Also,... If I have offended you in anyway, I apologise. It was not my intention.
... John -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Aaron Stone Sent: Sunday, February 15, 2004 5:48 PM To: dbmail-dev@dbmail.org Subject: RE: [Dbmail-dev] some speed tests I think you can disagree with the statement without resenting it... My experience with MySQL has been phenominal speed *and* reliability, though at the expense of some pretty useful SQL features. If you've had trouble with it, you can easily get lots of help from this list and others just by asking. Bashing MySQL is fine, but please label it as such (possibly even being so kind as to qualify your bashes with experience or reason). Instead, you've gotten several people, myself included, into a thread arguing about all sorts of things really just because of an infusion of bad karma that nobody needs. Aaron "John Hansen" <[EMAIL PROTECTED]> said: > Personally, I recent the statement; 'Considering MySQL has proven > itself time and time again in terms of reliability, licencing > flexibility and performance, such statements are baseless regardless > of what arguments you make for which features'; based on experience, > mysql proved that it was not reliable, tho performance was top of the > line. > > In my opinion, if you're concerned with reliability, mysql should not > be an option. I had daily table corruptions, and thus one of my main > tasks was to run mysql repair jobs regularly, just to keep everything > running. > > Granted, postgresql has it's own problems, mainly with performance and > lack of a proper master / slave replication model, but that's a small > price to pay for reliability. > > Just my $0.02 worth. > > Regards, > > John Hansen > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > On Behalf Of Chris Nolan > Sent: Sunday, February 15, 2004 4:42 PM > To: dbmail-dev@dbmail.org > Subject: Re: [Dbmail-dev] some speed tests > > > Dear Aaron, > > My comments are also inline. :-) > > On Sun, 2004-02-15 at 12:27, Aaron Stone wrote: > > Comments inline... > > > > Chris Nolan <[EMAIL PROTECTED]> said: > > > > > Forgive the bluntness of the statement, but why is anyone even > > > worrying about transactions as they relate to MySQL??? > > > > Because we are currently structured to have a single set of > > mid-level > > database operations that are translated into specific low-level > > database function calls. The upside is that there isn't any database > > specific handling outside of these mid-level functions. The downside > > is that we need to make sure that function calls for certain features > > are consistent with analogous features in each database and that they > > carry with them enough information to make the appropriate low-level > > call. A good example is the last inserted id number. In MySQL, you > > only need the database connection identifier to get this. In > > PostgreSQL, yo need both the database connection and the table > > identifier. For DBMail to have a mid-level function that worked for > > both, we'd have to make sure that it took both arguments and used them > > > as needed for whichever database's low-level calls were being used. > > (Those were off the top of my head, so they may be incorrect, but > > they > > > do illustrate my point.) > > I've looked through the DBMail source code on a few occassions and > even released a dodgy tool to convert Cyrus mailboxes to DBMail a > while ago. The fact that I can use the calls present in the DB modules > and avoid having to write queries by hand for each different DB is an > excellent feature of the DBMail API. I have nothing negative to say > here at all. > > > > > > COMMIT in MySQL is passed to the table handler. In the case of > > > MyISAM tables, the handler disregards the statement. For InnoDB > > > and BDB > tables, > > > COMMIT acts as it does in PostgreSQL. > > > > So then we have THREE different configurations to consider, and need > > to be sure to design the mid-level interface appropriately. > > My statement was meant to say that the MyISAM table handler will just > disregard BEGIN and COMMIT statements, just as it parses but ignores > CHECK and FOREIGN KEY constraints in table creation, thus illustrating > that you wouldn't need to add a mysql-with-transactions directory to > the source tree. > > > > > > So various people in this thread implying that MySQL isn't really > > > a database need to do some more reading. > > > > If you're referring to my suggestion that the transaction functions > > are a noop for MySQL, then you're reading too deeply... I just > > didn't realize that InnoDB would handle transactions entirely > > normally. > > My apologies, I was not referring to you at all! Yourself and your > collegues have provided the world with a very, very funky mail > repository! > > I was referring to someone who said in the body of their message > posted to another branch of this thread "the supposed database mysql". > Considering MySQL has proven itself time and time again in terms of > reliability, licencing flexibility and performance, such statements > are baseless regardless of what arguments you make for which features. > For example, Visual FoxPro's backend is technically a database but > provides nothing in the way of a privilege system (you need write > access to record locking, so filesystem-level controls are no good > either). > > > > > > In summary, just encapsulate everything in transaction blocks and > > > the underlaying database will act appropriately. > > > > Right. That's what we're talking about. > > > > Is the entire point of your comment that we can safely use > > > > BEGIN; > > > > .. whatever dbmail does... > > > > COMMIT; > > > > regardless of whether or not we know if the host database actually > > supports these keywords? You could have just said that. > > I could have, but then I would have risked putting an end to the > thread. > :-) > > Please accept my apology - I never meant to offend yourself or anyone > else who contributes to DBMail. It seems my reading of the post I > mentioned above caused me to be a bit heavier than I should have been. > > But yes, you have perfectly summarised the point of my comment. > > > > > Regards, > > > > > > Chris > > > > > > Aaron Stone wrote: > > > > > > >I don't even know where to begin in terms of designing the > > > >delivery > > > > >chain around transactions. Could we do it as simply as adding > > > >functions... > > > > > > > > void db_begin_transaction(void); > > > > void db_flush_transaction(void); (or db_commit_...?) > > > > > > > >and then calling these functions before and after each major > > > >section of database code? For the delivery chain, we could do it > > > >inside of insert_message(). For dbmail-smtp, this basically means > > > >that the execution of the whole program is within one > > > >transaction. For dbmail-lmtpd, it means that each message is > > > >delivered within a transaction but the miscellaneous queries > > > >before the main message delivery chain are not transacted. For > > > >MySQL, these functions would > > > > >be noops. > > > > > > > >Thing that might work? > > > > > > > >Aaron > > > > > > > > > > > >Thomas Mueller <[EMAIL PROTECTED]> said: > > > > > > > > > > > > > > > >>Hi Aaron, > > > >> > > > >> > > > >> > > > >>>Do you have any way of narrowing this down to specific queries > > > >>>that are taking the longest and/or are being executed the most? > > > >>>That would identify which low-level database functions are > > > >>>being called, then we can just trace our way up the call chain > > > >>>to see who's misbehaving or acting on a flawed design. Also, if > > > >>>you could run similar tests against the latest 1.2, it would > > > >>>help to give a frame of reference, particularly for my delivery > > > >>>chain design. > > > >>> > > > >>> > > > >>That's simple: the main design flaw (actually that's no design > > > >>flaw I think, that's because the so called database MySQL > > > >>couldn't > > > > >>do transactions in the past) is that dbmail doesn't use > > > >>transaction. > > > >> > > > >>Because of that AutoCommit is used and whenever dbmail does > > > >>anySqlQuery Postgres does 'BEGIN; anySqlQuery; COMMIT;' - and > > > >>that > > > > >>is terribly slow. To ensure the Durability in ACID the database > > > >>has to fflush() every transaction to stable storage! That's why > > > >>there is only one solution: we have to use transaction. > > > >> > > > >>With transactions we could remove the integrity checks of > > > >>dbmail-maintenance too, because the database guarantees > > > >>integrity. > > > >> > > > >>Anyway, I did a trace of all SQL queries when a mail is copied > > > >>using IMAP. I got 35 SELECT, 4 INSERT, 5 UPDATE (44 db > > > >>operations to insert one mail?). > > > >> > > > >>When searching for the sequential scan I found something quite > > > >>interesting in the docs: the planer decides for every scan if a > > > >>seqScan is cheaper that an index scan, and does a seqScan even > > > >>if an index > > > >>exists: > > > >> > > > >>dbmail=> explain SELECT mailbox_idnr FROM mailboxes WHERE > owner_idnr=2; > > > >> QUERY PLAN > > > >>--------------------------------------------------------- > > > >> Seq Scan on mailboxes (cost=0.00..1.06 rows=3 width=8) > > > >> Filter: (owner_idnr = 2) > > > >>(2 rows) > > > >> > > > >>The table has an index on owner_idnr. > > > >> > > > >>So I should repeat this test with a database with several > > > >>hundred > > > >>to thousand user, several dozen mailboxes for each user and > > > >>several dozen mails in each mailbox to find out if all required > > > >>indizes are there. Did anyone write a script to create such a > > > >>database? > > > >> > > > >>But I found a strange query: > > > >>SELECT mailbox_idnr FROM mailboxes WHERE mailbox_idnr = '4' AND > > > >>owner_idnr = '2' mailbox_idnr is the primary key so that could > > > >>be optimized to: SELECT 4 > > > >>;-) > > > >> > > > >> > > > >>I don't have a 1.2 installation, I'm sorry. > > > >> > > > >> > > > >>-- > > > >>MfG Thomas Mueller - http://www.tmueller.com for pgp key > (95702B3B) > > > >>_______________________________________________ > > > >>Dbmail-dev mailing list > > > >>Dbmail-dev@dbmail.org > > > >>http://twister.fastxs.net/mailman/listinfo/dbmail-dev > > > >> > > > >> > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > Dbmail-dev mailing list > > > Dbmail-dev@dbmail.org > > > http://twister.fastxs.net/mailman/listinfo/dbmail-dev > > > > > > > > > _______________________________________________ > Dbmail-dev mailing list > Dbmail-dev@dbmail.org > http://twister.fastxs.net/mailman/listinfo/dbmail-dev > _______________________________________________ > Dbmail-dev mailing list > Dbmail-dev@dbmail.org > http://twister.fastxs.net/mailman/listinfo/dbmail-dev > -- _______________________________________________ Dbmail-dev mailing list Dbmail-dev@dbmail.org http://twister.fastxs.net/mailman/listinfo/dbmail-dev
