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https://issues.apache.org/jira/browse/HUDI-4882?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jian Feng updated HUDI-4882:
----------------------------
Description:
Let's give you some background about why we need multiple ordering fields
For example, we have 2 sources, one target table
* source1's fields: *id, ts, name*
* source2's fields:*id, ts, price*
* target tables's fields:*id,ts,name, price*
ts is the precombine field;
in the 1st batch, we got two records from both sources:
Source1:
||id||ts||name||
|1|1|name_1|
Source 2:
||id||ts||price||
|1|3|price_3|
so the records in the target table should be:
||id||ts||name||price||
|1|3|name_1|price_3|
let's say in the 2nd batch, we got one event from the source1:
Source1:
||id||ts||name||
|1|2|name_2|
name_2 won't be updated to target table, since its ts value is smaller than ts
value in the target table.
This feature will allow users to perform partial updates across
sub-tables/sources by determining the state of a set of columns in a row based
on an ordering/precombine column.
As such, a table can have MULTIPLE ordering fields.
This use case is suitable for wide Hudi tables that are created from smaller
sub-tables, where each of its sub-tables has its own precombine column, and
where its records could be upserted out of order.
!image-2022-09-20-22-46-52-907.png!
was:
Let's give you some background about why we need multiple ordering fields
For example, we have 2 sources, one target table
* source1's fields: *id, ts, name*
* source2's fields:* id, ts, price*
* target tables's fields:* id,ts,name, price*
ts is the precombine field;
in the 1st batch, we got two records from both sources:
Source1:
||id||ts||name||
|1|1|name_1|
Source 2:
||id||ts||price||
|1|3|price_3|
so the records in the target table should be:
||id||ts||name||price||
|1|3|name_1|price_3|
let's say in the 2nd batch, we got one event from the source1:
Source1:
||id||ts||name||
|1|2|name_2|
name_2 won't be updated to target table, since its ts value is smaller than ts
value in the target table.
This feature will allow users to perform partial updates across
sub-tables/sources by determining the state of a set of columns in a row based
on an ordering/precombine column.
As such, a table can have MULTIPLE ordering fields.
This use case is suitable for wide Hudi tables that are created from smaller
sub-tables, where each of its sub-tables has its own precombine column, and
where its records could be upserted out of order.
!image-2022-09-20-22-46-52-907.png!
> Multiple ordering fields for partial update to handle out-of-order events
> -------------------------------------------------------------------------
>
> Key: HUDI-4882
> URL: https://issues.apache.org/jira/browse/HUDI-4882
> Project: Apache Hudi
> Issue Type: New Feature
> Reporter: Jian Feng
> Priority: Major
> Attachments: image-2022-09-20-22-42-19-445.png,
> image-2022-09-20-22-46-52-907.png
>
>
> Let's give you some background about why we need multiple ordering fields
> For example, we have 2 sources, one target table
> * source1's fields: *id, ts, name*
> * source2's fields:*id, ts, price*
> * target tables's fields:*id,ts,name, price*
> ts is the precombine field;
> in the 1st batch, we got two records from both sources:
> Source1:
>
> ||id||ts||name||
> |1|1|name_1|
> Source 2:
>
> ||id||ts||price||
> |1|3|price_3|
> so the records in the target table should be:
> ||id||ts||name||price||
> |1|3|name_1|price_3|
>
> let's say in the 2nd batch, we got one event from the source1:
> Source1:
> ||id||ts||name||
> |1|2|name_2|
> name_2 won't be updated to target table, since its ts value is smaller than
> ts value in the target table.
> This feature will allow users to perform partial updates across
> sub-tables/sources by determining the state of a set of columns in a row
> based on an ordering/precombine column.
> As such, a table can have MULTIPLE ordering fields.
> This use case is suitable for wide Hudi tables that are created from smaller
> sub-tables, where each of its sub-tables has its own precombine column, and
> where its records could be upserted out of order.
> !image-2022-09-20-22-46-52-907.png!
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