MiniDB

A small database engine written in C for study purposes.

File structure

Offset	Size	Name	Description
0	8	data_size	The size of each row (data size).
8	8	row_count	Counts how many rows are stored in the database.
16	8	free_count	The number of entries stored in the freelist index.

Usage

Define a structure

typedef struct Human
{
    char name[50];
    int age;
} Human;

minidb_create: Creates a new database file and opens a connection.

MiniDb db;
MiniDbState state = minidb_create(&db, "./mini.db", sizeof(Human));

if (state != MINIDB_OK) {
    printf("Error: %s\n", minidb_error_get_str(state));
}

minidb_open: Opens a connection to an existing database file.

MiniDb db;
MiniDbState state = minidb_open(&db, "./mini.db");

if (state != MINIDB_OK) {
    printf("Error: %s\n", minidb_error_get_str(state));
}

minidb_close: Closes a connection to the database.

MiniDb db;
MiniDbState state = minidb_open(&db, "./mini.db");

if (state != MINIDB_OK) {
    printf("Error: %s\n", minidb_error_get_str(state));
}

minidb_close(&db);

Commands

select

int64_t key = 1;
Human result;

MiniDbState state = minidb_select(&db, key, &result);
if (state == MINIDB_OK) {
    printf("Name: %s\n", result.name);
    printf("Age: %d\n", result.age);
}

insert

int64_t key = 1;
Human result;

strncpy(result.name, "John Doe", sizeof(result.name));
result.age = 20;

MiniDbState state = minidb_insert(&db, key, &result);
if (state != MINIDB_OK) {
    printf("Error: %s\n", minidb_error_get_str(state));
}

update

int64_t key = 1;
Human result;

strncpy(result.name, "A dragon", sizeof(result.name));
result.age = 5000;

MiniDbState state = minidb_update(&db, key, &result);
if (state != MINIDB_OK) {
    printf("Error: %s\n", minidb_error_get_str(state));
}

delete

int64_t key = 1;

MiniDbState state = minidb_delete(&db, key);
if (state != MINIDB_OK) {
    printf("Error: %s\n", minidb_error_get_str(state));
}