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authorFujii Masao2019-11-21 12:10:37 +0000
committerFujii Masao2019-11-21 12:10:37 +0000
commite6d8069522c8bde8239dd1fedfb4984efa4b3a1a (patch)
treeb0d38edfd892bdd52f3086616c36d1bce5d350ab
parent30840c92ac0c4073fb7bc8222317630571b8cf25 (diff)
Make DROP DATABASE command generate less WAL records.
Previously DROP DATABASE generated as many XLOG_DBASE_DROP WAL records as the number of tablespaces that the database to drop uses. This caused the scans of shared_buffers as many times as the number of the tablespaces during recovery because WAL replay of one XLOG_DBASE_DROP record needs that full scan. This could make the recovery time longer especially when shared_buffers is large. This commit changes DROP DATABASE so that it generates only one XLOG_DBASE_DROP record, and registers the information of all the tablespaces into it. Then, WAL replay of XLOG_DBASE_DROP record needs full scan of shared_buffers only once, and which may improve the recovery performance. Author: Fujii Masao Reviewed-by: Kirk Jamison, Simon Riggs Discussion: https://postgr.es/m/CAHGQGwF8YwNH0ZaL+2wjZPkj+ji9UhC+Z4ScnG97WKtVY5L9iw@mail.gmail.com
-rw-r--r--src/backend/access/rmgrdesc/dbasedesc.c7
-rw-r--r--src/backend/commands/dbcommands.c67
-rw-r--r--src/include/commands/dbcommands_xlog.h5
3 files changed, 56 insertions, 23 deletions
diff --git a/src/backend/access/rmgrdesc/dbasedesc.c b/src/backend/access/rmgrdesc/dbasedesc.c
index c7d60ce10d6..d08c5758729 100644
--- a/src/backend/access/rmgrdesc/dbasedesc.c
+++ b/src/backend/access/rmgrdesc/dbasedesc.c
@@ -35,9 +35,12 @@ dbase_desc(StringInfo buf, XLogReaderState *record)
else if (info == XLOG_DBASE_DROP)
{
xl_dbase_drop_rec *xlrec = (xl_dbase_drop_rec *) rec;
+ int i;
- appendStringInfo(buf, "dir %u/%u",
- xlrec->tablespace_id, xlrec->db_id);
+ appendStringInfo(buf, "dir");
+ for (i = 0; i < xlrec->ntablespaces; i++)
+ appendStringInfo(buf, " %u/%u",
+ xlrec->tablespace_ids[i], xlrec->db_id);
}
}
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 446813f0f0b..a70e75a219e 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1411,10 +1411,11 @@ movedb(const char *dbname, const char *tblspcname)
xl_dbase_drop_rec xlrec;
xlrec.db_id = db_id;
- xlrec.tablespace_id = src_tblspcoid;
+ xlrec.ntablespaces = 1;
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, sizeof(xl_dbase_drop_rec));
+ XLogRegisterData((char *) &src_tblspcoid, sizeof(Oid));
(void) XLogInsert(RM_DBASE_ID,
XLOG_DBASE_DROP | XLR_SPECIAL_REL_UPDATE);
@@ -1946,6 +1947,11 @@ remove_dbtablespaces(Oid db_id)
Relation rel;
TableScanDesc scan;
HeapTuple tuple;
+ List *ltblspc = NIL;
+ ListCell *cell;
+ int ntblspc;
+ int i;
+ Oid *tablespace_ids;
rel = table_open(TableSpaceRelationId, AccessShareLock);
scan = table_beginscan_catalog(rel, 0, NULL);
@@ -1974,23 +1980,41 @@ remove_dbtablespaces(Oid db_id)
(errmsg("some useless files may be left behind in old database directory \"%s\"",
dstpath)));
- /* Record the filesystem change in XLOG */
- {
- xl_dbase_drop_rec xlrec;
+ ltblspc = lappend_oid(ltblspc, dsttablespace);
+ pfree(dstpath);
+ }
- xlrec.db_id = db_id;
- xlrec.tablespace_id = dsttablespace;
+ ntblspc = list_length(ltblspc);
+ if (ntblspc == 0)
+ {
+ table_endscan(scan);
+ table_close(rel, AccessShareLock);
+ return;
+ }
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, sizeof(xl_dbase_drop_rec));
+ tablespace_ids = (Oid *) palloc(ntblspc * sizeof(Oid));
+ i = 0;
+ foreach(cell, ltblspc)
+ tablespace_ids[i++] = lfirst_oid(cell);
- (void) XLogInsert(RM_DBASE_ID,
- XLOG_DBASE_DROP | XLR_SPECIAL_REL_UPDATE);
- }
+ /* Record the filesystem change in XLOG */
+ {
+ xl_dbase_drop_rec xlrec;
- pfree(dstpath);
+ xlrec.db_id = db_id;
+ xlrec.ntablespaces = ntblspc;
+
+ XLogBeginInsert();
+ XLogRegisterData((char *) &xlrec, MinSizeOfDbaseDropRec);
+ XLogRegisterData((char *) tablespace_ids, ntblspc * sizeof(Oid));
+
+ (void) XLogInsert(RM_DBASE_ID,
+ XLOG_DBASE_DROP | XLR_SPECIAL_REL_UPDATE);
}
+ list_free(ltblspc);
+ pfree(tablespace_ids);
+
table_endscan(scan);
table_close(rel, AccessShareLock);
}
@@ -2197,8 +2221,7 @@ dbase_redo(XLogReaderState *record)
{
xl_dbase_drop_rec *xlrec = (xl_dbase_drop_rec *) XLogRecGetData(record);
char *dst_path;
-
- dst_path = GetDatabasePath(xlrec->db_id, xlrec->tablespace_id);
+ int i;
if (InHotStandby)
{
@@ -2228,11 +2251,17 @@ dbase_redo(XLogReaderState *record)
/* Clean out the xlog relcache too */
XLogDropDatabase(xlrec->db_id);
- /* And remove the physical files */
- if (!rmtree(dst_path, true))
- ereport(WARNING,
- (errmsg("some useless files may be left behind in old database directory \"%s\"",
- dst_path)));
+ for (i = 0; i < xlrec->ntablespaces; i++)
+ {
+ dst_path = GetDatabasePath(xlrec->db_id, xlrec->tablespace_ids[i]);
+
+ /* And remove the physical files */
+ if (!rmtree(dst_path, true))
+ ereport(WARNING,
+ (errmsg("some useless files may be left behind in old database directory \"%s\"",
+ dst_path)));
+ pfree(dst_path);
+ }
if (InHotStandby)
{
diff --git a/src/include/commands/dbcommands_xlog.h b/src/include/commands/dbcommands_xlog.h
index 46be8a615ac..4e8a442c89f 100644
--- a/src/include/commands/dbcommands_xlog.h
+++ b/src/include/commands/dbcommands_xlog.h
@@ -32,10 +32,11 @@ typedef struct xl_dbase_create_rec
typedef struct xl_dbase_drop_rec
{
- /* Records dropping of a single subdirectory incl. contents */
Oid db_id;
- Oid tablespace_id;
+ int ntablespaces; /* number of tablespace IDs */
+ Oid tablespace_ids[FLEXIBLE_ARRAY_MEMBER];
} xl_dbase_drop_rec;
+#define MinSizeOfDbaseDropRec offsetof(xl_dbase_drop_rec, tablespace_ids)
extern void dbase_redo(XLogReaderState *rptr);
extern void dbase_desc(StringInfo buf, XLogReaderState *rptr);