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VTable Data/Records Location

Permanent Tables

A regular Valentina Table created by

CREATE TABLE

command of SQL, or

VDatabase.CreateTable()

API command, is created as a permanent table on disk. Such table keeps records in the ”.dat” volume of database, except BLOB values that are stored in the ”.blb” volume.

Temporary Tables

Valentina allows to create temporary tables, which makes guarantee to not affect your main data in case of system failure. Temporary tables are stored in special place, and automatically are destroyed on close of database. [Read More...] .

RAM Tables

When you create a new table you can specify where it should be located:

  • kDisk - default choice.
  • kRam

Usually you will create tables on the hard disk. But small temporary tables you may want keep in the RAM of computer.

ATTENTION: A RAM Table is Temporary always, even if this is not specified.

The main advantage of RAM Tables is the speed. They can work much faster (x10 times) than disk based tables because there is no hard disk access. But you should be very carefully with them. If you make too many/big RAM tables then OS will start swap RAM pages to the disk swap file, and you will lose any advantage.

System Tables

Valentina engine creates few system tables to keep description of database schema there.

Such system tables are stored in the “db_name.vdb” volume. This is a major volume of Valentina database! If you lost this file or corrupt it, you will not be able open database.

TIP: You can copy this file to another computer (folder) and open it by any app with Valentina engine. Engine will automatically create rest files (.dat, .blb, .ind) with empty tables, links, indexes …

User-Defined System Tables

Valentina have quite unique feature. It allows you to create own SYSTEM tables. Such table keeps own data not in the “db_name.dat” volume, but in the “db_name.vdb” volume, where is other system-level information.

This allows you to EXTEND Valentina database features and save additional information that describes your DATABASE SCHEMA to .VDB volume. For example, Valentina Studio uses this feature to add system table with Diagrams.