Struct ParameterTypes 

pub struct ParameterTypes(Arc<RwLock<HashMap<u64, Option<DataType>>>>);

ParameterTypes is used to record the types of the parameters during binding prepared stataments. It works by following the rules:

1. At the beginning, it contains the user specified parameters type.
2. When the binder encounters a parameter, it will record it as unknown(call record_new_param) if it didn’t exist in ParameterTypes.
3. When the binder encounters a cast on parameter, if it’s a unknown type, the cast function will record the target type as infer type for that parameter(call record_infer_type). If the parameter has been inferred, the cast function will act as a normal cast.
4. After bind finished: (a) parameter not in ParameterTypes means that the user didn’t specify it and it didn’t occur in the query. export will return error if there is a kind of parameter. This rule is compatible with PostgreSQL (b) parameter is None means that it’s a unknown type. The user didn’t specify it and we can’t infer it in the query. We will treat it as VARCHAR type finally. This rule is compatible with PostgreSQL. (c) parameter is Some means that it’s a known type.

Tuple Fields

0: Arc<RwLock<HashMap<u64, Option<DataType>>>>

Implementations

impl ParameterTypes

pub fn new(specified_param_types: Vec<Option<DataType>>) -> Self

pub fn has_infer(&self, index: u64) -> bool

pub fn read_type(&self, index: u64) -> Option<DataType>

pub fn record_new_param(&mut self, index: u64)

pub fn record_infer_type(&mut self, index: u64, data_type: &DataType)

pub fn export(&self) -> Result<Vec<DataType>>

Trait Implementations

impl Clone for ParameterTypes

fn clone(&self) -> ParameterTypes

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ParameterTypes

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.