MySQL Bugs: #31750: mysql-test-run slow to evaluate 'if' statements

Bug #31750	mysql-test-run slow to evaluate 'if' statements
Submitted:	22 Oct 2007 13:08	Modified:	22 Oct 2007 16:01
Reporter:	Patrick Crews	Email Updates:
Status:	Not a Bug	Impact on me:	None
Category:	Tests	Severity:	S3 (Non-critical)
Version:	5.0, 5.1	OS:	MacOS (10.4.10)
Assigned to:	Magnus Blåudd	CPU Architecture:	Any
Tags:	mysql-test-run

Description:
Found that evaluation of an 'if' statement is very expensive (time-wise) for mysql-test-run.

Results are as follows:

Average run time w/ IF statement:  766.47ms
Average run time w/o IF statement:  132.7 ms

This is for a single IF statement in the .test file, and seems like significant overhead to be incurred.  Only tested on Mac OSX, but suspect this will be the same for other OS.

Writing defect per Magnus' request for tracking purposes.

How to repeat:
Use attached files:

Can put attached files into the mysql-test/suites directory and run from there.

File wIF.test uses IF statement.  Other .test file w/o.  

Files are modified from key.test of the test suite.

Suggested fix:
Look into how mysql-test-run processes 'if' to see if performance can be improved.

set of files for mysql-test/suite to demonstrate.

Attachment: slow_if.zip (application/zip, text), 29.61 KiB.

Revision:

IF processes slowly w/ 4 IF's (one that evaluates to TRUE and 3 to FALSE).

When single IF, performance is comparable to w/o IF time.