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Filesort Probes

The filesort probes are triggered whenever a filesort operation is applied to a table. For morę

information on filesort and the conditions under which it occurs, see

Section 8.13.13, “ORDER BY

Optimization".

filesort-start(database, table) filesort-done(status, rows)

•    filesort-start: Triggered when the filesort operation starts on a table. The two arguments to the

probe, iatabase and table, will identify the table being sorted.

•    filesort-done: Triggered when the filesort operation completes. Two arguments are supplied, the

status (0 for success, 1 for failure), and the number of rows sorted during the filesort process.

An example of this is in the following script, which tracks the duration of the filesort process in addition to the duration of the main query:

#!/usr/sbin/dtrace -s #pragma D option quiet dtrace:::BEGIN {

printf("%-2s %-10s %-10s %9s %18s %-s \n",

"St", "Who", "DB", "ConnID", "Dur microsec", "Query");

}

mysql*:::query-start {

self->query = copyinstr(argO);

self->who = strjoin(copyinstr(arg3),strjoin("0",copyinstr(arg4)));