Michael Monashev wrote:
> How to select 5 random rows from big table with WHERE clause?
Maybe something like this:
SELECT col1, col2 FROM table WHERE col3=123 AND (id_col=RAND() OR
id_col=RAND() OR id_col=RAND() OR id_col=RAND() OR id_col=RAND())
the problem is that there is the (low) probability of 2 equal id_cols
get randomly generated, return only 4 different rows
> This query very slow on 1 mln rows:
> SELECT col1, col2 FROM table WHERE col3=123 ORDER BY RAND() LIMIT 5
but that problem can also occur in your slow query
Note: I have already sent this privatly forgeting to sen do the list
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