How to diagnose ORACLE Database problems: Common Errors

ORACLE errors are detailed in the ORALCE documentation, but the causes and measures are not detailed. This article focuses on how to solve these errors.
　　
1 ORA-12571, ORA-03113, ORA-03114, ORA-01041
　　
Feature: This type of disconnection error is reported on the client (proxy or Application Server ).
　　
Cause: if this occurs occasionally, it may be due to network or abnormal user suspension. If this happens frequently, the character set of the client and the server is inconsistent.
　　
Measure: if this happens occasionally, add a line to the PROTOCOL configuration file PROTOCOL. ORA on the server.
　　
TCP. NODELAY = YES;
　　
If this occurs frequently, it is because the character set of the client and the server is inconsistent or the network is caused.
　　
The character set of the client is defined in the Registry: hkey1_local1_machine/SOFTWARE/ORACLE/nls1_lang
　　
Set TCPMAXDATARETRANSMITIONS = 20 in the TCP Parameter item in the client registry.
　　
2 ORA-01000
　　
Feature: Maximum number of cursors allowed by the session
　　
Cause: the maximum number of cursors allowed by the session is reached.
　　
There are two solutions:
　　
(1) Add the number of OPEN_CURSORS to the INIT. ORA file of the initialization file. Generally, the value must be greater than 200.
　　
(2) at the application level, it is related to development tools, such as setting MAXOPEN_CURSORS.
　　
3 ORA-01545
　　
Feature: a rollback segment is unavailable
　　
Cause: (1) when the rollback segment is ONLINE, but the rollback segment is unavailable, for example, the tablespace of the rollback segment is OFFLINE;
　　
(2) When the rollback segment is ONLINE, but the rollback segment is ONLINE, for example, the rollback segment is used twice. In typical cases such as OPS, the rollback segment cannot be public;
　　
(3) When a rollback segment is deleted, there are active transactions in the rollback segment;
　　
Measures: (1) Ensure that the rollback segment is correct.
　　
(2) Delete the specified ROLLBACK segment from the initialization file INIT. ORA parameter ROLLBACK) SEGMENTS.
　　
(3) You can delete the tablespace of the rollback segment and cancel the UNDO transaction.
　　
4 ORA-0165x
　　
Feature: The tablespace does not have enough space for allocation.
　　
Cause: the tablespace is full; the storage parameter is unreasonable, and NEXT is too small; there is no continuous Interval
　　
Measure: If the tablespace is full, you need to add files to the tablespace. If the storage parameter is unreasonable, you need to add INITIAL and NEXT. If there is no continuous interval, You need to merge idle tablespaces.
　　
View space fragments with DBA_FREE_SPACE
　　
ORA-01555
　　
Feature: the current session cannot read data of previous versions.
　　
Cause: there are many reasons, mainly because: the rollback segment is too small, too small; rollback segment conflict; Cross commit (fetch_1_ss)
　　
Measure: Increase the number of rollback segments;
　　
ORA-04031
　　
Features: insufficient memory in the memory area of the shared pool, or memory fragments are generated.
　　
Cause: when you try to load a large package or execute a large stored procedure, the shared pool does not have continuous memory space.
　　
Measure: if the memory is insufficient, add SHARE) POOL_SIZE;
　　
For memory fragments, run alter system flush into _pool.
　　
7 ORA-04091
　　
Feature: the trigger is abnormal.
　　
Cause: this error occurs when a row triggers reading or modifying a changed table (being modified or inserted.
　　
Measure: Check the trigger script to ensure the integrity of the reference.
　　
8 ORA-01242, ORA-01113
　　
Feature: Database downtime caused by media faults
　　
Cause: Media fault.
　　
Measure: Check for hardware faults. Modify the dbshut script and change the STARTUP command:
　　
& Nbs
　　
P; Startup open recover
　　
Alter database open