From c30f1770a93db1492755934048656ea809c1f569 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 4 Aug 2017 11:45:18 -0400 Subject: [PATCH] Apply ALTER ... SET NOT NULL recursively in ALTER ... ADD PRIMARY KEY. If you do ALTER COLUMN SET NOT NULL against an inheritance parent table, it will recurse to mark all the child columns as NOT NULL as well. This is necessary for consistency: if the column is labeled NOT NULL then reading it should never produce nulls. However, that didn't happen in the case where ALTER ... ADD PRIMARY KEY marks a target column NOT NULL that wasn't before. That was questionable from the beginning, and now Tushar Ahuja points out that it can lead to dump/restore failures in some cases. So let's make that case recurse too. Although this is meant to fix a bug, it's enough of a behavioral change that I'm pretty hesitant to back-patch, especially in view of the lack of similar field complaints. It doesn't seem to be too late to put it into v10 though. Michael Paquier, editorialized on slightly by me Discussion: https://postgr.es/m/b8794d6a-38f0-9d7c-ad4b-e85adf860fc9@enterprisedb.com --- src/backend/catalog/index.c | 9 ++++----- src/test/regress/expected/alter_table.out | 2 +- 2 files changed, 5 insertions(+), 6 deletions(-) diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d25b39bb54..25c5bead9f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -185,6 +185,9 @@ relationHasPrimaryKey(Relation rel) * created NOT NULL during CREATE TABLE), do an ALTER SET NOT NULL to mark * them so --- or fail if they are not in fact nonnull. * + * As of PG v10, the SET NOT NULL is applied to child tables as well, so + * that the behavior is like a manual SET NOT NULL. + * * Caller had better have at least ShareLock on the table, else the not-null * checking isn't trustworthy. */ @@ -253,17 +256,13 @@ index_check_primary_key(Relation heapRel, } /* - * XXX: Shouldn't the ALTER TABLE .. SET NOT NULL cascade to child tables? - * Currently, since the PRIMARY KEY itself doesn't cascade, we don't - * cascade the notnull constraint(s) either; but this is pretty debatable. - * * XXX: possible future improvement: when being called from ALTER TABLE, * it would be more efficient to merge this with the outer ALTER TABLE, so * as to avoid two scans. But that seems to complicate DefineIndex's API * unduly. */ if (cmds) - AlterTableInternal(RelationGetRelid(heapRel), cmds, false); + AlterTableInternal(RelationGetRelid(heapRel), cmds, true); } /* diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out index 13d6a4b747..e9fd1aacce 100644 --- a/src/test/regress/expected/alter_table.out +++ b/src/test/regress/expected/alter_table.out @@ -328,7 +328,7 @@ Number of child tables: 1 (Use \d+ to list them.) Table "public.constraint_rename_test2" Column | Type | Collation | Nullable | Default --------+---------+-----------+----------+--------- - a | integer | | | + a | integer | | not null | b | integer | | | c | integer | | | d | integer | | | -- 2.40.0