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How to force caching of Firebird database to file cache of OS

As you know, Firebird uses the file cache of OS intensively (especially on Classic/SuperClassic), and on modern servers, we can often have a lot of RAM, so, potentially, the database file can be 100% cached in RAM.
So, how to force it? (please notice, that question "Is it a good idea to force caching" is not discussed here :))

The fastest way to force caching of the database file to the file cache is to run the database statistics command.
Do the following:

  1. Download RAMMap tool
  2. Run it and open tab Files, then sort on size, to see the current allocation of memory, make the screenshot
  3. Run the following command gstat -r localhost:Path/to/your/database -user SYSDBA -pass yourpass > 1.txt  (remember, gstat reads the database from the beginning to the end, so this operation can take a long time, usually depends on the speed of disks)
  4. In RAMMap, hit F5 to renew the memory information
Of course, ## 1,2,4 are needed just to see the effect of #3, and work only on Windows.

In our example, we did gstat for 11Gb database:

gstat -r localhost:Path/to/your/database -user SYSDBA -pass yourpass > 1.txt 


And then, RAMMap shows the following

As you can see, the database is fully cached (11Gb, total RAM on this computer is 32Gb).

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