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Daniel Westermann

Be careful when putting the Oracle ADR on xfs, or better 4K sector format drives

By | Database Administration & Monitoring | No Comments

Today, after we did a fresh setup of a Grid Infrastructure cluster (12.1.0.2.170814) we faced two issues reported in the alert.log of the ASM instances (in fact you would see the same for the alert logs of any instance in that configuration but we did not had any other instance up and running at that time): This: ORA-00700: soft internal error, arguments: [dbgrfrbf_1], [/disk00/app/grid/diag/asm/+asm/+ASM2/metadata/INC_METER_SUMMARY.ams], [0], [4], [], [], [], [], [], [], [], [] ORA-27072:…

 
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Franck Pachot

impdp content=metadata_only locks the stats

By | Oracle | No Comments

With Oracle you can learn something every day. Today, preparing a migration to 12.2, I found all tables had locked statistics. I learned that it is the expected behavior since 10.2 when importing metadata_only including statistics, to avoid that the automatic job gathering comes and replaces the stats by ‘0 rows’.  

 
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Franck Pachot

Postgres vs. Oracle access paths IX – Tid Scan

By | Oracle, Postgres | No Comments

In the previous post we have seen how Postgres and Oracle finds the table row from the index entry. It uses the TID / ROWID. I’ll focus on this access path and I will have covered all Postgres access paths to table data. Oracle ACCESS BY ROWID I start with Oracle because we already have seen the TABLE ACCESS BY ROWID. I’ll decompose an index acces to the table. The first step is getting the…

 
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Franck Pachot

Improving Statspack Experience

By | Oracle | No Comments

I’ve published a few month ago an article in the UKOUG OracleScene magazine on Improving Statspack Experience: quick setup script, changing settings, filling Idle Events,etc. In the article, I used dbms_job to schedule the snapshots, because I have this script for years and never took the time to do it with dbms_scheduler. Thanks to Nicolas Jardot here is the equivalent script using dbms_scheduler.  

 
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Franck Pachot

Get trace file from server to client

By | Database Administration & Monitoring | No Comments

The old way to get a user dump trace file, for sql_trace (10046), Optimizer compilation trace (10053), lock trace (10704), Optimizer execution trace (10507),… is to go to the server trace directory. But if you don’t have access to the server (as in the ☁) the modern (12cR2) way is to select from V$DIAG_TRACE_FILE_CONTENTS. Before everybody is on 12.2 I’m sharing here a sqlplus script that I use for a long time to get the…

 
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Franck Pachot

Postgres vs. Oracle access paths VIII – Index Scan and Filter

By | Oracle, Postgres | 2 Comments

In the previous post we have seen a nice optimization to lower the consequences of bad correlation between the index and the table physical order: a bitmap, which may include false positives and then requires a ‘recheck’ of the condition, but with the goal to read each page only once. Now we are back to the well-clustered table where we have seen two possible access paths: IndexOnlyScan when all columns we need are in the…

 
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