Merge Sales Data from 2022 and 2023 Partitions Using UNION

Use UNION to Query Specific Partitions

Write a PostgreSQL query to fetch data from Sales_2022 and Sales_2023 partitions using UNION.

Solution:

-- Combine data from Sales_2022 and Sales_2023 partitions using UNION ALL
SELECT * FROM Sales_2022  -- Select all columns from the Sales_2022 partition
UNION ALL                -- Combine the results from both partitions without eliminating duplicates
SELECT * FROM Sales_2023; -- Select all columns from the Sales_2023 partition

Explanation:

• Purpose of the Query:
• Manually selects and merges data from specific partitions.
• Key Components:
• UNION ALL: Combines multiple partition results without duplicate removal.
• Real-World Application:
• Useful for reports requiring explicit partition selection.

Notes:

• UNION (instead of UNION ALL) removes duplicates but is slower.

For more Practice: Solve these Related Problems:

• Write a PostgreSQL query to combine data from three specified partitions using UNION ALL to maintain all duplicate rows.
• Write a PostgreSQL query to merge data from specific partitions using UNION to remove duplicate rows automatically.
• Write a PostgreSQL query to combine partitioned data where each partition query includes a different filtering condition.
• Write a PostgreSQL query to retrieve and union data from specific partitions and then sort the combined result set by a common column.

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Previous PostgreSQL Exercise: Query Data using Index Scan on Partitioned Table.