properties`field stores meta and schema i
 - `spark.datasource.flint.customAWSCredentialsProvider`: default is empty.   
 - `spark.datasource.flint.write.id_name`: no default value.
 - `spark.datasource.flint.ignore.id_column` : default value is true.
-- `spark.datasource.flint.write.batch_size`: default value is 1000.
-- `spark.datasource.flint.write.refresh_policy`: default value is wait_for. valid values [NONE
-  (false), IMMEDIATE(true), WAIT_UNTIL(wait_for)]
+- `spark.datasource.flint.write.batch_size`: "The number of documents written to Flint in a single batch request. Default value is Integer.MAX_VALUE.
+- `spark.datasource.flint.write.batch_bytes`: The approximately amount of data in bytes written to Flint in a single batch request. The actual data write to OpenSearch may more than it. Default value is 4mb. The writing process checks after each document whether the total number of documents (docCount) has reached batch_size or the buffer size has surpassed batch_bytes. If either condition is met, the current batch is flushed and the document count resets to zero.
+- `spark.datasource.flint.write.refresh_policy`: default value is false. valid values [NONE(false), IMMEDIATE(true), WAIT_UNTIL(wait_for)]
 - `spark.datasource.flint.read.scroll_size`: default value is 100.
 - `spark.datasource.flint.read.scroll_duration`: default value is 5 minutes. scroll context keep alive duration.
 - `spark.datasource.flint.retry.max_retries`: max retries on failed HTTP request. default value is 3. Use 0 to disable retry.