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August 2010

db_block_size=8Kでdb_file_multiblock_read_count

TPC-Hベンチマークの続き、

PROTOCOL=IPC でディスク転送量7%アップ

TPC-Hベンチマークの続き

前回のSQLを見てみると、やはりTPC-H。TPC-Cとはぜんぜん違う。
実行結果もたくさん返される:

TPC-Cのときは:

ネットワークバッファを広げてみる。
sqlnet.ora


DEFAULT_SDU_SIZE=32768
RECV_BUF_SIZE=524288
SEND_BUF_SIZE=524288


Oracle用語集から

セッション・データ・ユニット(session data unit: SDU)
Oracle Netがネットワーク間でデータを転送する前にデータを配置するバッファ。Oracle Netがバッファ内のデータを送信するのは、データ送信が要求されたとき、またはバッファがデータでいっぱいになったときである。

hammeroraでTPC-Hベンチマークを再び行い、ディスク転送量をみる:

前回のほぼ最大が400MB/sから安定した420MB/s強に改善された。5%アップだ。

もう少し突っ込んでIPC接続でもテストをした(tnsnames.oraにORACLE2を追加):

Data Breach Survey Results

Lindsay Hamilton of Cervello Consultants has just started a new blog aimed at data security, data breaches and data security vulnerability scanning and activity monitoring. This should be worth watching as data breaches are certainly an in topic subject with....[Read More]

Posted by Pete On 03/08/10 At 04:18 PM

Notes on Learning MySQL (as an Oracle DBA)

This post originally appeared over at Pythian. There are also some very smart comments over there that you shouldn’t miss, go take a look!

I spent some time last month getting up to speed on MySQL. One of the nice perks of working at Pythian is the ability to study during the workday. They could have easily said “You are an Oracle DBA, you don’t need to know MySQL. We have enough REAL MySQL experts”, but they didn’t, and I appreciate.

Joins

There are only three join mechanisms used by Oracle: merge join, hash join and nested loop join. Here’s an important thought: all three join methods are nested loop joins with different startup cost. Discuss. (I’ll be saying more about this in about a week’s time.) And while I’m asking questions: what’s the perfect tense of [...]

試作機でTPC-Hベンチマークテストを行う

前回の続きでKingstonのお買い得SSD4本で構築したRAID-0のTPC-Hベンチマークを行った。

初めは、1セッション、パラレル度=6でテスト:

そのときのディスク転送量は:
300-400MB/s程度しか出ていない。

CrystalDiskMarkで計った限界量は
1GBのReadで最高522MB/sを出しているのに、およそ120MB足りない。

そこで、4セッションにして、もう一度実行してみた:

Partition-Wise Join of List-Partitioned Tables

When two tables are equi-partitioned on their join keys, the query optimizer is able to take advantage of partition-wise joins. To make sure that the tables are equi-partitioned, as of Oracle Database 11g reference partitioning can be used. In fact, per definition, with reference partitioning all “related” tables have exactly the same partitioning schema. If [...]

外部表 in SSD

TPC-Hの環境をKingstonのお買い得SSD4本で構築したRAID-0に構築した。
以前のCrystalDiskMarkの結果は以下のとおりだった(SATA直結のRAID-0、exFAT 512K):
比較対象としたのは、Western Digital社のWD6000HLHX。SATAIII 6Gb/秒で接続可能な10,000 RPMハードドライブ
CrystalDiskMarkの結果は以下のとおりだった:
150万件のORDERSを外部表として使う:


SQL> desc orders
名前 NULL? 型
----------------------------------------- -------- ----------------------------
O_ORDERDATE DATE
O_ORDERKEY NOT NULL NUMBER
O_CUSTKEY NOT NULL NUMBER
O_ORDERPRIORITY CHAR(15)
O_SHIPPRIORITY NUMBER
O_CLERK CHAR(15)

New Outfit, New Style

Back on June 17th WordPress 3.0 “Thelonious” was released and it offered up a handful of new features. Just a few days ago (July 29th) the 3.0.1 release went GA so I decided it was time to investigate what the new 3.0 ready themes had to offer. After looking through a handful of themes I decided to give the Magazine Basic theme a try for now. It offered a 1024 pixel wide layout and threaded comments; two of the features I was really looking for.  Feel free to share your comments: good, bad or otherwise.  Thanks! Here is a capture of the previous version just in case you don’t recall what it looked like (click for full size).