I Oracle Database 18c ændrer vi nu partitioneringsstrategien online for en tabel via SQL-sætningen "ALTER TABLE MODIFY PARTITION".
Denne nye funktion gør det muligt for os at tilpasse partitioneringsmetoden til en tabel uden at kræve nogen tilhørende nedetid for at foretage ændringen.
Medmindre du angiver "UPDATE INDEXES"-klausulen som en del af "ALTER TABLE"-sætningen:
– Databasen markerer UNUSBLE alle resulterende tilsvarende lokale indekspartitioner eller underpartitioner.
– Globale indekser, eller alle partitioner af partitionerede globale indekser, er markeret UNUSBLE og skal genopbygges.
Dette eksempel giver en trinvis demonstration af de opgaver, der kræves for at konvertere RANGE-partitionstabel til en HASH-partitionstabel.
Vis partitionerne i tabellen ATP01_CRED_PAG:
# sqlplus / as sysdba SQL*Plus: Release 18.0.0.0.0 - Production on Wed Jun 17 16:39:51 2020 Version 18.2.0.0.0 Copyright (c) 1982, 2018, Oracle. All rights reserved. Connected to: Oracle Database 18c Enterprise Edition Release 18.0.0.0.0 - Production Version 18.2.0.0.0 SQL> select table_name, partition_name, partition_position from dba_tab_partitions where table_name='ATP01_CRED_PAG'; TABLE_NAME PARTITION_NAME PARTITION_POSITION ----------------------------------------------------- ATP01_CRED_PAG PART_199501 1 ATP01_CRED_PAG PART_199412 2 ATP01_CRED_PAG PART_199506 3 SQL> select count(1) from ATP01_CRED_PAG partition (PART_199501); COUNT(1) ---------- 3908 SQL> select count(1) from ATP01_CRED_PAG partition (PART_199412); COUNT(1) ---------- 3984 SQL> select count(1) from ATP01_CRED_PAG partition (PART_199506); COUNT(1) ---------- 1363
Vis partitioneringsmetoden (RANGE) i tabellen ATP01_CRED_PAG:
SQL> select owner, table_name, partitioning_type, autolist, interval, autolist_subpartition from dba_part_tables where table_name = 'ATP01_CRED_PAG'; OWNER TABLE_NAME PARTITION AUT INTERVAL AUT -------- -------------- -------- ---- --------- ------ ADMIN ATP01_CRED_PAG RANGE NO NO
Konverter RANGE-partitioneret tabel til HASH-partitioneret tabel ONLINE:
SQL> ALTER TABLE ATP01_CRED_PAG MODIFY PARTITION BY HASH (DT_COMPETENCIA) PARTITIONS 3 ONLINE; Table altered.
Viser den nye partitioneringsmetode (HASH):
SQL> select owner, table_name, partitioning_type, autolist, interval, autolist_subpartition from dba_part_tables where table_name = 'ATP01_CRED_PAG'; OWNER TABLE_NAME PARTITION AUT INTERVAL AUT -------- ------------- --------- --- -------- ----- ADMIN ATP01_CRED_PAG HASH NO NO
Vis tabellens partitioner:
SQL> select table_name, partition_name, partition_position from dba_tab_partitions where table_name='ATP01_CRED_PAG'; TABLE_NAME PARTITION_NAME PARTITION_POSITION ----------------- ---------------- ------------------ ATP01_CRED_PAG SYS_P621 1 ATP01_CRED_PAG SYS_P622 2 ATP01_CRED_PAG SYS_P623 3 SQL> select count(1) from ATP01_CRED_PAG partition (SYS_P621); COUNT(1) ---------- 2651 SQL> select count(1) from ATP01_CRED_PAG partition (SYS_P622); COUNT(1) ---------- 6604 SQL> select count(1) from ATP01_CRED_PAG partition (SYS_P623); COUNT(1) ---------- 0
Referencer
Vedligeholdelseshandlinger for opdelte tabeller og indekser. Tilgængelig på https://docs.oracle.com/en/database/oracle/oracle-database/18/vldbg/maintenance-partition-tables-indexes.html#GUID-0E7793F7-B38A-427E-846B-7A8651F2A523