diff --git a/src/backend/commands/event_trigger.c b/src/backend/commands/event_trigger.c index 6a3002f..17b0818 100644 --- a/src/backend/commands/event_trigger.c +++ b/src/backend/commands/event_trigger.c @@ -42,11 +42,14 @@ #include "utils/syscache.h" #include "tcop/utility.h" - +/* + * Data Structure for sql_drop and table_rewrite Event Trigger support. + */ typedef struct EventTriggerQueryState { slist_head SQLDropList; bool in_sql_drop; + Oid table_rewrite_oid; MemoryContext cxt; struct EventTriggerQueryState *previous; } EventTriggerQueryState; @@ -119,11 +122,14 @@ static void AlterEventTriggerOwner_internal(Relation rel, HeapTuple tup, Oid newOwnerId); static event_trigger_command_tag_check_result check_ddl_tag(const char *tag); +static event_trigger_command_tag_check_result check_table_rewrite_ddl_tag( + const char *tag); static void error_duplicate_filter_variable(const char *defname); static Datum filter_list_to_array(List *filterlist); static Oid insert_event_trigger_tuple(char *trigname, char *eventname, Oid evtOwner, Oid funcoid, List *tags); static void validate_ddl_tags(const char *filtervar, List *taglist); +static void validate_table_rewrite_tags(const char *filtervar, List *taglist); static void EventTriggerInvoke(List *fn_oid_list, EventTriggerData *trigdata); /* @@ -154,7 +160,8 @@ CreateEventTrigger(CreateEventTrigStmt *stmt) /* Validate event name. */ if (strcmp(stmt->eventname, "ddl_command_start") != 0 && strcmp(stmt->eventname, "ddl_command_end") != 0 && - strcmp(stmt->eventname, "sql_drop") != 0) + strcmp(stmt->eventname, "sql_drop") != 0 && + strcmp(stmt->eventname, "table_rewrite") != 0) ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR), errmsg("unrecognized event name \"%s\"", @@ -183,6 +190,9 @@ CreateEventTrigger(CreateEventTrigStmt *stmt) strcmp(stmt->eventname, "sql_drop") == 0) && tags != NULL) validate_ddl_tags("tag", tags); + else if (strcmp(stmt->eventname, "table_rewrite") == 0 + && tags != NULL) + validate_table_rewrite_tags("tag", tags); /* * Give user a nice error message if an event trigger of the same name @@ -281,6 +291,38 @@ check_ddl_tag(const char *tag) } /* + * Validate DDL command tags for event table_rewrite. + */ +static void +validate_table_rewrite_tags(const char *filtervar, List *taglist) +{ + ListCell *lc; + + foreach(lc, taglist) + { + const char *tag = strVal(lfirst(lc)); + event_trigger_command_tag_check_result result; + + result = check_table_rewrite_ddl_tag(tag); + if (result == EVENT_TRIGGER_COMMAND_TAG_NOT_SUPPORTED) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + /* translator: %s represents an SQL statement name */ + errmsg("event triggers are not supported for %s", + tag))); + } +} + +static event_trigger_command_tag_check_result +check_table_rewrite_ddl_tag(const char *tag) +{ + if (pg_strcasecmp(tag, "ALTER TABLE") == 0) + return EVENT_TRIGGER_COMMAND_TAG_OK; + + return EVENT_TRIGGER_COMMAND_TAG_NOT_SUPPORTED; +} + +/* * Complain about a duplicate filter variable. */ static void @@ -641,8 +683,18 @@ EventTriggerCommonSetup(Node *parsetree, const char *dbgtag; dbgtag = CreateCommandTag(parsetree); - if (check_ddl_tag(dbgtag) != EVENT_TRIGGER_COMMAND_TAG_OK) - elog(ERROR, "unexpected command tag \"%s\"", dbgtag); + if (event == EVT_DDLCommandStart || + event == EVT_DDLCommandEnd || + event == EVT_SQLDrop) + { + if (check_ddl_tag(dbgtag) != EVENT_TRIGGER_COMMAND_TAG_OK) + elog(ERROR, "unexpected command tag \"%s\"", dbgtag); + } + else if (event == EVT_TableRewrite) + { + if (check_table_rewrite_ddl_tag(dbgtag) != EVENT_TRIGGER_COMMAND_TAG_OK) + elog(ERROR, "unexpected command tag \"%s\"", dbgtag); + } } #endif @@ -838,6 +890,77 @@ EventTriggerSQLDrop(Node *parsetree) list_free(runlist); } + +/* + * Fire table_rewrite triggers. + */ +void +EventTriggerTableRewrite(Node *parsetree, Oid tableOid) +{ + List *runlist; + EventTriggerData trigdata; + + elog(DEBUG1, "EventTriggerTableRewrite(%u)", tableOid); + + /* + * Event Triggers are completely disabled in standalone mode. There are + * (at least) two reasons for this: + * + * 1. A sufficiently broken event trigger might not only render the + * database unusable, but prevent disabling itself to fix the situation. + * In this scenario, restarting in standalone mode provides an escape + * hatch. + * + * 2. BuildEventTriggerCache relies on systable_beginscan_ordered, and + * therefore will malfunction if pg_event_trigger's indexes are damaged. + * To allow recovery from a damaged index, we need some operating mode + * wherein event triggers are disabled. (Or we could implement + * heapscan-and-sort logic for that case, but having disaster recovery + * scenarios depend on code that's otherwise untested isn't appetizing.) + */ + if (!IsUnderPostmaster) + return; + + runlist = EventTriggerCommonSetup(parsetree, + EVT_TableRewrite, + "table_rewrite", + &trigdata); + if (runlist == NIL) + return; + + /* + * Make sure pg_event_trigger_table_rewrite_oid only works when running + * these triggers. Use PG_TRY to ensure table_rewrite_oid is reset even + * when one trigger fails. (This is perhaps not necessary, as the + * currentState variable will be removed shortly by our caller, but it + * seems better to play safe.) + */ + currentEventTriggerState->table_rewrite_oid = tableOid; + + /* Run the triggers. */ + PG_TRY(); + { + EventTriggerInvoke(runlist, &trigdata); + } + PG_CATCH(); + { + currentEventTriggerState->table_rewrite_oid = InvalidOid; + PG_RE_THROW(); + } + PG_END_TRY(); + + currentEventTriggerState->table_rewrite_oid = InvalidOid; + + /* Cleanup. */ + list_free(runlist); + + /* + * Make sure anything the event triggers did will be visible to the main + * command. + */ + CommandCounterIncrement(); +} + /* * Invoke each event trigger in a list of event triggers. */ @@ -871,6 +994,8 @@ EventTriggerInvoke(List *fn_oid_list, EventTriggerData *trigdata) FunctionCallInfoData fcinfo; PgStat_FunctionCallUsage fcusage; + elog(DEBUG1, "EventTriggerInvoke %u", fnoid); + /* * We want each event trigger to be able to see the results of the * previous event trigger's action. Caller is responsible for any @@ -1026,8 +1151,9 @@ EventTriggerBeginCompleteQuery(void) MemoryContext cxt; /* - * Currently, sql_drop events are the only reason to have event trigger - * state at all; so if there are none, don't install one. + * Currently, sql_drop and table_rewrite events are the only reason to + * have event trigger state at all; so if there are none, don't install + * one. */ if (!trackDroppedObjectsNeeded()) return false; @@ -1041,6 +1167,7 @@ EventTriggerBeginCompleteQuery(void) state->cxt = cxt; slist_init(&(state->SQLDropList)); state->in_sql_drop = false; + state->table_rewrite_oid = InvalidOid; state->previous = currentEventTriggerState; currentEventTriggerState = state; @@ -1080,8 +1207,9 @@ EventTriggerEndCompleteQuery(void) bool trackDroppedObjectsNeeded(void) { - /* true if any sql_drop event trigger exists */ - return list_length(EventCacheLookup(EVT_SQLDrop)) > 0; + /* true if any sql_drop or table_rewrite event trigger exists */ + return list_length(EventCacheLookup(EVT_SQLDrop)) > 0 || + list_length(EventCacheLookup(EVT_TableRewrite)) > 0; } /* @@ -1297,3 +1425,25 @@ pg_event_trigger_dropped_objects(PG_FUNCTION_ARGS) return (Datum) 0; } + +/* + * pg_event_trigger_table_rewrite_oid + * + * Make the Oid of the table going to be rewritten available to the user + * function run by the Event Trigger. + */ +Datum +pg_event_trigger_table_rewrite_oid(PG_FUNCTION_ARGS) +{ + /* + * Protect this function from being called out of context + */ + if (!currentEventTriggerState || + currentEventTriggerState->table_rewrite_oid == InvalidOid) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("%s can only be called in a table_rewrite event trigger function", + "pg_event_trigger_table_rewrite_oid()"))); + + PG_RETURN_OID(currentEventTriggerState->table_rewrite_oid); +} diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 2333e1b..776ae78 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -46,6 +46,7 @@ #include "commands/cluster.h" #include "commands/comment.h" #include "commands/defrem.h" +#include "commands/event_trigger.h" #include "commands/policy.h" #include "commands/sequence.h" #include "commands/tablecmds.h" @@ -303,13 +304,15 @@ static void validateForeignKeyConstraint(char *conname, static void createForeignKeyTriggers(Relation rel, Oid refRelOid, Constraint *fkconstraint, Oid constraintOid, Oid indexOid); -static void ATController(Relation rel, List *cmds, bool recurse, LOCKMODE lockmode); +static void ATController(AlterTableStmt *parsetree, + Relation rel, List *cmds, bool recurse, LOCKMODE lockmode); static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd, bool recurse, bool recursing, LOCKMODE lockmode); static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode); static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel, AlterTableCmd *cmd, LOCKMODE lockmode); -static void ATRewriteTables(List **wqueue, LOCKMODE lockmode); +static void ATRewriteTables(AlterTableStmt *parsetree, + List **wqueue, LOCKMODE lockmode); static void ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode); static AlteredTableInfo *ATGetQueueEntry(List **wqueue, Relation rel); static void ATSimplePermissions(Relation rel, int allowed_targets); @@ -2724,7 +2727,8 @@ AlterTable(Oid relid, LOCKMODE lockmode, AlterTableStmt *stmt) CheckTableNotInUse(rel, "ALTER TABLE"); - ATController(rel, stmt->cmds, interpretInhOption(stmt->relation->inhOpt), + ATController(stmt, + rel, stmt->cmds, interpretInhOption(stmt->relation->inhOpt), lockmode); } @@ -2747,7 +2751,7 @@ AlterTableInternal(Oid relid, List *cmds, bool recurse) rel = relation_open(relid, lockmode); - ATController(rel, cmds, recurse, lockmode); + ATController(NULL, rel, cmds, recurse, lockmode); } /* @@ -3016,7 +3020,8 @@ AlterTableGetLockLevel(List *cmds) } static void -ATController(Relation rel, List *cmds, bool recurse, LOCKMODE lockmode) +ATController(AlterTableStmt *parsetree, + Relation rel, List *cmds, bool recurse, LOCKMODE lockmode) { List *wqueue = NIL; ListCell *lcmd; @@ -3036,7 +3041,7 @@ ATController(Relation rel, List *cmds, bool recurse, LOCKMODE lockmode) ATRewriteCatalogs(&wqueue, lockmode); /* Phase 3: scan/rewrite tables as needed */ - ATRewriteTables(&wqueue, lockmode); + ATRewriteTables(parsetree, &wqueue, lockmode); } /* @@ -3607,7 +3612,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel, * ATRewriteTables: ALTER TABLE phase 3 */ static void -ATRewriteTables(List **wqueue, LOCKMODE lockmode) +ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode) { ListCell *ltab; @@ -3710,6 +3715,19 @@ ATRewriteTables(List **wqueue, LOCKMODE lockmode) heap_close(OldHeap, NoLock); /* + * Fire off an Event Trigger now, before actually rewriting the + * table. + * + * We don't support Event Trigger for nested commands anywhere, + * here included, and parstree is given NULL when comming from + * AlterTableInternal. + * + * And fire it only once. + */ + if (parsetree) + EventTriggerTableRewrite((Node *)parsetree, tab->relid); + + /* * Create transient table that will receive the modified data. * * Ensure it is marked correctly as logged or unlogged. We have diff --git a/src/backend/utils/cache/evtcache.c b/src/backend/utils/cache/evtcache.c index ae71bd6..b9d442c 100644 --- a/src/backend/utils/cache/evtcache.c +++ b/src/backend/utils/cache/evtcache.c @@ -169,6 +169,8 @@ BuildEventTriggerCache(void) event = EVT_DDLCommandEnd; else if (strcmp(evtevent, "sql_drop") == 0) event = EVT_SQLDrop; + else if (strcmp(evtevent, "table_rewrite") == 0) + event = EVT_TableRewrite; else continue; diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h index 56399ac..a3faf2c 100644 --- a/src/include/catalog/pg_proc.h +++ b/src/include/catalog/pg_proc.h @@ -5039,6 +5039,8 @@ DESCR("peek at binary changes from replication slot"); /* event triggers */ DATA(insert OID = 3566 ( pg_event_trigger_dropped_objects PGNSP PGUID 12 10 100 0 0 f f f f t t s 0 0 2249 "" "{26,26,23,25,25,25,25}" "{o,o,o,o,o,o,o}" "{classid, objid, objsubid, object_type, schema_name, object_name, object_identity}" _null_ pg_event_trigger_dropped_objects _null_ _null_ _null_ )); DESCR("list objects dropped by the current command"); +DATA(insert OID = 4566 ( pg_event_trigger_table_rewrite_oid PGNSP PGUID 12 10 100 0 0 f f f f t t s 0 0 26 "" "{26}" "{o}" "{oid}" _null_ pg_event_trigger_table_rewrite_oid _null_ _null_ _null_ )); +DESCR("return Oid of the table getting rewritten"); /* generic transition functions for ordered-set aggregates */ DATA(insert OID = 3970 ( ordered_set_transition PGNSP PGUID 12 1 0 0 0 f f f f f f i 2 0 2281 "2281 2276" _null_ _null_ _null_ _null_ ordered_set_transition _null_ _null_ _null_ )); diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h index 0233f4c..5080f4f 100644 --- a/src/include/commands/event_trigger.h +++ b/src/include/commands/event_trigger.h @@ -46,6 +46,7 @@ extern bool EventTriggerSupportsObjectClass(ObjectClass objclass); extern void EventTriggerDDLCommandStart(Node *parsetree); extern void EventTriggerDDLCommandEnd(Node *parsetree); extern void EventTriggerSQLDrop(Node *parsetree); +extern void EventTriggerTableRewrite(Node *parsetree, Oid tableOid); extern bool EventTriggerBeginCompleteQuery(void); extern void EventTriggerEndCompleteQuery(void); diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h index 417fd17..ecc11cf 100644 --- a/src/include/utils/builtins.h +++ b/src/include/utils/builtins.h @@ -1196,6 +1196,7 @@ extern Datum unique_key_recheck(PG_FUNCTION_ARGS); /* commands/event_trigger.c */ extern Datum pg_event_trigger_dropped_objects(PG_FUNCTION_ARGS); +extern Datum pg_event_trigger_table_rewrite_oid(PG_FUNCTION_ARGS); /* commands/extension.c */ extern Datum pg_available_extensions(PG_FUNCTION_ARGS); diff --git a/src/include/utils/evtcache.h b/src/include/utils/evtcache.h index c4c284f..4bbd80a 100644 --- a/src/include/utils/evtcache.h +++ b/src/include/utils/evtcache.h @@ -20,7 +20,8 @@ typedef enum { EVT_DDLCommandStart, EVT_DDLCommandEnd, - EVT_SQLDrop + EVT_SQLDrop, + EVT_TableRewrite } EventTriggerEvent; typedef struct diff --git a/src/test/regress/expected/event_trigger.out b/src/test/regress/expected/event_trigger.out index d4723b2..dbbb05e 100644 --- a/src/test/regress/expected/event_trigger.out +++ b/src/test/regress/expected/event_trigger.out @@ -294,3 +294,40 @@ SELECT * FROM dropped_objects WHERE type = 'schema'; DROP ROLE regression_bob; DROP EVENT TRIGGER regress_event_trigger_drop_objects; DROP EVENT TRIGGER undroppable; +-- only allowed from within an event trigger function, should fail +select pg_event_trigger_table_rewrite_oid(); +ERROR: pg_event_trigger_table_rewrite_oid() can only be called in a table_rewrite event trigger function +-- test Table Rewrite Event Trigger +CREATE OR REPLACE FUNCTION test_evtrig_no_rewrite() RETURNS event_trigger +LANGUAGE plpgsql AS $$ +BEGIN + RAISE EXCEPTION 'I''m sorry Sir, No Rewrite Allowed.'; +END; +$$; +create event trigger no_rewrite_allowed on table_rewrite + execute procedure test_evtrig_no_rewrite(); +create table rewriteme (id serial primary key, foo float); +insert into rewriteme + select x * 1.001 from generate_series(1, 500) as t(x); +alter table rewriteme alter column foo type numeric; +ERROR: I'm sorry Sir, No Rewrite Allowed. +alter table rewriteme add column baz int default 0; +ERROR: I'm sorry Sir, No Rewrite Allowed. +-- test with more than one reason to rewrite a single table +CREATE OR REPLACE FUNCTION test_evtrig_no_rewrite() RETURNS event_trigger +LANGUAGE plpgsql AS $$ +BEGIN + RAISE NOTICE 'Table ''%'' is being rewritten', + pg_event_trigger_table_rewrite_oid()::regclass; +END; +$$; +alter table rewriteme + add column onemore int default 0, + add column another int default -1, + alter column foo type numeric(10,4); +NOTICE: Table 'rewriteme' is being rewritten +-- shouldn't trigger a table_rewrite event +alter table rewriteme alter column foo type numeric(12,4); +drop table rewriteme; +drop event trigger no_rewrite_allowed; +drop function test_evtrig_no_rewrite(); diff --git a/src/test/regress/sql/event_trigger.sql b/src/test/regress/sql/event_trigger.sql index 11d2ce5..5b452b0 100644 --- a/src/test/regress/sql/event_trigger.sql +++ b/src/test/regress/sql/event_trigger.sql @@ -206,3 +206,44 @@ DROP ROLE regression_bob; DROP EVENT TRIGGER regress_event_trigger_drop_objects; DROP EVENT TRIGGER undroppable; + +-- only allowed from within an event trigger function, should fail +select pg_event_trigger_table_rewrite_oid(); + +-- test Table Rewrite Event Trigger +CREATE OR REPLACE FUNCTION test_evtrig_no_rewrite() RETURNS event_trigger +LANGUAGE plpgsql AS $$ +BEGIN + RAISE EXCEPTION 'I''m sorry Sir, No Rewrite Allowed.'; +END; +$$; + +create event trigger no_rewrite_allowed on table_rewrite + execute procedure test_evtrig_no_rewrite(); + +create table rewriteme (id serial primary key, foo float); +insert into rewriteme + select x * 1.001 from generate_series(1, 500) as t(x); +alter table rewriteme alter column foo type numeric; +alter table rewriteme add column baz int default 0; + +-- test with more than one reason to rewrite a single table +CREATE OR REPLACE FUNCTION test_evtrig_no_rewrite() RETURNS event_trigger +LANGUAGE plpgsql AS $$ +BEGIN + RAISE NOTICE 'Table ''%'' is being rewritten', + pg_event_trigger_table_rewrite_oid()::regclass; +END; +$$; + +alter table rewriteme + add column onemore int default 0, + add column another int default -1, + alter column foo type numeric(10,4); + +-- shouldn't trigger a table_rewrite event +alter table rewriteme alter column foo type numeric(12,4); + +drop table rewriteme; +drop event trigger no_rewrite_allowed; +drop function test_evtrig_no_rewrite();