ORACLE – enq: TX row lock contention

Enqueues are locks that coordinate access to database resources. enq: wait eventindicates that the session is waiting for a lock that is held by another session. The amount of wait time associated with this wait event is excessive and can be responsible for performance issues observed in the application. TX enqueue are acquired exclusive when a transaction initiates its first change and held until the transaction does a COMMIT or ROLLBACK.  Some situations of TX enqueue: – Waits for TX in mode 6 occurs when a session is waiting for a row level lock that is already held by another Read More

ORACLE 12C: Dataguard Far Sync

Oracle Dataguard Far Sync instance is a new feature introduced in Oracle Database 12c, which simply works like a archive/redo repeater.. Far sync instance is something different than the Oracle Database instance, as its mission is accepting redo from the primary database and then shipping that redo to other members of the Oracle Data Guard configuration.. Far Sync instance is an instance without a database.. Although; it has controlfile, and capability to read from standby redolog files and write them into its local archive log files, Far Sync instance does not map any database file, in other words, does not Read More


When you work with xml file you should be solve the scenery that have an node with its properly sub node. In our case the following nodes () ; () . It is quite delicate find exactly approach that gives to you the requirement expected. The problems that I have got they were two different: – Duplicate row – ORA-19025 EXTRACTVALUE returns value of only one node or ORA-19279: XPTY0004 – XQuery dynamic type mismatch: expected singleton sequence – got multi-item sequence The following image shows the scenery described: Duplicate row means the query extract the values that are not Read More

Oracle Database 18c: My preferred new features for DBAs

Oracle Databse 18c comes with some cool new features for DBAs. In this article I’ll list my preferred ones. Just one note: I think the name “Autonomous Database” is quite misleading, as it means that some of the new features COULD be used to configure your database as “autonomous” where previous versions required some maintenance, and this will be the direction of the next Oracle Database generations. 1. PRIVATE TEMPORARY TABLES You can create temporary tables with these characteristics: – NAME must be prefixed by “ORA$PTT_” (or the current value of PRIVATE_TEMP_TABLE_PREFIX initialization parameter) – DATA is automatically deleted at Read More