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I have a Postgres table with more than 8 million rows. Given the following two ways of doing the same query, I get wildly different results.

$q .= '%'; ## query 1 my $sql = qq{ SELECT a, b, c FROM t WHERE Lower( a ) LIKE '$q' }; my $sth1 = $dbh->prepare($sql); $sth1->execute(); ## query 2 my $sth2 = $dbh->prepare(qq{ SELECT a, b, c FROM t WHERE Lower( a ) LIKE ? }); $sth2->execute($q);

query 2 is at least an order of magnitude slower than query 1... seems like it is not using the indexes, while query 1 is using the index.

Would love hear why.



when small people start casting long shadows, it is time to go to bed

In reply to same query, different execution, different performance by punkish

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