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Allow specifying column list for foreign key ON DELETE SET actions

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Extend the foreign key ON DELETE actions SET NULL and SET DEFAULT by
allowing the specification of a column list, like

    CREATE TABLE posts (
        ...
        FOREIGN KEY (tenant_id, author_id) REFERENCES users ON DELETE SET NULL (author_id)
    );

If a column list is specified, only those columns are set to
null/default, instead of all the columns in the foreign-key
constraint.

This is useful for multitenant or sharded schemas, where the tenant or
shard ID is included in the primary key of all tables but shouldn't be
set to null.

Author: Paul Martinez <paulmtz@google.com>
Discussion: https://www.postgresql.org/message-id/flat/CACqFVBZQyMYJV=njbSMxf+rbDHpx=W=B7AEaMKn8dWn9OZJY7w@mail.gmail.com
This commit is contained in:
Peter Eisentraut
2021-12-08 11:09:44 +01:00
parent e464cb7af3
commit d6f96ed94e
22 changed files with 557 additions and 72 deletions
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10
src/backend/utils/adt/ruleutils.c
View File

@ -2287,6 +2287,16 @@ pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
if (string)
appendStringInfo(&buf, " ON DELETE %s", string);
/* Add columns specified to SET NULL or SET DEFAULT if provided. */
val = SysCacheGetAttr(CONSTROID, tup,
Anum_pg_constraint_confdelsetcols, &isnull);
if (!isnull)
{
appendStringInfo(&buf, " (");
decompile_column_index_array(val, conForm->conrelid, &buf);
appendStringInfo(&buf, ")");
}
break;
}
case CONSTRAINT_PRIMARY: