How do I find the largest value in a column in postgres sql?

Extraction of max value alongside related data

Fetching the highest value via a subquery

SELECT * FROM table WHERE column = (SELECT MAX(column) FROM table);
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This command fetches the complete record corresponding to the highest value. Do keep an eye on the performance as you scale because subqueries can add complexity.

Efficient fetching with ORDER BY and LIMIT

SELECT * FROM table ORDER BY column DESC LIMIT 1;
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Better performance is observed with ORDER BY and LIMIT as this stops scanning once the highest value is fetched instead of going through the whole table.

Steering clear of null values

SELECT MAX(column) FROM table WHERE column IS NOT NULL;
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This command ensures that NULLs have been considered during the process of discovering the numeric maximum.

Aggregate handling with specific groups

SELECT group_column, MAX(column) FROM table GROUP BY group_column;
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For the prompt discovery of the maximum value across distinct categories within your table, GROUP BY comes in handy.

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Tackling repeats and nulls

Avoid repetition with DISTINCT:

SELECT DISTINCT ON (column) * FROM table ORDER BY column DESC, tiebreaker_column;
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Place NULLs at the end:

SELECT * FROM table ORDER BY column DESC NULLS LAST;
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Grouping for ease of perception

SELECT category, MAX(value) FROM table GROUP BY category;
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Optimise, because who doesn't like performing well

Index to skip full-table scans

CREATE INDEX IF NOT EXISTS idx_column ON table(column);
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Building an index on the column used in ORDER BY ensures faster fetches.

Aggregate functions and array compositions

ARRAY_AGG() with ORDER BY gives an ordered list of values. Fetch the first from this list:

SELECT ARRAY_AGG(column ORDER BY column DESC)[1] FROM table;
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The right tools for the job

For bigger datasets, ORDER BY and LIMIT perform better than MAX() within a subquery for large datasets. Use ARRAY_AGG() only when it's absolutely necessary.