JetGetLogInfo Function

Article
08/26/2021

Applies to: Windows | Windows Server

JetGetLogInfo Function

The JetGetLogInfo function is used during a backup initiated by JetBeginExternalBackup to query an instance for the names of database patch files and transaction log files that should become part of the backup file set. These files may subsequently be opened using JetOpenFile and read using JetReadFile.

    JET_ERR JET_API JetGetLogInfo(
      __out_opt     tchar* szz,
      __in          unsigned long cbMax,
      __out_opt     unsigned long* pcbActual
    );

Parameters

szz

The output buffer that will receive the list of null terminated strings describing the set of database patch files and transaction log files that should be a part of the backup file set.

The list of strings returned in this buffer is in the same format as a multi-string used by the registry. Each null terminated string is returned in sequence followed by a final null terminator.

cbMax

The maximum size in bytes of the output buffer.

pcbActual

Receives the actual amount of string data received in the output buffer.

Return Value

This function returns the JET_ERR datatype with one of the following return codes. For more information about the possible ESE errors, see Extensible Storage Engine Errors and Error Handling Parameters.

Return code	Description
JET_errSuccess	The operation completed successfully.
JET_errBackupAbortByServer	The operation failed because the current external backup has been aborted by a call to JetStopBackup. This error will only be returned by Windows XP and later releases.
JET_errClientRequestToStopJetService	It is not possible to complete the operation because all activity on the instance associated with the session has ceased as a result of a call to JetStopService.
JET_errInstanceUnavailable	It is not possible to complete the operation because the instance associated with the session has encountered a fatal error that requires that access to all data be revoked to protect the integrity of that data. This error will only be returned by Windows XP and later releases.
JET_errInvalidBackupSequence	The backup operation failed because it was called out of sequence. JetGetLogInfo will return this error if there are any outstanding file handles created using JetOpenFile for the instance.
JET_errInvalidParameter	One of the parameters provided contained an unexpected value or contained a value that did not make sense when combined with the value of another parameter. This can happen for JetGetLogInfo when the specified instance handle is invalid (Windows XP and later releases).
JET_errNoBackup	The operation failed because no external backup is in progress.
JET_errNotInitialized	It is not possible to complete the operation because the instance associated with the session has not been initialized yet.
JET_errRestoreInProgress	It is not possible to complete the operation because a restore operation is in progress on the instance associated with the session.
JET_errRunningInMultiInstanceMode	The operation failed because an attempt was made to use the engine in legacy mode (Windows 2000 compatibility mode) where only one instance is supported when in fact multiple instances already exist.
JET_errTermInProgress	It is not possible to complete the operation because the instance associated with the session is being shut down.

On success, the requested information on the set of database patch files and transaction log files that should be part of the backup file set will be placed in the output buffers where provided. The backup state machine will be advanced such that the backup of database files is no longer allowed. Only database patch files and transaction log files are permitted to be opened for backup beyond this point.

On failure, the state of the output buffers is undefined. The failure will result in the cancellation of the entire backup process for the instance.

Remarks

It is important to note that this API does not return an error or warning if the output buffer is too small to accept the full list of files that should be part of the backup file set. The application should always provide a buffer to receive the actual size of this list and use that information to determine if the list was truncated.

Requirements

Requirement	Value
Client	Requires Windows Vista, Windows XP, or Windows 2000 Professional.
Server	Requires Windows Server 2008, Windows Server 2003, or Windows 2000 Server.
Header	Declared in Esent.h.
Library	Use ESENT.lib.
DLL	Requires ESENT.dll.
Unicode	Implemented as JetGetLogInfoW (Unicode) and JetGetLogInfoA (ANSI).

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JetGetLogInfo Function