in backend/query/information_schema_catalog.cc [2159:2343]
void InformationSchemaCatalog::FillConstraintColumnUsageTable() {
auto constraint_column_usage =
tables_by_name_.at(GetNameForDialect(kConstraintColumnUsage)).get();
std::vector<std::vector<zetasql::Value>> rows;
for (const auto* table : default_schema_->tables()) {
const auto& [table_schema_part, table_name_part] =
GetSchemaAndNameForInformationSchema(table->Name());
// Add the primary key columns.
for (const auto* key_column : table->primary_key()) {
rows.push_back({
// table_catalog
DialectTableCatalog(),
// table_schema
String(table_schema_part),
// table_name
String(table_name_part),
// column_name
String(key_column->column()->Name()),
// constraint_catalog
DialectTableCatalog(),
// constraint_schema
String(table_schema_part),
// constraint_name
String(PrimaryKeyName(table)),
});
}
// Add the NOT NULL check constraints.
for (const auto* column : table->columns()) {
if (column->is_nullable()) {
continue;
}
rows.push_back({
// table_catalog
DialectTableCatalog(),
// table_schema
String(table_schema_part),
// table_name
String(table_name_part),
// column_name
String(column->Name()),
// constraint_catalog
DialectTableCatalog(),
// constraint_schema
String(table_schema_part),
// constraint_name
String(CheckNotNullName(table, column)),
});
}
// Add the check constraints defined by the ZETASQL_VLOG keyword.
for (const auto* check_constraint : table->check_constraints()) {
for (const auto* dep_column : check_constraint->dependent_columns()) {
rows.push_back({
// table_catalog
DialectTableCatalog(),
// table_schema
String(table_schema_part),
// table_name
String(table_name_part),
// column_name
String(dep_column->Name()),
// constraint_catalog
DialectTableCatalog(),
// constraint_schema
String(table_schema_part),
// constraint_name
String(SDLObjectName::GetInSchemaName(check_constraint->Name())),
});
}
}
// Add the foreign keys.
for (const auto* foreign_key : table->foreign_keys()) {
const auto& [referenced_table_schema_part, referenced_table_name_part] =
GetSchemaAndNameForInformationSchema(
foreign_key->referenced_table()->Name());
// Add the foreign key referenced columns.
for (const auto* column : foreign_key->referenced_columns()) {
rows.push_back({
// table_catalog
DialectTableCatalog(),
// table_schema
String(referenced_table_schema_part),
// table_name
String(referenced_table_name_part),
// column_name
String(column->Name()),
// constraint_catalog
DialectTableCatalog(),
// constraint_schema
String(table_schema_part),
// constraint_name
String(SDLObjectName::GetInSchemaName(foreign_key->Name())),
});
}
// Add the foreign key's unique backing index columns.
if (foreign_key->referenced_index()) {
for (const auto* key_column :
foreign_key->referenced_index()->key_columns()) {
rows.push_back({
// table_catalog
DialectTableCatalog(),
// table_schema
String(referenced_table_schema_part),
// table_name
String(referenced_table_name_part),
// column_name
String(key_column->column()->Name()),
// constraint_catalog
DialectTableCatalog(),
// constraint_schema
String(table_schema_part),
// constraint_name
String(SDLObjectName::GetInSchemaName(
foreign_key->referenced_index()->Name())),
});
}
}
}
}
// Production doesn't add constraint column usage for the information schema
// so we also don't add it in the emulator.
if (dialect_ != DatabaseDialect::POSTGRESQL) {
// Add the information schema primary key columns.
for (const auto& table : this->tables()) {
for (int i = 0; i < table->NumColumns(); ++i) {
const auto* column = table->GetColumn(i);
const auto* metadata = FindKeyColumnMetadata(dialect_, table, column);
if (metadata == nullptr) {
continue; // Not a primary key column.
}
rows.push_back({
// table_catalog
DialectTableCatalog(),
// table_schema
String(kInformationSchema),
// table_name
String(table->Name()),
// column_name
String(metadata->column_name),
// constraint_catalog
DialectTableCatalog(),
// constraint_schema
String(kInformationSchema),
// constraint_name
String(PrimaryKeyName(table)),
});
}
}
// Add the information schema NOT NULL check constraints.
for (const auto& table : this->tables()) {
for (int i = 0; i < table->NumColumns(); ++i) {
const auto* column = table->GetColumn(i);
const auto& metadata = GetColumnMetadata(dialect_, table, column);
if (IsNullable(metadata)) {
continue;
}
rows.push_back({
// table_catalog
DialectTableCatalog(),
// table_schema
String(kInformationSchema),
// table_name
String(table->Name()),
// column_name
String(metadata.column_name),
// constraint_catalog
DialectTableCatalog(),
// constraint_schema
String(kInformationSchema),
// constraint_name
String(CheckNotNullName(table, column)),
});
}
}
}
constraint_column_usage->SetContents(rows);
}