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From Maryann Xue <>
Subject Re: Using Hints in Phoenix
Date Mon, 09 Mar 2015 14:59:35 GMT
Hi Matt,

So far in Phoenix, hints are only supported as specified right after
keywords SELECT, UPSERT and DELETE. Same for join queries. It is currently
impossible to hint a certain join algorithm for a specific join node in a
multiple join query. However, for subqueries, the inner query can have its
own hints, independent of the outer query, like "SELECT /*+ INDEX(t idx1)*/
col1, col2 FROM t WHERE col3 IN (SELECT /*+ NO_INDEX*/ id FROM r WHERE name
= 'x')".


On Mon, Mar 9, 2015 at 7:26 AM, Matthew Johnson <>

> Hi guys,
> This is more of a general question than a problem – but I’m just wondering
> if someone can clarify for me what the syntax rules are for hints in
> Phoenix. Does it matter where in the query they go? Do they always go
> something like *SELECT <insert hint> x from y*? Or, if the hint is for a
> join (eg Sort Merge) does it go in the join part (*SELECT x from y inner
> join <insert hint> z on j = k*)?
> Couldn’t seem to find anything specific on this in the docs, and haven’t
> worked much with database hints in general so maybe there is a convention
> that I am not aware of – apologies if it’s a stupid question!
> Cheers,
> Matt

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