database - How is a data dictionary/table stored in memory? -



database - How is a data dictionary/table stored in memory? -

a ddl (data definition language) compiler generates set of tables stored in info dictionary.

what info dictionary mean , how stored in memory? is because of storage dictionary in memory databases preferred on file systems? also on general note how relational table stored in memory?

(1) have false perception of ddl compiler does. first , foremost, compiler nil else compile statements. if statements executed ddl processor this. (granted, not visible beingness separate component of scheme because there no point in keeping "compiled ddl" stored somewhere repeated execution. compile & execute go hand in hand.) second, scope of operation not @ limited "generating sets of tables". example, ddl can create user-defined info types. ddl can define inter-table constraints. etc. etc.

(2) info dictionary mean ? info dictionary dictionary contains every piece of info needed describe database structures applications use.

(3) how stored in memory ? irrelevant question. interface info dictionary front-end component of ddl processing system. how own internal info structured, vendor choose, , not know.

(4) because ... ? no. info dictionaries have come hand in hand dbms systems long programmers can remember. not exclusive in-memory dbms systems.

(5) how relational table stored in memory ? tables zillions of rows aren't "stored in memory" @ all. other that, question 1 time 1 time again irrelevant. physical info independence not bug, feature. means programmers can freed having know internal structures used dbms. means programs can operate independently nitty gritty internal construction details. , means dbms vendors @ finish freedom take internal structures utilize (or not) in particular dbms product, , implies in turn question not answerable in general.

database dictionary filesystems relational-database ddl

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