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Apache Ignite supports only hash-based sharding, so partition could be extracted only from equality conditions.

In further examples affinity function is denoted as '{...}'. Extracted partition is either concrete number, or query argument indexparameter index which will be converted to concrete number later. We will denote first type as "NPn" (e.g. 1P1, 2, 3P2), and second as ":NINDEX" (e.g. :1, :2). If partition cannot be extracted from condtition, :3). 

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we will denote it as ALL.

Equality

For equality we simply apply affinity function to the value.

SELECT * FROM emp WHERE emp.id = 100
=> {id=100} => P1

SELECT * FROM emp WHERE emp.id = :1
=> {id=:1} => :1

SELECT * FROM emp WHERE emp.id != 100
=> {name!=100} => (ALL)

SELECT * FROM emp WHERE emp.name = :1
=> {name=:1} => (ALL)

IN

IN condition with list of values results in a merged list of affected partitions. IN condition with nested SELECT statement will not be supported for now.

SELECT * FROM emp WHERE emp.id IN (100, :1)
=> ({name=100}, {name=:1}) => (P1, :1)

Composite expressions (AND, OR)

Every WHERE expression can be represented as sequence conjunctive expressions separated by disjunctions. For two OR

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expressions we return disjunctive set. For AND expressions we return conjunctive set. Concrete partitions can be merged together. Partition placeholders can only be merged with {ALL} on the other side.

{P1} AND {P2} => ()
{P1, P2} AND {P3, P4} => () 
{P1, P2} AND {P2, P3} => {P2}
{P1} AND {ALL} => (P1)
{P1, P2} AND {ALL} => (P1, P2)


{:1} AND {:2} => (:1) AND (:2)
{:1} AND {ALL} => (:1)


{P1} AND {:2} => P1 AND (:2) // Cannot merge as final result depends on concrete value of :2
{P1, :1} AND {P2} => (P1, :1) AND (P2)




{1} OR {2} => (1, 2)
{1} OR {ALL} => {ALL}

TODO

IN

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Ranges on integer types

TODO

AND

TODO

Subquery

TODO

OR

TODO

Merging Partition Info

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