Re: slow building index and reference after Sybase to Pg - Mailing list pgsql-general

On 02/25/11 18:11, Gary Fu wrote:
> 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@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
>
>
>
Here are the more test results on the 3rd ref and parallel on 2nd and
3rd references:

  325 mins on FK_FM_ALL_REF_FILE   (334 mins previous)

parallel results on 2nd and 3rd references: (much worse on 2nd ref)

    610 mins on FK_EXPORT_FILES_REF_FILE   (??? almost double the time)
    340 mins on FK_FM_ALL_REF_FILE

There are more than 250 millions records in table FileMeta_All and 80
millions records in table Export_Files that have references on the 280
millions records of File table on index FileId.

Here are some information on my system:

1:07pm 20 gfu@moddblads:/dump/gfu> free -m   (48MB of memory)
              total       used       free     shared    buffers     cached
Mem:         48036      47867        168          0        294      46960

1:08pm 21 gfu@moddblads:/dump/gfu> hinv
Total CPU's: 24
  Intel(R) Xeon(R) CPU           X5660  @ 2.80GHz  2793 MHZ
  Cache Size:  12288 KB

4:19pm 23 gfu@moddblads:/dump/gfu> df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1              8123168   5682344   2021532  74% /
/dev/sdb1            1134323348 576046660 499726996  54% /db

4:19pm 24 gfu@moddblads:/dump/gfu> cat /etc/fstab
LABEL=/                 /                       ext3    defaults        1 1
LABEL=/db               /db                     ext3    defaults        1 2

Any comments and suggestions ?

Thanks,
Gary