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Fix event triggers for partitioned tables

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Index DDL cascading on partitioned tables introduced a way for ALTER
TABLE to be called reentrantly.  This caused an an important deficiency
in event trigger support to be exposed: on exiting the reentrant call,
the alter table state object was clobbered, causing a crash when the
outer alter table tries to finalize its processing.  Fix the crash by
creating a stack of event trigger state objects.  There are still ways
to cause things to misbehave (and probably other crashers) with more
elaborate tricks, but at least it now doesn't crash in the obvious
scenario.

Backpatch to 9.5, where DDL deparsing of event triggers was introduced.

Reported-by: Marco Slot
Authors: Michaël Paquier, Álvaro Herrera
Discussion: https://postgr.es/m/CANNhMLCpi+HQ7M36uPfGbJZEQLyTy7XvX=5EFkpR-b1bo0uJew@mail.gmail.com
This commit is contained in:
Alvaro Herrera
2018-10-06 19:17:46 -03:00
parent 6bf278df89
commit 1a852f7c1e
11 changed files with 78 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
src/backend/commands/event_trigger.c
View File

@ -1696,11 +1696,6 @@ EventTriggerCollectSimpleCommand(ObjectAddress address,
* Note we don't collect the command immediately; instead we keep it in
* currentCommand, and only when we're done processing the subcommands we will
* add it to the command list.
*
* XXX -- this API isn't considering the possibility of an ALTER TABLE command
* being called reentrantly by an event trigger function. Do we need stackable
* commands at this level? Perhaps at least we should detect the condition and
* raise an error.
*/
void
EventTriggerAlterTableStart(Node *parsetree)
@ -1725,6 +1720,7 @@ EventTriggerAlterTableStart(Node *parsetree)
command->d.alterTable.subcmds = NIL;
command->parsetree = copyObject(parsetree);
command->parent = currentEventTriggerState->currentCommand;
currentEventTriggerState->currentCommand = command;
MemoryContextSwitchTo(oldcxt);
@ -1765,6 +1761,7 @@ EventTriggerCollectAlterTableSubcmd(Node *subcmd, ObjectAddress address)
return;
Assert(IsA(subcmd, AlterTableCmd));
Assert(OidIsValid(currentEventTriggerState->currentCommand));
Assert(OidIsValid(currentEventTriggerState->currentCommand->d.alterTable.objectId));
oldcxt = MemoryContextSwitchTo(currentEventTriggerState->cxt);
@ -1790,11 +1787,15 @@ EventTriggerCollectAlterTableSubcmd(Node *subcmd, ObjectAddress address)
void
EventTriggerAlterTableEnd(void)
{
CollectedCommand *parent;
/* ignore if event trigger context not set, or collection disabled */
if (!currentEventTriggerState ||
currentEventTriggerState->commandCollectionInhibited)
return;
parent = currentEventTriggerState->currentCommand->parent;
/* If no subcommands, don't collect */
if (list_length(currentEventTriggerState->currentCommand->d.alterTable.subcmds) != 0)
{
@ -1805,7 +1806,7 @@ EventTriggerAlterTableEnd(void)
else
pfree(currentEventTriggerState->currentCommand);
currentEventTriggerState->currentCommand = NULL;
currentEventTriggerState->currentCommand = parent;
}
/*

3
src/backend/commands/indexcmds.c
View File

@ -34,6 +34,7 @@
#include "commands/comment.h"
#include "commands/dbcommands.h"
#include "commands/defrem.h"
#include "commands/event_trigger.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "mb/pg_wchar.h"
@ -666,7 +667,7 @@ DefineIndex(Oid relationId,
* Extra checks when creating a PRIMARY KEY index.
*/
if (stmt->primary)
index_check_primary_key(rel, indexInfo, is_alter_table);
index_check_primary_key(rel, indexInfo, is_alter_table, stmt);
/*
* If this table is partitioned and we're creating a unique index or a

2
src/backend/commands/tablecmds.c
View File

@ -7045,7 +7045,7 @@ ATExecAddIndexConstraint(AlteredTableInfo *tab, Relation rel,
/* Extra checks needed if making primary key */
if (stmt->primary)
index_check_primary_key(rel, indexInfo, true);
index_check_primary_key(rel, indexInfo, true, stmt);
/* Note we currently don't support EXCLUSION constraints here */
if (stmt->primary)

4
src/backend/commands/view.c
View File

@ -61,6 +61,8 @@ validateWithCheckOption(const char *value)
*
* Create a view relation and use the rules system to store the query
* for the view.
*
* EventTriggerAlterTableStart must have been called already.
*---------------------------------------------------------------------
*/
static ObjectAddress
@ -186,6 +188,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
atcmds = lappend(atcmds, atcmd);
}
/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
AlterTableInternal(viewOid, atcmds, true);
/* Make the new view columns visible */
@ -217,6 +220,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
atcmd->def = (Node *) options;
atcmds = list_make1(atcmd);
/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
AlterTableInternal(viewOid, atcmds, true);
ObjectAddressSet(address, RelationRelationId, viewOid);