checkpoint ngfw

First, you must understand some concepts: The information in the log file ensures that the transaction can be restored when the system fails. When a user finishes sending a commit, the commit complete information is always received only after the lgwr process writes the redo information required by the transaction to the log file (which may have been in the redo buffer before. The dbwr process is always slower than the lgwr process (the dbwr process is a random write, the lgwr process is a s

restorememento () method of the initiator object to restore the state of the initiator object to the state stored by the memorandum object, that is, the "on" state. Because the internal class memento of the initiator object implements the mementoif interface, this internal class is the actual type of the input memo object, therefore, the initiator object can read the internal state of the object using the private interface of the internal class memento.Multiple checkpoints The schematic Impleme

1 Definition RBA is the address corresponding to redo entries in the redo log file. 2Composition RBA consists of three parts:Serial number (4 bytes)Block number (4 bytes)Start byte (2 bytes)All of the above are in hexadecimal storage. 3 type 3.1 lrba Definition: Position of the redo entries corresponding to the first dirty block in the redo log file Note: The CKPT-Q maintains dirty blocks in the order of lrba, and dbwn writes from the CKPT-Q in the order of lrba when a

Theory: logs are active, that is, logs overwritten by RBA pointers. If the checkpoint is complete, RBA will immediately redo the last redo log group. If RBA is absent Theory: logs are active, that is, logs overwritten by RBA pointers. If the checkpoint is complete, RBA will immediately redo the last redo log group. If RBA is absent The incremental checkpoint

do too many projects. There is a checkpoint every week. The topic of the checkpoint is provided by the mentor. The intern will do the presentation on the checkpoint. The main content is what you did in the past week. I made a total of seven checkpoints during my internship, and I felt a lot of GAINS. I can send my intern summary, mainly about my internship exper

The metaserver metadata persistence of the KFS file system adopts the checkpoint + Log method,The following uses the source code to analyze the persistence mechanism and implementation details of metadata in KFS metaserver. 1. Related source code files KFS metaserver metadata persistenceCodeThe directory is KFS-[version]/src/CC/meta, where,KFSThe source code of metadata persistence is as follows: (1) Meta/statup. CC:ResponsibleKFSIn the startup

CKPTQ: The data block in the Checkpoint Queue records the LRBA address of each data block. RBA: Redo Block Address (Address of the Redo log Block, which is equivalent to the rowid in the data file. You can use this Address to locate the Redo log Block) Consists of three parts: 4 byte + 4 byte + 2 byte Logfile sequence number (log file serial number) Logfile block number (Log File block number) Byte offset into the block (number of starting offset b

1. Sybase ASE transaction log Each database of Sybase ASE, whether it is a system database (master, model, sybsystemprocs, tempdb) or a user database, has its own transaction log, and each database has a syslogs table. Logs record user operations on the database, so if you do not need to clear the log, the log will continue to grow until the occupied space. You can run the dump transaction command to clear logs, or use the trunc log on chkpt option to clear logs automatically at intervals. Manag

the memo object, which is the "on" state. Because the initiator object's inner class memento implements the Mementoif interface, this inner class is the true type of the incoming memo object, so the initiator object can read out the internal state of the object using the private interface of the inner class memento.Multiple checkpointsThe schematic implementations of the white box and the black box given above are simple implementations that store only a single state, or they can be called only

only the latest SCN number, After a commit, this transaction slot can be used by another transaction. If the user roolback, the server process reconstructs the corresponding modified copy based on the transaction list and the SCN and the rollback segment address of the block in the data file block and DB buffer, and uses the original values to restore the modified but uncommitted changes in the current data file. If there are multiple "front images", the server process finds the rollback segme

Xlog file corresponding to the log can also be inferred from Current_xlog_location:Timeline 0000000000000045----> 000000010000000000000045(iii) LSN when used for recovery1) Use Pg_controldata to obtain control information from the controls file:Appledemacbook-pro-2:pg_xlog apple$ Pg_controldataPg_control version number:942Catalog version number:201510051Database system identifier:6451705940496018968Database Cluster State:in ProductionPg_control Last Modified: 4/9 10:52:12 2018Latest

BackgroundIn Flink 1.5 above, it provides a new Kafka producer implementation:flinkkafkaproducer011, aligning with Kafka 0.11 above that supports transaction. Kafka transaction allows multiple Kafka messages sent by producer to deliver on an atomic the-and either all success or All fail. The messages can belong to different partitions. Before Flink 1.5, it provides exact once semantics only for its internal state via check point. However, if you write the stream state to external storage such as

As an important mechanism in Oracle, SCN (system Chang number) plays an important role in data recovery, data guard, streams replication, and synchronization between RAC nodes. Understanding the operating mechanism of SCN can help you gain a deeper understanding of the above functions. Before understanding SCN, Let's first look at how data changes in Oracle transactions write data files: 1. Start the transaction; 2. Find the required data block in the buffer cache. If no data block is found,

results allow the application to process the information background process. The processes used by the Oracle DB system are collectively referred to as "background processes". An Oracle DB instance can have multiple background processes. Common background processes in non-RAC and non-ASM environments-DBWn database write process-LGWR log write process-CKPT Checkpoint Process-SMON system monitoring process-PMON process monitoring process-RECO restorer

Tags: understanding of roll-forward and rollback for Oracle instance RecoverySome of the understanding of Oracle instance recovery, has been a misunderstanding, today by looking at relevant information and discussion with students, found their own mistakes, the results are as follows:Instance recovery: When the database is not properly shut down (power off or Shu abort, etc.), when you start the database, the database-related process automatically perform instance recovery without human interven

① DefinitionGrep is a row-level device that analyzes a row of information. If there is any information we need, the whole row is returned.② FunctionCompares string data to print the strings that meet your needs.③ FormatGrep [-acinv] [-- color = auto] 'query string' filenameParameters:-A: searches for data in the format of a binary file and a text file.-C: calculates the number of times a 'query string' is found.-I: case-insensitive-N: Output row number-V: displays the row without the 'query stri

Sybase ase transaction log Each database of sybase ase, whether it is a system database master, model, sybsystemprocs, tempdb) or a user database, has its own transaction log, and each database has a syslogs table. Logs record user operations on the database, so if you do not need to clear the Log, the log will continue to grow until the occupied space. You can run the dump transaction command to clear logs, or use the trunc log on chkpt option to clear logs automatically at intervals. Managing

-- color = auto: color of the keyword ④ example www.2cto.com eg01: find the flag of a checkpoint event [SQL] [oracle @ localhost bdump] $ grep-in -- color = auto 'checkpoint' alert_orcl.log 64: checkpoint is 446074 66: checkpoint is 446074 69: checkpoint is 446074 72: