Hi!
>>>>> "Lopez" == Lopez David <E-r9374c <[EMAIL PROTECTED]>> writes:
<cut>
Lopez> If no row is returned, then the following happens:
Lopez> 1) lock table ...
Lopez> 2) select ...
Lopez> 3) if no row is returned,
Lopez> 4) insert ...
Lopez> 5) use LAST_INSERT_ID() to get the value of the key
Lopez> 6) else get the key-value pair
Lopez> 7) unlock table
Lopez> 8) put key-value pair in RAM hash
Lopez> 9) insert row in main table (using new key-value pair)
Why not instead do as follows:
(This assumes you have an unique index on the thing you are selecting
on)
select ...
if no row is returned,
insert ...
if insert works without a duplicate key error:
use LAST_INSERT_ID() to get the value of the key
else
select to find the row some other thread inserted
put key-value pair in RAM hash
insert row in main table (using new key-value pair)
<cut>
Lopez> Hope that clears the insertion process on the hash tables. I'm
Lopez> glad that if a connection is lost in steps 2-6, mysql would
Lopez> automatically unlock the tables. That will satisfy the db
Lopez> specification nicely. The architecture for our db came
Lopez> from the optimization chapter in the manual. Thanks!
If the connection dies on the client side, the server will notice it
as once. The thing you will not notice if a client goes into an
endless loop and will not release the connection to the MySQL server.
I will add to our TODO to add to SHOW OPEN TABLES a list of threads
that has locks on the table (or maybe a SHOW LOCKS command) to better
cover this case in the future.
Regards,
Monty
--
For technical support contracts, goto https://order.mysql.com/
__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Mr. Michael Widenius <[EMAIL PROTECTED]>
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, CTO
/_/ /_/\_, /___/\___\_\___/ Helsinki, Finland
<___/ www.mysql.com
---------------------------------------------------------------------
Before posting, please check:
http://www.mysql.com/manual.php (the manual)
http://lists.mysql.com/ (the list archive)
To request this thread, e-mail <[EMAIL PROTECTED]>
To unsubscribe, e-mail <[EMAIL PROTECTED]>
Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
