Hi, On Sun, Feb 21, 2010 at 1:42 PM, mos <mo...@fastmail.fm> wrote: > I am loading 35 million rows of data into an empty MyISAM table. This table > has 1 primary key (AutoInc) and 1 unique index and 2 non-unique indexes. > > Is it going to be any faster if I remove the indexes from the table before > loading the data, load the data, then do an Alter Table .. add index .... > for all of the indexes? > Or is it faster to just leave the indexes in place prior to loading the > data. > > I know if the table is empty and optimized, the non-unique indexes will be > built AFTER the data is loaded using Load Data Infile, but the unique and > primary indexes will be built as the data is being loaded and this is going > to slow down the import. > > There is no point doing a Disable Indexes on the table because this only > affects non-unique indexes and that is already taken care of since the table > is already empty and optimized. > > But if I remove the indexes from the empty table then load the data, then > execute the Alter Table Add Index ... for all 4 indexes at one time, isn't > the Alter Table going to create a copy of the table so it is just going to > reload the data all over again?
Yes. It is going to create a new table, copy the rows into it, and then delete the old one. > Is there any way to add a primary or unique index without copy the data all > over again? Create Index ... can't be used to create a primary index. Dirty hacks with .frm files and REPAIR TABLE have sometimes been known to help in cases like this. But it's not for the faint of heart. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
