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tablefunc: Reject negative number of tuples passed to normal_rand()

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The function converted the first argument i.e. the number of tuples to
return into an unsigned integer which turns out to be huge number when
a negative value is passed.  This causes the function to take much
longer time to execute.  Instead, reject a negative value.

(If someone really wants to generate many more result rows, they
should consider adding a bigint or numeric variant.)

While at it, improve SQL test to test the number of tuples returned by
this function.

Author: Ashutosh Bapat <ashutosh.bapat@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/CAG-ACPW3PUUmSnM6cLa9Rw4BEC5cEMKjX8Gogc8gvQcT3cYA1A@mail.gmail.com
This commit is contained in:
Peter Eisentraut
2020-11-25 15:30:18 +01:00
parent 2fbd786c34
commit f73999262e
3 changed files with 18 additions and 6 deletions
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4
contrib/tablefunc/sql/tablefunc.sql
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@ -4,7 +4,9 @@ CREATE EXTENSION tablefunc;
-- normal_rand()
-- no easy way to do this for regression testing
--
SELECT avg(normal_rand)::int FROM normal_rand(100, 250, 0.2);
SELECT avg(normal_rand)::int, count(*) FROM normal_rand(100, 250, 0.2);
-- negative number of tuples
SELECT avg(normal_rand)::int, count(*) FROM normal_rand(-1, 250, 0.2);
--
-- crosstab()