lamedb

This is a simplistic database that functions as a key-value store. It doesn't do much: it's that lame, hence lamedb. lamedb has only 2 fields: key and value. The db is .txt file named lamedb_kv.txt. This file holds all the records in the db. So what little does lamedb do?

1. Adds record or updates (existing) record.
2. Gets a specific record.
3. Deletes a specific record.
4. Deletes all records.
5. Shows all records.

Why is it lame?

1. It only does the aforementioned things.
2. It only supports two fields: key and value. (key, which MUST be greater than 0, is our guarantee of uniquess: no two records can have the same key.)
3. It's not thread safe, hence ill-suited for concurrent queries. (Even though you can pass multiple queries each time, we process said queries sequentially.)
4. It uses linked lists which are terrible for search. (The cpu time taken to search for records in the db grows linearly with the number of records - the time complexity is O(n), n being the number of records in the db.)

Implementation

While the db is a .txt file, every query (get, put, etc) works with an in-memory linked list. This list contains all the records in the db. And now the implementation:

1. init(ialize) db: Returns a list containing the db records. (Creates an empty file and by extension, an empty list if the db doesn't exist). Other methods can accept this list as a param.
2. p(ut) record: Adds a record to the list (if it doesn't exist). Updates existing record (if it exists). Finally, overwrites the file with the updated list.
3. g(et) record: Looks up <key> in the list. Also prints the corresponding record if the <key> exists.
4. d(elete) record: Overwrites db file with list (leaving out the record that we seek to delete).
5. c(lear) db: Drops all records. Here, we simply overwrite the db file with an empty file.
6. a(all) db: Prints all records in the db.

Compilation

$ make

Example Queries

Get a record:

$ ./lamedb g,<key>

Add a record:

$ ./lamedb p,<key>,"<value>"

Update an existing record:

$ ./lamedb p,<key>,"<value>"

Delete a record:

$ ./lamedb d,<key>

Delete/Clear all records:

$ ./lamedb c

Show all records:

$ ./lamedb a

NOTE:

1. Ideally, <value> should be a string.
2. To add a record: ./lamedb p,1,"first"; to get that record: ./lamedb g,1; to update that record: ./lamedb p,1,"one"; to delete that record ./lamedb d,1.
3. To do the above in one command: ./lamedb p,1,"first" g,1 p,1,"one" d,1. (Queries must be space separated.)