hi Gerwin, long time no see! Thanks for answering, but i don't know, that specific table isn't that big. SQL> select bytes from dba_segments where owner='SYS'and segment_name='WRI$_OPTSTAT_HISTGRM_HISTORY'; BYTES ------------------ 31457280 and i doubt that that column is so small that 30mb makes it overflow. Also: the values do not seem to be consistent with anything i can find space related e.g. select a.owner, a.segment_name, sum(a.bytes) , sum(b.value) from dba_segments a , v$segment_statistics b where a.segment_name=b.object_name and b.statistic_name='space used' and a.owner='SYS' group by a.owner, a.segment_name order by 3,4,2; gives values like SYS I_ARGUMENT2 9437184 0 SYS I_H_OBJ#_COL# 9437184 23278 SYS WRH$_FILESTATXS_PK 9437184 273456 SYS WRH$_SGASTAT_U 9437184 273456 SYS WRI$_ADV_OBJECTS 9437184 393219 SYS WRH$_WAITSTAT_PK 9437184 638064 So for the same number of bytes in dba_segments you can have different values of 'space used' in v$segment_statistics which i would not have expected in a column overflow. and also SYS IDL_UB2$ 34603008 0 SYS IDL_UB1$ 201326592 0 SYS AUD$ 226492416 0 SYS SOURCE$ 285212672 0 SYS WRI$_ADV_TASKS 262144 -983 SYS WRH$_LOG 131072 -1065 SYS WRH$_LIBRARYCACHE 196608 -1147 SYS WRH$_SEG_STAT_OBJ 524288 -1966 There are small tables with negative values and large tables with a 'space used' of 0. What do you think? What could it be measuring? Baziel On Wed, Oct 6, 2010 at 3:23 PM, Gerwin Hendriksen < gerwin.hendriksen@xxxxxxxxx> wrote: > Hi Baziel, > > I think the problem here is a column overflow as sometimes happens with for > example the statistic "redo size" in v$sesstat, when the number are getting > really big, above 4294967296 (32 bit border), the number wents to negative. > > Regards, > > Gerwin > > 2010/10/6 Baziel de Leeuw <baziel@xxxxxxxxxx> > > Hi, >> >> What does the statistic_name='space used' column in v$segment_statistics >> show? >> >> I get results i don't understand at all, e.g. >> >> SQL> select owner, object_name, statistic_name, value from >> v$segment_statistics where owner='SYS' and >> object_name='WRI$_OPTSTAT_HISTGRM_HISTORY' and statistic_name='space used'; >> >> OWNER OBJECT_NAME STATISTIC_NAME >> VALUE >> ---------- ------------------------------ --------------- >> ------------------ >> SYS WRI$_OPTSTAT_HISTGRM_HISTORY space used >> -554110 >> >> Yes, that is a negative value. >> >> I expected beforehand that space_used would be something like bytes in >> memory or something like that. >> >> Does anyone know what it actually is? >> >> Baziel >> >> >> >