Long-running INSERT
On one of the databases I’m looking after (11.2.0.4, Solaris, non-RAC), several different INSERT statements (all into tablespaces with manually managed segments) suffer from occasional hiccups. The...
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Followup on the 4k DML bug
Another piece of good news — Oracle has opened a bug for yet another anomaly I reported earlier in my blog: row-by-row processing of bulk DML when the block size on the target table is less than the...
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Log parallelism bug now has a number
A few weeks ago I wrote a post about log parallelism causing excessive log file sync waits. Ever since, I’m finding more and more examples how this bug affects OLTP and hybrid databases (and even some...
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Block size and multirow DML peformance
While 8k is the default block size, Oracle supports other block sizes, too. Smaller block sizes (more commonly, 4k) are encouraged for OLTP workloads to reduce concurrency, and even smaller block size,...
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Caution: hot patches
For many Oracle database patches there is an option to apply them “online”, i.e. without stopping the database and related services (listener, ASM etc.). This is very convenient when downtime is...
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A problem with dbms_stats.copy_table_stats
Last week, when I was tuning a SQL statement at a 10.2.0.4 database, I came across a rather interesting issue. The SQL was performing poorly because of an inefficient plan (wrong join order), and it...
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