Re:

Denis Gasparin <denis@edinet.it> writes:

> Hi to all!
>     I have created a table using the CREATE TABLE new_table
> (col1,col2,col3) AS SELECT col1,col2,col3 FROM org_table.
>
>     I create an index on this table using the statement:
> CREATE UNIQUE INDEX table_idx ON new_table (col1).
>     Then i do a select as this:
> SELECT * FROM new_table WHERE col1 = 'value'.
>
>     The problem is that when i do an explain this is the query plan:
>
> Seq Scan on new_table  (cost=0.00..1116.38 rows=500 width=44)>
>
> Can anyone explain me why it doesn't use the index I have created?

How populated is the table?  If it's small, or if you haven't done
VACUUM ANALYZE, the statistics may end up preferring a sequential
scan.

-Doug
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