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From "Matthew Jacobs (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-5644: Reject queries if min reservation is too large
Date Thu, 17 Aug 2017 22:44:50 GMT
Matthew Jacobs has posted comments on this change.

Change subject: IMPALA-5644: Reject queries if min reservation is too large

Patch Set 4:

File be/src/runtime/bufferpool/reservation-util.h:

PS4, Line 44: buffer reservation limi
> is it clear that this is talking about the query limit as opposed to the bu

PS4, Line 53: minimum
> i think that should be deleted, i.e. you might want to ask this for a poten

PS4, Line 57: GetMemLimitFromBufferReservation
> the name makes it sound like an inverse of GetBufferReservationLimitFromMem
File be/src/runtime/

PS4, Line 153: if (query_options().__isset.buffer_pool_limit
             :       && query_options().buffer_pool_limit > 0) {
             :     max_reservation = query_options().buffer_pool_limit;
             :   }
Question for Tim & Dan:

Should this really be exclusive w/ checking the mem limit? Don't we want:

max_reservation = mem_limit == -1 ? max_int64 : ResUtil::GetBufferReservationLimitFromMemLimit(mem_limit)
if (buffer_pool_limit is set):
  max_reservation = min(query_options.buffer_pool_limit,
File be/src/scheduling/

PS4, Line 119: greater than
> at least? (off by one?) 

Line 125:     "more information.";
> both of these two reasons aren't really admission control specific, right? 
That's right, at least not as we currently think about admission control. It could go somewhere
else but I thought it made sense to do all of our resource-related query 'rejecting' in one
place, and I think it makes sense for admission control to be that place.

I also don't think people should be running with AC disabled anymore. It's better to leave
AC enabled but w/ unlimited limits (which is the default behavior). I think there shouldn't
be many users with AC explicitly disabled anymore. Maybe I'll mark those flags as deprecated
and remove in Impala 3.0?

PS4, Line 428: buffer_reservation_limit
> might be nice to name this consistently with naming, to make

PS4, Line 429: GetBufferReservationLimitFromMemLimit
> what about the case of buffer_pool_limit set explicitly?
Do you mean something besides what gets handled on l416-l424?

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Gerrit-MessageType: comment
Gerrit-Change-Id: Iabe87ce8f460356cfe4d1be4d7092c5900f9d79b
Gerrit-PatchSet: 4
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Matthew Jacobs <>
Gerrit-Reviewer: Dan Hecht <>
Gerrit-Reviewer: Matthew Jacobs <>
Gerrit-Reviewer: Tim Armstrong <>
Gerrit-HasComments: Yes

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