Structure of the DB

A zeroskip DB is a directory that has one or many DB files in it. There is only one 'active' file at any point in time. The active file is the one that new records are written into. The other files are finalised files and are read-only.

Every zeroskip DB is associated with a uuid (128 bit). The uuid is internal to the DB and is not known to the end user. The DB itself is identified by the name of the directory.

A zeroskip DB will typically look like this on disk:

$ ls -lRa foobar/
foobar/:
total 16
drwxr-xr-x 2 partha partha 4096 Dec 21 16:13 .
drwxr-xr-x 9 partha partha 4096 Dec 21 11:36 ..
-rw-r--r-- 1 partha partha 4524 Dec 21 11:36 zeroskip-53e8bca4-77c8-4a1f-b8a9-acbe503ae8dd-1-2
-rw-r--r-- 1 partha partha 5252 Dec 21 11:36 zeroskip-53e8bca4-77c8-4a1f-b8a9-acbe503ae8dd-3-3
-rw-r--r-- 1 partha partha  324 Dec 21 11:36 zeroskip-53e8bca4-77c8-4a1f-b8a9-acbe503ae8dd-4
-rw-r--r-- 1 partha partha   45 Dec 21 11:36 .zsdb
$

In the directory listing above, the Zeroskip DB is named foobar and the uuid of the DB is 53e8bca4-77c8-4a1f-b8a9-acbe503ae8dd. There are 4 files listed, and each one of them is explained below:

• .zsdb: This is an internal file that is used to store some metadata about the DB.
• zeroskip-53e8bca4-77c8-4a1f-b8a9-acbe503ae8dd-4: The current active file on the Zeroskip DB. This is where all the records are written to.
• zeroskip-53e8bca4-77c8-4a1f-b8a9-acbe503ae8dd-3-3: is a finalised file, that hasn't been packed yet. Files that are finalised are read-only. Multiple inalised files are packed together by a seperate process/command.
• zeroskip-53e8bca4-77c8-4a1f-b8a9-acbe503ae8dd-1-2: is a packed file. The records in packed file are sorted based on the key. As with finalised files, packed files are read-only.

The file name format of each of the files in the DB is as follows:

• zeroskip-<uuid>-<index> : represents an unpacked and unfinalised file
• zeroskip-<uuid>-<index>-<index> : represents an unpacked finalised file
• zeroskip-<uuid>-<startindex>-<endindex> : represents a packed file that includes data from files with startindex to endindex.