Hi Stephen, [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] wrote:
> > Ok... on the coat-tails of the recent discusison of 'update > statistics' doing a lock... has further consideration been > given to changing loadercli > so that a extract (SELECT) does not lock the tables? Some > option to set the isolation level? > Yes, it will be made an option for the user to set the isolation level for the Loader. The default level will be 3 though. But this will not have any effect on working with format PAGES. This means you can make a snapshot of your database in format RECORDS for instance. But as soon as you work with PAGES the Loader will lock the table it is processing. Otherwise we cannot assure the integrity of the records of a single table: Suppose you want to extract the data of table TAB1 in format PAGES. This table may have 10 pages. The data is ordered in user defined primary key order. Lets say for simplicity reasons the primary key is an int column. Records are so long that every page may store 10 records. At time T1 the Loader has extracted pages 1 to 4. Page 4 has the records with the following key order: 15,16,17,18,19,20,21,22,23,25. At that same time T1 another user inserts the record with key 24 into that table. This causes the kernel to reorganize page 4 to put this record in and move record with key 25 to page 5. Now the Loader gets the other 5 pages. Page 5 will then contain the record with key 25. But page 4 will have this record, too. The record with key 24 will not be in the data at all. Thus you have not only not committed data but wrong data. If you load this data you'll get the error 300 - Integrity violation. This is of course only an example. It becomes certainly more complicated on loading data in format PAGES into a table that is not exclusively locked for this process. Any objections on this? > Do you need someone to test the revised loadercli :) ? > I will certainly get back to you ;-) Regards, Steffen -- Steffen Schildberg SAP DB Team SAP Labs Berlin -- MaxDB Discussion Mailing List For list archives: http://lists.mysql.com/maxdb To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
