Invalid SQL being sent to the database is something to watch out for, it’s a real performance killer because once SQL is rejected by parser, it is not cached in shared pool, resulting in hard parse every time the SQL is encountered. One cool new feature of Oracle 12.2 is the fact that such SQL …
Fun with SQL Translation Framework – By-Passing Parse Errors Read More »
With version 12.2 there seems to have a some change in behavior of Materialised View Logs which caught us by surprise; I haven’t seen it documented elsewhere, so let me demonstrate. My test instance is un-patched 12.2.0.1 running on Oracle Linux. For the setup, I create a table, a mview log on that table, a …
The behavior of the LAST_LOGIN field on DBA_USERS has changed with respect to proxy authentication (for the better I think). Proxy authentication is an feature of the Oracle Database that effective allows you to be connected as one user (the client user to use Oracle’s terminology), but using the credentials of another user (the proxy …
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After implementing a recent change, and I pulled of a quick AWR report to compare performance. At first glance I was impressed by significant improvement in “log file parallel write” event, which had halved from 2 millisecond to 1 millisecond, but something about the numbers didn’t quite look right. Before: After: Let’s calculate the average …
Update (2018-07-28) Lukas Eder highlighted via twitter that my comparison was invalid dues to some PL/SQL optimizations. I have updated the testcase, there is still significant improvement, just not as much as my previous test Recently I’ve been noticing a lot of frequently called PL/SQL code that has structure similar to the following: SELECT TO_CHAR(l_date, …
We’ve just upgraded the database containing our recovery catalog to 12.2. Although rman operations seemed to be completing OK, we noticed the following slightly worrying error message in the alert log: PDB(3):WARNING: too many parse errors, count=44106 SQL hash=0x2473a808 PDB(3):PARSE ERROR: ospid=398064, error=6550 for statement: 2018-07-22T17:06:22.313262+08:00 PDB(3):BEGIN :owner := dbms_rai_owner; END; PDB(3):Additional information: hd=0x26ee29a560 phd=0x26ee122418 …
“WARNING: too many parse errors”: dbms_rai_owner Read More »
Just a quick note in case anyone else hits this issue. We use make extensive use of Kerberos to give us Windows single-sign on. For database connections via Enterprise Manger we use “Database Kerberos Credentials” credential type and have no problems connecting to 11.2 and 12.1 databases (apart from slight pain points that it’s not …
Problems with Kerberos Credentials to 12.2 Databases in Enterprise Manger Read More »
Update (2018-03-16) Seems WordPress or SQLPlus messed up my testcase, I have updated post to include unedited testcase as well as output. Update (2018-03-22) Oracle Support have created a new bug for this issue, Bug 27730925 – WRONG CARDINALITY ESTIMATION FROM HYBRID HISTOGRAM ON NCHAR COLUMN Update (2018-07-24) Tested the patch for bug 27730925 resolves …
I’ll try to write this up further when I make progress, but just wanted somewhere to share testcase. I’m guessing it’s a multi-tenant bug, but if that’s the case I’m a little surprised why no-one else has hit it. SQL> CREATE TABLE DUMMY AS SELECT * FROM DBA_OBJECTS WHERE 1=0; Table created. SQL> SELECT resource_consumer_group …