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From Yingyi Bu <buyin...@gmail.com>
Subject Re: [jira] [Commented] (ASTERIXDB-1249) Self index join chooses wrong probe/index branch
Date Fri, 08 Jan 2016 02:36:06 GMT
Sorry, to be more precise:
Left-outer hash join cannot preserve all local data properties for its
probe branch (because spilling can happen) but can preserve (or downgrade)
some when certain conditions meet.

On Thu, Jan 7, 2016 at 6:28 PM, Yingyi Bu <buyingyi@gmail.com> wrote:

> In the logical/physical query plan, I think it is statically determined.
> However, that doesn't mean the execution is faithful to that probe/build
> decision because we have the "role reversal" optimization for inner hash
> joins:-)
> (That's also why our inner hash join cannot maintain any local data
> property from its probe branch, but left-outer hash can preserve that.)
>
> Best,
> Yingyi
>
>
> On Thu, Jan 7, 2016 at 5:34 PM, Mike Carey <dtabass@gmail.com> wrote:
>
>> Also, do we (separately want to make sure that our hash join behavior is
>> comparable - i.e., that the initial build/probe decision is statically
>> determined from the query?  (I think we do want that, and I think it is in
>> fact that way - but I'm not 100% sure, as its been awhile since that was
>> discussed, and it's not in-cache for me. :-))
>>
>>
>> On 1/7/16 3:22 PM, Taewoo Kim wrote:
>>
>>> Thanks Yingyi. Yes. If there is an equality condition and if we can't
>>> transform a join into an index-nested loop join, then a hybrid hash join
>>> will be used.
>>>
>>> Best,
>>> Taewoo
>>>
>>> On Thu, Jan 7, 2016 at 3:14 PM, Yingyi Bu <buyingyi@gmail.com> wrote:
>>>
>>> +1!
>>>>
>>>>> 3. We only try to use applicable indexes from the inner branch. So, if
>>>>>> there are no applicable indexes from the inner branch, we abort
>>>>>> transforming a join into an index-nested-loop join.
>>>>>>
>>>>> "index-nested-loop join" -> "hybrid hash join"?
>>>>
>>>> Thanks!
>>>>
>>>> Yingyi
>>>>
>>>>
>>>>
>>>> On Thu, Jan 7, 2016 at 3:01 PM, Taewoo Kim <wangsaeu@gmail.com> wrote:
>>>>
>>>> Hello dev,
>>>>>
>>>>> Regarding this issue (ASTERIXDB-1249), I would like to make an
>>>>> index-join
>>>>> hint clarification. Let's start with an example query other than a
>>>>> self-join query in this issue.
>>>>>
>>>>> for $c in dataset('Customers')
>>>>>
>>>>> for $o in dataset('Orders')
>>>>>
>>>>> where $c.cid /*+ indexnl */ = $o.cid
>>>>>
>>>>> order by $c.cid, $o.oid
>>>>>
>>>>> return {"cid":$c.cid, "oid": $o.oid}
>>>>>
>>>>> Right now, in the master branch, the first dataset (e.g., Customers)
>>>>> becomes the outer branch and the second dataset (e.g., Orders) becomes
>>>>>
>>>> the
>>>>
>>>>> inner branch. And, when the optimizer tries to honor the given indexnl
>>>>>
>>>> hint
>>>>
>>>>> (transforming a join into an index-nested-loop join), if there are
>>>>> applicable indexes from the inner branch (e.g., Orders), then it is
>>>>> going
>>>>> to use one of those indexes. If there are no applicable indexes from
>>>>> the
>>>>> inner branch, it tries to use indexes from the outer branch (e.g.,
>>>>> Customers). We are going to change the last part; we will not use
>>>>> indexes
>>>>> from the outer branch. So, the following are refined rules for
>>>>>
>>>> transforming
>>>>
>>>>> a join into an index-nested-loop join.
>>>>>
>>>>> 1. The first dataset in a join (the first parameter of the given join)
>>>>> becomes the outer branch.
>>>>> 2. The second dataset in a join (the second parameter of the given
>>>>> join)
>>>>> becomes the inner branch.
>>>>> 3. We only try to use applicable indexes from the inner branch. So, if
>>>>> there are no applicable indexes from the inner branch, we abort
>>>>> transforming a join into an index-nested-loop join.
>>>>> 4. Variable order in the given join predicate is not important. It can
>>>>> be
>>>>> either outer.fieldA = inner.fieldB or inner.fieldB = outer.fieldA.
>>>>>
>>>>> So, for the left-outer join and inner join altogether, the left subtree
>>>>>
>>>> is
>>>>
>>>>> the probing side and the right subtree is the index side. So, this can
>>>>> be
>>>>> applied to the self-join case, too just like the following query in
>>>>> this
>>>>> issue. In the following query, $t1 becomes the outer and $t2 becomes
>>>>> the
>>>>> inner.
>>>>>
>>>>> for $t1 in dataset('TweetMessages')
>>>>>
>>>>> for $t2 in dataset('TweetMessages')
>>>>>
>>>>> let $c := $t1.countA + 20
>>>>>
>>>>> where $c /* +indexnl */= $t2.countB
>>>>>
>>>>> order by $t2.tweetid
>>>>>
>>>>> return {"tweetid2": $t2.tweetid, "count2":$t2.countB};
>>>>>
>>>>> Thank you. Any opinion would be appreciated before I finalize this fix.
>>>>>
>>>>> Best,
>>>>> Taewoo
>>>>>
>>>>> ---------- Forwarded message ----------
>>>>> From: Yingyi Bu (JIRA) <jira@apache.org>
>>>>> Date: Wed, Jan 6, 2016 at 10:23 AM
>>>>> Subject: [jira] [Commented] (ASTERIXDB-1249) Self index join chooses
>>>>>
>>>> wrong
>>>>
>>>>> probe/index branch
>>>>> To: notifications@asterixdb.incubator.apache.org
>>>>>
>>>>>
>>>>>
>>>>>      [
>>>>>
>>>>>
>>>>>
>>>> https://issues.apache.org/jira/browse/ASTERIXDB-1249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15085992#comment-15085992
>>>>
>>>>> ]
>>>>>
>>>>> Yingyi Bu commented on ASTERIXDB-1249:
>>>>> --------------------------------------
>>>>>
>>>>> That's right. Basically in AcessMethod implementations, e.g.:
>>>>>
>>>>>
>>>>>
>>>> https://github.com/apache/incubator-asterixdb/blob/master/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/RTreeAccessMethod.java#L124
>>>>
>>>>> Choosing probe/index branch is only based on dataset names, instead of
>>>>> being based on the join condition.
>>>>>
>>>>> Self index join chooses wrong probe/index branch
>>>>>> ------------------------------------------------
>>>>>>
>>>>>>                  Key: ASTERIXDB-1249
>>>>>>                  URL:
>>>>>>
>>>>> https://issues.apache.org/jira/browse/ASTERIXDB-1249
>>>>>
>>>>>>              Project: Apache AsterixDB
>>>>>>           Issue Type: Bug
>>>>>>           Components: Optimizer
>>>>>>             Reporter: Yingyi Bu
>>>>>>             Assignee: Taewoo Kim
>>>>>>
>>>>>> DDLs:
>>>>>> {noformat}
>>>>>> drop dataverse test if exists;
>>>>>> create dataverse test;
>>>>>> use dataverse test;
>>>>>> create type TwitterUserType as closed {
>>>>>>      screen-name: string,
>>>>>>      lang: string,
>>>>>>      friends-count: int64,
>>>>>>      statuses-count: int64,
>>>>>>      name: string,
>>>>>>      followers-count: int64
>>>>>> }
>>>>>> create type TweetMessageType as closed {
>>>>>>      tweetid: int64,
>>>>>>          user: TwitterUserType,
>>>>>>          sender-location: point,
>>>>>>      send-time: datetime,
>>>>>>          referred-topics: {{ string }},
>>>>>>      message-text: string,
>>>>>>      countA: int64,
>>>>>>      countB: int64
>>>>>> }
>>>>>> create dataset TweetMessages(TweetMessageType)
>>>>>> primary key tweetid;
>>>>>> create index twmSndLocIx on TweetMessages(sender-location) type rtree;
>>>>>> create index msgCountAIx on TweetMessages(countA) type btree;
>>>>>> create index msgCountBIx on TweetMessages(countB) type btree;
>>>>>> create index msgTextIx on TweetMessages(message-text) type keyword;
>>>>>> {noformat}
>>>>>> Query:
>>>>>> {noformat}
>>>>>> for $t1 in dataset('TweetMessages')
>>>>>> for $t2 in dataset('TweetMessages')
>>>>>> let $n :=  create-circle($t1.sender-location, 0.5)
>>>>>> where spatial-intersect($t2.sender-location, $n)
>>>>>> order by $t2.tweetid
>>>>>> return {"tweetid2":$t2.tweetid, "loc2":$t2.sender-location};
>>>>>> {noformat}
>>>>>> Optimized plan:
>>>>>> {noformat}
>>>>>> distribute result [%0->$$10]
>>>>>> -- DISTRIBUTE_RESULT  |PARTITIONED|
>>>>>>    exchange
>>>>>>    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
>>>>>>      project ([$$10])
>>>>>>      -- STREAM_PROJECT  |PARTITIONED|
>>>>>>        assign [$$10] <- [function-call:
>>>>>>
>>>>> asterix:closed-record-constructor,
>>>>
>>>>> Args:[AString: {tweetid2}, %0->$$15, AString: {loc2}, %0->$$13]]
>>>>>
>>>>>>        -- ASSIGN  |PARTITIONED|
>>>>>>          exchange
>>>>>>          -- SORT_MERGE_EXCHANGE [$$15(ASC) ]  |PARTITIONED|
>>>>>>            order (ASC, %0->$$15)
>>>>>>            -- STABLE_SORT [$$15(ASC)]  |PARTITIONED|
>>>>>>              exchange
>>>>>>              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
>>>>>>                project ([$$13, $$15])
>>>>>>                -- STREAM_PROJECT  |PARTITIONED|
>>>>>>                  select (function-call: asterix:spatial-intersect,
>>>>>>
>>>>> Args:[%0->$$13, function-call: asterix:create-circle,
>>>>>
>>>> Args:[function-call:
>>>>
>>>>> asterix:field-access-by-index, Args:[%0->$$0, AInt32: {2}], ADouble:
>>>>> {0.5}]])
>>>>>
>>>>>>                  -- STREAM_SELECT  |PARTITIONED|
>>>>>>                    project ([$$0, $$13, $$15])
>>>>>>                    -- STREAM_PROJECT  |PARTITIONED|
>>>>>>                      exchange
>>>>>>                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
>>>>>>                        unnest-map [$$14, $$0] <- function-call:
>>>>>>
>>>>> asterix:index-search, Args:[AString: {TweetMessages}, AInt32: {0},
>>>>>
>>>> AString:
>>>>
>>>>> {test}, AString: {TweetMessages}, ABoolean: {true}, ABoolean: {false},
>>>>> ABoolean: {false}, AInt32: {1}, %0->$$27, AInt32: {1}, %0->$$27,
TRUE,
>>>>> TRUE, TRUE]
>>>>>
>>>>>>                        -- BTREE_SEARCH  |PARTITIONED|
>>>>>>                          exchange
>>>>>>                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
>>>>>>                            order (ASC, %0->$$27)
>>>>>>                            -- STABLE_SORT [$$27(ASC)]  |PARTITIONED|
>>>>>>                              exchange
>>>>>>                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
>>>>>>                                project ([$$27, $$13, $$15])
>>>>>>                                -- STREAM_PROJECT  |PARTITIONED|
>>>>>>                                  exchange
>>>>>>                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
>>>>>>                                    unnest-map [$$23, $$24, $$25,
$$26,
>>>>>>
>>>>> $$27] <- function-call: asterix:index-search, Args:[AString:
>>>>>
>>>> {twmSndLocIx},
>>>>
>>>>> AInt32: {1}, AString: {test}, AString: {TweetMessages}, ABoolean:
>>>>> {true},
>>>>> ABoolean: {false}, ABoolean: {true}, AInt32: {4}, %0->$$19, %0->$$20,
>>>>> %0->$$21, %0->$$22]
>>>>>
>>>>>>                                    -- RTREE_SEARCH  |PARTITIONED|
>>>>>>                                      exchange
>>>>>>                                      -- BROADCAST_EXCHANGE
>>>>>>
>>>>> |PARTITIONED|
>>>>
>>>>>                                        assign [$$19, $$20, $$21, $$22]
>>>>>>
>>>>> <-
>>>>
>>>>> [function-call: asterix:create-mbr, Args:[%0->$$13, AInt32: {2},
>>>>> AInt32:
>>>>> {0}], function-call: asterix:create-mbr, Args:[%0->$$13, AInt32: {2},
>>>>> AInt32: {1}], function-call: asterix:create-mbr, Args:[%0->$$13,
>>>>> AInt32:
>>>>> {2}, AInt32: {2}], function-call: asterix:create-mbr, Args:[%0->$$13,
>>>>> AInt32: {2}, AInt32: {3}]]
>>>>>
>>>>>>                                        -- ASSIGN  |PARTITIONED|
>>>>>>                                          project ([$$13, $$15])
>>>>>>                                          -- STREAM_PROJECT
>>>>>>
>>>>> |PARTITIONED|
>>>>
>>>>>                                            assign [$$13] <-
>>>>>>
>>>>> [function-call: asterix:field-access-by-index, Args:[%0->$$1, AInt32:
>>>>>
>>>> {2}]]
>>>>
>>>>>                                            -- ASSIGN  |PARTITIONED|
>>>>>>                                              exchange
>>>>>>                                              -- ONE_TO_ONE_EXCHANGE
>>>>>>
>>>>> |PARTITIONED|
>>>>>
>>>>>>                                                data-scan []<-[$$15,
>>>>>> $$1]
>>>>>>
>>>>> <- test:TweetMessages
>>>>>
>>>>>>                                                -- DATASOURCE_SCAN
>>>>>>
>>>>> |PARTITIONED|
>>>>>
>>>>>>                                                  exchange
>>>>>>                                                  --
>>>>>> ONE_TO_ONE_EXCHANGE
>>>>>>
>>>>> |PARTITIONED|
>>>>>
>>>>>>                                                    empty-tuple-source
>>>>>>                                                    --
>>>>>> EMPTY_TUPLE_SOURCE
>>>>>>
>>>>> |PARTITIONED|
>>>>>
>>>>>> {noformat}
>>>>>> The optimized plan is incorrect --- the index search doesn't use
the
>>>>>>
>>>>> right join condition and hence the result is different from expected.
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> This message was sent by Atlassian JIRA
>>>>> (v6.3.4#6332)
>>>>>
>>>>>
>>
>

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