Lazy column loading does not work with if and CTEs #79771
Description
Company or project name
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Describe the unexpected behaviour
We came across an unexpected behaviour on a query that was working on v24.5 that is not working as expected on v25.3. We belive it is due to the lazy column loading behaviour recently introduced.
How to reproduce
ClickHouse server version: 25.3
Original query:
:) create table a (id Int32) Engine=Memory;
:) create table b (id Int32, email Nullable(String)) Engine=Memory;
:) insert into a values (1), (2), (3);
:) insert into b values (2, 'two@example.com');
:) select a.id, if(b.email is null, false, true) as has_email from a left join b on a.id = b.id;
┌─id─┬─has_email─┐
1. │ 1 │ true │
2. │ 2 │ true │
3. │ 3 │ true │
└────┴───────────┘Works as expected when explicitly projecting the column inside the if function.
:) select a.id, b.email, if(b.email is null, false, true) as has_email from a left join b on a.id = b.id;
┌─id─┬─email───────────┬─has_email─┐
1. │ 1 │ ᴺᵁᴸᴸ │ false │
2. │ 2 │ two@example.com │ true │
3. │ 3 │ ᴺᵁᴸᴸ │ false │
└────┴─────────────────┴───────────┘Selecting inside CTEs fails to load the column as well:
:) with ds as (select a.id, b.email, if(b.email is null, false, true) as has_email from a left join b on a.id = b.id) select id, has_email from ds;
┌─id─┬─has_email─┐
1. │ 1 │ true │
2. │ 2 │ true │
3. │ 3 │ true │
└────┴───────────┘
:) with ds as (select a.id, b.email, if(b.email is null, false, true) as has_email from a left join b on a.id = b.id) select id, email, has_email from ds;
┌─id─┬─email───────────┬─has_email─┐
1. │ 1 │ ᴺᵁᴸᴸ │ false │
2. │ 2 │ two@example.com │ true │
3. │ 3 │ ᴺᵁᴸᴸ │ false │
└────┴─────────────────┴───────────┘Expected behavior
Columns inside funtion calls should be loaded. CTEs should be evaluated eagerly. Behaviour should at least show a warning.
Error message and/or stacktrace
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Additional context
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