8000 Incorrect sorting with sort criteria partially covered by index · Issue #10440 · arangodb/arangodb · GitHub
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mpoeter opened this issue Nov 14, 2019 · 5 comments
Closed

Incorrect sorting with sort criteria partially covered by index #10440

mpoeter opened this issue Nov 14, 2019 · 5 comments
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@jsteemann
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1 Bug 2 Fixed Resolution 3 AQL Query language related 3 Index
Milestone
3.4.9

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@mpoeter
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mpoeter commented Nov 14, 2019

My Environment

  • ArangoDB Version: 3.4.8 & self-compiled devel branch
  • Storage Engine: RocksDB
  • Deployment Mode: Single Server
  • Operating System: Ubuntu 18.04
  • Total RAM in your machine: 16GB

Component, Query & Data

Affected feature:
AQL query using web interface

AQL query (if applicable):

FOR a in activities
    FILTER a.user_id == "31132147"
    SORT a.datetime DESC, a.order DESC, a._key DESC
    LIMIT 10
    RETURN KEEP(a, "_key", "name", "order", "datetime")

AQL explain (if applicable):

Query String (178 chars, cacheable: true):
 FOR a in activities
     FILTER a.user_id == "31132147"
     SORT a.datetime DESC, a.order DESC, a._key DESC
     LIMIT 10
     RETURN KEEP(a, "_key", "name", "order", "datetime")

Execution plan:
 Id   NodeType          Est.   Comment
  1   SingletonNode        1   * ROOT
 12   IndexNode          589     - FOR a IN activities   /* reverse skiplist index scan */
  6   CalculationNode    589       - LET #5 = a.`order`   /* attribute expression */   /* collections used: a : activities */
  7   CalculationNode    589       - LET #7 = a.`_key`   /* attribute expression */   /* collections used: a : activities */
  8   SortNode           589       - SORT #5 DESC, #7 DESC
  9   LimitNode           10       - LIMIT 0, 10
 10   CalculationNode     10       - LET #9 = KEEP(a, "_key", "name", "order", "datetime")   /* simple expression */   /* collections used: a : activities */
 11   ReturnNode          10       - RETURN #9

Indexes used:
 By   Type       Collection   Unique   Sparse   Selectivity   Fields                                 Ranges
 12   skiplist   activities   false    false        37.29 %   [ `user_id`, `datetime`, `_key` ]   (a.`user_id` == "31132147")

Functions used:
 Name   Deterministic   Cacheable   Uses V8
 KEEP   true            true        false  

Optimization rules applied:
 Id   RuleName
  1   move-calculations-up
  2   move-filters-up
  3   move-calculations-up-2
  4   move-filters-up-2
  5   use-indexes
  6   remove-filter-covered-by-index
  7   use-index-for-sort
  8   remove-unnecessary-calculations-2

Problem:
The query optimizer recognizes correctly that the filter and the first sorting criterion are covered by the index on [user_id, datetime, _key], so it removes them. However, this still leaves the SORT node with the two remaining criteria and the query therefore produces a result that is not sorted correctly.

Expected result:
Result is sorted correctly

Workaround:
Create an index that covers all fields used for sorting.

Steps to reproduce

  1. Create a collection activities
  2. Insert these sample documents sample.json.gz
  3. Create an index for [user_id, datetime, _key]
  4. Run the query
@jsteemann
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I think the dataset does not match the query somehow.
The dataset does not include any user_id attributes for any of the documents.

However, I will make up some data on my own and try to reproduce.

@OmarAyo OmarAyo added 3 AQL Query language related 3 Index labels Nov 14, 2019
@jsteemann
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Reproduced. Looking into it...

@jsteemann jsteemann self-assigned this Nov 14, 2019
@mpoeter
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mpoeter commented Nov 14, 2019

Right, sorry. I simply took the result of the query and forgot that it doesn't include a user_id.

jsteemann added a commit that referenced this issue Nov 14, 2019
@jsteemann
fixed issue #10440: Incorrect sorting with sort criteria partially co…
daac8ee 
…vered by index
jsteemann added a commit that referenced this issue Nov 14, 2019
@jsteemann
fixed issue #10440: Incorrect sorting with sort criteria partially co…
894adb5 
…vered by index
jsteemann added a commit that referenced this issue Nov 14, 2019
@jsteemann
fixed issue #10440: Incorrect sorting with sort criteria partially co…
be8d1db 
…vered by index
This was referenced Nov 14, 2019
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@jsteemann jsteemann added the 2 Fixed Resolution label Nov 14, 2019
@jsteemann
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The above PRs address this issue.
They are expected to land in

@jsteemann jsteemann added this to the 3.4.9 milestone Nov 14, 2019
jsteemann added a commit that referenced this issue Nov 18, 2019
@jsteemann
fixed issue #10440: Incorrect sorting with sort criteria partially co…
c142e8b 
…vered by index (#10442)
ObiWahn added a commit that referenced this issue Nov 19, 2019
@ObiWahn
Merge branch 'devel' of https://github.com/arangodb/arangodb into fea…
2b6a0a2 
…ture/dump-db-properties

* 'devel' of https://github.com/arangodb/arangodb:
  Feature/aql subquery splicing with gather (#10341)
  Add braces (#10460)
  fixed issue #10440: Incorrect sorting with sort criteria partially covered by index (#10442)
  Remove as now unused SingleBlockFetcher (#10416)
ObiWahn added a commit that referenced this issue Nov 19, 2019
@ObiWahn
Merge branch 'devel' of https://github.com/arangodb/arangodb into fea…
5f3b179 
…ture/remove-db-properties-route

* 'devel' of https://github.com/arangodb/arangodb:
  Feature/aql subquery splicing with gather (#10341)
  Add braces (#10460)
  fixed issue #10440: Incorrect sorting with sort criteria partially covered by index (#10442)
KVS85 pushed a commit that referenced this issue Nov 20, 2019
@jsteemann @KVS85
fixed issue #10440: Incorrect sorting with sort criteria partially co…
dd52f0f 
…vered by index (#10443)

* fixed issue #10440: Incorrect sorting with sort criteria partially covered by index

* Update CHANGELOG
KVS85 pushed a commit that referenced this issue Nov 20, 2019
@jsteemann @KVS85
fixed issue #10440: Incorrect sorting with sort criteria partially co…
ef9ea2c 
…vered by index (#10443)

* fixed issue #10440: Incorrect sorting with sort criteria partially covered by index

* Update CHANGELOG
ObiWahn added a commit that referenced this issue Nov 26, 2019
@ObiWahn
Merge branch '3.5' of https://github.com/arangodb/arangodb into featu…
5f4483e 
…re-3.5/query-timeout

* '3.5' of https://github.com/arangodb/arangodb:
  Allow the optimizer to use indexes (#10543)
  Updated arangosync to 0.7.0 (#10532)
  Bug fix 3.5/little weekend fix (#10527)
  Bug fix 3.5/issue 10470 (#10497)
  add tests for inventory (#10464) (#10495)
  fixed issue #10440: Incorrect sorting with sort criteria partially covered by index (#10443)
  [3.5] Added precondition to ensure that server is still as seen before. (#10477)
  improve error message (#10478)
  allow in-place analyzer creation via link definition (#10466) (#10481)
  make replication timeouts configurable via startup options (#10473)
  [3.5] no coordinators left behind (#10420)
  don't return any in-progress indexes (#10431)
  fix invalid assertion (#10428)
  show type of index when non-implemented exception is thrown (#10425)
  Fix dump tests
  Improve syncer error message (#10404)
  DEVSUP-492 (#10379) (#10402)
KVS85 pushed a commit that referenced this issue Dec 26, 2019
@jsteemann @KVS85
fixed issue #10440: Incorrect sorting with sort criteria partially co…
d8ee8fd 
…vered by index (#10444)
@maxkernbach
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Hi @mpoeter,

Version 3.4.9, which includes a fix for the sorting, has just been released.
From the Changelog:

In case this issue still occurs after upgrading, please comment and we will reopen the ticket.

Please find the latest release in the download section.

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