Tag Archives: 12c

12.1.0.2 Introduction to Zone Maps Part III (Little By Little)

I’ve previously discussed the new Zone Map database feature and how they work in a similar manner to Exadata Storage indexes. Just like Storage Indexes (and conventional indexes for that manner), they work best when the data is well clustered in relation to the Zone Map or index. By having the data in the table […]

Oracle Database 12c : EXPAND_SQL_TEXT, APPROX_COUNT_DISTINCT, Session Sequences and Temporary Undo

While I was away on the OTN APAC tour, I wasn’t really able to sink my teeth into anything, so inspired by Connor McDonald‘s session in Perth, I decided to write up a few bits and pieces in my free moments in the hotels and planes (when I had enough elbow room to type). Here […]


Oracle Database 12c : EXPAND_SQL_TEXT, APPROX_COUNT_DISTINCT, Session Sequences and Temporary Undo was first posted on November 23, 2014 at 2:21 pm.
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KeepAlive socket in 12c listener

A not uncommon issue with firewalls and listeners are timeouts. Your production database may be behind a firewall, you may connect from a remote location, even your Windows workstation may have some firewall activated, possibly you use ssh tunnels or TCPS. All those occasionally lead to timeouts and connection abortion, for instance ORA-03113 end-of-file on […]

12.1.0.2 on AIX

just released today http://www.oracle.com/technetwork/database/enterprise-edition/downloads/index.html only in Enterprise Edition at the moment, and now available on HPUX, zLinux and AIX #oracle12c #db12102 is out for a bunch of platform #aix #os390 #hpux #zlinux — laurentsch (@laurentsch) November 17, 2014 This is the first and last patchset for 12cR1 #oracle 12.1.0.2 is the last patch set for […]

OLTP Compression, Drop Column, Partition Exchange

With Basic Compression, you cannot drop a column. But with Basic Compression, you can set as unused. With OLTP Compression, on the face of it, you can drop a column. But this is a lie/misdirection. In reality, the dropped column is just renamed. We see the column is not dropped but hidden: Note 1. The […]

Index Advanced Compression vs. Bitmap Indexes (Candidate)

A good question from Robert Thorneycroft I thought warranted its own post. He asked: “I have a question regarding bitmapped indexes verses index compression. In your previous blog titled ‘So What Is A Good Cardinality Estimate For A Bitmap Index Column ? (Song 2)’ you came to the conclusion that ‘500,000 distinct values in a 1 […]

12.1.0.2 Introduction to Zone Maps Part II (Changes)

In Part I, I discussed how Zone Maps are new index like structures, similar to Exadata Storage Indexes, that enables the “pruning” of disk blocks during accesses of the table by storing the min and max values of selected columns for each “zone” of a table. A Zone being a range of contiguous (8M) blocks. I […]