postgres.git / summary / log / commit / refs

commit    c7ea68ff8dfafc22c6cfefdb5929e12ec5d1e02a
Author:   Robert Haas <rhaas@postgresql.org>
Date:     Fri May 06 18:43:34 2016 +0000

    Limit maximum parallel degree to 1024.
    
    This new limit affects both the max_parallel_degree GUC and the
    parallel_degree reloption.  There may some day be a use case for using
    more than 1024 CPUs for a single query, but that's surely not the case
    right now.  Not only do not very many people have that many CPUs, but
    the code hasn't been tested at that kind of scale and is very unlikely
    to perform well, or even work at all, without a lot more work.  The
    issue addressed by commit 06bd458cb812623c3f1fdd55216c4c08b06a8447 is
    probably just one problem of many.
    
    The idea of a more reasonable limit here was suggested by Tom Lane;
    the value of 1024 was suggested by Amit Kapila.


 src/backend/access/common/reloptions.c | 2 +-
 src/backend/utils/misc/guc.c           | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 797be63c44b..7448c7f30fe 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -275,7 +275,7 @@ static relopt_int intRelOpts[] =
 			RELOPT_KIND_HEAP,
 			AccessExclusiveLock
 		},
-		-1, 0, MAX_BACKENDS
+		-1, 0, 1024
 	},
 
 	/* list terminator */
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 752f823a164..e246a9c2f0b 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2662,7 +2662,7 @@ static struct config_int ConfigureNamesInt[] =
 			NULL
 		},
 		&max_parallel_degree,
-		2, 0, MAX_BACKENDS,
+		2, 0, 1024,
 		NULL, NULL, NULL
 	},
 


[parent: 73b9952e8278]