ORA-20000 index is in unusable

one of the clients send me the error msg below to identify the problem

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ORA-20000: index “IRSW”.”PK_T06_BD_BDUW_RELA” or partition of such index is in unusable state
*** 2012-05-29 22:00:04.458
GATHER_STATS_JOB: GATHER_TABLE_STATS(‘”IRSW”‘,'”T06_BD_BDUW_RELA”‘,'””‘, …)
ORA-20000: index “IRSW”.”PK_T06_BD_BDUW_RELA” or partition of such index is in unusable state
*** 2012-05-29 22:00:05.183
GATHER_STATS_JOB: GATHER_TABLE_STATS(‘”CLIRS”‘,'”T06_BD_BDUW_RELA”‘,'””‘, …)
ORA-20000: index “CLIRS”.”PK_T06_BD_BDUW_RELA” or partition of such index is in unusable state

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It’s quit clear from the log info, just rebuild the index when the system is in low overload which depends on the size of table.

alter index index_name rebuild online or offline. maybe the table is much bigger, you can choose a time drop and recreate the index.

cause:

some operation must be done on the table which contain the index. some as direct load…or move

more details:the dev of clients use the direct load to insert some data to table and disable the index which is the root of this issue.