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Oracle and SQL Server Index Comparison

This post has a lot of the support code and data for my Oak Table Talk that I’ll be giving at IOUG Collaborate 2017 in Las Vegas on April 5th, 2017.  

A performance deep dive into column encryption

Actually, this is a follow up post from my performance deep dive into tablespace encryption. After having investigated how tablespace encryption works, this blogpost is looking at the other encryption option, column encryption. A conclusion that can be shared upfront is that despite they basically perform the same function, the implementation and performance consequences are quite different.

Block Names

There are a number of tiny details that I can never remember when I’m sketching out models to test ideas, and one of those is the PL/SQL block name. Virtually every piece of PL/SQL I write ends up with variables which have one of two prefixes in their names “M_” or “G_” (for memory or global, respectively) but I probably ought to be formal than that, so here’s an example of labelling blocks – specifically, labelling anonymous blocks from SQL*Plus using a trivial and silly bit of code:

A performance deep dive into tablespace encryption

This is a run through of a performance investigation into Oracle tablespace encryption. These are the versions this test was performed on:

$ cat /etc/oracle-release
Oracle Linux Server release 6.8
$ /u01/app/oracle/product/12.1.0.2/dbhome_1/OPatch/opatch lspatches
24315824;Database PSU 12.1.0.2.161018, Oracle JavaVM Component (OCT2016)
24006101;Database Patch Set Update : 12.1.0.2.161018 (24006101)

In this test I created an encrypted tablespace:

SQL> create tablespace is_encrypted datafile size 10m autoextend on next 10m encryption default storage(encrypt);

(this assumes you have setup a master encryption key already)
And I created an encrypted simple heap table with one row:

Collaborate 2017

Every year I make the trek to Vegas for the large Collaborate conference and 2017 is no different!

Preparing an AzureEnvironment- Part I

Azure is the second most popular cloud platform to date, so it’s where Delphix naturally is going to support second on our road to the cloud.  As I start to work with the options for us deploying Delphix, there are complexities I need to educate myself on in Azure.

Adding Indexes

The following question came up on the OTN database forum recently:


We have below table with columns,

Table T1
Columns:
-----------
Col_1, Col_2, Col_3, Col_4, Col_5, Col_6, Col_7, Col_8, Col_9, Col_10, Col_11, Col_12, Col_13, Col_14, Col_15

on which below indexes are created.

XXTEST_Col_1    Col_1
XXTEST_Col_2    Col_2
XXTEST_Col_3    Col_3
XXTEST_Col_5    Col_5
XXTEST_Col_6    Col_6
XXTEST_Col_7    Col_7
XXTEST_Col_8    Col_8
XXTEST_Col_8    (Col_4, Col_10, Col_11)

I have requirement to update table T1 as below and it’s taking really long. [JPL: I’m assuming that the naming of the second xxtest_col_8 index is a trivial error introduced while the OP was concealing names.)

Index out of range

I’ve waxed lyrical in the past about creating suitable column group statistics whenever you drop an index because even when the optimizer doesn’t use an index in its execution path it might have used the number of distinct keys of the index (user_indexes.distinct_keys) in its estimates of cardinality.

12.2 Online Conversion of a Non-Partitioned Table to a Partitioned Table (A Small Plot Of Land)

In my previous post, I discussed how you can now move heap tables online with Oracle Database 12.2 and how this can be very beneficial in helping to address issues with the Clustering Factor of key indexes. A problem with this technique is that is requires the entire table to be effectively reorganised when most of […]

min/max Upgrade

A question came up on the OTN database forum a little while ago about a very simple query that was taking different execution paths on two databases with the same table and index definitions and similar data. In one database the plan used the “index full scan (min/max)” operation while the other database used a brute force “index fast full scan” operation.