Kevin Kempf's Blog

May 18, 2009

11i Compression – A First Look

Filed under: 11g, advanced compression, Oracle — Tags: — kkempf @ 2:07 pm

Took the plunge during the maintenance window this month and compressed the top 5 tables in my buffer cache.  Just compressing 5 tables I freed up 20-25% of my buffer cache (Oracle is managing my memory via AMM, and generally it allocates about 4gb to Shared Pool and 20 to the Buffer Cache)

Uncompressed Compressed
Table Block Count % in Cache Block Count % in Cache GB Saved
INV.MTL_MATERIAL_TRANSACTIONS 200563 100 99263 100 0.77
INV.MTL_TRANSACTION_ACCOUNTS 210645 100 67470 100 1.09
BOM.CST_ITEM_COST_DETAILS 256731 99 50159 100 1.58
INV.MTL_TRANSACTION_LOT_NUMBERS 118761 100 48175 100 0.54
WIP.WIP_TRANSACTIONS 102027 100 42543 100 0.45
Sum 4.43

* Calculations assume the uncompressed object was 100% in cache, so may be off slightly, and are based on an 8k block size in case you want to check my math.

First impressions? Everything is running fine, if a little heavier on CPU and lighter on I/O. It’s really hard to quantify this early in the game. Next maintenance window, I’ll probably compress 50 more tables, and ultimately we’ll be really close to a “11i Database in Memory” environment.

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