Insert Into Multiple Partitions with one Query

ChineduLB — Sun, 19 May 2024 11:29:38 GMT

We have 3 regional intake tables partitioned by date and a client-view table partioned by date and region.

is there a way to populate the client-view table with data from the 3 source tables in one atomic transaction instead of three separate insert commands:

currently we do multiple insert statement like:

insert into client_view_tbl ( col, col2, col3... )partition(cobdate='20240915', region='region1') select col2, col2, col3... from region1_table where cobdate='20240915'; insert into client_view_tbl ( col, col2, col3... )partition(cobdate='20240915', region='region2') select col2, col2, col3... from region2_table where cobdate='20240915'; insert into client_view_tbl ( col, col2, col3... )partition(cobdate='20240915', region='region3') select col2, col2, col3... from region3_table where cobdate='20240915';

Re: Insert Into Multiple Partitions with one Query

RAGHUY — Mon, 20 May 2024 06:32:58 GMT

@ChineduLB Apache Impala does not enable multi-statement transactions, so you cannot perform an atomic transaction that spans many INSERT statements directly. You can achieve a similar effect by combining the INSERT INTO commands into a single INSERT INTO... SELECT statement that includes a UNION ALL. This method assures that all partitions are loaded within the same query run.

you can consolidate your insert statements into one query

INSERT INTO client_view_tbl PARTITION (cobdate, region)
SELECT col, col2, col3, '20240915' AS cobdate, 'region1' AS region
FROM region1_table
WHERE cobdate = '20240915'
UNION ALL
SELECT col, col2, col3, '20240915' AS cobdate, 'region2' AS region
FROM region2_table
WHERE cobdate = '20240915'
UNION ALL
SELECT col, col2, col3, '20240915' AS cobdate, 'region3' AS region
FROM region3_table
WHERE cobdate = '20240915';

Single Query Execution: This approach consolidates multiple INSERT statements into one, which can improve performance and ensure consistency within the query execution context.

Simplified Management: Managing a single query is easier than handling multiple INSERT statements.

Ensure that your source tables (region1_table, region2_table, region3_table) and the client_view_tbl table have compatible schemas, especially regarding the columns being selected and inserted.

Be mindful of the performance implications when dealing with large datasets. Test the combined query to ensure it performs well under your data volume.

By using this combined INSERT INTO ... SELECT ... UNION ALL approach, you can effectively populate multiple partitions of the client_view_tbl table in one query.

"please accept it as a solution if it it helps"

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Insert Into Multiple Partitions with one Query

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