Data Migration in Database
Download as PPTX, PDF•0 likes•356 views
This document discusses direct-path inserts in Oracle and how they affect performance, table size, and redo generation. Direct-path inserts append new rows to the end of the table without using the buffer cache, which can increase table size even with free space. Redo generation depends on the combination of table logging mode, insert mode (append or not), and archivelog mode. The document provides examples demonstrating the different combinations.
Data Migration in Database
- 1. 鄭 鎮健 (Jingun Jung) 1
- 2. 0.9 : 2014/1/16, 新規作成 2
- 3. Append Hint Affect Performance Affect the Table Size Affect Redo Generation 1, 2, 3 Website 3
- 4. Data is appended to the end of the table, rather attempting to use existing free space within the table. Data is written directly to the data files, by passing the buffer cache. Referential integrity constraints are ignored. 4
- 5. As direct-path inserts append data to the end of the table, they constantly increase the table high water mark, even if there is lots of free space within the table. 5
- 6. Table Mode Insert Mode ArchiveLog Mode Result LOGGING APPEND Archive Log Redo Generated NOLOGGING APPEND Archive Log No Redo LOGGING NO APPEND Archive Log Redo Generated NOLOGGING NO APPEND Archive Log Redo Generated LOGGING APPEND No Archive Log No Redo NOLOGGING APPEND No Archive Log No Redo LOGGING NO APPEND No Archive Log Redo Generated NOLOGGING NO APPEND No Archive Log Redo Generated 6
- 7. SQL> CREATE TABLE t1 AS SELECT * FROM all_objects WHERE 1=2; SQL> archive log list; Database log mode No Archive Mode Automatic archival Disabled Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 7 Current log sequence 9 SQL> SET AUTOTRACE ON STATISTICS SQL> INSERT INTO t1 SELECT * FROM all_objects; 55671 rows created. Statistics ---------------------------------------------------------3077 recursive calls 8127 db block gets 64112 consistent gets 6 physical reads 6608264 redo size 830 bytes sent via SQL*Net to client 796 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1529 sorts (memory) 0 sorts (disk) 55671 rows processed SQL> COMMIT; Commit complete. SQL> DROP TABLE t1 PURGE; SQL> CREATE TABLE t1 AS SELECT * FROM all_objects WHERE 1=2; SQL> archive log list; Database log mode No Archive Mode Automatic archival Disabled Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 7 Current log sequence 9 SQL> SET AUTOTRACE ON STATISTICS SQL> INSERT /*+ APPEND */ INTO t1 SELECT * FROM all_objects; 55671 rows created. Statistics ---------------------------------------------------------849 recursive calls 1418 db block gets 60376 consistent gets 2 physical reads 51360 redo size 820 bytes sent via SQL*Net to client 810 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1491 sorts (memory) 0 sorts (disk) 55671 rows processed SQL> COMMIT; Commit complete. SQL> DROP TABLE t1 PURGE; 7
- 8. SQL> CREATE TABLE t1 AS SELECT * FROM all_objects WHERE 1=2; SQL> archive log list; Database log mode Archive Mode Automatic archival Enabled Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 8 Next log sequence to archive 10 Current log sequence 10 SQL> SET AUTOTRACE ON STATISTICS SQL> INSERT INTO t1 SELECT * FROM all_objects; 55671 rows created. Statistics ---------------------------------------------------------3378 recursive calls 7930 db block gets 62636 consistent gets 318 physical reads 6594052 redo size 832 bytes sent via SQL*Net to client 796 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1553 sorts (memory) 0 sorts (disk) 55671 rows processed SQL> COMMIT; Commit complete. SQL> DROP TABLE t1 PURGE; SQL> CREATE TABLE t1 AS SELECT * FROM all_objects WHERE 1=2; SQL> archive log list; Database log mode Archive Mode Automatic archival Enable Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 8 Next log sequence to archive 10 Current log sequence 10 SQL> SET AUTOTRACE ON STATISTICS SQL> INSERT /*+ APPEND */ INTO t1 SELECT * FROM all_objects; 55671 rows created. Statistics ---------------------------------------------------------1146 recursive calls 1417 db block gets 60536 consistent gets 71 physical reads 6656776 redo size 823 bytes sent via SQL*Net to client 810 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1494 sorts (memory) 0 sorts (disk) 55671 rows processed SQL> COMMIT; Commit complete. SQL> DROP TABLE t1 PURGE; 8
- 9. SQL> CREATE TABLE t1 AS SELECT * FROM all_objects WHERE 1=2; SQL> archive log list; Database log mode Archive Mode Automatic archival Enabled Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 8 Next log sequence to archive 10 Current log sequence 10 SQL> ALTER TABLE t1 NOLOGGING; Table altered. SQL> SET AUTOTRACE ON STATISTICS SQL> INSERT INTO t1 SELECT * FROM all_objects; 55671 rows created. Statistics ---------------------------------------------------------1097 recursive calls 7969 db block gets 61504 consistent gets 3 physical reads 6595468 redo size 839 bytes sent via SQL*Net to client 796 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1499 sorts (memory) 0 sorts (disk) 55671 rows processed SQL> COMMIT; Commit complete. SQL> DROP TABLE t1 PURGE; SQL> CREATE TABLE t1 AS SELECT * FROM all_objects WHERE 1=2; SQL> archive log list; Database log mode Archive Mode Automatic archival Enable Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 8 Next log sequence to archive 10 Current log sequence 10 SQL> ALTER TABLE t1 NOLOGGING; Table altered. SQL> SET AUTOTRACE ON STATISTICS SQL> INSERT /*+ APPEND */ INTO t1 SELECT * FROM all_objects; 55671 rows created. Statistics ---------------------------------------------------------845 recursive calls 1418 db block gets 60397 consistent gets 2 physical reads 51292 redo size 825 bytes sent via SQL*Net to client 810 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1491 sorts (memory) 0 sorts (disk) 55671 rows processed SQL> COMMIT; Commit complete. SQL> DROP TABLE t1 PURGE; 9