mirror/postgresql
2
0
Fork 0
mirror of https://git.postgresql.org/git/postgresql.git synced 2025-03-31 20:20:44 +08:00
Code Issues Packages Projects Releases Wiki Activity

Set all variable-length fields of pg_attribute to null on column drop

Browse Source 
When a column is dropped, the fields attacl, attoptions, and
attfdwoptions were kept unchanged.  This is probably harmless, but it
seems wasteful, and leaves potentially dangling data lying around (for
example, attacl could contain references to users that are later also
dropped).

Change this to set those fields to null when a column is marked as
dropped.

Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://www.postgresql.org/message-id/flat/249d819d-1763-4580-8110-0bf91a0f08b7@eisentraut.org
This commit is contained in:
Peter Eisentraut 2023-12-22 21:44:55 +01:00
parent e2b73f4a4d
commit 3e2e0d5ad7
1 changed files with 19 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
src/backend/catalog/heap.c
View File

@ -1647,6 +1647,9 @@ RemoveAttributeById(Oid relid, AttrNumber attnum)
HeapTuple tuple;
Form_pg_attribute attStruct;
char newattname[NAMEDATALEN];
Datum valuesAtt[Natts_pg_attribute] = {0};
bool nullsAtt[Natts_pg_attribute] = {0};
bool replacesAtt[Natts_pg_attribute] = {0};
/*
* Grab an exclusive lock on the target table, which we will NOT release
@ -1695,24 +1698,24 @@ RemoveAttributeById(Oid relid, AttrNumber attnum)
"........pg.dropped.%d........", attnum);
namestrcpy(&(attStruct->attname), newattname);
/* clear the missing value if any */
if (attStruct->atthasmissing)
{
Datum valuesAtt[Natts_pg_attribute] = {0};
bool nullsAtt[Natts_pg_attribute] = {0};
bool replacesAtt[Natts_pg_attribute] = {0};
/* Clear the missing value */
attStruct->atthasmissing = false;
nullsAtt[Anum_pg_attribute_attmissingval - 1] = true;
replacesAtt[Anum_pg_attribute_attmissingval - 1] = true;
/* update the tuple - set atthasmissing and attmissingval */
valuesAtt[Anum_pg_attribute_atthasmissing - 1] =
BoolGetDatum(false);
replacesAtt[Anum_pg_attribute_atthasmissing - 1] = true;
valuesAtt[Anum_pg_attribute_attmissingval - 1] = (Datum) 0;
nullsAtt[Anum_pg_attribute_attmissingval - 1] = true;
replacesAtt[Anum_pg_attribute_attmissingval - 1] = true;
/*
* Clear the other variable-length fields. This saves some space in
* pg_attribute and removes no longer useful information.
*/
nullsAtt[Anum_pg_attribute_attacl - 1] = true;
replacesAtt[Anum_pg_attribute_attacl - 1] = true;
nullsAtt[Anum_pg_attribute_attoptions - 1] = true;
replacesAtt[Anum_pg_attribute_attoptions - 1] = true;
nullsAtt[Anum_pg_attribute_attfdwoptions - 1] = true;
replacesAtt[Anum_pg_attribute_attfdwoptions - 1] = true;
tuple = heap_modify_tuple(tuple, RelationGetDescr(attr_rel),
valuesAtt, nullsAtt, replacesAtt);
}
tuple = heap_modify_tuple(tuple, RelationGetDescr(attr_rel),
valuesAtt, nullsAtt, replacesAtt);
CatalogTupleUpdate(attr_rel, &tuple->t_self, tuple);