Journal Metadata and Index

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In this article, I show you an insight into the internals of Journal Metadata and its index.

Location

Each journal record is identified by its location which consists of the data file Id, offset, size of the journal record and its type. Offset is measured from the beginning of the data file.

 

Journal Metadata and Index

 

If we know the data file Id and offset, we can move the file pointer to the offset and read the next two components which are size and type. Size includes the record header and the data length.
Journal Metadata and Index

Stored Destination

 

Journal Metadata and Index

Journal Metadata

Metadata sits in the first page of the index file. It holds the destinations page Id where the destination indexes are stored.

 

Journal Metadata and Index

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