Re: slow building index and reference after Sybase to Pg

On 02/25/11 17:22, Andy Colson wrote:
> On 2/23/2011 12:31 PM, Gary Fu wrote:
>> Hi,
>>
>> I'm testing on converting a big Sybase db to Pg. It took about 45 hours
>> to convert all sybase tables (bcp) to Pg (copy) without index and
>> reference. After that I built the index (one by one, sequentially) and
>> it took about 25 hours and then I started to add the references (one by
>> one), however, it has been more than 30 hours and still has no sign of
>> finishing. I wonder, is there any suggestion that may speed up the index
>> and reference building (on Pg).
>>
>> Thanks,
>> Gary
>>
>
> In addition to Toms answer, disable fsync for a bit.
>
> ( http://www.postgresql.org/docs/9.0/static/non-durability.html )
>
> Also, why one at a time? Are you IO bound? If you are IO bound then
> ok, but otherwise try a few at a time. (I mean COPY, create index,
> and add constraint)
>
> While this was going on, did you view vmstat? Did you look at PG's log?
>
>
> -Andy

Thanks for your information. Here are more information about my situation:

Below is the listing of the time for creating the references after we
ported the tables and built the indexes with the following configuration
info:

wal_buffers = 8MB
checkpoint_segments = 30
effective_cache_size = 21GB
maintenance_work_mem = 1GB
fsync = on

5.301638 min FK_FILE_REF_FILETYPE
7.250384 min FK_PGE_REF_PGE_DEF
15.024702 min FK_FILESONDISKLOST_REF_FILE
21.143256 min FK_FILEEXPORTED_REF_FILE
22.404361 min FK_PGE_INPUTFILE_REF_PGE
23.439486 min FK_FMC_METFILEID_REF_FILE
24.942795 min FK_FM_ARCHIVESET_REF_FMC
33.286959 min FK_PGE_LOGFILE_PCF_REF_FILE
46.875006 min FK_FILEMETA_NV_REF_FMC
51.223537 min FK_FM_BJ_REF_FMC
52.603217 min FK_FM_L1L2_REF_FMC
73.314357 min FK_FM_L3L4T_REF_FMC
76.118838 min FK_FMC_REF_PGE
89.317196 min FK_FMC_REF_FM_ALL
248.595640 min FK_EMS_FILES_REF_FILE
258.633713 min FK_EXPORT_FILES_REF_FILE
269.605100 min FK_FILESONDISK_REF_FILE
299.187822 min FK_FILEREQHF_REF_FILE
331.076144 min FK_FILESNOTON_REF_FILE
334.494474 min FK_FM_ALL_REF_FILE
608.402847 min FK_PGE_INPUTFILE_REF_FILE

We changed with the following configuration and tried to rebuild some of the references with worse results:

wal_buffers = 16MB
checkpoint_segments = 256
effective_cache_size = 30GB
maintenance_work_mem = 2GB
fsync = on

75 min FK_FM_L1L2_REF_FMC (52 min previous)
311 min FK_EXPORT_FILES_REF_FILE (258 min previous)
still running FK_FM_ALL_REF_FILE

We are also going to run parallel (2 refs) at at a time to see what happen.

Also, after that we are going to try Andy's suggestion to set fsync = off.

By the way, I just did vmstat -n 1 with the following results (building the reference
FK_FM_ALL_REF_FILE). However, I don't know how to interpret it.

6:02pm 116 gfu(at)moddblads:/dump/gfu> vmstat -n 1
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
r b swpd free buff cache si so bi bo in cs us sy id wa st
0 1 556 137340 70280 48446004 0 0 10 24 0 0 0 0 100 0 0
0 1 556 132896 70296 48449828 0 0 4212 328 1655 1115 0 0 96 4 0
0 1 556 140768 70296 48442580 0 0 4240 28 1585 956 0 0 96 4 0
0 1 556 132368 70296 48451308 0 0 8424 0 1573 820 0 0 96 4 0
0 1 556 130800 70272 48452784 0 0 13536 0 1589 755 1 0 96 3 0
0 1 556 136148 70264 48447920 0 0 6344 0 1611 1082 0 0 96 4 0
0 1 556 132368 70280 48451416 0 0 3960 376 1492 829 0 0 96 4 0
0 1 556 135784 70284 48448180 0 0 8240 0 1856 957 0 0 96 4 0
0 1 556 139092 70288 48444668 0 0 8700 0 1828 917 1 0 96 4 0
0 1 556 134052 70292 48449608 0 0 5076 0 1566 880 0 0 96 4 0
0 1 556 140460 70276 48443636 0 0 5536 0 1509 724 0 0 96 4 0
0 1 556 131648 70300 48452340 0 0 8616 336 1598 826 0 0 96 4 0
1 0 556 135524 70284 48448112 0 0 8004 0 1588 836 0 0 96 4 0

Any other suggestions that I should try ?

By the way, as far as I know that Sybase does not check the reference for
each records when creating the reference. Is there a way for pg to do the
same ?

Thanks,
Gary