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mergetable optimizer messes up sample #6179

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monetdb-team opened this issue Nov 30, 2020 · 0 comments
Closed

mergetable optimizer messes up sample #6179

monetdb-team opened this issue Nov 30, 2020 · 0 comments

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@monetdb-team monetdb-team commented Nov 30, 2020

Date: 2016-12-28 11:49:56 +0100
From: @sjoerdmullender
To: MonetDB5 devs <>
Version: 11.25.3 (Dec2016)

Last updated: 2017-01-26 14:56:13 +0100

Comment 24857

Date: 2016-12-28 11:49:56 +0100
From: @sjoerdmullender

The mergetable optimizer creates the following sequence from the instruction A := sample.subuniform(b,n):

t1 := sample.subuniform(b1,n);
t2 := sample.subuniform(b2,n);
t3 := sample.subuniform(b3,n);
t4 := sample.subuniform(b4,n);
a := mat.pack(t1,t2,t3,t4);
a := sample.subuniform(a,n);

This is wrong:
sample.subuniform() returns a candidate list for its argument bat, so the last call to sample.subuniform() returns an index into the result of the mat.pack(). The result should be subset of the result of the mat.pack(). In other words, there is an algebra.projection() missing.

Comment 24858

Date: 2016-12-28 11:51:20 +0100
From: MonetDB Mercurial Repository <>

Changeset d1af8f50919b made by Sjoerd Mullender sjoerd@acm.org in the MonetDB repo, refers to this bug.

For complete details, see http//devmonetdborg/hg/MonetDB?cmd=changeset;node=d1af8f50919b

Changeset description:

Add an extra algebra.projection call to the transformation of sample.subuniform.
This fixes bug #6179.

Comment 24913

Date: 2017-01-26 14:56:13 +0100
From: @kutsurak

Fixed in version Dec2016-SP1.

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