A Leaf Block is an index block. In a B*tree index, index blocks are either branch blocks (the "top" blocks within the B*tree index), or leaf blocks (the "lower" level index blocks). Branch blocks hold index data that point to lower level index blocks. Leaf blocks hold every indexed data value and a corresponding ROWID used to locate the actual row of data.
See: http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96524/c11schem .htm#3353 A tables High Water mark is a mark that is set against a table, pointing to the highest amount of data that has been inserted in to that table at any one time. Say you inserted 1,000,000 rows in to the table, then delete 200,000, the HWM would point at 1,000,000 rows. It is used as a boundary for space management, and can also be used by the optimiser to make poor choices under certain circumstances.. ;) You can't release space below the high water mark, even if there is no data below that high water mark (an empty table). The only way to do this is via the TRUNCATE command. See: http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96521/schema.h tm#6870 HTH Mark =================================================== Mark Leith | T: +44 (0)1905 330 281 Sales & Marketing | F: +44 (0)870 127 5283 Cool Tools UK Ltd | E: [EMAIL PROTECTED] =================================================== http://www.cool-tools.co.uk Maximising throughput & performance -----Original Message----- [EMAIL PROTECTED] Sent: 15 October 2003 10:39 To: Multiple recipients of list ORACLE-L can anyone explain what are leaf blocks and table high water marks? thanks. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.524 / Virus Database: 321 - Release Date: 06/10/2003 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.524 / Virus Database: 321 - Release Date: 06/10/2003 -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mark Leith INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
