On 2020-Aug-25, Tom Lane wrote:
> Oh wait a second. Matviews can have indexes, and getTables doesn't
> lock them (because we don't allow LOCK TABLE on views).
Here's a quick patchset that makes pg_dump do LOCK TABLE on all
relations it dumps; patch 0001 allows server-side LOCK TABLE to run on
any relkind, and then 0002 makes pg_dump test for that capability at
connection start, and if it exists, then it's used for all relations to
dump.
>From e09e08a25771dc1d84d8ed690d16ce6fdcb121a5 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@xxxxxxxxxxxxxx>
Date: Tue, 7 Jul 2020 18:45:39 -0400
Subject: [PATCH 1/2] accept any relkind in LOCK TABLE
---
src/backend/commands/lockcmds.c | 8 --------
1 file changed, 8 deletions(-)
diff --git a/src/backend/commands/lockcmds.c b/src/backend/commands/lockcmds.c
index d8cafc42bb..d9ff71aa69 100644
--- a/src/backend/commands/lockcmds.c
+++ b/src/backend/commands/lockcmds.c
@@ -83,14 +83,6 @@ RangeVarCallbackForLockTable(const RangeVar *rv, Oid relid, Oid oldrelid,
return; /* woops, concurrently dropped; no permissions
* check */
- /* Currently, we only allow plain tables or views to be locked */
- if (relkind != RELKIND_RELATION && relkind != RELKIND_PARTITIONED_TABLE &&
- relkind != RELKIND_VIEW)
- ereport(ERROR,
- (errcode(ERRCODE_WRONG_OBJECT_TYPE),
- errmsg("\"%s\" is not a table or view",
- rv->relname)));
-
/*
* Make note if a temporary relation has been accessed in this
* transaction.
--
2.20.1
>From 989833d61cd4ab0f922c2c4d1c11fdcf74d69b4f Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@xxxxxxxxxxxxxx>
Date: Tue, 7 Jul 2020 19:14:21 -0400
Subject: [PATCH 2/2] pg_dump: lock all rels, not just RELKIND_RELATION
---
src/bin/pg_dump/pg_backup.h | 2 ++
src/bin/pg_dump/pg_backup_db.c | 37 ++++++++++++++++++++++++++++++++++
src/bin/pg_dump/pg_backup_db.h | 2 ++
src/bin/pg_dump/pg_dump.c | 17 +++++++++-------
4 files changed, 51 insertions(+), 7 deletions(-)
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index a6a8e6f2fd..6c79319164 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -198,6 +198,8 @@ typedef struct Archive
int minRemoteVersion; /* allowable range */
int maxRemoteVersion;
+ bool hasGenericLockTable; /* can LOCK TABLE do non-table rels */
+
int numWorkers; /* number of parallel processes */
char *sync_snapshot_id; /* sync snapshot id for parallel operation */
diff --git a/src/bin/pg_dump/pg_backup_db.c b/src/bin/pg_dump/pg_backup_db.c
index 5ba43441f5..274c44c5ec 100644
--- a/src/bin/pg_dump/pg_backup_db.c
+++ b/src/bin/pg_dump/pg_backup_db.c
@@ -531,6 +531,43 @@ EndDBCopyMode(Archive *AHX, const char *tocEntryTag)
}
}
+/*
+ * Does LOCK TABLE work on non-table relations on this server?
+ *
+ * Note: assumes it is called out of any transaction
+ */
+bool
+IsLockTableGeneric(Archive *AHX)
+{
+ ArchiveHandle *AH = (ArchiveHandle *) AHX;
+ PGresult *res;
+ bool retval;
+
+ StartTransaction(AHX);
+
+ res = PQexec(AH->connection, "LOCK TABLE pg_catalog.pg_stats; ");
+ switch (PQresultStatus(res))
+ {
+ case PGRES_COMMAND_OK:
+ retval = true;
+ break;
+ case PGRES_FATAL_ERROR:
+ retval = false;
+ break;
+ default:
+ warn_or_exit_horribly(AH, "LOCK TABLE failed for \"%s\": %s",
+ "pg_catalog.pg_stats",
+ PQerrorMessage(AH->connection));
+ retval = false; /* not reached */
+ break;
+ }
+ PQclear(res);
+
+ CommitTransaction(AHX);
+
+ return retval;
+}
+
void
StartTransaction(Archive *AHX)
{
diff --git a/src/bin/pg_dump/pg_backup_db.h b/src/bin/pg_dump/pg_backup_db.h
index 8888dd34b9..355beec1f7 100644
--- a/src/bin/pg_dump/pg_backup_db.h
+++ b/src/bin/pg_dump/pg_backup_db.h
@@ -20,6 +20,8 @@ extern PGresult *ExecuteSqlQueryForSingleRow(Archive *fout, const char *query);
extern void EndDBCopyMode(Archive *AHX, const char *tocEntryTag);
+extern bool IsLockTableGeneric(Archive *AHX);
+
extern void StartTransaction(Archive *AHX);
extern void CommitTransaction(Archive *AHX);
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index ff45e3fb8c..dde8683d47 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -1176,6 +1176,10 @@ setup_connection(Archive *AH, const char *dumpencoding,
ExecuteSqlStatement(AH, "SET row_security = off");
}
+ /* Detect whether LOCK TABLE can handle non-table relations */
+ AH->hasGenericLockTable =
+ AH->remoteVersion >= 90500 ? IsLockTableGeneric(AH) : false;
+
/*
* Start transaction-snapshot mode transaction to dump consistent data.
*/
@@ -6843,16 +6847,15 @@ getTables(Archive *fout, int *numTables)
* assume our lock on the child is enough to prevent schema
* alterations to parent tables.
*
- * NOTE: it'd be kinda nice to lock other relations too, not only
- * plain or partitioned tables, but the backend doesn't presently
- * allow that.
- *
- * We only need to lock the table for certain components; see
+ * We only need to lock the relation for certain components; see
* pg_dump.h
+ *
+ * On server versions that support it, we lock all relations not just
+ * plain tables.
*/
if (tblinfo[i].dobj.dump &&
- (tblinfo[i].relkind == RELKIND_RELATION ||
- tblinfo->relkind == RELKIND_PARTITIONED_TABLE) &&
+ (fout->hasGenericLockTable ||
+ tblinfo[i].relkind == RELKIND_RELATION) &&
(tblinfo[i].dobj.dump & DUMP_COMPONENTS_REQUIRING_LOCK))
{
resetPQExpBuffer(query);
--
2.20.1
