Simple Query returns no result

Question

We have a problem with a simple query on a "old" Table in our Database. The Table has following Structure:
CREATE TABLE <table_name>
    ROLE_ID INTEGER NOT NULL,
    ROLE_NAME VARCHAR (99) ascii NOT NULL,
    OBJECTDATA LONG BYTE,
    UNIQUE (ROLE_NAME)
The table containts two rows and following querys get these results:
select role_id, role_name from <schema>.<table_name>
--> 2 rows
select role_id, role_name from <schema>.<table_name>
order by role_id
--> 2 rows
select role_id, role_name from <schema>.<table_name>
order by role_name
--> 0 rows  ?? confusion
When we create a "new" table with the same structure, and insert the same content to this new table,  the queries are working correctly.
What happened with our "old" table,  so that these simple queries don't function anymore?
(Database Kernel    7.6.05   Build 009-123-191-997)
thx
gerri
Edited by: Gerfried on Jul 17, 2009 11:42 AM

Answer 1

Ok, Gerfried send me the dump file and this is what was in it:
INV ROOT/LEAF 15857  perm  entries : 0        [block 0]
     bottom  : 81         filevers: dummy     convvers: 9
                                              writecnt: 1
00001      nodepage.pno: 15857             nodepage.pt : data
00006      nodepage.pt2: inv               nodepage.chk: checksumData
00008      nodepage.mde: empty
08181      nd_checksum : 61937             nodepge2.pno: 15857
08189      nodepge2.pt : data              nodepge2.pt2: inv
08191      nodepge2.chk: checksumData
08192      nodepge2.mde: empty
00009      nd_bottom   : 81                nd_rec_cnt  : 0
00017      nd_level    : 0
00019      nd_filestate: empty
00020      nd_sorted   : false             nd_root     : 15857/F13D0000
00025      nd_right    : nil_pno           nd_left     : nil_pno
00033      nd_last     : nil_pno           nd_conv_vers: 9
00045      nd_str_vers : nil_pno           nd_file_vers: dummy
00052      ndPageVersio: 0                 nd_inv_usage: 0
00057      nd_leaf_cnt : 1                 nd_treeleavs: nil
00065      nd_trans_id : nil               ndInvRoot   : nil_pno
00077      nd_write_cnt: 1
END OF FILE
Obviously the reason for not delivering any data for the query is: this index is empty.
See "nd_filestate: empty" !
For some reasons (that I really don't know - sorry about that) this index had not been maintained anymore, since a very long time.
"nd_conv_vers: 9" tells us that it was the 9th savepoint that wrote down this page to the disks and that it had not been touched since then.
To view the current converter version you may just use the db_restartinfo command in dbmcli.
If you were a SAP customer the next thing I'd check would be with which database version these indexes had been created, what the internal file state is etc. - just to figure out the root cause.
As such an analysis is basically not possible via this forum all I can propose is to look for those indexes (containing 0 entries although the table has more rows) and rebuild them.
This statement should do the trick:
select i.owner, i.indexname, i.tablename, if.*
from files if join files tf  on if.primaryfileid=tf.fileid
               join indexes i on if.fileid=i.fileid
where if.entrycount =0
and if.type ='INDEX'
and tf.entrycount >0
best regards,
Lars