stats on cursor and query execution troubleshooting

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От Alban Médici (NetCentrex)
Тема stats on cursor and query execution troubleshooting
Дата
Msg-id 4163C5C3.3030304@fr.netcentrex.net
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Ответы Re: [PERFORM] stats on cursor and query execution troubleshooting
Список pgsql-benchmarks
Hi,

I'm looking for the statistic of memory,  CPU,  filesystem access while executing some regular SQL query,  and I want to compare them to
same kind of results while executing a cursor function.

The stat collector give me good results (sequencial scans ,  acceded tuple .....)  for regular query but nor for cursor (as explain in the documentation)

For more results, i have activated some log level in the postgresql.conf :
    show_query_stats = true

But I have some trouble in the results interpretation  such as :

! system usage stats:
!       2.776053 elapsed 1.880000 user 0.520000 system sec
!       [1.910000 user 0.540000 sys total]
!       0/0 [0/0] filesystem blocks in/out
!       5/1 [319/148] page faults/reclaims, 0 [0] swaps
!       0 [0] signals rcvd, 0/0 [0/0] messages rcvd/sent
!       0/0 [0/0] voluntary/involuntary context switches
! postgres usage stats:
!       Shared blocks:       3877 read,          0 written, buffer hit rate = 0.00%
!       Local  blocks:          0 read,          0 written, buffer hit rate = 0.00%
!       Direct blocks:          0 read,          0 written

Here is  result done after fetching ALL a row with 178282 records in the table.
looking at the i/o stat of linux I saw a filesystem access while executing this request but not in the previous log !!!
!       0/0 [0/0] filesystem blocks in/out

I'm running postgresql 7.2.4  under redhat 7.2

Does am i wrong in my interpretation ?

Does any newest postgresql version could told me execution paln for a fetch AND better stats ?

thx

Ps: please excuse my poor english

-- 
Alban Médici
R&D software engineer
------------------------------
you can contact me @ :
http://www.netcentrex.net
------------------------------

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