> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: Friday, September 23, 2005 10:25 > To: Jeff > Cc: mysql@lists.mysql.com > Subject: RE: MyISAM to InnoDB > > > "Jeff" <[EMAIL PROTECTED]> wrote on 09/23/2005 09:57:06 AM: > > > > -----Original Message----- > > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > > > Sent: Friday, September 23, 2005 09:40 > > > To: Jeff > > > Cc: mysql@lists.mysql.com > > > Subject: RE: MyISAM to InnoDB > > > > > > > > > Sorry to butt in but I wanted to make sure you didn't do > > > actually do what > > > you proposed to do, yet. More responses interspersed... > > > > > > > Nope nothing yet, I don't rush things when I'm unsure... ;o) > > > > > "Jeff" <[EMAIL PROTECTED]> wrote on 09/23/2005 08:32:57 AM: > > > > > > > > -----Original Message----- > > > > > From: Devananda [mailto:[EMAIL PROTECTED] > > > > > Sent: Thursday, September 22, 2005 19:03 > > > > > To: Jeff > > > > > Cc: mysql@lists.mysql.com > > > > > Subject: Re: MyISAM to InnoDB > > > > > > > > > > > > > > > Jeff wrote: > > > > > >>-----Original Message----- > > > > > >>From: Devananda [mailto:[EMAIL PROTECTED] > > > > > >>Sent: Thursday, September 22, 2005 16:14 > > > > > >>To: Jeff > > > > > >>Cc: mysql@lists.mysql.com > > > > > >>Subject: Re: MyISAM to InnoDB > > > > > >> > > > > > >> > > > > > >>Jeff wrote: > > > > > >> > > > > > >>>True, is there a way to tell a slave to not replicate > > > > > >> > > > > > >>certain queries > > > > > >> > > > > > >>>like alter table or would I need to get creative and stop > > > > > >> > > > > > >>replication > > > > > >> > > > > > >>>and all writes to the main database, then issue the > > > alter table > > > > > >>>statement, then restart replication with a set global > > > > > >>>slave_sql_skip_counter=1 so that it skips the > alter statemtent? > > > > > >> > > > > > >>There's a much easier way - issue the statement "SET > > > SQL_LOG_BIN = > > > > > >>0;" before issuing any ALTER TABLE statements. This > > > will cause all > > > > > >>statements for the duration of that session to not be > > > > > written to the > > > > > >>binlog. See > http://dev.mysql.com/doc/mysql/en/set-option.html > > > > > >>for more > > > > > >>information. > > > > > >> > > > > > > > > > > > > > > > > > > First off, thanks for the help to you and Bruce both! > > > > > > > > > > > You're quite welcome, Jeff :) > > > > > > > > > > > When you say here, "for the duration of that session" does > > > > > that mean > > > > > > that only queries I issue with my connection skip the > > > > > binlog? Or do > > > > > > all queries during that time skip the binlog. In other > > > > > words, when I > > > > > > SET SQL_LOG_BIN = 0; should I first stop all applications > > > > > writing to > > > > > > the database to prevent missing data in the slaves? > > > > > > > > > > > > > > > > > > > > > It only affects that connection. Bruce wrote a response > > > at about the > > > > > same time I did; his covers this topic as well. SQL_LOG_BIN > > > > > is a session > > > > > variable, meaning that it only affects the current session > > > > > (connection). > > > > > So, any applications running at the same time will not be > > > > > affected by a > > > > > change to this variable, and if you close your client and > > > > > reconnect, you > > > > > will have to set the variable again. As Bruce suggested, > > > it's best to > > > > > set it only when you need it and unset it immediately > > > > > afterwards (as a > > > > > precaution against operator error, not because it affects > > > the server). > > > > > > > > > > I do want to point out that while the commands you > issue (after > > > > > setting SQL_LOG_BIN to 0) will not be written to the binlog > > > > > (thus will not run > > > > > on any slave reading from this server), they may affect > > > other running > > > > > processes on the server. If, for example, you run an > > > ALTER TABLE on a > > > > > table currently in MyISAM format, the table will be > > > locked and all > > > > > processes running on that server that read from / write > > > to that table > > > > > will wait until that ALTER finishes. Setting SQL_LOG_BIN > > > to 0 doesn't > > > > > affect this in any way - it _only_ affects whether statements > > > > > from that > > > > > specific session are recorded in the binary log. > > > > > > > > > > > > > Thanks, that answer my question regarding SQL_LOG_BIN varialbe. > > > > > > > > > Side question - you've stated that you are planning > to migrate > > > > > to InnoDB, but you haven't said anything to the list about > > > how much data > > > > > you have. Just be aware that it can take a lot of time > > > and disk space > > > > > for MySQL to transfer all your data from one format to > > > the other (of > > > > > course depending on how much data you have) and if anything > > > > > goes wrong > > > > > during that time, the results will probably not be what you > > > > > expect, or > > > > > want. I would advise you to at least investigate an alternate > > > > > approach > > > > > if you have a lot of data - take the server you are going to > > > > > migrate out > > > > > of the 'cluster' and make sure it is not processing > any data / no > > > > > clients are connecting to it; dump all your data to > text files, > > > > > preferably separating your data definition statements (ie > > > > > CREATE TABLE > > > > > statements) from your actual data; modify the CREATE > > > statements to > > > > > specify the InnoDB engine; lastly load all the data from the > > > > > text files > > > > > into MySQL, and bring this server back into the 'cluster'. > > > > > > > > > > If you don't have a _lot_ of data, then it may not be > > > worth all that > > > > > work. Of course, "a lot" is subjective; I'd say, based purely > > > > > on my own > > > > > experiences with this, that if you are going to migrate 1G of > > > > > data, you > > > > > will probably be better off exporting / alter the > text files / > > > > > importing. If you have 10's or 100's of G of data, I > > > would strongly > > > > > recommend that you do it this way. And regardless of how much > > > > > data you > > > > > have, it is, IMHO, safer to export/import. > > > > > > > > Well like you say a "lot" of data is subjective. Our > situation is > > > > this; we currently have a DB01 up and running and in > production. > > > > We're moving to a more redundant data center and have > purchased new > > > > hardware to migrate the database to (new server will be > DB03). The > > > > speed of the database directly affects our profitability. > > > This being > > > > the case I've suggested to our developers that we take the > > > opertunity > > > > to migrate the tables involved in heavy write actions from > > > MyISAM to > > > > InnoDB on the new DB03 server before we put it into production. > > > > Currently I have DB03 up and running (all MyISAM) at the new > > > > datacenter and doing circular replication with DB01 over > > > VPN. No apps > > > > or users are currently writing or even reading from DB03 yet. > > > > > > > > Even if we migrate selected tables in DB03 to InnoDB I'd > > > like to keep > > > > the downstream (one way) replicated servers using > MyISAM as most > > > > of > > > > the activity on those is read only. > > > > > > > > As for the size of the tables in question, they are currently; > > > > > > > > 2gig Table1.MYD > > > > 200M Table1.MYI > > > > 14k Table1.frm > > > > > > > > 422k Table2.MYD > > > > 114k Table2.MYI > > > > 11k Table2.frm > > > > > > > > Our lead developer here has made the statement, "why not > > > just convert > > > > the entire db to InnoDB for the sake of simplicity and ease?" > > > > > > The tables in the mysql database cannot be InnoDB. InnoDB > > > does not yet > > > support fulltext searching. Other than those two major > > > restrictions, a > > > full InnoDb setup is possible. > > > > > > > Shawn, > > > > What do you mean by "The tables in the mysql database cannot be > > InnoDB?" You kinda lost me there... > > Yes, I meant exactly that. Within each MySQL server is a "special" > database called `mysql`. That is the database that contains > the tables of > all of the user login and permission information for the server (and > several other important bits of system-wide metadata). None > of the tables > in that database can be converted to InnoDB. That would be a > "bad thing". >
Yep, I knew that ;o) > The tables of every OTHER database on the server (including > yours) are > eligible for InnoDB conversion so long as you do not want to > use fulltext > searching. If you need a FT index, you have to keep that > table as MyISAM > for now (they are working on enabling FT indexes in InnoDB > but there is no > release date yet) > Is that the only diff (other than the "select count(*)" thing) between InnoDB and MyISAM? Aren't select statements faster from MyISAM tables than from InnoDB's? There's also been a statement from our lead developer that having a db with mixed tables (some InnoDB and some MyISAM) will make life harder on them because it makes development of application more difficult. I do quite a bit of php and some perl programming that interacts with MySQL and I can't think of any major problems created by a mixed engine type environment. Sure "select count(*) from table" won't be as fast in an InnoDB table and obviously full text indexes won't be there but other than that, I don't see this as causing any "difficulties" for a programmer. I'm also under the belief that it's not the world's job to make the programmer's life easier, it's the programmers job to make the world's life easier. Does anyone have any input on that? <<<<<Truncated thread, getting too big>>>>>> -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
