In this article I discuss about the impact of batch size on the Elasticsearch (ES) indexing and update performance.
We tested with 5 parallel clients indexing documents. We used an index with a single shard without any replica. We kept on increasing the number of batch size to see the impact on performance. We tested with 100K documents. The size of each document was around 400KB.
We tested against Elasticsearch version 5.1.1.
We did our test with single ES node without any replica. We tested the same index with batch size of 5, 10 and 15 documents in a single batch file.
Our node was a blank node with no other indexes but had 6 unrelated shards on it.
To the surprise of development team and to my surprise as well, we got same performance with batch size of 5, 10 and 15 documents i.e. batch size had no impact on ES indexing and update performance.
It was taking around 55 mins to index and 60 mins to update 100K documents irrespective of the batch size.
During my research I could find no articles or blogs discussing about the impact of batch size on ES performance.