<refsynopsisdiv>
<synopsis>
-BEGIN [ WORK | TRANSACTION ] [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ]
+BEGIN [ WORK | TRANSACTION ] [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ] [ WAIT FOR LSN <replaceable class="parameter">lsn_value</replaceable> [TIMEOUT <replaceable class="parameter">number_of_milliseconds</replaceable> ] ]
<phrase>where <replaceable class="parameter">transaction_mode</replaceable> is one of:</phrase>
<xref linkend="sql-set-transaction"/>
was executed.
</para>
+
+ <para>
+ The <literal>WAIT FOR</literal> clause allows to wait for the target log
+ sequence number (<acronym>LSN</acronym>) to be replayed on standby before
+ starting the transaction in <productname>PostgreSQL</productname> databases
+ with master-standby asynchronous replication. Wait time can be limited by
+ specifying a timeout, which is measured in milliseconds and must be a positive
+ integer. If <acronym>LSN</acronym> was not reached before timeout, transaction
+ doesn't begin. Waiting can be interrupted by cancelling
+ <literal>BEGIN</literal> command.
+ </para>
</refsect1>
<refsect1>
different purpose in embedded SQL. You are advised to be careful
about the transaction semantics when porting database applications.
</para>
+
+ <para>
+ There is no <literal>WAIT FOR</literal> clause in the SQL standard.
+ </para>
</refsect1>
<refsect1>
<refsynopsisdiv>
<synopsis>
-START TRANSACTION [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ]
+START TRANSACTION [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ] [ WAIT FOR LSN <replaceable class="parameter">lsn_value</replaceable> [TIMEOUT <replaceable class="parameter">number_of_milliseconds</replaceable> ] ]
<phrase>where <replaceable class="parameter">transaction_mode</replaceable> is one of:</phrase>
characteristics, as if <xref linkend="sql-set-transaction"/> was executed. This is the same
as the <xref linkend="sql-begin"/> command.
</para>
+
+ <para>
+ The <literal>WAIT FOR</literal> clause allows to wait for the target log
+ sequence number (<acronym>LSN</acronym>) to be replayed on standby before
+ starting the transaction in <productname>PostgreSQL</productname> databases
+ with master-standby asynchronous replication. Wait time can be limited by
+ specifying a timeout, which is measured in milliseconds and must be a positive
+ integer. If <acronym>LSN</acronym> was not reached before timeout, transaction
+ doesn't begin. Waiting can be interrupted by cancelling
+ <literal>START TRANSACTION</literal> command.
+ </para>
</refsect1>
<refsect1>
omitted.
</para>
+ <para>
+ There is no <literal>WAIT FOR</literal> clause in the SQL standard.
+ </para>
+
<para>
See also the compatibility section of <xref linkend="sql-set-transaction"/>.
</para>
#include "catalog/pg_database.h"
#include "commands/progress.h"
#include "commands/tablespace.h"
+#include "commands/wait.h"
#include "common/controldata_utils.h"
#include "executor/instrument.h"
#include "miscadmin.h"
do
{
bool switchedTLI = false;
+ XLogRecPtr minWaitedLSN;
#ifdef WAL_DEBUG
if (XLOG_DEBUG ||
break;
}
+ /*
+ * If we replayed an LSN that someone was waiting for, set
+ * latches in shared memory array to notify the waiter.
+ */
+ minWaitedLSN = WaitLSNGetMin();
+ if (!XLogRecPtrIsInvalid(minWaitedLSN) &&
+ minWaitedLSN <= XLogCtl->lastReplayedEndRecPtr)
+ {
+ WaitLSNSetLatch(XLogCtl->lastReplayedEndRecPtr);
+ }
+
/* Else, try to fetch the next WAL record */
record = ReadRecord(xlogreader, LOG, false);
} while (record != NULL);
user.o \
vacuum.o \
variable.o \
- view.o
+ view.o \
+ wait.o
include $(top_srcdir)/src/backend/common.mk
--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * wait.c
+ * Implements WAIT FOR clause for BEGIN and START TRANSACTION commands.
+ * This clause allows waiting for given LSN to be replayed on standby.
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * src/backend/commands/wait.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <math.h>
+
+#include "access/xlog.h"
+#include "access/xlogdefs.h"
+#include "commands/wait.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "pgstat.h"
+#include "storage/backendid.h"
+#include "storage/pmsignal.h"
+#include "storage/proc.h"
+#include "storage/shmem.h"
+#include "storage/sinvaladt.h"
+#include "storage/spin.h"
+#include "utils/builtins.h"
+#include "utils/pg_lsn.h"
+#include "utils/timestamp.h"
+
+/*
+ * Shared memory structure representing information about LSNs, which backends
+ * are waiting for replay.
+ */
+typedef struct
+{
+ slock_t mutex; /* mutex protecting the fields below */
+ int max_backend_id; /* max backend_id present in lsns[] */
+ pg_atomic_uint64 min_lsn; /* minimal waited LSN */
+ /* per-backend array of waited LSNs */
+ XLogRecPtr lsns[FLEXIBLE_ARRAY_MEMBER];
+} WaitLSNState;
+
+static WaitLSNState * state;
+
+/*
+ * Add the wait event of the current backend to shared memory array
+ */
+static void
+WaitLSNAdd(XLogRecPtr lsn_to_wait)
+{
+ SpinLockAcquire(&state->mutex);
+ if (state->max_backend_id < MyBackendId)
+ state->max_backend_id = MyBackendId;
+
+ state->lsns[MyBackendId] = lsn_to_wait;
+
+ if (lsn_to_wait < state->min_lsn.value)
+ state->min_lsn.value = lsn_to_wait;
+ SpinLockRelease(&state->mutex);
+}
+
+/*
+ * Delete wait event of the current backend from the shared memory array.
+ */
+void
+WaitLSNDelete(void)
+{
+ int i;
+ XLogRecPtr deleted_lsn;
+
+ SpinLockAcquire(&state->mutex);
+
+ deleted_lsn = state->lsns[MyBackendId];
+ state->lsns[MyBackendId] = InvalidXLogRecPtr;
+
+ /* If we are deleting the minimal LSN, then choose the next min_lsn */
+ if (!XLogRecPtrIsInvalid(deleted_lsn) &&
+ deleted_lsn == state->min_lsn.value)
+ {
+ state->min_lsn.value = InvalidXLogRecPtr;
+ for (i = 2; i <= state->max_backend_id; i++)
+ {
+ if (!XLogRecPtrIsInvalid(state->lsns[i]) &&
+ (state->lsns[i] < state->min_lsn.value ||
+ XLogRecPtrIsInvalid(state->min_lsn.value)))
+ {
+ state->min_lsn.value = state->lsns[i];
+ }
+ }
+ }
+
+ /* If deleting from the end of the array, shorten the array's used part */
+ if (state->max_backend_id == MyBackendId)
+ {
+ for (i = (MyBackendId); i >= 2; i--)
+ if (!XLogRecPtrIsInvalid(state->lsns[i]))
+ {
+ state->max_backend_id = i;
+ break;
+ }
+ }
+
+ SpinLockRelease(&state->mutex);
+}
+
+/*
+ * Report amount of shared memory space needed for WaitLSNState
+ */
+Size
+WaitLSNShmemSize(void)
+{
+ Size size;
+
+ size = offsetof(WaitLSNState, lsns);
+ size = add_size(size, mul_size(MaxBackends + 1, sizeof(XLogRecPtr)));
+ return size;
+}
+
+/*
+ * Initialize an shared memory structure for waiting for LSN
+ */
+void
+WaitLSNShmemInit(void)
+{
+ bool found;
+ uint32 i;
+
+ state = (WaitLSNState *) ShmemInitStruct("pg_wait_lsn",
+ WaitLSNShmemSize(),
+ &found);
+ if (!found)
+ {
+ SpinLockInit(&state->mutex);
+
+ for (i = 0; i < (MaxBackends + 1); i++)
+ state->lsns[i] = InvalidXLogRecPtr;
+
+ state->max_backend_id = 0;
+ pg_atomic_init_u64(&state->min_lsn, InvalidXLogRecPtr);
+ }
+}
+
+/*
+ * Set latches in shared memory to signal that new LSN has been replayed
+ */
+void
+WaitLSNSetLatch(XLogRecPtr cur_lsn)
+{
+ uint32 i;
+ int max_backend_id;
+ PGPROC *backend;
+
+ SpinLockAcquire(&state->mutex);
+ max_backend_id = state->max_backend_id;
+
+ for (i = 2; i <= max_backend_id; i++)
+ {
+ backend = BackendIdGetProc(i);
+
+ if (backend && state->lsns[i] != 0 &&
+ state->lsns[i] <= cur_lsn)
+ {
+ SetLatch(&backend->procLatch);
+ }
+ }
+ SpinLockRelease(&state->mutex);
+}
+
+/*
+ * Get minimal LSN that some backend is waiting for
+ */
+XLogRecPtr
+WaitLSNGetMin(void)
+{
+ return state->min_lsn.value;
+}
+
+/*
+ * On WAIT use a latch to wait till LSN is replayed, postmaster dies or timeout
+ * happens. Timeout is specified in milliseconds. Returns true if LSN was
+ * reached and false otherwise.
+ */
+bool
+WaitLSNUtility(XLogRecPtr target_lsn, const int timeout_ms)
+{
+ XLogRecPtr cur_lsn;
+ int latch_events;
+ float8 endtime;
+ bool res = false;
+ bool wait_forever = (timeout_ms <= 0);
+
+ endtime = GetNowFloat() + timeout_ms / 1000.0;
+
+ latch_events = WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH;
+
+ /* Check if we already reached the needed LSN */
+ cur_lsn = GetXLogReplayRecPtr(NULL);
+ if (cur_lsn >= target_lsn)
+ return true;
+
+ WaitLSNAdd(target_lsn);
+ ResetLatch(MyLatch);
+
+ /* Recheck if LSN was reached while WaitLSNAdd() and ResetLatch() */
+ cur_lsn = GetXLogReplayRecPtr(NULL);
+ if (cur_lsn >= target_lsn)
+ return true;
+
+ for (;;)
+ {
+ int rc;
+ float8 time_left = 0;
+ long time_left_ms = 0;
+
+ time_left = endtime - GetNowFloat();
+
+ /* Use 1 second as the default timeout to check for interrupts */
+ if (wait_forever || time_left < 0 || time_left > 1.0)
+ time_left_ms = 1000;
+ else
+ time_left_ms = (long) ceil(time_left * 1000.0);
+
+ /* If interrupt, LockErrorCleanup() will do WaitLSNDelete() for us */
+ CHECK_FOR_INTERRUPTS();
+
+ /* If postmaster dies, finish immediately */
+ if (!PostmasterIsAlive())
+ break;
+
+ rc = WaitLatch(MyLatch, latch_events, time_left_ms,
+ WAIT_EVENT_CLIENT_READ);
+
+ ResetLatch(MyLatch);
+
+ if (rc & WL_LATCH_SET)
+ cur_lsn = GetXLogReplayRecPtr(NULL);
+
+ if (rc & WL_TIMEOUT)
+ {
+ time_left = endtime - GetNowFloat();
+ /* If the time specified by user has passed, stop waiting */
+ if (!wait_forever && time_left <= 0.0)
+ break;
+ cur_lsn = GetXLogReplayRecPtr(NULL);
+ }
+
+ /* If LSN has been replayed */
+ if (target_lsn <= cur_lsn)
+ break;
+ }
+
+ WaitLSNDelete();
+
+ if (cur_lsn < target_lsn)
+ ereport(WARNING,
+ (errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
+ errmsg("didn't start transaction because LSN was not reached"),
+ errhint("Try to increase wait timeout.")));
+ else
+ res = true;
+
+ return res;
+}
+
+/*
+ * Implementation of WAIT FOR clause for BEGIN and START TRANSACTION commands
+ */
+int
+WaitLSNMain(WaitClause *stmt, DestReceiver *dest)
+{
+ TupleDesc tupdesc;
+ TupOutputState *tstate;
+ XLogRecPtr target_lsn;
+ bool res = false;
+
+ target_lsn = DatumGetLSN(DirectFunctionCall1(pg_lsn_in,
+ CStringGetDatum(stmt->lsn)));
+ res = WaitLSNUtility(target_lsn, stmt->timeout);
+
+ /* Need a tuple descriptor representing a single TEXT column */
+ tupdesc = CreateTemplateTupleDesc(1);
+ TupleDescInitEntry(tupdesc, (AttrNumber) 1, "LSN reached", TEXTOID, -1, 0);
+
+ /* Prepare for projection of tuples */
+ tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsMinimalTuple);
+
+ /* Send the result */
+ do_text_output_oneline(tstate, res ? "t" : "f");
+ end_tup_output(tstate);
+ return res;
+}
COPY_STRING_FIELD(savepoint_name);
COPY_STRING_FIELD(gid);
COPY_SCALAR_FIELD(chain);
+ COPY_NODE_FIELD(wait);
return newnode;
}
+static WaitClause *
+_copyWaitClause(const WaitClause *from)
+{
+ WaitClause *newnode = makeNode(WaitClause);
+
+ COPY_STRING_FIELD(lsn);
+ COPY_SCALAR_FIELD(timeout);
+
+ return newnode;
+};
+
static CompositeTypeStmt *
_copyCompositeTypeStmt(const CompositeTypeStmt *from)
{
case T_TransactionStmt:
retval = _copyTransactionStmt(from);
break;
+ case T_WaitClause:
+ retval = _copyWaitClause(from);
+ break;
case T_CompositeTypeStmt:
retval = _copyCompositeTypeStmt(from);
break;
COMPARE_STRING_FIELD(savepoint_name);
COMPARE_STRING_FIELD(gid);
COMPARE_SCALAR_FIELD(chain);
+ COMPARE_NODE_FIELD(wait);
+
+ return true;
+}
+
+static bool
+_equalWaitClause(const WaitClause *a, const WaitClause *b)
+{
+ COMPARE_STRING_FIELD(lsn);
+ COMPARE_SCALAR_FIELD(timeout);
return true;
}
case T_TransactionStmt:
retval = _equalTransactionStmt(a, b);
break;
+ case T_WaitClause:
+ retval = _equalWaitClause(a, b);
+ break;
case T_CompositeTypeStmt:
retval = _equalCompositeTypeStmt(a, b);
break;
WRITE_LOCATION_FIELD(location);
}
+static void
+_outTransactionStmt(StringInfo str, const TransactionStmt *node)
+{
+ WRITE_NODE_TYPE("TRANSACTIONSTMT");
+
+ WRITE_STRING_FIELD(savepoint_name);
+ WRITE_STRING_FIELD(gid);
+ WRITE_NODE_FIELD(options);
+ WRITE_BOOL_FIELD(chain);
+ WRITE_ENUM_FIELD(kind, TransactionStmtKind);
+ WRITE_NODE_FIELD(wait);
+}
+
+static void
+_outWaitClause(StringInfo str, const WaitClause *node)
+{
+ WRITE_NODE_TYPE("WAITCLAUSE");
+
+ WRITE_STRING_FIELD(lsn);
+ WRITE_UINT_FIELD(timeout);
+}
+
static void
_outTableLikeClause(StringInfo str, const TableLikeClause *node)
{
case T_PartitionRangeDatum:
_outPartitionRangeDatum(str, obj);
break;
+ case T_TransactionStmt:
+ _outTransactionStmt(str, obj);
+ break;
+ case T_WaitClause:
+ _outWaitClause(str, obj);
+ break;
default:
%type <partboundspec> PartitionBoundSpec
%type <list> hash_partbound
%type <defelt> hash_partbound_elem
+%type <ival> wait_time
+%type <node> wait_for
/*
* Non-keyword token types. These are hard-wired into the "flex" lexer.
LABEL LANGUAGE LARGE_P LAST_P LATERAL_P
LEADING LEAKPROOF LEAST LEFT LEVEL LIKE LIMIT LISTEN LOAD LOCAL
- LOCALTIME LOCALTIMESTAMP LOCATION LOCK_P LOCKED LOGGED
+ LOCALTIME LOCALTIMESTAMP LOCATION LOCK_P LOCKED LOGGED LSN
MAPPING MATCH MATERIALIZED MAXVALUE METHOD MINUTE_P MINVALUE MODE MONTH_P MOVE
SUBSCRIPTION SUBSTRING SUPPORT SYMMETRIC SYSID SYSTEM_P
TABLE TABLES TABLESAMPLE TABLESPACE TEMP TEMPLATE TEMPORARY TEXT_P THEN
- TIES TIME TIMESTAMP TO TRAILING TRANSACTION TRANSFORM
+ TIES TIME TIMEOUT TIMESTAMP TO TRAILING TRANSACTION TRANSFORM
TREAT TRIGGER TRIM TRUE_P
TRUNCATE TRUSTED TYPE_P TYPES_P
VACUUM VALID VALIDATE VALIDATOR VALUE_P VALUES VARCHAR VARIADIC VARYING
VERBOSE VERSION_P VIEW VIEWS VOLATILE
- WHEN WHERE WHITESPACE_P WINDOW WITH WITHIN WITHOUT WORK WRAPPER WRITE
+ WAIT WHEN WHERE WHITESPACE_P WINDOW
+ WITH WITHIN WITHOUT WORK WRAPPER WRITE
XML_P XMLATTRIBUTES XMLCONCAT XMLELEMENT XMLEXISTS XMLFOREST XMLNAMESPACES
XMLPARSE XMLPI XMLROOT XMLSERIALIZE XMLTABLE
n->chain = $3;
$$ = (Node *)n;
}
- | BEGIN_P opt_transaction transaction_mode_list_or_empty
+ | BEGIN_P opt_transaction transaction_mode_list_or_empty wait_for
{
TransactionStmt *n = makeNode(TransactionStmt);
n->kind = TRANS_STMT_BEGIN;
n->options = $3;
+ n->wait = $4;
$$ = (Node *)n;
}
- | START TRANSACTION transaction_mode_list_or_empty
+ | START TRANSACTION transaction_mode_list_or_empty wait_for
{
TransactionStmt *n = makeNode(TransactionStmt);
n->kind = TRANS_STMT_START;
n->options = $3;
+ n->wait = $4;
$$ = (Node *)n;
}
| COMMIT opt_transaction opt_transaction_chain
| BY VALUE_P
;
+/*
+ * WAIT FOR clause of BEGIN and START TRANSACTION statements
+ */
+wait_for:
+ WAIT FOR LSN Sconst wait_time
+ {
+ WaitClause *n = makeNode(WaitClause);
+ n->lsn = $4;
+ n->timeout = $5;
+ $$ = (Node *)n;
+ }
+ | /* EMPTY */ { $$ = NULL; }
+ ;
+
+wait_time:
+ TIMEOUT Iconst { $$ = $2; }
+ | /* EMPTY */ { $$ = 0; }
+ ;
+
/*
* Aggregate decoration clauses
| LOCK_P
| LOCKED
| LOGGED
+ | LSN
| MAPPING
| MATCH
| MATERIALIZED
| TEMPORARY
| TEXT_P
| TIES
+ | TIMEOUT
| TRANSACTION
| TRANSFORM
| TRIGGER
| VIEW
| VIEWS
| VOLATILE
+ | WAIT
| WHITESPACE_P
| WITHIN
| WITHOUT
#include "access/subtrans.h"
#include "access/twophase.h"
#include "commands/async.h"
+#include "commands/wait.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/autovacuum.h"
size = add_size(size, BTreeShmemSize());
size = add_size(size, SyncScanShmemSize());
size = add_size(size, AsyncShmemSize());
+ size = add_size(size, WaitLSNShmemSize());
#ifdef EXEC_BACKEND
size = add_size(size, ShmemBackendArraySize());
#endif
SyncScanShmemInit();
AsyncShmemInit();
+ /*
+ * Init array of Latches in shared memory for WAIT
+ */
+ WaitLSNShmemInit();
+
#ifdef EXEC_BACKEND
/*
#include "access/transam.h"
#include "access/twophase.h"
#include "access/xact.h"
+#include "commands/wait.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/autovacuum.h"
AbortStrongLockAcquire();
+ /* If BEGIN WAIT FOR LSN was interrupted, then stop waiting for that LSN */
+ WaitLSNDelete();
+
/* Nothing to do if we weren't waiting for a lock */
if (lockAwaited == NULL)
{
#include "commands/user.h"
#include "commands/vacuum.h"
#include "commands/view.h"
+#include "commands/wait.h"
#include "miscadmin.h"
#include "parser/parse_utilcmd.h"
#include "postmaster/bgwriter.h"
case TRANS_STMT_START:
{
ListCell *lc;
+ WaitClause *waitstmt = (WaitClause *) stmt->wait;
+
+ /* WAIT FOR cannot be used on master */
+ if (stmt->wait && !RecoveryInProgress())
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("WAIT FOR can only be "
+ "used on standby")));
+
+ /* If needed to WAIT FOR something but failed */
+ if (stmt->wait && WaitLSNMain(waitstmt, dest) == 0)
+ break;
BeginTransactionBlock();
foreach(lc, stmt->options)
* less than the specified time when WaitLatch is terminated early by a
* non-query-canceling signal such as SIGHUP.
*/
-#define GetNowFloat() ((float8) GetCurrentTimestamp() / 1000000.0)
-
endtime = GetNowFloat() + secs;
for (;;)
--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * wait.h
+ * prototypes for commands/wait.c
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/commands/wait.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef WAIT_H
+#define WAIT_H
+
+#include "tcop/dest.h"
+#include "nodes/parsenodes.h"
+
+extern bool WaitLSNUtility(XLogRecPtr lsn, const int timeout_ms);
+extern Size WaitLSNShmemSize(void);
+extern void WaitLSNShmemInit(void);
+extern void WaitLSNSetLatch(XLogRecPtr cur_lsn);
+extern XLogRecPtr WaitLSNGetMin(void);
+extern int WaitLSNMain(WaitClause *stmt, DestReceiver *dest);
+extern void WaitLSNDelete(void);
+
+#endif /* WAIT_H */
T_StartReplicationCmd,
T_TimeLineHistoryCmd,
T_SQLCmd,
+ T_WaitClause,
/*
* TAGS FOR RANDOM OTHER STUFF
int location; /* token location, or -1 if unknown */
} OnConflictClause;
+/*
+ * WaitClause -
+ * representation of WAIT FOR clause for BEGIN and START TRANSACTION.
+ */
+typedef struct WaitClause
+{
+ NodeTag type;
+ char *lsn; /* LSN to wait for */
+ int timeout; /* Number of milliseconds to limit wait time */
+} WaitClause;
+
/*
* CommonTableExpr -
* representation of WITH list element
char *savepoint_name; /* for savepoint commands */
char *gid; /* for two-phase-commit related commands */
bool chain; /* AND CHAIN option */
+ Node *wait; /* WAIT FOR clause */
} TransactionStmt;
/* ----------------------
PG_KEYWORD("lock", LOCK_P, UNRESERVED_KEYWORD)
PG_KEYWORD("locked", LOCKED, UNRESERVED_KEYWORD)
PG_KEYWORD("logged", LOGGED, UNRESERVED_KEYWORD)
+PG_KEYWORD("lsn", LSN, UNRESERVED_KEYWORD)
PG_KEYWORD("mapping", MAPPING, UNRESERVED_KEYWORD)
PG_KEYWORD("match", MATCH, UNRESERVED_KEYWORD)
PG_KEYWORD("materialized", MATERIALIZED, UNRESERVED_KEYWORD)
PG_KEYWORD("then", THEN, RESERVED_KEYWORD)
PG_KEYWORD("ties", TIES, UNRESERVED_KEYWORD)
PG_KEYWORD("time", TIME, COL_NAME_KEYWORD)
+PG_KEYWORD("timeout", TIMEOUT, UNRESERVED_KEYWORD)
PG_KEYWORD("timestamp", TIMESTAMP, COL_NAME_KEYWORD)
PG_KEYWORD("to", TO, RESERVED_KEYWORD)
PG_KEYWORD("trailing", TRAILING, RESERVED_KEYWORD)
PG_KEYWORD("view", VIEW, UNRESERVED_KEYWORD)
PG_KEYWORD("views", VIEWS, UNRESERVED_KEYWORD)
PG_KEYWORD("volatile", VOLATILE, UNRESERVED_KEYWORD)
+PG_KEYWORD("wait", WAIT, UNRESERVED_KEYWORD)
PG_KEYWORD("when", WHEN, RESERVED_KEYWORD)
PG_KEYWORD("where", WHERE, RESERVED_KEYWORD)
PG_KEYWORD("whitespace", WHITESPACE_P, UNRESERVED_KEYWORD)
extern bool TimestampTimestampTzRequiresRewrite(void);
+#define GetNowFloat() ((float8) GetCurrentTimestamp() / 1000000.0)
+
#endif /* TIMESTAMP_H */
--- /dev/null
+# Checks for BEGIN WAIT FOR LSN
+use strict;
+use warnings;
+
+use PostgresNode;
+use TestLib;
+use Test::More tests => 8;
+
+# Initialize master node
+my $node_master = get_new_node('master');
+$node_master->init(allows_streaming => 1);
+$node_master->start;
+
+# And some content and take a backup
+$node_master->safe_psql('postgres',
+ "CREATE TABLE wait_test AS SELECT generate_series(1,10) AS a");
+my $backup_name = 'my_backup';
+$node_master->backup($backup_name);
+
+# Using the backup, create a streaming standby with a 1 second delay
+my $node_standby = get_new_node('standby');
+my $delay = 1;
+$node_standby->init_from_backup($node_master, $backup_name,
+ has_streaming => 1);
+$node_standby->append_conf('postgresql.conf', qq[
+ recovery_min_apply_delay = '${delay}s'
+]);
+$node_standby->start;
+
+
+# Check that timeouts make us wait for the specified time (1s here)
+my $current_time = $node_standby->safe_psql('postgres', "SELECT now()");
+my $two_seconds = 2000; # in milliseconds
+my $start_time = time();
+$node_standby->safe_psql('postgres',
+ "BEGIN WAIT FOR LSN '0/FFFFFFFF' TIMEOUT $two_seconds");
+my $time_waited = (time() - $start_time) * 1000; # convert to milliseconds
+ok($time_waited >= $two_seconds, "WAIT FOR TIMEOUT waits for enough time");
+
+
+# Check that timeouts let us stop waiting right away, before reaching target LSN
+$node_master->safe_psql('postgres',
+ "INSERT INTO wait_test VALUES (generate_series(11, 20))");
+my $lsn1 = $node_master->safe_psql('postgres', "SELECT pg_current_wal_lsn()");
+my ($ret, $out, $err) = $node_standby->psql('postgres',
+ "BEGIN WAIT FOR LSN '$lsn1' TIMEOUT 1");
+
+ok($ret == 0, "zero return value when failed to WAIT FOR LSN on standby");
+ok($err =~ /WARNING: didn't start transaction because LSN was not reached/,
+ "correct error message when failed to WAIT FOR LSN on standby");
+ok($out eq "f", "if given too little wait time, WAIT doesn't reach target LSN");
+
+
+# Check that WAIT FOR works fine and reaches target LSN if given no timeout
+
+# Add data on master, memorize master's last LSN
+$node_master->safe_psql('postgres',
+ "INSERT INTO wait_test VALUES (generate_series(21, 30))");
+my $lsn2 = $node_master->safe_psql('postgres', "SELECT pg_current_wal_lsn()");
+
+# Wait for it to appear on replica, memorize replica's last LSN
+$node_standby->safe_psql('postgres',
+ "BEGIN WAIT FOR LSN '$lsn2'");
+my $reached_lsn = $node_standby->safe_psql('postgres',
+ "SELECT pg_last_wal_replay_lsn()");
+
+# Make sure that master's and replica's LSNs are the same after WAIT
+my $compare_lsns = $node_standby->safe_psql('postgres',
+ "SELECT pg_lsn_cmp('$reached_lsn'::pg_lsn, '$lsn2'::pg_lsn)");
+ok($compare_lsns eq 0,
+ "standby reached the same LSN as master before starting transaction");
+
+
+# Make sure that it's not allowed to use WAIT FOR on master
+($ret, $out, $err) = $node_master->psql('postgres',
+ "BEGIN WAIT FOR LSN '0/FFFFFFFF'");
+
+ok($ret != 0, "non-zero return value when trying to WAIT FOR LSN on master");
+ok($err =~ /ERROR: WAIT FOR can only be used on standby/,
+ "correct error message when trying to WAIT FOR LSN on master");
+ok($out eq '', "empty output when trying to WAIT FOR LSN on master");
+
+
+$node_standby->stop;
+$node_master->stop;
WSADATA
WSANETWORKEVENTS
WSAPROTOCOL_INFO
+WaitClause
WaitEvent
WaitEventActivity
WaitEventClient
WaitEventIPC
WaitEventSet
WaitEventTimeout
+WaitLSNState
WaitPMResult
WalCloseMethod
WalLevel
projects / users / c2main / postgres.git / commitdiff