Absolutely not a Database (WorkTable)

WorkTable is in-memory (on-disk persistence is in progress currently) storage.

Usage

WorkTable can be used just in user's code with worktable! macro. It will generate table structs and other related structs that will be used for table logic.

worktable!(
    name: Test,
    columns: {
        id: u64 primary_key autoincrement,
        test: i64,
        another: u64 optional,
        exchange: String
    },
    indexes: {
        test_idx: test unique,
        exchnage_idx: exchange,
    }
    queries: {
        update: {
            AnotherByExchange(another) by exchange,
            AnotherByTest(another) by test,
            AnotherById(another) by id,
        },
        delete: {
            ByAnother() by another,
            ByExchange() by exchange,
            ByTest() by test,
        }
    }
);

Declaration parts

name declaration

name field is used to define table's name, and is a prefix for generated objects. For example declaration above will generate struct TestWorkTable, so table struct will always have name as <name>WorkTable.

let table = TestWorkTable::default ();
let name = table.name();
assert_eq!(name, "Test");

columns declaration

columns field is used to define table's row schema. Default usage is <column_name>: <type>. But also there are some flags that can be applied to columns as <column_name>: <type> <flags>*.

Flags list:

• primary_key flag and related to it.
• optional flag.

primary_key flag declaration

If user want to mark column as primary key primary_key flag is used. This flag can be used on multiple columns at a time. Primary key generation is also supported. For some basic types autoincrement is supported. Also custom generation is available. In this case user must provide his own implementation.

#[derive(
    Archive,
    Debug,
    Default,
    Deserialize,
    Clone,
    Eq,
    From,
    PartialOrd,
    PartialEq,
    Ord,
    Serialize,
    SizeMeasure,
)]
#[rkyv(compare(PartialEq), derive(Debug))]
struct CustomId(u64);

#[derive(Debug, Default)]
pub struct Generator(AtomicU64);

impl PrimaryKeyGenerator<TestPrimaryKey> for Generator {
    fn next(&self) -> TestPrimaryKey {
        let res = self.0.fetch_add(1, Ordering::Relaxed);
        if res >= 10 {
            self.0.store(0, Ordering::Relaxed);
        }
        CustomId::from(res).into()
    }
}

impl TablePrimaryKey for TestPrimaryKey {
    type Generator = Generator;
}

worktable!(
  name: Test,
  columns: {
    id: CustomId primary_key custom,
    test: u64
  }
);

For primary key newtype is generated for declared type:

// Generated code
#[derive(
    Clone,
    rkyv::Archive,
    Debug,
    rkyv::Deserialize,
    rkyv::Serialize,
    From,
    Eq,
    Into,
    PartialEq,
    PartialOrd,
    Ord
)]
pub struct TestPrimaryKey(u64);

optional flag declaration

If column field is Option<T>, optional flag can be used like it was done in declaration.

another: u64 optional,

Row type generation

For described column row type struct is generated:

// Generated code
#[derive(
    rkyv::Archive,
    Debug,
    rkyv::Deserialize,
    Clone,
    rkyv::Serialize,
    PartialEq
)]
#[rkyv(derive(Debug))]
#[repr(C)]
pub struct TestRow {
    pub id: u64,
    pub test: i64,
    pub another: Option<u64>,
    pub exchange: String,
}

This struct is used in WorkTable interface and will be used by users.

indexes declaration

indexes field is used to define table's index schema. Default usage is <index_name>: <column_name> <unique>?.

Index allows faster access to data by some field. Adding indexes field adds methods to the generated WorkTable. This method for now is select_by_<indexed_column_name>. It will be described below.

Default implemented queries

There are some default query implementations that are available for all WorkTable's:

• select(&self, pk: <Name>PrimaryKey) -> Option<<Name>Row>;
• insert(&self, row: <Name>Row) -> Result<<Name>PrimaryKey, WorkTableError>;
• upsert(&self, row: <Name>Row) -> Result<(), WorkTableError>;
• update(&self, row: <Name>Row) -> Result<(), WorkTableError>;
• delete(&self, pk: <Name>PrimaryKey) -> Result<(), WorkTableError>;
• select_all<'a>(&'a self) -> SelectQueryBuilder<'a, <Name>Row, Self>;

queries declaration

indexes field is used to define table's queries schema. Queries are used to update/select/delete data.

queries: {
    update: {
        AnotherByExchange(another) by exchange,
        AnotherByTest(another) by test,
        AnotherById(another) by id,
    },
    delete: {
        ByAnother() by another,
        ByExchange() by exchange,
        ByTest() by test,
    }
}

Default query declaration is <QueryName>(<column_name>*) by <column_name>. It is same for update/select/delete.

For each query <QueryName>Query and <QueryName>By structs are generated. They will be used by user to call the query.

update query declaration

update queries are used to update row's data partially. Default generated update allows only full update of the row. But if user's logic needs some simultaneous update of row parts from different code parts. update logic supports smart lock logic that allows simultaneous update of not overlapping row fields.

WorkTable internals structure

worktable
    pub struct WorkTable   -- The main container that holds all data and manages its structure.

Fields

    data: DataPages<Row, DATA_LENGTH>       // stores data as pages (DataPages)
    pk_map: IndexType                       // primary index ensuring the uniqueness of records
    indexes: SecondaryIndexes               // secondary indexes for efficient searches across other columns
    pk_gen: PkGen                           // Primary Key Generator 
    lock_map: LockMap                       // from indexset crate, supports data ordering with LockMap
    table_name: &'static str                // table name (e.g., Test, which generates TestWorkTable and TestRow
    pk_phantom: PhantomData<PrimaryKey>     // a helper field for type management

Implementations 

   pub fn default() -- creates default WorkTable

worktable::in_memory
    pub struct DataPages  -- A container for managing data pages

Fields (/*private*/)

    pages: RwLock<Vec<Arc<Data<...>>>>,  // an array of pages (Data) that hold the records
    empty_links: Stack<Link>,            // a stack for storing links to deleted records
    row_count: AtomicU64,                // a counter for the current number of records
    last_page_id: AtomicU32,             // identifier for last page 
    current_page_id: AtomicU32,          // identifier for current page

Implementations

   pub fn new() -> Self
   pub fn from_data(vec: Vec<Arc<Data<<Row as StorableRow>::WrappedRow, DATA_LENGTH>>>,) -> Self
   pub fn insert(&self, row: Row) -> Result<Link, ExecutionError>   
   pub fn select(&self, link: Link) -> Result<Row, ExecutionError>
   pub fn with_ref<Op, Res>(&self, link: Link, op: Op,) -> Result<Res, ExecutionError>
   pub unsafe fn with_mut_ref<Op, Res>(&self, link: Link, op: Op,) -> Result<Res, ExecutionError>
   pub unsafe fn update<const N: usize>(&self, row: Row, link: Link,) -> Result<Link, ExecutionError>
   pub fn delete(&self, link: Link) -> Result<(), ExecutionError>
   pub fn get_bytes(&self) -> Vec<([u8; DATA_LENGTH], u32)>
   pub fn get_page_count(&self) -> usize
   pub fn get_empty_links(&self) -> Vec<Link>
   pub fn with_empty_links(self, links: Vec<Link>) -> Self

in-memory::data
    pub struct Data  -- Data itself 

Fields
    pub free_offset: AtomicU32,                        // the offset to the first free byte 
    (/* private */)   
    id: PageId,                                        // the identifier of the page
    inner_data: UnsafeCell<AlignedBytes<DATA_LENGTH>>, // a byte array where rows are stored 
    _phantom: PhantomData<Row>,                        // a helper field for type management

Implementations 

   pub fn new(id: PageId) -> Self 
   pub fn from_data_page(page: GeneralPage<DataPage<DATA_LENGTH>>) -> Self 
   pub fn set_page_id(&mut self, id: PageId) 
   pub fn save_row(&self, row: &Row) -> Result<Link, ExecutionError
   pub unsafe fn save_row_by_link(&self, row: &Row, link: Link) -> Result<Link, ExecutionError
   pub unsafe fn get_mut_row_ref
   pub fn get_row_ref(&self, link: Link) -> Result<&<Row as Archive>::Archived, ExecutionError
   pub fn get_row(&self, link: Link) -> Result<Row, ExecutionError
   pub fn get_bytes(&self) -> [u8; DATA_LENGTH] 

enum WorkTableError
    NotFound,
    AlreadyExists,
    SerializeError,
    PagesError(in_memory::PagesExecutionError),

Examples

Check out - Examples