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Asked: 2026-06-15T02:58:12+00:00

I wonder if SELECT * FROM foo will execute faster than SELECT * FROM

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I wonder if SELECT * FROM foo will execute faster than SELECT * FROM foo WHERE name LIKE '%' assuming name is NOT NULL?

Any references to documentation?

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  1. Editorial Team

    Both of your queries will scan the entire table. Whether or not name is NOT NULL is only important in extremely rare circumstances where there is (1) an index on name and (2) it is very, very sparse. Only then will PostgreSQL consider looking up the records from the name index.

    In all other situations, this SQLFiddle shows that the LIKE version adds a filter, which must be checked. PostgreSQL has no optimization to remove LIKE '%' against a not-null varchar column, as much as it seems sensible.

    Table SELECT * all rows

    QUERY PLAN
Seq Scan on foo (cost=0.00..15.00 rows=1000 width=62)

    Table SELECT * all rows with `LIKE ‘%’`

    QUERY PLAN
Seq Scan on foo (cost=0.00..17.50 rows=1000 width=62)
Filter: ((name)::text ~~ '%'::text)
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