diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index f043433..e01e002 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2591,10 +2591,10 @@ include_dir 'conf.d'
data to support WAL archiving and replication, including running
read-only queries on a standby server. minimal removes all
logging except the information required to recover from a crash or
- immediate shutdown. Finally,
+ immediate shutdown. none generates no WAL in any case. Finally,
logical adds information necessary to support logical
- decoding. Each level includes the information logged at all lower
- levels. This parameter can only be set at server start.
+ decoding. Each level except for none includes the
+ information logged at all lower levels. This parameter can only be set at server start.
In minimal level, no information is logged for
@@ -2615,6 +2615,13 @@ include_dir 'conf.d'
data from a base backup and the WAL logs, so replica or
higher must be used to enable WAL archiving
() and streaming replication.
+ In the same way, none does not create WAL logs.
+ Therefore, this wal_level can be used to maximize the speed of data loading.
+ For example, bulk loading into a data warehouse environemnt or version upgrade using pg_dumpall.
+ On the other hand, an unexpected crash of the server makes the database cluster
+ inconsistent. For that reason, before utilizing this level, get a full backup of the cluster and
+ backup of the entire operations that are done under the condition that
+ wal_level is none.
In logical level, the same information is logged as
@@ -3372,7 +3379,8 @@ include_dir 'conf.d'
changed without leaving archiving mode.
This parameter can only be set at server start.
archive_mode cannot be enabled when
- wal_level is set to minimal.
+ wal_level is set to none or
+ minimal.
diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml
index 117a1f7..f035c84 100644
--- a/doc/src/sgml/perform.sgml
+++ b/doc/src/sgml/perform.sgml
@@ -1741,7 +1741,8 @@ SELECT * FROM x, y, a, b, c WHERE something AND somethingelse;
new base backup after the load has completed than to process a large
amount of incremental WAL data. To prevent incremental WAL logging
while loading, disable archiving and streaming replication, by setting
- to minimal,
+ to either none
+ or minimal,
to off, and
to zero.
But note that changing these settings requires a server restart.
@@ -1751,7 +1752,8 @@ SELECT * FROM x, y, a, b, c WHERE something AND somethingelse;
Aside from avoiding the time for the archiver or WAL sender to process the
WAL data, doing this will actually make certain commands faster, because
they do not to write WAL at all if wal_level
- is minimal and the current subtransaction (or top-level
+ is either minimal or minimal
+ and the current subtransaction (or top-level
transaction) created or truncated the table or index they change. (They
can guarantee crash safety more cheaply by doing
an fsync at the end than by writing WAL.)
diff --git a/src/backend/access/rmgrdesc/xlogdesc.c b/src/backend/access/rmgrdesc/xlogdesc.c
index 3200f77..8293b3b 100644
--- a/src/backend/access/rmgrdesc/xlogdesc.c
+++ b/src/backend/access/rmgrdesc/xlogdesc.c
@@ -25,6 +25,7 @@
* GUC support
*/
const struct config_enum_entry wal_level_options[] = {
+ {"none", WAL_LEVEL_NONE, false},
{"minimal", WAL_LEVEL_MINIMAL, false},
{"replica", WAL_LEVEL_REPLICA, false},
{"archive", WAL_LEVEL_REPLICA, true}, /* deprecated */
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 52a67b1..4a5e43b 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -4907,6 +4907,27 @@ UpdateControlFile(void)
}
/*
+ * Perform an inspection of wal_level='none'.
+ */
+void
+SafelyFinishedNoneLevel(void)
+{
+ bool unexpected_shutdown;
+
+ /*
+ * Detect if we previously crashed under wal_level='none' or not.
+ */
+ unexpected_shutdown = ControlFile->state != DB_SHUTDOWNED &&
+ ControlFile->state != DB_SHUTDOWNED_IN_RECOVERY;
+ if ((ControlFile->wal_level == WAL_LEVEL_NONE && unexpected_shutdown))
+ {
+ ereport(ERROR,
+ (errmsg("Server was unexpectedly shut down when WAL logging was disabled"),
+ errhint("It looks like you need to deploy a new cluster from your full backup again.")));
+ }
+}
+
+/*
* Returns the unique system identifier from control file.
*/
uint64
@@ -4937,6 +4958,21 @@ DataChecksumsEnabled(void)
}
/*
+ * Returns the latest LSN.
+ */
+XLogRecPtr
+GetLatestCheckPointLSN(void)
+{
+ XLogRecPtr latestLSN;
+
+ LWLockAcquire(ControlFileLock, LW_SHARED);
+ latestLSN = ControlFile->checkPoint;
+ LWLockRelease(ControlFileLock);
+
+ return latestLSN;
+}
+
+/*
* Returns a fake LSN for unlogged relations.
*
* Each call generates an LSN that is greater than any previous value
diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c
index 1f0e4e0..39765ad 100644
--- a/src/backend/access/transam/xloginsert.c
+++ b/src/backend/access/transam/xloginsert.c
@@ -449,6 +449,13 @@ XLogInsert(RmgrId rmid, uint8 info)
return EndPos;
}
+ /* Issues WAL only for transaction end and check point */
+ if (wal_level == WAL_LEVEL_NONE && rmid != RM_XLOG_ID)
+ {
+ XLogResetInsertion();
+ return GetLatestCheckPointLSN();
+ }
+
do
{
XLogRecPtr RedoRecPtr;
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 959e3b8..a365cbf 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -918,10 +918,13 @@ PostmasterMain(int argc, char *argv[])
ReservedBackends, MaxConnections);
ExitPostmaster(1);
}
- if (XLogArchiveMode > ARCHIVE_MODE_OFF && wal_level == WAL_LEVEL_MINIMAL)
+ if ((XLogArchiveMode > ARCHIVE_MODE_OFF && wal_level == WAL_LEVEL_NONE) ||
+ (XLogArchiveMode > ARCHIVE_MODE_OFF && wal_level == WAL_LEVEL_MINIMAL))
ereport(ERROR,
- (errmsg("WAL archival cannot be enabled when wal_level is \"minimal\"")));
- if (max_wal_senders > 0 && wal_level == WAL_LEVEL_MINIMAL)
+ (errmsg("WAL archival cannot be enabled when wal_level is \"%s\"",
+ wal_level == WAL_LEVEL_MINIMAL ? "minimal" : "none")));
+ if ((max_wal_senders > 0 && wal_level == WAL_LEVEL_NONE) ||
+ (max_wal_senders > 0 && wal_level == WAL_LEVEL_MINIMAL))
ereport(ERROR,
(errmsg("WAL streaming (max_wal_senders > 0) requires wal_level \"replica\" or \"logical\"")));
@@ -989,6 +992,12 @@ PostmasterMain(int argc, char *argv[])
LocalProcessControlFile(false);
/*
+ * Check some conditions specific to wal_level='none' and ensures the
+ * database isn't inconsistent.
+ */
+ SafelyFinishedNoneLevel();
+
+ /*
* Register the apply launcher. Since it registers a background worker,
* it needs to be called before InitializeMaxBackends(), and it's probably
* a good idea to call it before any modules had chance to take the
diff --git a/src/bin/pg_controldata/pg_controldata.c b/src/bin/pg_controldata/pg_controldata.c
index 3e00ac0..90ec0dc 100644
--- a/src/bin/pg_controldata/pg_controldata.c
+++ b/src/bin/pg_controldata/pg_controldata.c
@@ -74,6 +74,8 @@ wal_level_str(WalLevel wal_level)
{
switch (wal_level)
{
+ case WAL_LEVEL_NONE:
+ return "none";
case WAL_LEVEL_MINIMAL:
return "minimal";
case WAL_LEVEL_REPLICA:
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 221af87..e21b3cc 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -161,7 +161,8 @@ extern int XLogArchiveMode;
/* WAL levels */
typedef enum WalLevel
{
- WAL_LEVEL_MINIMAL = 0,
+ WAL_LEVEL_NONE = 0,
+ WAL_LEVEL_MINIMAL,
WAL_LEVEL_REPLICA,
WAL_LEVEL_LOGICAL
} WalLevel;
@@ -316,9 +317,11 @@ extern TimestampTz GetLatestXTime(void);
extern TimestampTz GetCurrentChunkReplayStartTime(void);
extern void UpdateControlFile(void);
+extern void SafelyFinishedNoneLevel(void);
extern uint64 GetSystemIdentifier(void);
extern char *GetMockAuthenticationNonce(void);
extern bool DataChecksumsEnabled(void);
+extern XLogRecPtr GetLatestCheckPointLSN(void);
extern XLogRecPtr GetFakeLSNForUnloggedRel(void);
extern Size XLOGShmemSize(void);
extern void XLOGShmemInit(void);