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//! Table implementation for columnar database.
use std::collections::HashMap;
use std::path::{Path, PathBuf};
use crate::error::{Error, Result};
use crate::columnar::schema::{Schema, Field, DataType};
use crate::columnar::column::{Column, ColumnBuilder};
use crate::columnar::compression::CompressionType;
/// A table in a columnar database.
pub struct Table {
/// Table name
name: String,
/// Table schema
schema: Schema,
/// Columns in the table
columns: HashMap<String, Column>,
/// Base directory for table files
base_dir: PathBuf,
/// Number of rows in the table
row_count: u64,
}
impl Table {
/// Open a table from a directory.
pub fn open(name: &str, base_dir: &str) -> Result<Self> {
let base_path = Path::new(base_dir).join(name);
// Check if the directory exists
if !base_path.exists() || !base_path.is_dir() {
return Err(Error::InvalidArgument(format!(
"Table directory {} does not exist",
base_path.display()
)));
}
// Load schema
let schema_path = base_path.join("schema.json");
if !schema_path.exists() {
return Err(Error::InvalidArgument(format!(
"Schema file {} does not exist",
schema_path.display()
)));
}
// In a real implementation, we would parse the schema from the file
// For this example, we'll create a simple schema
let schema = Schema::new(vec![
Field::new("id", DataType::UInt64, false),
Field::new("name", DataType::String, false),
Field::new("age", DataType::UInt8, true),
Field::new("email", DataType::String, true),
Field::new("active", DataType::Boolean, false),
Field::new("created_at", DataType::Timestamp, false),
]);
// Load columns
let mut columns = HashMap::new();
let mut row_count = 0;
for field in &schema.fields {
let column_path = base_path.join(format!("{}.col", field.name));
if !column_path.exists() {
return Err(Error::InvalidArgument(format!(
"Column file {} does not exist",
column_path.display()
)));
}
let column = Column::open(column_path.to_str().unwrap())?;
// Verify that all columns have the same number of rows
if columns.is_empty() {
row_count = column.row_count();
} else if column.row_count() != row_count {
return Err(Error::InvalidArgument(format!(
"Column {} has {} rows, but expected {}",
field.name,
column.row_count(),
row_count
)));
}
columns.insert(field.name.clone(), column);
}
Ok(Table {
name: name.to_string(),
schema,
columns,
base_dir: base_path,
row_count,
})
}
/// Get the table name.
pub fn name(&self) -> &str {
&self.name
}
/// Get the table schema.
pub fn schema(&self) -> &Schema {
&self.schema
}
/// Get the number of rows in the table.
pub fn row_count(&self) -> u64 {
self.row_count
}
/// Get a column by name.
pub fn column(&self, name: &str) -> Option<&Column> {
self.columns.get(name)
}
/// Get all columns.
pub fn columns(&self) -> &HashMap<String, Column> {
&self.columns
}
/// Get the base directory path.
pub fn base_dir(&self) -> &Path {
&self.base_dir
}
}
/// Builder for creating a table.
pub struct TableBuilder {
/// Table name
name: String,
/// Table schema
schema: Schema,
/// Column builders
column_builders: HashMap<String, ColumnBuilder>,
/// Base directory for table files
base_dir: PathBuf,
/// Compression type to use for columns
#[allow(dead_code)]
compression: CompressionType,
}
impl TableBuilder {
/// Create a new table builder.
pub fn new(name: &str, schema: Schema, base_dir: &str, compression: CompressionType) -> Self {
let base_path = Path::new(base_dir).join(name);
// Create column builders
let mut column_builders = HashMap::new();
for field in &schema.fields {
let builder = ColumnBuilder::new(field.clone(), compression);
column_builders.insert(field.name.clone(), builder);
}
TableBuilder {
name: name.to_string(),
schema,
column_builders,
base_dir: base_path,
compression,
}
}
/// Add a row to the table.
pub fn add_row(&mut self, values: &HashMap<String, Option<Vec<u8>>>) -> Result<()> {
// Check that all required fields are present
for field in &self.schema.fields {
if !field.nullable && !values.contains_key(&field.name) {
return Err(Error::InvalidArgument(format!(
"Missing required field: {}",
field.name
)));
}
}
// Add values to column builders
for (name, value_opt) in values {
if let Some(builder) = self.column_builders.get_mut(name) {
if let Some(value) = value_opt {
match self.schema.field(name).unwrap().data_type {
DataType::Boolean => {
if value.len() != 1 {
return Err(Error::InvalidArgument(format!(
"Invalid boolean value for field {}",
name
)));
}
builder.append_bool(value[0] != 0)?;
},
DataType::Int8 => {
if value.len() != 1 {
return Err(Error::InvalidArgument(format!(
"Invalid i8 value for field {}",
name
)));
}
builder.append_i8(value[0] as i8)?;
},
DataType::UInt8 => {
if value.len() != 1 {
return Err(Error::InvalidArgument(format!(
"Invalid u8 value for field {}",
name
)));
}
builder.append_u8(value[0])?;
},
DataType::Int16 => {
if value.len() != 2 {
return Err(Error::InvalidArgument(format!(
"Invalid i16 value for field {}",
name
)));
}
let val = i16::from_le_bytes([value[0], value[1]]);
builder.append_i16(val)?;
},
DataType::UInt16 => {
if value.len() != 2 {
return Err(Error::InvalidArgument(format!(
"Invalid u16 value for field {}",
name
)));
}
let val = u16::from_le_bytes([value[0], value[1]]);
builder.append_u16(val)?;
},
DataType::Int32 => {
if value.len() != 4 {
return Err(Error::InvalidArgument(format!(
"Invalid i32 value for field {}",
name
)));
}
let val = i32::from_le_bytes([value[0], value[1], value[2], value[3]]);
builder.append_i32(val)?;
},
DataType::UInt32 => {
if value.len() != 4 {
return Err(Error::InvalidArgument(format!(
"Invalid u32 value for field {}",
name
)));
}
let val = u32::from_le_bytes([value[0], value[1], value[2], value[3]]);
builder.append_u32(val)?;
},
DataType::Int64 => {
if value.len() != 8 {
return Err(Error::InvalidArgument(format!(
"Invalid i64 value for field {}",
name
)));
}
let val = i64::from_le_bytes([
value[0], value[1], value[2], value[3],
value[4], value[5], value[6], value[7],
]);
builder.append_i64(val)?;
},
DataType::UInt64 => {
if value.len() != 8 {
return Err(Error::InvalidArgument(format!(
"Invalid u64 value for field {}",
name
)));
}
let val = u64::from_le_bytes([
value[0], value[1], value[2], value[3],
value[4], value[5], value[6], value[7],
]);
builder.append_u64(val)?;
},
DataType::Float32 => {
if value.len() != 4 {
return Err(Error::InvalidArgument(format!(
"Invalid f32 value for field {}",
name
)));
}
let val = f32::from_le_bytes([value[0], value[1], value[2], value[3]]);
builder.append_f32(val)?;
},
DataType::Float64 => {
if value.len() != 8 {
return Err(Error::InvalidArgument(format!(
"Invalid f64 value for field {}",
name
)));
}
let val = f64::from_le_bytes([
value[0], value[1], value[2], value[3],
value[4], value[5], value[6], value[7],
]);
builder.append_f64(val)?;
},
DataType::String => {
let s = String::from_utf8(value.clone())
.map_err(|_| Error::InvalidArgument(format!(
"Invalid UTF-8 string for field {}",
name
)))?;
builder.append_string(&s)?;
},
DataType::Binary => {
builder.append_binary(value)?;
},
DataType::FixedBinary(size) => {
if value.len() != size {
return Err(Error::InvalidArgument(format!(
"Invalid fixed binary value for field {}: expected size {}, got {}",
name,
size,
value.len()
)));
}
builder.append_binary(value)?;
},
DataType::Date => {
if value.len() != 4 {
return Err(Error::InvalidArgument(format!(
"Invalid date value for field {}",
name
)));
}
let val = i32::from_le_bytes([value[0], value[1], value[2], value[3]]);
builder.append_date(val)?;
},
DataType::Timestamp => {
if value.len() != 8 {
return Err(Error::InvalidArgument(format!(
"Invalid timestamp value for field {}",
name
)));
}
let val = i64::from_le_bytes([
value[0], value[1], value[2], value[3],
value[4], value[5], value[6], value[7],
]);
builder.append_timestamp(val)?;
},
DataType::Decimal(_, _) => {
// For simplicity, we'll skip decimal implementation in this example
return Err(Error::InvalidArgument(format!(
"Decimal type not implemented for field {}",
name
)));
},
}
} else {
builder.append_null()?;
}
}
}
Ok(())
}
/// Build the table and write it to disk.
pub fn build(&self) -> Result<Table> {
// Create the table directory
std::fs::create_dir_all(&self.base_dir)?;
// Write schema to file
// In a real implementation, we would serialize the schema to JSON
// For this example, we'll skip this step
// Write columns to files
let mut columns = HashMap::new();
let mut row_count = 0;
for (name, builder) in &self.column_builders {
let column_path = self.base_dir.join(format!("{}.col", name));
builder.write_to_file(column_path.to_str().unwrap())?;
let column = Column::open(column_path.to_str().unwrap())?;
// Verify that all columns have the same number of rows
if columns.is_empty() {
row_count = column.row_count();
} else if column.row_count() != row_count {
return Err(Error::InvalidArgument(format!(
"Column {} has {} rows, but expected {}",
name,
column.row_count(),
row_count
)));
}
columns.insert(name.clone(), column);
}
Ok(Table {
name: self.name.clone(),
schema: self.schema.clone(),
columns,
base_dir: self.base_dir.clone(),
row_count,
})
}
}