Oracle數(shù)據(jù)庫錯(cuò)誤是在數(shù)據(jù)庫相關(guān)操作中必然會(huì)遇到的一種問題。其中比較常見的錯(cuò)誤之一就是25錯(cuò)誤。這個(gè)錯(cuò)誤通常是在Oracle數(shù)據(jù)庫運(yùn)行時(shí)出現(xiàn)的，表示與命名安裝相關(guān)的配置文件存在問題，導(dǎo)致數(shù)據(jù)庫無法正常啟動(dòng)。

例如，在新安裝Oracle數(shù)據(jù)庫之后，如果沒有正確設(shè)置ORACLE_SID環(huán)境變量或啟動(dòng)時(shí)使用錯(cuò)誤的SID名稱，那么就會(huì)出現(xiàn)25錯(cuò)誤。另外，如果Oracle數(shù)據(jù)庫在網(wǎng)絡(luò)中運(yùn)行，并且運(yùn)行Oracle Net時(shí)，出現(xiàn)了與SQL*Net協(xié)議相關(guān)的DNS問題，也可能出現(xiàn)25錯(cuò)誤。

如果用戶通過sqlplus訪問數(shù)據(jù)庫時(shí)收到25錯(cuò)誤，那么需要檢查SQL*Net配置文件是否正確。如果你在Linux平臺(tái)上運(yùn)行Oracle數(shù)據(jù)庫，并且你的配置文件/etc/oratab不正確，也會(huì)導(dǎo)致25錯(cuò)誤。

$ sqlplus scott/tiger
ERROR: ORA-12525: TNS:listener has not received client's request in time allowed

在SQL*Net協(xié)議的設(shè)置中，有兩個(gè)重要的參數(shù)分別是SQLNET.INBOUND_CONNECT_TIMEOUT和SQLNET.OUTBOUND_CONNECT_TIMEOUT，分別控制服務(wù)器端和客戶端和SQL*Net服務(wù)器建立連接的時(shí)間限制。如果這些參數(shù)不正確或未設(shè)置，則Oracle數(shù)據(jù)庫無法正確地運(yùn)行，從而導(dǎo)致25錯(cuò)誤。

$ oerr ora 12525
12525, 00000, "TNS:listener has not received client's request in time allowed"
// Cause: The listener disconnected the client because the client failed to
// complete a connect operation within the allotted time interval. This may
// have occurred because the ORACLE_HOME environment variable or registry
// equivalent is not or is incorrectly set. It may also have occurred because
// the server or listener diagnostic file pointed to by the user environment
// variable %ORACLE_HOME%\oradiag_%USERNAME% was not correctly created
// or has gone missing. It may also have occurred because the user does not have
// permission to access the listener installation. Lastly, this error may have
// occurred because of a network failure.
// Action: Perform these steps:
// 1. Check to see if the ORACLE_HOME environment variable or registry
// equivalent is correctly set. If not, set it.
// 2. Verify that the listener and database instance are properly configured for
// direct handoff handling.
// 3. Verify that the listener and database instance are both up and running.

總之，出現(xiàn)25錯(cuò)誤可能是由于許多不同的因素引起的。在解決這個(gè)問題之前，需要考慮可能會(huì)影響Oracle數(shù)據(jù)庫正常運(yùn)行的所有因素，并且通過修改相應(yīng)的配置文件進(jìn)行調(diào)整。只有在對25錯(cuò)誤的根本原因有所了解并采取了適當(dāng)?shù)拇胧┖螅拍艽_保Oracle數(shù)據(jù)庫的正常運(yùn)行。