In the last days, I am running a number of tests based on the TPC-DS benchmark against Oracle’s Autonomous Data Warehouse Cloud service (ADWC). One of the first thing I did is of course to create the TPC-DS schema and populate it. The aim of this blog post is to share some observations related to the population step.
I started by generating the data with the tool provided by TPC-DS: dsdgen. With the following command, I generated 1TB of data:
$ dsdgen -scale 1000 -dir /data/tpcdsdata
The tool generated, in about 24 hours, the following files:
Partition-wise operations are not something new. I do not remember when they were introduced, but at that time the release number was still a single digit. Anyway, the aim of this post is not to describe the basics, but only to describe what is new in that area in 12c and 18c.
The new features can be grouped in three categories:
Before looking at the new features, here are the SQL statements I executed to create a partitioned table that I use through the examples. You can download the script here.
Performance feedback is one of the adaptive query optimizer features introduced in Oracle Database 12c. The aim of this short post isn’t to explain how it works, but to simply warn you about a buggy behavior in its configuration.
The parameters that control performance feedback in 12c are the following:
So far, so good.
From version 11.2 onward, the PARALLEL hint supports two syntaxes: object-level and statement-level. The object-level syntax, which is the only one available up to version 11.1, overrides the DOP associated to a tables. The statement-level syntax can not only override the PARALLEL_DEGREE_POLICY initialization parameter at the SQL statement level, but also force the utilization of parallel processing.
The statement-level PARALLEL hint supports the following values:
With the INMEMORY clause you can specify 4 sub-clauses:
Even though in general parallel full table scans performs direct reads, some exceptions exist. The aim of this post is to show such an exception.
For test purposes I build in my own schema a copy of the SH.SALES table (the one distributed by Oracle with the demo schemas…). On that table I build an [...]
As clearly stated in the Licensing Information guide, all features related to parallel processing (parallel backup and recovery, parallel query/DML, parallel statistics gathering, parallel index build/scans, parallel Data Pump export/import, in-memory parallel execution, parallel statement queuing and parallel spatial index builds) are only available with the Enterprise Edition. However, as of Oracle Database 11g Release [...]
In the first and second post of this series I shared with you some basics about smart scan and gave some details about projection and restriction. The aim of this post is to cover the third basic technique: join filtering.
Join filtering is not something specific to the Exadata Storage Server. In fact, it is an [...]
The short answer to this question is “yes”, it does. Unfortunately, the distribution costs are not externalized through the execution plans and, as a result, this limitation (yes, it is really a limitation in the current implementation, not a bug) confuses everyone that carefully look at the information provided in an execution plan of a [...]
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