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This article mainly introduces "what is the field meaning of the Sequoiadb database snapshot". In the daily operation, I believe that many people have doubts about the field meaning of the Sequoiadb database snapshot. The editor consulted all kinds of materials and sorted out a simple and easy-to-use operation method. I hope it will be helpful for you to answer the doubt of "what is the field meaning of the Sequoiadb database snapshot?" Next, please follow the editor to study!

[problem description]

How to understand the following fields in the database snapshot of the orchestration node for the SDB2.8.4 version:

TotalNumConnects: the document indicates the number of database connections

How to understand the following fields in the database snapshot of a non-reconciled node:

TotalNumConnects: the document indicates the number of database connections and which connections are referred to

FreeLogSpace: documentation indicates free log space. What kind of log does it refer to?

TransInfo.BeginLSN: the document description is the offset of the transaction start LSN

Can CurrentActiveSessions+CurrentIdleSystem be understood as the total number of sessions on this node?

[reply to questions]

The above fields of snapshot SDB_SNAP_DATABASE have the following meanings:

1. For the coord node:

TotalNumConnects is the total number of connections from the client to the current cluster (including the number of connections from the client to all coord nodes in the current cluster + all data nodes + all catalog nodes). However, because v2.8coord nodes are not able to share data with each other in a distributed environment, TotalNumConnects does not show "total connections to the current cluster". In v2.8, the TotalNumConnects meaning of a coord node is: 1 coord node + all data nodes + the number of connections to all catalog nodes. Obviously, the result doesn't make much sense to users. It is recommended that users use this field after using v3.0.

two。 Corresponding to non-coord nodes:

1) TotalNumConnects: the total number of connections that all users connect directly to the current node. (pay attention to understanding the "direct connection" mentioned here.)

2) freeLogSpace: refers to the total remaining space of the synchronization log for each node. There are 20 synchronization logs per node by default, each with a default of 64m. So, at the beginning, the freeLogSpace of the node is 20 * 64m.

3) TransInfo.BeginLSN: refers to the LSN at the beginning of the oldest transaction. Because SequoiaDB transactions use synchronous logs, this field is typically used to calculate whether there is enough synchronous log space for the next write in the transaction. (this parameter does not make much sense to users, it is mainly for key developers of SequoiaDB to locate the problem.)

4) CurrentActiveSessions: the number of sessions (threads) that are working for the current node.

CurrentIdleSessions: the number of threads idle for the current node. The number of idle connections varies with the load of the node.

The number of threads such as CurrentSystemSessions:SequoiaDB internal communication threads. In general, users do not have to care about this value.

CurrentTaskSessionsSequoiaDB internal background tasks (such as asynchronous sharding, etc.). In general, users do not have to care about this value.

At this point, the study on "what is the field meaning of Sequoiadb database snapshot" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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