Re: Writing data to blobspace

In article <2iru6q$u9@corolla.eng.sc.rolm.com> daniel@corolla.eng.sc.rolm.com (Dan Jatnieks) writes: >From: daniel@corolla.eng.sc.rolm.com (Dan Jatnieks) >Subject: Writing data to blobspace >Date: 3 Feb 1994 14:35:06 -0800 >The Informix-Online Administrator's Guide (v5.0) has the following to >say about storing data in blobspace: > "At any time, only one set of blobspace blob buffers can be > used to transfer blobspace blob data. That is, only one user > process can transfer blobspace blob data to the disk at a time." >This seems to be saying that all access to blobspace is serial by user >process. E.g. If I write a large, say 1Mb, piece of data into blobspace, >then some other user must wait until all 1Mb of my data is stored to disk >before writing their, say 2K piece of data. >My question is why is this? It would seem to make accessing blobspace >very slow. Can't this be designed so as to interleave by blobpage size? >This would improve blob throughput, IMO. >Also: > "Blob data is transferred from the application development tool > to the Online database server in 1-kilobyte chunks." >The question is why doesn't it transfer the size of a blobspace page >(at least up to some reasonable maximum size)? >-- > ============================================================================= I have analyzed detailed sar output from our benchmarks doing blob reads and writes. At least on NCR platforms, I can guarantee that the actual data transfer is done in blobspace page size units. ========================================================================== John Sutherland Principal Consultant Systems Performance Group 1490 Liveoak Drive Mississauga, Ontario Canada L5E 2X1 phone: (905) 891-8593 e-mail: jsutherl@tron.waterloo.ncr.com