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https://issues.apache.org/jira/browse/PHOENIX-4602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16362414#comment-16362414
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John Leach commented on PHOENIX-4602:
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[~comnetwork] I am new to Phoenix, but when I look at the WhereOptimizer.java
it is not clear to me how or when the predicates are moved to Conjunctive
Normal Form ([https://en.wikipedia.org/wiki/Conjunctive_normal_form).] I have
always seen the following process when dealing with predicates.
1. Move to Conjunctive Normal Form all predicates.
2. Mark predicates on the key.
3. Apply a function on the key predicates to assemble a set of scans.
4. Apply a function on the remaining predicates to assemble a filter (Usually
in list is an exception case).
Do you know where CNF occurs?
> OrExpression should can also push non-leading pk columns to scan
> ----------------------------------------------------------------
>
> Key: PHOENIX-4602
> URL: https://issues.apache.org/jira/browse/PHOENIX-4602
> Project: Phoenix
> Issue Type: Improvement
> Affects Versions: 4.13.0
> Reporter: chenglei
> Priority: Major
> Attachments: PHOENIX-4602_v1.patch
>
>
> Given following table:
> {code}
> CREATE TABLE test_table (
> PK1 INTEGER NOT NULL,
> PK2 INTEGER NOT NULL,
> PK3 INTEGER NOT NULL,
> DATA INTEGER,
> CONSTRAINT TEST_PK PRIMARY KEY (PK1,PK2,PK3))
> {code}
> and a sql:
> {code}
> select * from test_table t where (t.pk1 >=2 and t.pk1<5) and ((t.pk2 >= 4
> and t.pk2 <6) or (t.pk2 >= 8 and t.pk2 <9))
> {code}
> Obviously, it is a typical case for the sql to use SkipScanFilter,however,
> the sql actually does not use Skip Scan, it use Range Scan and just push the
> leading pk column expression {{(t.pk1 >=2 and t.pk1<5)}} to scan,the explain
> sql is :
> {code:sql}
> CLIENT PARALLEL 1-WAY RANGE SCAN OVER TEST_TABLE [2] - [5]
> SERVER FILTER BY ((PK2 >= 4 AND PK2 < 6) OR (PK2 >= 8 AND PK2 < 9))
> {code}
> I think the problem is affected by the
> {{WhereOptimizer.KeyExpressionVisitor.orKeySlots}} method, in the following
> line 763, because the pk2 column is not the leading pk column,so this method
> return null, causing the expression
> {{((t.pk2 >= 4 and t.pk2 <6) or (t.pk2 >= 8 and t.pk2 <9))}} is not pushed
> to scan:
> {code:java}
> 757 boolean hasFirstSlot = true;
> 758 boolean prevIsNull = false;
> 759 // TODO: Do the same optimization that we do for IN if the childSlots
> specify a fully qualified row key
> 760 for (KeySlot slot : childSlot) {
> 761 if (hasFirstSlot) {
> 762 // if the first slot is null, return null immediately
> 763 if (slot == null) {
> 764 return null;
> 765 }
> 766 // mark that we've handled the first slot
> 767 hasFirstSlot = false;
> 768 }
> {code}
> For above {{WhereOptimizer.KeyExpressionVisitor.orKeySlots}} method, it seems
> that it is not necessary to make sure the PK Column in OrExpression is
> leading PK Column,just guarantee there is only one PK Column in OrExpression
> is enough.
>
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