| From: | Jim Nasby <jim(at)nasby(dot)net> |
|---|---|
| To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | "Simon Riggs" <simon(at)2ndquadrant(dot)com>, <alvherre(at)commandprompt(dot)com>, <david(at)fetter(dot)org>, "Jeff Janes" <jeff(dot)janes(at)gmail(dot)com>, "Robert Haas" <robertmhaas(at)gmail(dot)com>, <pgsql-hackers(at)postgresql(dot)org>, <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Subject: | Re: Page Checksums + Double Writes |
| Date: | 2012-01-04 21:30:30 |
| Message-ID: | 915C4B92-64FF-4DD4-8DF8-01E191167088@nasby.net |
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| Lists: | pgsql-hackers |
On Jan 4, 2012, at 2:02 PM, Kevin Grittner wrote:
> Jim Nasby <jim(at)nasby(dot)net> wrote:
>> Here's output from our largest OLTP system... not sure exactly how
>> to interpret it, so I'm just providing the raw data. This spans
>> almost exactly 1 month.
>
> Those number wind up meaning that 18% of the 256-byte blocks (1024
> transactions each) were all commits. Yikes. That pretty much
> shoots down Robert's idea of summarized CLOG data, I think.
Here's another data point. This is for a londiste slave of what I posted earlier. Note that this slave has no users on it.
054A 654
054B 835
054C 973
054D 1020
054E 1012
054F 1022
0550 284
And these clog files are from Sep 15-30... I believe that's the period when we were building this slave, but I'm not 100% certain.
04F0 194
04F1 253
04F2 585
04F3 243
04F4 176
04F5 164
04F6 358
04F7 505
04F8 168
04F9 180
04FA 369
04FB 318
04FC 236
04FD 437
04FE 242
04FF 625
0500 222
0501 139
0502 174
0503 91
0504 546
0505 220
0506 187
0507 151
0508 199
0509 491
050A 232
050B 170
050C 191
050D 414
050E 557
050F 231
0510 173
0511 159
0512 436
0513 789
0514 354
0515 157
0516 187
0517 333
0518 599
0519 483
051A 300
051B 512
051C 713
051D 422
051E 291
051F 596
0520 785
0521 825
0522 484
0523 238
0524 151
0525 190
0526 256
0527 403
0528 551
0529 757
052A 837
052B 418
052C 256
052D 161
052E 254
052F 423
0530 469
0531 757
0532 627
0533 325
0534 224
0535 295
0536 290
0537 352
0538 561
0539 565
053A 833
053B 756
053C 485
053D 276
053E 241
053F 270
0540 334
0541 306
0542 700
0543 821
0544 402
0545 199
0546 226
0547 250
0548 354
0549 587
This is for a slave of that database that does have user activity:
054A 654
054B 835
054C 420
054D 432
054E 852
054F 666
0550 302
0551 243
0552 600
0553 295
0554 617
0555 504
0556 232
0557 304
0558 580
0559 156
--
Jim C. Nasby, Database Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net
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