Monday Feb 23, 2015

2回のSQL実行でのセッション統計の差分の比較

(主に同一の)SQLを(主に少し違う条件下で)複数回実行しその詳細の差分を調べるツールはいくつかあります。

Thomas Kyte's Runstats.sql

V$STATNAME, V$MYSTAT, v$TIMER and V$LATCH

上記のオリジナルはかなり古いもので派生版があります。

oracle-developer.net utilities

A variation on Tom Kyte's invaluable RUNSTATS utility that compares the resource consumption of two alternative units of work.

How to Tune Using v$mystat

When reviewing the performance of some queries, it is sometimes useful to review the session statistics for each execution of the query.

このコメントに snapper というツールがあるとも書かれています。

SQL Developerでもいつのバージョンからかはまだ確認できていませんがV$MYSTATの比較はできます(またはできるようになります)。

以下の画面キャプチャー中の数字順に操作すれば最下部にあるような統計の比較が出ます。2回の実行で同じ値だったものは黒、異なる値の行は赤で表示されています。

 

Thursday Feb 19, 2015

Exadata X4 vs. X5 DB node CPU comparison

New generation of Exadata was announced last month.

Exadata Database Machine X5-2 | Oracle

Accelerate performance for all workloads by up to 10x

Now with Database In-Memory, DB node's CPU and memory specs more directly influences DB performance.
The article below compares the very models of Xeons which are used in X4 and X5.

Intel Ups Performance Ante With 'Haswell' Xeon E5 Chips

12-core Xeon E5-2697 v2 against an 18-core E5-2699 v3, software makers are seeing anywhere from 20 to 90 percent improvement.

Improvement in Database In-Memory going from X4 to X5 "depends" on many factors.
One of the DBIM characteristic on CPU usage is SIMD instruction. i.e.) AVX, AVX2.

The blog below by famed Oracle expert has info about X5 and SIMD. This is non-Oracle site and I can't comment about the accuracy.

Oracle In-Memory Column Store Internals – Part 1 – Which SIMD extensions are getting used? | Tanel Poder's Performance & Troubleshooting blog

X4 in the lab wouldn’t have helped with finding a CPU with AVX2 – the X4 doesn’t have that. But the new Intel E5 v3 chips that will be in the X5 do


I googled for SIMD benchmark of sort but could not find it. I don't thin Linpack fits. Even if I can, I wouldn't rely too much on it.

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