uqa-sql 0.4.8

PostgreSQL-compatible SQL compiler built on libpg_query
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69

//
// Unified Query Algebra
//
// Copyright (c) 2023-2026 Cognica, Inc.
//

//! Discover foreign keys that depend on a deleted column in catalog order.
use crate::{
    assignment::columns::ColumnCatalogError,
    ast::{ForeignKey, TableKeyConstraint},
    SQLError,
};
pub trait ColumnRemovalCatalog {
    fn try_resolve_table_name(&self, table: &str) -> Result<Option<String>, ColumnCatalogError>;
    fn table_names(&self) -> Result<Vec<String>, ColumnCatalogError>;
    fn try_foreign_keys(&self, table: &str) -> Result<Vec<ForeignKey>, ColumnCatalogError>;
    fn try_key_constraints(
        &self,
        table: &str,
    ) -> Result<Vec<TableKeyConstraint>, ColumnCatalogError>;
}
/// Foreign keys that reference `column`, or that reference the key of a constraint whose supporting index includes it: dropping an included column drops that constraint.
pub fn foreign_keys_referencing_column(
    catalog: &dyn ColumnRemovalCatalog,
    table: &str,
    column: &str,
) -> Result<Vec<(String, String)>, SQLError> {
    let canonical = catalog
        .try_resolve_table_name(table)
        .map_err(|error| {
            crate::catalog::errors::storage_error("ALTER TABLE DROP COLUMN", error.as_ref())
        })?
        .ok_or_else(|| SQLError::UnknownTable(table.to_string()))?;
    let included_keys = catalog
        .try_key_constraints(&canonical)
        .map_err(|error| {
            crate::catalog::errors::storage_error("ALTER TABLE DROP COLUMN", error.as_ref())
        })?
        .into_iter()
        .filter(|constraint| {
            constraint
                .included_columns
                .iter()
                .any(|name| name == column)
        })
        .map(|constraint| constraint.columns)
        .collect::<Vec<_>>();
    let mut dependents = Vec::new();
    for referrer in catalog.table_names().map_err(|error| {
        crate::catalog::errors::storage_error("ALTER TABLE DROP COLUMN", error.as_ref())
    })? {
        for foreign_key in catalog.try_foreign_keys(&referrer).map_err(|error| {
            crate::catalog::errors::storage_error("ALTER TABLE DROP COLUMN", error.as_ref())
        })? {
            if foreign_key.ref_table == canonical
                && (foreign_key.ref_columns.iter().any(|name| name == column)
                    || included_keys.contains(&foreign_key.ref_columns))
            {
                dependents.push((
                    referrer.clone(),
                    foreign_key.name.clone().ok_or_else(|| {
                        SQLError::Internal("dependent FOREIGN KEY has no durable name".into())
                    })?,
                ));
            }
        }
    }
    Ok(dependents)
}