RE: sysmaster question
My bad. My script is pulling the wrong value for page reads from syschkio.
The actual number is 20 million page reads from syschkio.
j.
-----Original Message-----
From: informix-list-bounces@iiug.org
[mailto:informix-list-bounces@iiug.org]On Behalf Of Jack Parker
Sent: Thursday, January 25, 2007 5:29 PM
To: FRANK
Cc: Informix-List@Iiug. Org
Subject: RE: sysmaster question
create table "informix".message
(
msg_id serial not null ,
subject char(60),
msg_text text,
msg_date_time char(30),
src_id char(20)
) extent size 16 next size 16 lock mode page;
revoke all on "informix".message from "public";
no storage clause. no indices.
j.
-----Original Message-----
From: FRANK [mailto:yunyaoqu@gmail.com]
Sent: Thursday, January 25, 2007 5:03 PM
To: Jack Parker
Cc: Informix-List@Iiug. Org
Subject: Re: sysmaster question
Jack,
What is your table definition (dbschema -d xx -t yy -ss) ?
Frank
On 1/25/07, Jack Parker < jack.parker4@verizon.net> wrote:
Yes, it is in one chunk.
Here is the table info I gather:
=== Most Physically Active Tables ===
Table: cdi:message Created: 01/18/2007 Size: 0.35 GB
Pagesize: 2048 Allocated: 186376 Used: 185935 Data:
16889
Pgs Free: 441 0.0024%
Rowsize: 170 Columns: 5 Keys: 0
1st Ext: 8 Next Ext: 16
Other info from Flags:
Page level locking
Percent of entire engine activity:
Isam Ops: 0.29% Buffer Ops: 1.09% Page Ops: 88.76%
Rows according to SMI: 185778 Rows according to Stats 185778
Chunk: 2 dbspace: dbsp1 file: /opt/informix/dev/dbsp1
Reads: 18364082 Writes: 20129981 PgReads: 3560744 PgWrites:
5811620
Pagesize: 2048
Avg Rows/Page: 2 Avg Freeptr: 1667 Avg Empty Bytes: 367
Avg Extent size: 31062 Extents this chk: 6
Number of extents: 6
Pages:
Room for rows: 1
Blob semi-full: 1
Idx/Bitmap: 47
Blob Full: 97088
Full: 16888
Blob Very Full: 71910
Locks Mode: Page
Requests: 9307658 Waits: 0 Deadlocks: 0 Lock Time outs: 0
Total Activity:
Sequential Scans: 3
Isam Reads: 216838 Writes: 3426054 Rewrites: 0 Deletes: 0
Buffer Reads: 19749173 Writes: 17061814
Page Reads: 4246956 Writes: 3443422
Buffer/Isam Reads: 91.08 Buffer/Isam Writes: 4.98
Page/Isam Reads: 19.59 Page/Isam Writes: 1.01
-----Original Message-----
From: FRANK [mailto:yunyaoqu@gmail.com]
Sent: Thursday, January 25, 2007 4:16 PM
To: Jack Parker
Cc: Informix-List@Iiug. Org
Subject: Re: sysmaster question
Sorry, in one chunk. Frank
On 1/25/07, FRANK <yunyaoqu@gmail.com> wrote:
HI, Jack,
Is this table fragmented to more than one chunk?
Frank
On 1/25/07, Jack Parker < jack.parker4@verizon.net> wrote:
poking about.
I have a table, in a single dbspace, in a single chunk. (Cooked).
According to sysptprof, there have been 4.2 million page reads against the
table.
According to syschkio, there have been 3.6 million pages read from the
chunk.
Obviously this is a discrepancy, how is it getting resolved? A request is
made to disk to read a page, and the page has already been read? Then why
doesn't it count in bufreads?
This particular table accounts for 88% of my i/o against this disk, so add
another 400K or so page reads to the 4.2 million number.
Page writes seem to be more consistent with what I'd expect.
cheeers
j.
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