Stephen,
Here is what you need to do. I have these commands in a RMD file. I then RBEDIT
explain.dat
To the best of my knowledge there is virtually no information on how to
interpret the various parts of data that appears in the EXPLAIN.DAT file. It
does however break down how it processes the various tables in the command.
"SET DEBUG ON
SET VAR MICRORIM_EXPLAIN = 47
RETURN
*(MICRORIM_EXPLAIN
This variable shows the decision the optimizer made when executing a
particular command. The optimizer results are placed in the file
EXPLAIN.DAT. The DEBUG command must be on to use microrim_ explain.
The available options for microrim_ explain are
1 - output the table order.
2 - force optimization of joins over five tables. This option is
ignored if microrim_fullopt is set.
4 - output the command file name and next byte offset.
8 - output the current date and time.
32 - display the sort technique used.
To use multiple options, add the option numbers together and set the
variable to the result. For example:
SET VAR microrim_explain = (1 + 4 + 8)
SET VAR microrim_explain = 13
)
Jim Bentley
American Celiac Society
[email protected]
tel: 1-504-737-3293
________________________________
From: Stephen Markson <[email protected]>
To: RBASE-L Mailing List <[email protected]>
Sent: Wednesday, May 27, 2009 7:36:53 PM
Subject: [RBASE-L] - Query Optimization
Is there any info on how the RBase engine parses queries to use indexes
effectively? Are there are any techniques that can force the engine to use a
particular index? I seem to recall that in the old days there was a system
variable, MICRORIM_EXPLAIN_PLAN or something like that would show how R:Base
had parsed the query.
Regards,
Stephen Markson
ForenSys The Forensic Systems Group
www.ForenSys.ca<http://www.forensys.ca/>
416 512 6950
