Re: Informix vs. Sybase vs. Oracle vs. (gasp) MS SQL Server
On 01 Dec 1997 15:29:49 -0700, Pablo Sanchez <pablo@sgi.com> wrote: :>>>>> "David" == David Williams <djw@smooth1.demon.co.uk> writes: :David> :David> Imagine 1 page with 2 rows one it. :David> :David> 1. Page level locking :David> :David> User A updates row 1 :David> At the same time user B updates row 2. User B has to wait for :David> User B to commit. :David> :David> 2. With row level locking :David> User A updates row 1 :David> User B updates row 2 (with no waiting). :David> :David> How can 1 be faster than 2 if user B has to wait? : :You're forgetting the RDBMS's latency to acquire and release :locks for the rows. It all adds up and offsets the gain. :You can't just look at a small piece of *anything*. You :have to, pardon my Boulderism, look at the problem holistically. : :>> If you look at the TPC-C's (as I've mentioned, before) :>> you'll see another highly tuned (OLTP) application. If I :>> compare the *currently* submitted numbers for Sybase :>> vs Informix I see the following: :>> :>> Sybase..... 39,469 tpmC :>> Informix... 24,309 tpmC :>> :>> That's a 62% performance increase by using Sybase. Now I :>> grant you that I believe that we'll see Informix :>> Inc. publishing even higher numbers but that's not my :>> point. My point is: :>> :David> I checked the results, these figure come from different machines. :David> So Sybase runs their TPC benchmarks on larger hardware..so? : :If your first example had validity, then your above :statement wouldn't matter. A faster machine would mean that :you'd get to the wait that much faster, but that's not what :is happening. We're seeing that Sybase is scaling with the :hardware provided. : :You buy a bigger machine to get more throughput... : :>> For a finely tuned application, row level locking :>> does *not* matter. :David> Lock granularity is still a problem. Why do UNIX kernels lock :David> individual files and data structures rather than having one large :David> kernel lock? : :We're not talking database locks versus page level/row :level. We're talking page level and row level. There lies :the difference. Question: If row level locking isn't important, why does sybase tell you how to sorta-do row level locking by setting the size of a row to the size of a page? gburnore@netcom dot com or gburnore@netcom databasix com --------------------------------------------------------------------------- How you look depends on where you go. --------------------------------------------------------------------------- Gary L. Burnore | '۳'''''''ۺ''''''''''۳ | '۳'''''''ۺ''''''''''۳ DOH! | '۳'''''''ۺ''''''''''۳ | '۳ 3 4 1 4 2 '' 6 9 0 6 9 '۳ spamgard(tm): zamboni | Official Proof of Purchase =========================================================================== PGPprint: C63B CF4E 1B71 4D7E C6F8 AF4E 338D 5CB4 KeyID: 0x0F7EDBD9 (RSA) finger gburnore@netcom.com for public key ---------------------------------------------------------------------------