From 37e7779c5c44224d987a987538fb550fc7e067a3 Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Thu, 28 Sep 2023 15:07:10 +0300 Subject: [PATCH] Add support of event triggers on authenticated login The patch introduces trigger on login event, allowing to fire some actions right on the user connection. This can be useful for logging or connection check purposes as well as for some personalization of environment. Usage details are described in the documentation included, but shortly usage is the same as for other triggers: create function returning event_trigger and then create event trigger on login event. --- doc/src/sgml/event-trigger.sgml | 94 +++++++++++ src/backend/commands/event_trigger.c | 60 ++++++- src/backend/tcop/postgres.c | 4 + src/backend/utils/cache/evtcache.c | 2 + src/bin/pg_dump/t/002_pg_dump.pl | 32 ++++ src/bin/psql/tab-complete.c | 4 +- src/include/commands/event_trigger.h | 1 + src/include/tcop/cmdtaglist.h | 1 + src/include/utils/evtcache.h | 3 +- .../authentication/t/005_login_trigger.pl | 157 ++++++++++++++++++ src/test/recovery/t/001_stream_rep.pl | 23 +++ src/test/regress/expected/event_trigger.out | 31 ++++ src/test/regress/sql/event_trigger.sql | 21 +++ 13 files changed, 427 insertions(+), 6 deletions(-) create mode 100644 src/test/authentication/t/005_login_trigger.pl diff --git a/doc/src/sgml/event-trigger.sgml b/doc/src/sgml/event-trigger.sgml index 3b6a5361b34..10b20f0339a 100644 --- a/doc/src/sgml/event-trigger.sgml +++ b/doc/src/sgml/event-trigger.sgml @@ -28,6 +28,7 @@ An event trigger fires whenever the event with which it is associated occurs in the database in which it is defined. Currently, the only supported events are + login, ddl_command_start, ddl_command_end, table_rewrite @@ -35,6 +36,24 @@ Support for additional events may be added in future releases. + + The login event occurs when an authenticated user logs + into the system. Any bug in a trigger procedure for this event may + prevent successful login to the system. Such bugs may be fixed by + setting is set to false + either in a connection string or configuration file. Alternative is + restarting the system in single-user mode (as event triggers are + disabled in this mode). See the reference + page for details about using single-user mode. + The login event will also fire on standby servers. + To prevent servers from becoming inaccessible, such triggers must avoid + writing anything to the database when running on a standby. + Also, it's recommended to avoid long-running queries in + login event triggers. Notes that, for instance, + cancelling connection in psql wouldn't cancel + the in-progress login trigger. + + The ddl_command_start event occurs just before the execution of a CREATE, ALTER, DROP, @@ -1300,4 +1319,79 @@ CREATE EVENT TRIGGER no_rewrite_allowed + + + A Database Login Event Trigger Example + + + The event trigger on the login event can be + useful for logging user logins, for verifying the connection and + assigning roles according to current circumstances, or for session + data initialization. It is very important that any event trigger using + the login event checks whether or not the database is + in recovery before performing any writes. Writing to a standby server + will make it inaccessible. + + + + The following example demonstrates these options. + +-- create test tables and roles +CREATE TABLE user_login_log ( + "user" text, + "session_start" timestamp with time zone +); +CREATE ROLE day_worker; +CREATE ROLE night_worker; + +-- the example trigger function +CREATE OR REPLACE FUNCTION init_session() + RETURNS event_trigger SECURITY DEFINER + LANGUAGE plpgsql AS +$$ +DECLARE + hour integer = EXTRACT('hour' FROM current_time at time zone 'utc'); + rec boolean; +BEGIN +-- 1. Forbid logging in between 2AM and 4AM. +IF hour BETWEEN 2 AND 4 THEN + RAISE EXCEPTION 'Login forbidden'; +END IF; + +-- The checks below cannot be performed on standby servers so +-- ensure the database is not in recovery before we perform any +-- operations. +SELECT pg_is_in_recovery() INTO rec; +IF rec THEN + RETURN; +END IF; + +-- 2. Assign some roles. At daytime, grant the day_worker role, else the +-- night_worker role. +IF hour BETWEEN 8 AND 20 THEN + EXECUTE 'REVOKE night_worker FROM ' || quote_ident(session_user); + EXECUTE 'GRANT day_worker TO ' || quote_ident(session_user); +ELSE + EXECUTE 'REVOKE day_worker FROM ' || quote_ident(session_user); + EXECUTE 'GRANT night_worker TO ' || quote_ident(session_user); +END IF; + +-- 3. Initialize user session data +CREATE TEMP TABLE session_storage (x float, y integer); +ALTER TABLE session_storage OWNER TO session_user; + +-- 4. Log the connection time +INSERT INTO public.user_login_log VALUES (session_user, current_timestamp); + +END; +$$; + +-- trigger definition +CREATE EVENT TRIGGER init_session + ON login + EXECUTE FUNCTION init_session(); +ALTER EVENT TRIGGER init_session ENABLE ALWAYS; + + + diff --git a/src/backend/commands/event_trigger.c b/src/backend/commands/event_trigger.c index bd812e42d94..0a5649f84dd 100644 --- a/src/backend/commands/event_trigger.c +++ b/src/backend/commands/event_trigger.c @@ -20,6 +20,7 @@ #include "catalog/dependency.h" #include "catalog/indexing.h" #include "catalog/objectaccess.h" +#include "catalog/pg_database.h" #include "catalog/pg_event_trigger.h" #include "catalog/pg_namespace.h" #include "catalog/pg_opclass.h" @@ -37,15 +38,18 @@ #include "miscadmin.h" #include "parser/parse_func.h" #include "pgstat.h" +#include "storage/lmgr.h" #include "tcop/deparse_utility.h" #include "tcop/utility.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/evtcache.h" #include "utils/fmgroids.h" +#include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" #include "utils/rel.h" +#include "utils/snapmgr.h" #include "utils/syscache.h" typedef struct EventTriggerQueryState @@ -133,6 +137,7 @@ CreateEventTrigger(CreateEventTrigStmt *stmt) if (strcmp(stmt->eventname, "ddl_command_start") != 0 && strcmp(stmt->eventname, "ddl_command_end") != 0 && strcmp(stmt->eventname, "sql_drop") != 0 && + strcmp(stmt->eventname, "login") != 0 && strcmp(stmt->eventname, "table_rewrite") != 0) ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR), @@ -582,10 +587,15 @@ EventTriggerCommonSetup(Node *parsetree, { CommandTag dbgtag; - dbgtag = CreateCommandTag(parsetree); + if (event == EVT_Login) + dbgtag = CMDTAG_LOGIN; + else + dbgtag = CreateCommandTag(parsetree); + if (event == EVT_DDLCommandStart || event == EVT_DDLCommandEnd || - event == EVT_SQLDrop) + event == EVT_SQLDrop || + event == EVT_Login) { if (!command_tag_event_trigger_ok(dbgtag)) elog(ERROR, "unexpected command tag \"%s\"", GetCommandTagName(dbgtag)); @@ -604,7 +614,10 @@ EventTriggerCommonSetup(Node *parsetree, return NIL; /* Get the command tag. */ - tag = CreateCommandTag(parsetree); + if (event == EVT_Login) + tag = CMDTAG_LOGIN; + else + tag = CreateCommandTag(parsetree); /* * Filter list of event triggers by command tag, and copy them into our @@ -805,6 +818,47 @@ EventTriggerSQLDrop(Node *parsetree) list_free(runlist); } +/* + * Fire login event triggers if any are present. + */ +void +EventTriggerOnLogin(void) +{ + List *runlist; + EventTriggerData trigdata; + + /* + * See EventTriggerDDLCommandStart for a discussion about why event + * triggers are disabled in single user mode or via a GUC. We also need a + * database connection (some background workers doesn't have it). + */ + if (!IsUnderPostmaster || !event_triggers || !OidIsValid(MyDatabaseId)) + return; + + StartTransactionCommand(); + + /* Find login triggers and run what was found */ + runlist = EventTriggerCommonSetup(NULL, + EVT_Login, "login", + &trigdata); + + if (runlist != NIL) + { + /* Event trigger execution may require an active snapshot. */ + PushActiveSnapshot(GetTransactionSnapshot()); + + /* Run the triggers. */ + EventTriggerInvoke(runlist, &trigdata); + + /* Cleanup. */ + list_free(runlist); + + PopActiveSnapshot(); + } + + CommitTransactionCommand(); +} + /* * Fire table_rewrite triggers. diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 21b9763183e..20d8202cb7d 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -36,6 +36,7 @@ #include "access/xact.h" #include "catalog/pg_type.h" #include "commands/async.h" +#include "commands/event_trigger.h" #include "commands/prepare.h" #include "common/pg_prng.h" #include "jit/jit.h" @@ -4288,6 +4289,9 @@ PostgresMain(const char *dbname, const char *username) initStringInfo(&row_description_buf); MemoryContextSwitchTo(TopMemoryContext); + /* Fire any defined login event triggers, if appropriate */ + EventTriggerOnLogin(); + /* * POSTGRES main processing loop begins here * diff --git a/src/backend/utils/cache/evtcache.c b/src/backend/utils/cache/evtcache.c index b080f7a35f3..ab5111c90fd 100644 --- a/src/backend/utils/cache/evtcache.c +++ b/src/backend/utils/cache/evtcache.c @@ -167,6 +167,8 @@ BuildEventTriggerCache(void) event = EVT_SQLDrop; else if (strcmp(evtevent, "table_rewrite") == 0) event = EVT_TableRewrite; + else if (strcmp(evtevent, "login") == 0) + event = EVT_Login; else continue; diff --git a/src/bin/pg_dump/t/002_pg_dump.pl b/src/bin/pg_dump/t/002_pg_dump.pl index 55e98ec8e39..04813d0e511 100644 --- a/src/bin/pg_dump/t/002_pg_dump.pl +++ b/src/bin/pg_dump/t/002_pg_dump.pl @@ -2133,6 +2133,25 @@ my %tests = ( }, }, + 'CREATE FUNCTION dump_test.login_event_trigger_func' => { + create_order => 32, + create_sql => 'CREATE FUNCTION dump_test.login_event_trigger_func() + RETURNS event_trigger LANGUAGE plpgsql + AS $$ BEGIN RETURN; END;$$;', + regexp => qr/^ + \QCREATE FUNCTION dump_test.login_event_trigger_func() RETURNS event_trigger\E + \n\s+\QLANGUAGE plpgsql\E + \n\s+AS\ \$\$ + \Q BEGIN RETURN; END;\E + \$\$;/xm, + like => + { %full_runs, %dump_test_schema_runs, section_pre_data => 1, }, + unlike => { + exclude_dump_test_schema => 1, + only_dump_measurement => 1, + }, + }, + 'CREATE OPERATOR FAMILY dump_test.op_family' => { create_order => 73, create_sql => @@ -2245,6 +2264,19 @@ my %tests = ( like => { %full_runs, section_post_data => 1, }, }, + 'CREATE EVENT TRIGGER test_login_event_trigger' => { + create_order => 33, + create_sql => 'CREATE EVENT TRIGGER test_login_event_trigger + ON login + EXECUTE FUNCTION dump_test.login_event_trigger_func();', + regexp => qr/^ + \QCREATE EVENT TRIGGER test_login_event_trigger \E + \QON login\E + \n\s+\QEXECUTE FUNCTION dump_test.login_event_trigger_func();\E + /xm, + like => { %full_runs, section_post_data => 1, }, + }, + 'CREATE TRIGGER test_trigger' => { create_order => 31, create_sql => 'CREATE TRIGGER test_trigger diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c index d30d719a1f8..2eb8ff1afca 100644 --- a/src/bin/psql/tab-complete.c +++ b/src/bin/psql/tab-complete.c @@ -3552,8 +3552,8 @@ psql_completion(const char *text, int start, int end) COMPLETE_WITH("ON"); /* Complete CREATE EVENT TRIGGER ON with event_type */ else if (Matches("CREATE", "EVENT", "TRIGGER", MatchAny, "ON")) - COMPLETE_WITH("ddl_command_start", "ddl_command_end", "sql_drop", - "table_rewrite"); + COMPLETE_WITH("ddl_command_start", "ddl_command_end", "login", + "sql_drop", "table_rewrite"); /* * Complete CREATE EVENT TRIGGER ON . EXECUTE FUNCTION diff --git a/src/include/commands/event_trigger.h b/src/include/commands/event_trigger.h index 1c925dbf257..9e3ece50d5f 100644 --- a/src/include/commands/event_trigger.h +++ b/src/include/commands/event_trigger.h @@ -56,6 +56,7 @@ extern void EventTriggerDDLCommandStart(Node *parsetree); extern void EventTriggerDDLCommandEnd(Node *parsetree); extern void EventTriggerSQLDrop(Node *parsetree); extern void EventTriggerTableRewrite(Node *parsetree, Oid tableOid, int reason); +extern void EventTriggerOnLogin(void); extern bool EventTriggerBeginCompleteQuery(void); extern void EventTriggerEndCompleteQuery(void); diff --git a/src/include/tcop/cmdtaglist.h b/src/include/tcop/cmdtaglist.h index e738ac1c097..553a31874f1 100644 --- a/src/include/tcop/cmdtaglist.h +++ b/src/include/tcop/cmdtaglist.h @@ -186,6 +186,7 @@ PG_CMDTAG(CMDTAG_INSERT, "INSERT", false, false, true) PG_CMDTAG(CMDTAG_LISTEN, "LISTEN", false, false, false) PG_CMDTAG(CMDTAG_LOAD, "LOAD", false, false, false) PG_CMDTAG(CMDTAG_LOCK_TABLE, "LOCK TABLE", false, false, false) +PG_CMDTAG(CMDTAG_LOGIN, "LOGIN", true, false, false) PG_CMDTAG(CMDTAG_MERGE, "MERGE", false, false, true) PG_CMDTAG(CMDTAG_MOVE, "MOVE", false, false, true) PG_CMDTAG(CMDTAG_NOTIFY, "NOTIFY", false, false, false) diff --git a/src/include/utils/evtcache.h b/src/include/utils/evtcache.h index d340026518a..52052e6252a 100644 --- a/src/include/utils/evtcache.h +++ b/src/include/utils/evtcache.h @@ -22,7 +22,8 @@ typedef enum EVT_DDLCommandStart, EVT_DDLCommandEnd, EVT_SQLDrop, - EVT_TableRewrite + EVT_TableRewrite, + EVT_Login, } EventTriggerEvent; typedef struct diff --git a/src/test/authentication/t/005_login_trigger.pl b/src/test/authentication/t/005_login_trigger.pl new file mode 100644 index 00000000000..fec664fb865 --- /dev/null +++ b/src/test/authentication/t/005_login_trigger.pl @@ -0,0 +1,157 @@ +# Copyright (c) 2021-2023, PostgreSQL Global Development Group + +# Tests of authentication via login trigger. Mostly for rejection via +# exception, because this scenario cannot be covered with *.sql/*.out regress +# tests. + +use strict; +use warnings; + +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Execute a psql command and compare its output towards given regexps +sub psql_command +{ + local $Test::Builder::Level = $Test::Builder::Level + 1; + my ($node, $sql, $expected_ret, $test_name, %params) = @_; + + my $connstr; + if (defined($params{connstr})) + { + $connstr = $params{connstr}; + } + else + { + $connstr = ''; + } + + # Execute command + my ($ret, $stdout, $stderr) = $node->psql('postgres', $sql, + connstr => "$connstr"); + + # Check return code + is($ret, $expected_ret, "$test_name: exit code $expected_ret"); + + # Check stdout + if (defined($params{log_like})) + { + my @log_like = @{ $params{log_like} }; + while (my $regex = shift @log_like) + { + like($stdout, $regex, "$test_name: log matches"); + } + } + if (defined($params{log_unlike})) + { + my @log_unlike = @{ $params{log_unlike} }; + while (my $regex = shift @log_unlike) + { + unlike($stdout, $regex, "$test_name: log unmatches"); + } + } + if (defined($params{log_exact})) + { + is($stdout, $params{log_exact}, "$test_name: log equals"); + } + + # Check stderr + if (defined($params{err_like})) + { + my @err_like = @{ $params{err_like} }; + while (my $regex = shift @err_like) + { + like($stderr, $regex, "$test_name: err matches"); + } + } + if (defined($params{err_unlike})) + { + my @err_unlike = @{ $params{err_unlike} }; + while (my $regex = shift @err_unlike) + { + unlike($stderr, $regex, "$test_name: err unmatches"); + } + } + if (defined($params{err_exact})) + { + is($stderr, $params{err_exact}, "$test_name: err equals"); + } + + return; +} + +# New node +my $node = PostgreSQL::Test::Cluster->new('main'); +$node->init(extra => [ '--locale=C', '--encoding=UTF8' ]); +$node->append_conf( + 'postgresql.conf', q{ +wal_level = 'logical' +max_replication_slots = 4 +max_wal_senders = 4 +}); +$node->start; + +# Create temporary roles and log table +psql_command($node, 'CREATE ROLE alice WITH LOGIN; +CREATE ROLE mallory WITH LOGIN; +CREATE TABLE user_logins(id serial, who text); +GRANT SELECT ON user_logins TO public; +', 0, 'create tmp objects', log_exact => '', err_exact => ''), ; + +# Create login event function and trigger +psql_command($node, + 'CREATE FUNCTION on_login_proc() RETURNS event_trigger AS $$ +BEGIN + INSERT INTO user_logins (who) VALUES (SESSION_USER); + IF SESSION_USER = \'mallory\' THEN + RAISE EXCEPTION \'Hello %! You are NOT welcome here!\', SESSION_USER; + END IF; + RAISE NOTICE \'Hello %! You are welcome!\', SESSION_USER; +END; +$$ LANGUAGE plpgsql SECURITY DEFINER; +', 0, 'create trigger function', log_exact => '', err_exact => ''); + +psql_command($node, + 'CREATE EVENT TRIGGER on_login_trigger ' + .'ON login EXECUTE PROCEDURE on_login_proc();', 0, + 'create event trigger', log_exact => '', err_exact => ''); +psql_command($node, 'ALTER EVENT TRIGGER on_login_trigger ENABLE ALWAYS;', 0, + 'alter event trigger', log_exact => '', + err_like => [qr/You are welcome/]); + +# Check the two requests were logged via login trigger +psql_command($node, 'SELECT COUNT(*) FROM user_logins;', 0, 'select count', + log_exact => '2', err_like => [qr/You are welcome/]); + +# Try to log as allowed Alice and disallowed Mallory (two times) +psql_command($node, 'SELECT 1;', 0, 'try alice', connstr => 'user=alice', + log_exact => '1', err_like => [qr/You are welcome/], + err_unlike => [qr/You are NOT welcome/]); +psql_command($node, 'SELECT 1;', 2, 'try mallory', connstr => 'user=mallory', + log_exact => '', err_like => [qr/You are NOT welcome/], + err_unlike => [qr/You are welcome/]); +psql_command($node, 'SELECT 1;', 2, 'try mallory', connstr => 'user=mallory', + log_exact => '', err_like => [qr/You are NOT welcome/], + err_unlike => [qr/You are welcome/]); + +# Check that Alice's login record is here, while the Mallory's one is not +psql_command($node, 'SELECT * FROM user_logins;', 0, 'select *', + log_like => [qr/3\|alice/], log_unlike => [qr/mallory/], + err_like => [qr/You are welcome/]); + +# Check total number of successful logins so far +psql_command($node, 'SELECT COUNT(*) FROM user_logins;', 0, 'select count', + log_exact => '5', err_like => [qr/You are welcome/]); + +# Cleanup the temporary stuff +psql_command($node, 'DROP EVENT TRIGGER on_login_trigger;', 0, + 'drop event trigger', log_exact => '', + err_like => [qr/You are welcome/]); +psql_command($node, 'DROP TABLE user_logins; +DROP FUNCTION on_login_proc; +DROP ROLE mallory; +DROP ROLE alice; +', 0, 'cleanup', log_exact => '', err_exact => ''); + +done_testing(); diff --git a/src/test/recovery/t/001_stream_rep.pl b/src/test/recovery/t/001_stream_rep.pl index 0c72ba09441..8644854eb39 100644 --- a/src/test/recovery/t/001_stream_rep.pl +++ b/src/test/recovery/t/001_stream_rep.pl @@ -46,6 +46,24 @@ $node_standby_2->start; $node_primary->safe_psql('postgres', "CREATE TABLE tab_int AS SELECT generate_series(1,1002) AS a"); +$node_primary->safe_psql('postgres', q{ +CREATE TABLE user_logins(id serial, who text); + +CREATE FUNCTION on_login_proc() RETURNS EVENT_TRIGGER AS $$ +BEGIN + IF NOT pg_is_in_recovery() THEN + INSERT INTO user_logins (who) VALUES (session_user); + END IF; + IF session_user = 'regress_hacker' THEN + RAISE EXCEPTION 'You are not welcome!'; + END IF; +END; +$$ LANGUAGE plpgsql SECURITY DEFINER; + +CREATE EVENT TRIGGER on_login_trigger ON login EXECUTE FUNCTION on_login_proc(); +ALTER EVENT TRIGGER on_login_trigger ENABLE ALWAYS; +}); + # Wait for standbys to catch up $node_primary->wait_for_replay_catchup($node_standby_1); $node_standby_1->wait_for_replay_catchup($node_standby_2, $node_primary); @@ -384,6 +402,11 @@ sub replay_check replay_check(); +my $evttrig = $node_standby_1->safe_psql('postgres', "SELECT evtname FROM pg_event_trigger WHERE evtevent = 'login'"); +is($evttrig, 'on_login_trigger', 'Name of login trigger'); +$evttrig = $node_standby_2->safe_psql('postgres', "SELECT evtname FROM pg_event_trigger WHERE evtevent = 'login'"); +is($evttrig, 'on_login_trigger', 'Name of login trigger'); + note "enabling hot_standby_feedback"; # Enable hs_feedback. The slot should gain an xmin. We set the status interval diff --git a/src/test/regress/expected/event_trigger.out b/src/test/regress/expected/event_trigger.out index 0b87a42d0a9..a5f6ca76e49 100644 --- a/src/test/regress/expected/event_trigger.out +++ b/src/test/regress/expected/event_trigger.out @@ -638,3 +638,34 @@ NOTICE: DROP POLICY dropped policy CREATE POLICY pguc ON event_trigger_test USING (FALSE); SET event_triggers = 'off'; DROP POLICY pguc ON event_trigger_test; +-- Login event triggers +CREATE TABLE user_logins(id serial, who text); +GRANT SELECT ON user_logins TO public; +CREATE FUNCTION on_login_proc() RETURNS event_trigger AS $$ +BEGIN + INSERT INTO user_logins (who) VALUES (SESSION_USER); + RAISE NOTICE 'You are welcome!'; +END; +$$ LANGUAGE plpgsql; +CREATE EVENT TRIGGER on_login_trigger ON login EXECUTE PROCEDURE on_login_proc(); +ALTER EVENT TRIGGER on_login_trigger ENABLE ALWAYS; +\c +NOTICE: You are welcome! +SELECT COUNT(*) FROM user_logins; + count +------- + 1 +(1 row) + +\c +NOTICE: You are welcome! +SELECT COUNT(*) FROM user_logins; + count +------- + 2 +(1 row) + +-- Cleanup +DROP TABLE user_logins; +DROP EVENT TRIGGER on_login_trigger; +DROP FUNCTION on_login_proc(); diff --git a/src/test/regress/sql/event_trigger.sql b/src/test/regress/sql/event_trigger.sql index 6f0933b9e88..8340683fe10 100644 --- a/src/test/regress/sql/event_trigger.sql +++ b/src/test/regress/sql/event_trigger.sql @@ -495,3 +495,24 @@ DROP POLICY pguc ON event_trigger_test; CREATE POLICY pguc ON event_trigger_test USING (FALSE); SET event_triggers = 'off'; DROP POLICY pguc ON event_trigger_test; + +-- Login event triggers +CREATE TABLE user_logins(id serial, who text); +GRANT SELECT ON user_logins TO public; +CREATE FUNCTION on_login_proc() RETURNS event_trigger AS $$ +BEGIN + INSERT INTO user_logins (who) VALUES (SESSION_USER); + RAISE NOTICE 'You are welcome!'; +END; +$$ LANGUAGE plpgsql; +CREATE EVENT TRIGGER on_login_trigger ON login EXECUTE PROCEDURE on_login_proc(); +ALTER EVENT TRIGGER on_login_trigger ENABLE ALWAYS; +\c +SELECT COUNT(*) FROM user_logins; +\c +SELECT COUNT(*) FROM user_logins; + +-- Cleanup +DROP TABLE user_logins; +DROP EVENT TRIGGER on_login_trigger; +DROP FUNCTION on_login_proc(); -- 2.37.1 (Apple Git-137.1)