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https://issues.apache.org/jira/browse/HUDI-2369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17406147#comment-17406147
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ASF GitHub Bot commented on HUDI-2369:
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pratyakshsharma commented on a change in pull request #3549:
URL: https://github.com/apache/hudi/pull/3549#discussion_r697831983
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File path: website/blog/2021-08-27-bulk-insert-sort-modes.md
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@@ -0,0 +1,88 @@
+---
+title: "Bulk Insert Sort Modes with Apache Hudi"
+excerpt: "Different sort modes available with BulkInsert"
+author: shivnarayan
+category: blog
+---
+
+Apache Hudi supports a `bulk_insert` operation in addition to "insert" and
"upsert" to ingest data into a hudi table.
+There are different sort modes that one could employ while using bulk_insert.
This blog will talk about
+different sort modes available out of the box, and how each compares with
others.
+<!--truncate-->
+
+Apache Hudi supports “bulk_insert” to assist in initial loading to data to a
hudi table. This is expected
+to be faster when compared to using “insert” or “upsert” operations. Bulk
insert differs from insert in two
+aspects. Existing records are never looked up with bulk_insert, and some
writer side optimizations like
+small files are not managed with bulk_insert.
+
+Bulk insert offers 3 different sort modes to cater to different needs of
users, based on the following principles.
+
+- Sorting will give us good compression and upsert performance, if data is
laid out well. Especially if your record keys
+ have some sort of ordering (timestamp, etc) characteristics, sorting will
assist in trimming down a lot of files
+ during upsert. If data is sorted by frequently queried columns, queries will
leverage parquet predicate pushdown
+ to trim down the data to ensure lower latency as well.
+
+- Additionally, parquet writing is quite a memory intensive operation. When
writing large volumes of data into a table
+ that is also partitioned into 1000s of partitions, without sorting of any
kind, the writer may have to keep 1000s of
+ parquet writers open simultaneously incurring unsustainable memory pressure
and eventually leading to crashes.
+
+- It's also desirable to start with the smallest amount of files possible when
bulk importing data, as to avoid
+ metadata overhead later on for writers and queries.
+
+3 Sort modes supported out of the box are: `PARTITION_SORT`,`GLOBAL_SORT` and
`NONE`.
+
+## Configurations
+One can set the config
[“hoodie.bulkinsert.sort.mode”](https://hudi.apache.org/docs/configurations.html#withBulkInsertSortMode)
to either
+of the three values, namely NONE, GLOBAL_SORT and PARTITION_SORT. Default sort
mode is `GLOBAL_SORT`.
+
+## Different Sort Modes
+
+### Global Sort
+
+As the name suggests, Hudi sorts the records globally across the input
partitions, which maximizes the number of files
+pruned using key ranges, during index lookups for subsequent upserts. This is
because each file has non-overlapping
+min, max values for keys, which really helps, when the key has some ordering
characteristics such as a time based prefix.
+Given we are writing to a single parquet file on a single output partition
path on storage at any given time, this mode
+greatly helps control memory pressure during large partitioned writes. Also
due to global sorting, each small table
+partition path will be written from atmost two spark partition and thus
contain just 2 files.
Review comment:
I guess adding some visual representation might help here.
Also can you explain how a partition path will be written from at most 2
spark partitions? It depends on the file size and the amount of data present in
a particular spark partition right?
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> Blog on bulk insert sort modes
> ------------------------------
>
> Key: HUDI-2369
> URL: https://issues.apache.org/jira/browse/HUDI-2369
> Project: Apache Hudi
> Issue Type: Improvement
> Components: Docs
> Reporter: sivabalan narayanan
> Priority: Major
> Labels: pull-request-available
> Fix For: 0.10.0
>
>
> Blog on bulk insert sort modes
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