Entries by Arsalan

DBA_LOCK or DBA_LOCKS

Formatted view on V$LOCK that created via $ORACLE_HOME/rdbms/admin/catblock.sql SESSION_ID == SID in V$LOCK LOCK_TYPE, LOCK_ID1, LOCK_ID2 formatted value of TYPE, ID1, ID2 from V$LOCK MODE_HELD and MODE_REQUESTED formatted value of LMODE and REQUEST from V$LOCK LAST_CONVERT == CTIME of V$LOCK BLOCKING_OTHERS formatted value of BLOCK from V$LOCK Reference: https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/DBA_LOCK.html#GUID-B19FF191-AC89-498D-B2C1-2A18F63DC03D

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V$TRANSACTION

V$TRANSACTION lists the active transactions in the system. (i) The following columns together point to a transaction. (i.e.) The combination of the following should give a unique transaction id for that database. XIDUSN – Undo segment number XIDSLOT – NUMBER Slot number XIDSQN – NUMBER Sequence number (ii) The following columns explain the number of […]

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Oracle BUG DB RU 19.12.0.0.210720 or DB RUR 19.11.1.0.210720

After applying DB RU 19.12.0.0.210720 or DB RUR 19.11.1.0.210720, you may notice that the Block Change Tracking (BCT) file is getting created of a size that is not in line with the database size. Oracle recommends that you apply interim one-off Patch 33185773 to correct this problem(s) in the RU/RURs indicated above. Note the fix for this issue has […]

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Transitivity

Oracle CBO performs transitivity as the first step in optimization. Transitivity means generating additional predicates based on existing predicates. The main advantage is the inclusion of extra access methods. Transitivity is not done for join predicates. Assume A, B, and C are columns. If A=5 and A=B, you can conclude that B=5. This can be […]

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Oracle Multitenant: LICENSE CHANGES IN 2019

For all offerings using Oracle Database 19c or later, if you are not licensed for Oracle Multitenant, then you may have up to 3 user-created PDBs in a given container database at any time. For all offerings using Oracle Database 12.1 through 18c, if you are not licensed for Oracle Multitenant, then the container database […]

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Gradual Database Password Rollover for Applications

Starting with the Oracle Database 21c release, an application can change its database passwords without an administrator having to schedule downtime. To accomplish this, a database administrator can associate a profile having a non-zero limit for the PASSWORD_ROLLOVER_TIME password profile parameter, new with this release, with an application schema. This allows the database password of […]