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//! `Column` and column-level features (identity, generated, default, collation).
use serde::{Deserialize, Serialize};
use crate::identifier::{Identifier, QualifiedName};
use crate::ir::column_type::ColumnType;
use crate::ir::default_expr::DefaultExpr;
use crate::ir::eq::DiffMacro;
/// A table column.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, DiffMacro)]
pub struct Column {
/// Column name.
pub name: Identifier,
/// Canonical column type.
#[diff(via_debug)]
pub ty: ColumnType,
/// `NOT NULL` lives here, not in `Constraint`.
pub nullable: bool,
/// Optional column default.
#[diff(via_debug)]
pub default: Option<DefaultExpr>,
/// Identity specification (`GENERATED ALWAYS|BY DEFAULT AS IDENTITY`).
#[diff(via_debug)]
pub identity: Option<Identity>,
/// Generated-column specification (`GENERATED ALWAYS AS (expr) STORED`).
#[diff(via_debug)]
pub generated: Option<Generated>,
/// Optional collation.
#[diff(via_debug)]
pub collation: Option<QualifiedName>,
/// Per-column TOAST storage strategy. `None` means "PG type default".
#[diff(via_debug)]
pub storage: Option<StorageKind>,
/// Per-column TOAST compression codec. `None` means "cluster default".
#[diff(via_debug)]
pub compression: Option<Compression>,
/// Optional comment.
#[diff(via_debug)]
pub comment: Option<String>,
}
/// `GENERATED ... AS IDENTITY` specification.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct Identity {
/// `ALWAYS` or `BY DEFAULT`.
pub kind: IdentityKind,
/// Backing sequence options.
pub sequence: SequenceOptions,
}
/// Identity kind.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum IdentityKind {
/// `GENERATED ALWAYS AS IDENTITY`.
Always,
/// `GENERATED BY DEFAULT AS IDENTITY`.
ByDefault,
}
/// `GENERATED ALWAYS AS (expr) STORED` specification.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct Generated {
/// Stored vs virtual (PG only supports stored as of v17).
pub kind: GeneratedKind,
/// Generation expression.
pub expression: crate::ir::default_expr::NormalizedExpr,
}
/// Generated-column kind.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum GeneratedKind {
/// `STORED`.
Stored,
}
/// Per-column TOAST storage strategy.
///
/// Mirrors Postgres `pg_attribute.attstorage` (`p|e|x|m`). The semantic
/// effective value depends on the column's data type; see
/// [`crate::ir::canon::filter_pg_defaults`] for how an explicit
/// `Some(default)` is stripped to `None` so source and catalog round-trip equally.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum StorageKind {
/// `PLAIN` — inline only, never `TOASTed` or compressed.
Plain,
/// `EXTERNAL` — out-of-line allowed, compression forbidden.
External,
/// `EXTENDED` — out-of-line and compression allowed (default for most variable-width types).
Extended,
/// `MAIN` — compression allowed inline, out-of-line only as a last resort.
Main,
}
/// Per-column TOAST compression codec.
///
/// Mirrors the codec character stored in Postgres `pg_attribute.attcompression`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum Compression {
/// PGLZ — Postgres's historical lz-family codec; the default for clusters
/// shipped with `default_toast_compression = 'pglz'`.
Pglz,
/// LZ4 — added in PG 14; faster compression/decompression at lower ratio.
Lz4,
}
/// Sequence options that back an identity column.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct SequenceOptions {
/// Start value.
pub start: i64,
/// Increment.
pub increment: i64,
/// Min value (`None` = type minimum).
pub min_value: Option<i64>,
/// Max value (`None` = type maximum).
pub max_value: Option<i64>,
/// Cache size.
pub cache: i64,
/// Whether the sequence cycles.
pub cycle: bool,
}
#[cfg(test)]
mod tests {
use super::*;
use crate::ir::eq::Diff;
fn id(s: &str) -> Identifier {
Identifier::from_unquoted(s).unwrap()
}
fn base() -> Column {
Column {
name: id("email"),
ty: ColumnType::Text,
nullable: false,
default: None,
identity: None,
generated: None,
collation: None,
storage: None,
compression: None,
comment: None,
}
}
#[test]
fn equal_columns_have_no_diff() {
assert!(base().canonical_eq(&base()));
}
#[test]
fn type_change_diffs() {
let mut b = base();
b.ty = ColumnType::Varchar { len: Some(255) };
assert!(base().diff(&b).iter().any(|x| x.path == "ty"));
}
#[test]
fn nullability_change_diffs() {
let mut b = base();
b.nullable = true;
assert!(base().diff(&b).iter().any(|x| x.path == "nullable"));
}
#[test]
fn identity_change_diffs() {
let mut b = base();
b.identity = Some(Identity {
kind: IdentityKind::ByDefault,
sequence: SequenceOptions {
start: 1,
increment: 1,
min_value: None,
max_value: None,
cache: 1,
cycle: false,
},
});
assert!(base().diff(&b).iter().any(|x| x.path == "identity"));
}
#[test]
fn storage_change_diffs() {
let mut b = base();
b.storage = Some(StorageKind::External);
assert!(base().diff(&b).iter().any(|x| x.path == "storage"));
}
#[test]
fn compression_change_diffs() {
let mut b = base();
b.compression = Some(Compression::Lz4);
assert!(base().diff(&b).iter().any(|x| x.path == "compression"));
}
}