Boost - delete operation in boost_process_poller_output

[tuux1598g]

I'm currently deploying a rather large installation on minimal hardware and have been making a number of changes to achieve the desired results. Whilst I understand the merits of the delete operation currently in use within boost, using a temporary rcaston_[random] table in memory, over the older method whereby each record was deleted individually by iterating through the $results array, I do see a simpler way that this might be done.

Whilst this may not be as effective a delete statement (it could take marginally longer to process), it does save precious memory - which means a lot when using boost in very large systems...

Basically we could use the $sql_where variable from the initial select statement, which is still available at this point, to selectively delete from the poller_output_boost table. This does away with the need of creating a temporary table and inserting all of the data into that table, freeing up that little more memory for the boost data itself:

Code: Select all

    /* remove the entries from the table */
    if ($ok_to_delete) {
        if (!$single_local_data_id) {
            /* delete the records in bulk */
            db_execute("DELETE FROM `poller_output_boost` $sql_where");
        } else {
            db_execute("DELETE FROM `poller_output_boost`
                WHERE local_data_id=$orig_local_data_id");
        }
    }

This should only delete those records that have been committed to RRD files within this boost_process_poller_output - thus effectively achieving the same result as deleting anything existing in $results (since $results is simply the result of a SELECT statement using this same $sql_where).

Any thoughts or comments appreciated.

[Edit]
Performance-wise this doesn't seem to affect too much in testing:

Using a direct DELETE (preserving memory):
02/17/2009 04:21:31 PM - SYSTEM BOOST STATS: Time:1807.6645 RRDUpdates:2808330

Using rcaston temporary table:
02/17/2009 02:16:14 PM - SYSTEM BOOST STATS: Time:1808.7236 RRDUpdates:2804983

[TheWitness]

Make sure that you use a memory table. If your table is memory, the delete's are almost instantaneous. Also, make sure that the "output" column is not indexed on the poller_output_boost. Otherwise, I would say not enough disk I/O.

TheWitness