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OverviewThis will be explained beforehand.
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For internal monitoring of Altibase, it is necessary to understand the Altibase data dictionary, meta table, and performance view, called the data dictionary. In this document, the relationship between the meta table and the performance view is expressed using the entity-relationship diagram (ERD) in consideration of user understanding and convenience. This We will be explained beforehandexplain what needs to be know prior to this.
About ERD Notation
In consideration of the user's understanding and convenience, the performance view characteristics that do not have a base table are ignored, and the performance view is expressed as a table as shown below, and the key to be referenced when joining is express in FK form. To avoid confusion caused by this notation, the meta table has a yellow background and the performance view has a white background.
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Terms
This is a definition of some of the terms that may cause confusion prior to explanation.
Session
This refers to the user's access unit connected to the Altibase server. One user can have multiple sessions at the same time
Statement
As a term that means each SQL executed in a transaction, 'SQL (old) statement', 'Query(', 'Query statement),' often has the same meaning depending on the context. In this document, it is unified as 'query'.
Memory DB GC (Garbage Collector) or GC
When the user executes commit, the record before the change maintained by the MVCC (Multi Versioning Concurrency Control) technique should be deleted. Altibase operates separate threads to delete records before changes, which are called memory DB GC and disk DB GC respectively. However, since the MVCC method of the disk DB has changed since Altibase 5.3.3, the disk DB GC disappears, so only the memory DB GC exists, so it is called GC or Ager.
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