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Refactor: separate function to find all objects depending on a column

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Move code from ATExecAlterColumnType() that finds the all the objects
that depend on the column to a separate function.  A future patch will
reuse this code.

Author: Amul Sul <sulamul@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAAJ_b94yyJeGA-5M951_Lr+KfZokOp-2kXicpmEhi5FXhBeTog@mail.gmail.com
pull/152/head
Peter Eisentraut 2 years ago
parent 359a3c586d
commit d4e66a39eb
1 changed files with 214 additions and 194 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 408
      src/backend/commands/tablecmds.c

408
src/backend/commands/tablecmds.c
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@ -561,6 +561,8 @@ static void ATPrepAlterColumnType(List **wqueue,
static bool ATColumnChangeRequiresRewrite(Node *expr, AttrNumber varattno);
static ObjectAddress ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
AlterTableCmd *cmd, LOCKMODE lockmode);
static void RememberAllDependentForRebuilding(AlteredTableInfo *tab,
Relation rel, AttrNumber attnum, const char *colName);
static void RememberConstraintForRebuilding(Oid conoid, AlteredTableInfo *tab);
static void RememberIndexForRebuilding(Oid indoid, AlteredTableInfo *tab);
static void RememberStatisticsForRebuilding(Oid stxoid, AlteredTableInfo *tab);
@ -13298,6 +13300,215 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
* the info before executing ALTER TYPE, though, else the deparser will
* get confused.
*/
RememberAllDependentForRebuilding(tab, rel, attnum, colName);
/*
* Now scan for dependencies of this column on other things. The only
* things we should find are the dependency on the column datatype and
* possibly a collation dependency. Those can be removed.
*/
depRel = table_open(DependRelationId, RowExclusiveLock);
ScanKeyInit(&key[0],
Anum_pg_depend_classid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(RelationRelationId));
ScanKeyInit(&key[1],
Anum_pg_depend_objid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
ScanKeyInit(&key[2],
Anum_pg_depend_objsubid,
BTEqualStrategyNumber, F_INT4EQ,
Int32GetDatum((int32) attnum));
scan = systable_beginscan(depRel, DependDependerIndexId, true,
NULL, 3, key);
while (HeapTupleIsValid(depTup = systable_getnext(scan)))
{
Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(depTup);
ObjectAddress foundObject;
foundObject.classId = foundDep->refclassid;
foundObject.objectId = foundDep->refobjid;
foundObject.objectSubId = foundDep->refobjsubid;
if (foundDep->deptype != DEPENDENCY_NORMAL)
elog(ERROR, "found unexpected dependency type '%c'",
foundDep->deptype);
if (!(foundDep->refclassid == TypeRelationId &&
foundDep->refobjid == attTup->atttypid) &&
!(foundDep->refclassid == CollationRelationId &&
foundDep->refobjid == attTup->attcollation))
elog(ERROR, "found unexpected dependency for column: %s",
getObjectDescription(&foundObject, false));
CatalogTupleDelete(depRel, &depTup->t_self);
}
systable_endscan(scan);
table_close(depRel, RowExclusiveLock);
/*
* Here we go --- change the recorded column type and collation. (Note
* heapTup is a copy of the syscache entry, so okay to scribble on.) First
* fix up the missing value if any.
*/
if (attTup->atthasmissing)
{
Datum missingval;
bool missingNull;
/* if rewrite is true the missing value should already be cleared */
Assert(tab->rewrite == 0);
/* Get the missing value datum */
missingval = heap_getattr(heapTup,
Anum_pg_attribute_attmissingval,
attrelation->rd_att,
&missingNull);
/* if it's a null array there is nothing to do */
if (!missingNull)
{
/*
* Get the datum out of the array and repack it in a new array
* built with the new type data. We assume that since the table
* doesn't need rewriting, the actual Datum doesn't need to be
* changed, only the array metadata.
*/
int one = 1;
bool isNull;
Datum valuesAtt[Natts_pg_attribute] = {0};
bool nullsAtt[Natts_pg_attribute] = {0};
bool replacesAtt[Natts_pg_attribute] = {0};
HeapTuple newTup;
missingval = array_get_element(missingval,
1,
&one,
0,
attTup->attlen,
attTup->attbyval,
attTup->attalign,
&isNull);
missingval = PointerGetDatum(construct_array(&missingval,
1,
targettype,
tform->typlen,
tform->typbyval,
tform->typalign));
valuesAtt[Anum_pg_attribute_attmissingval - 1] = missingval;
replacesAtt[Anum_pg_attribute_attmissingval - 1] = true;
nullsAtt[Anum_pg_attribute_attmissingval - 1] = false;
newTup = heap_modify_tuple(heapTup, RelationGetDescr(attrelation),
valuesAtt, nullsAtt, replacesAtt);
heap_freetuple(heapTup);
heapTup = newTup;
attTup = (Form_pg_attribute) GETSTRUCT(heapTup);
}
}
attTup->atttypid = targettype;
attTup->atttypmod = targettypmod;
attTup->attcollation = targetcollid;
if (list_length(typeName->arrayBounds) > PG_INT16_MAX)
ereport(ERROR,
errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("too many array dimensions"));
attTup->attndims = list_length(typeName->arrayBounds);
attTup->attlen = tform->typlen;
attTup->attbyval = tform->typbyval;
attTup->attalign = tform->typalign;
attTup->attstorage = tform->typstorage;
attTup->attcompression = InvalidCompressionMethod;
ReleaseSysCache(typeTuple);
CatalogTupleUpdate(attrelation, &heapTup->t_self, heapTup);
table_close(attrelation, RowExclusiveLock);
/* Install dependencies on new datatype and collation */
add_column_datatype_dependency(RelationGetRelid(rel), attnum, targettype);
add_column_collation_dependency(RelationGetRelid(rel), attnum, targetcollid);
/*
* Drop any pg_statistic entry for the column, since it's now wrong type
*/
RemoveStatistics(RelationGetRelid(rel), attnum);
InvokeObjectPostAlterHook(RelationRelationId,
RelationGetRelid(rel), attnum);
/*
* Update the default, if present, by brute force --- remove and re-add
* the default. Probably unsafe to take shortcuts, since the new version
* may well have additional dependencies. (It's okay to do this now,
* rather than after other ALTER TYPE commands, since the default won't
* depend on other column types.)
*/
if (defaultexpr)
{
/*
* If it's a GENERATED default, drop its dependency records, in
* particular its INTERNAL dependency on the column, which would
* otherwise cause dependency.c to refuse to perform the deletion.
*/
if (attTup->attgenerated)
{
Oid attrdefoid = GetAttrDefaultOid(RelationGetRelid(rel), attnum);
if (!OidIsValid(attrdefoid))
elog(ERROR, "could not find attrdef tuple for relation %u attnum %d",
RelationGetRelid(rel), attnum);
(void) deleteDependencyRecordsFor(AttrDefaultRelationId, attrdefoid, false);
}
/*
* Make updates-so-far visible, particularly the new pg_attribute row
* which will be updated again.
*/
CommandCounterIncrement();
/*
* We use RESTRICT here for safety, but at present we do not expect
* anything to depend on the default.
*/
RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, true,
true);
StoreAttrDefault(rel, attnum, defaultexpr, true, false);
}
ObjectAddressSubSet(address, RelationRelationId,
RelationGetRelid(rel), attnum);
/* Cleanup */
heap_freetuple(heapTup);
return address;
}
/*
* Subroutine for ATExecAlterColumnType: Find everything that depends on the
* column (constraints, indexes, etc), and record enough information to let us
* recreate the objects.
*/
static void
RememberAllDependentForRebuilding(AlteredTableInfo *tab, Relation rel, AttrNumber attnum, const char *colName)
{
Relation depRel;
ScanKeyData key[3];
SysScanDesc scan;
HeapTuple depTup;
depRel = table_open(DependRelationId, RowExclusiveLock);
ScanKeyInit(&key[0],
@ -13414,10 +13625,9 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
col.objectSubId == attnum)
{
/*
* Ignore the column's own default expression, which
* we will deal with below.
* Ignore the column's own default expression. The
* caller deals with it.
*/
Assert(defaultexpr);
}
else
{
@ -13501,197 +13711,7 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
}
systable_endscan(scan);
/*
* Now scan for dependencies of this column on other things. The only
* things we should find are the dependency on the column datatype and
* possibly a collation dependency. Those can be removed.
*/
ScanKeyInit(&key[0],
Anum_pg_depend_classid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(RelationRelationId));
ScanKeyInit(&key[1],
Anum_pg_depend_objid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
ScanKeyInit(&key[2],
Anum_pg_depend_objsubid,
BTEqualStrategyNumber, F_INT4EQ,
Int32GetDatum((int32) attnum));
scan = systable_beginscan(depRel, DependDependerIndexId, true,
NULL, 3, key);
while (HeapTupleIsValid(depTup = systable_getnext(scan)))
{
Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(depTup);
ObjectAddress foundObject;
foundObject.classId = foundDep->refclassid;
foundObject.objectId = foundDep->refobjid;
foundObject.objectSubId = foundDep->refobjsubid;
if (foundDep->deptype != DEPENDENCY_NORMAL)
elog(ERROR, "found unexpected dependency type '%c'",
foundDep->deptype);
if (!(foundDep->refclassid == TypeRelationId &&
foundDep->refobjid == attTup->atttypid) &&
!(foundDep->refclassid == CollationRelationId &&
foundDep->refobjid == attTup->attcollation))
elog(ERROR, "found unexpected dependency for column: %s",
getObjectDescription(&foundObject, false));
CatalogTupleDelete(depRel, &depTup->t_self);
}
systable_endscan(scan);
table_close(depRel, RowExclusiveLock);
/*
* Here we go --- change the recorded column type and collation. (Note
* heapTup is a copy of the syscache entry, so okay to scribble on.) First
* fix up the missing value if any.
*/
if (attTup->atthasmissing)
{
Datum missingval;
bool missingNull;
/* if rewrite is true the missing value should already be cleared */
Assert(tab->rewrite == 0);
/* Get the missing value datum */
missingval = heap_getattr(heapTup,
Anum_pg_attribute_attmissingval,
attrelation->rd_att,
&missingNull);
/* if it's a null array there is nothing to do */
if (!missingNull)
{
/*
* Get the datum out of the array and repack it in a new array
* built with the new type data. We assume that since the table
* doesn't need rewriting, the actual Datum doesn't need to be
* changed, only the array metadata.
*/
int one = 1;
bool isNull;
Datum valuesAtt[Natts_pg_attribute] = {0};
bool nullsAtt[Natts_pg_attribute] = {0};
bool replacesAtt[Natts_pg_attribute] = {0};
HeapTuple newTup;
missingval = array_get_element(missingval,
1,
&one,
0,
attTup->attlen,
attTup->attbyval,
attTup->attalign,
&isNull);
missingval = PointerGetDatum(construct_array(&missingval,
1,
targettype,
tform->typlen,
tform->typbyval,
tform->typalign));
valuesAtt[Anum_pg_attribute_attmissingval - 1] = missingval;
replacesAtt[Anum_pg_attribute_attmissingval - 1] = true;
nullsAtt[Anum_pg_attribute_attmissingval - 1] = false;
newTup = heap_modify_tuple(heapTup, RelationGetDescr(attrelation),
valuesAtt, nullsAtt, replacesAtt);
heap_freetuple(heapTup);
heapTup = newTup;
attTup = (Form_pg_attribute) GETSTRUCT(heapTup);
}
}
attTup->atttypid = targettype;
attTup->atttypmod = targettypmod;
attTup->attcollation = targetcollid;
if (list_length(typeName->arrayBounds) > PG_INT16_MAX)
ereport(ERROR,
errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("too many array dimensions"));
attTup->attndims = list_length(typeName->arrayBounds);
attTup->attlen = tform->typlen;
attTup->attbyval = tform->typbyval;
attTup->attalign = tform->typalign;
attTup->attstorage = tform->typstorage;
attTup->attcompression = InvalidCompressionMethod;
ReleaseSysCache(typeTuple);
CatalogTupleUpdate(attrelation, &heapTup->t_self, heapTup);
table_close(attrelation, RowExclusiveLock);
/* Install dependencies on new datatype and collation */
add_column_datatype_dependency(RelationGetRelid(rel), attnum, targettype);
add_column_collation_dependency(RelationGetRelid(rel), attnum, targetcollid);
/*
* Drop any pg_statistic entry for the column, since it's now wrong type
*/
RemoveStatistics(RelationGetRelid(rel), attnum);
InvokeObjectPostAlterHook(RelationRelationId,
RelationGetRelid(rel), attnum);
/*
* Update the default, if present, by brute force --- remove and re-add
* the default. Probably unsafe to take shortcuts, since the new version
* may well have additional dependencies. (It's okay to do this now,
* rather than after other ALTER TYPE commands, since the default won't
* depend on other column types.)
*/
if (defaultexpr)
{
/*
* If it's a GENERATED default, drop its dependency records, in
* particular its INTERNAL dependency on the column, which would
* otherwise cause dependency.c to refuse to perform the deletion.
*/
if (attTup->attgenerated)
{
Oid attrdefoid = GetAttrDefaultOid(RelationGetRelid(rel), attnum);
if (!OidIsValid(attrdefoid))
elog(ERROR, "could not find attrdef tuple for relation %u attnum %d",
RelationGetRelid(rel), attnum);
(void) deleteDependencyRecordsFor(AttrDefaultRelationId, attrdefoid, false);
}
/*
* Make updates-so-far visible, particularly the new pg_attribute row
* which will be updated again.
*/
CommandCounterIncrement();
/*
* We use RESTRICT here for safety, but at present we do not expect
* anything to depend on the default.
*/
RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, true,
true);
StoreAttrDefault(rel, attnum, defaultexpr, true, false);
}
ObjectAddressSubSet(address, RelationRelationId,
RelationGetRelid(rel), attnum);
/* Cleanup */
heap_freetuple(heapTup);
return address;
table_close(depRel, NoLock);
}
/*

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