The Oracle mode of OceanBase Database imposes limitations on expressions of function-based indexes. This topic lists the system functions that are not supported for function-based indexes.
System functions not related to users
System functions not related to users are all prohibited in function-based indexes.
Other system functions
The following system functions are prohibited in function-based indexes.
| REGEXP_INSTR | CONNECT_BY_PATH | REGEXP_COUNT | CURRENT_TIMESTAMP |
| REGEXP_REPLACE | CURRENT_DATE | REGEXP_SUBSTR | HOST_IP |
| REGEXP_LIKE | RPC_PORT | DBTIMEZONE | IS_SERVING_TENANT |
| UID | LAST_TRACE_ID | SYSTIMESTAMP | SYSDATE |
| SESSIONTIMEZONE | LOCALTIMESTAMP | SYS_GUID | OB_VERSION |
| AT TIME ZONE | EXTRACT | AT LOCAL | USER |
| SYS_CONTEXT | CHARSET | ROWID_TO_CHAR | COLLATION |
| DBTIMEZONE | COERCIBILITY | CARDINALITY | DEFAULT |
| ROWIDIDTONCHAR | ROWNUM | DECODE | LNNVL |
| TIMESTAMP_TO_SCN | VALUES | SCN_TO_TIMESTAMP | USERENV |
| DUMP | - | - | - |
