Create VXID locks "lazily" in the main lock table.

Instead of entering them on transaction startup, we materialize them
only when someone wants to wait, which will occur only during CREATE
INDEX CONCURRENTLY.  In Hot Standby mode, the startup process must also
be able to probe for conflicting VXID locks, but the lock need never be
fully materialized, because the startup process does not use the normal
lock wait mechanism.  Since most VXID locks never need to touch the
lock manager partition locks, this can significantly reduce blocking
contention on read-heavy workloads.

Patch by me.  Review by Jeff Davis.

1 files changed, 0 insertions, 64 deletions

diff --git a/src/backend/storage/lmgr/lmgr.c b/src/backend/storage/lmgr/lmgr.c
index 3ac098b2a9..25ead29a48 100644
--- a/src/backend/storage/lmgr/lmgr.c
+++ b/src/backend/storage/lmgr/lmgr.c
@@ -515,70 +515,6 @@ ConditionalXactLockTableWait(TransactionId xid)
 	return true;
 }
 
-
-/*
- *		VirtualXactLockTableInsert
- *
- * Insert a lock showing that the given virtual transaction ID is running ---
- * this is done at main transaction start when its VXID is assigned.
- * The lock can then be used to wait for the transaction to finish.
- */
-void
-VirtualXactLockTableInsert(VirtualTransactionId vxid)
-{
-	LOCKTAG		tag;
-
-	Assert(VirtualTransactionIdIsValid(vxid));
-
-	SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
-
-	(void) LockAcquire(&tag, ExclusiveLock, false, false);
-}
-
-/*
- *		VirtualXactLockTableWait
- *
- * Waits until the lock on the given VXID is released, which shows that
- * the top-level transaction owning the VXID has ended.
- */
-void
-VirtualXactLockTableWait(VirtualTransactionId vxid)
-{
-	LOCKTAG		tag;
-
-	Assert(VirtualTransactionIdIsValid(vxid));
-
-	SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
-
-	(void) LockAcquire(&tag, ShareLock, false, false);
-
-	LockRelease(&tag, ShareLock, false);
-}
-
-/*
- *		ConditionalVirtualXactLockTableWait
- *
- * As above, but only lock if we can get the lock without blocking.
- * Returns TRUE if the lock was acquired.
- */
-bool
-ConditionalVirtualXactLockTableWait(VirtualTransactionId vxid)
-{
-	LOCKTAG		tag;
-
-	Assert(VirtualTransactionIdIsValid(vxid));
-
-	SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
-
-	if (LockAcquire(&tag, ShareLock, false, true) == LOCKACQUIRE_NOT_AVAIL)
-		return false;
-
-	LockRelease(&tag, ShareLock, false);
-
-	return true;
-}
-
-
 /*
  *		LockDatabaseObject
  *