[tarantool-patches] Re: [PATCH 2/2] sql: fix code generation for aggregate in HAVING clause
Vladislav Shpilevoy
v.shpilevoy at tarantool.org
Mon Feb 25 15:58:49 MSK 2019
Thanks for the patch! See 3 comments below.
On 21/02/2019 21:01, Nikita Pettik wrote:
> When we allowed using HAVING clause without GROUP BY (b40f2443a), one
> possible combination was forgotten to be tested:
>
> SELECT 1 FROM te40 HAVING SUM(s1) < 0;
>
> In other words, resulting set contains no aggregates, but HAVING does
> contain.
1. We have these tests: select5-9.10, select5-9.11, select5-9.12. They all
have no aggregates in the result set, but have in HAVING. So that was not
a problem. Problem was that we forgot to test a false condition.
> In this case no byte-code related to aggregate execution is
> emitted at all. Hence, query above equals to simple SELECT 1;
> Unfortunately, result of such query is the same when condition under
> HAVING clause is satisfied.
2. Did you mean **not** satisfied?
> To fix this behaviour, it is enough to
> indicate to byte-code generator that we should analyze aggregates not
> only in ORDER BY clauses, but also in HAVING clause.
>
> Closes #3932
> Follow-up #2364
> ---
> src/box/sql/resolve.c | 10 +++++++---
> test/sql-tap/select5.test.lua | 25 ++++++++++++++++++++++++-
> 2 files changed, 31 insertions(+), 4 deletions(-)
>
> diff --git a/src/box/sql/resolve.c b/src/box/sql/resolve.c
> index bc208cc9d..e9a1b09f7 100644
> --- a/src/box/sql/resolve.c
> +++ b/src/box/sql/resolve.c
> @@ -1290,12 +1290,16 @@ resolveSelectStep(Walker * pWalker, Select * p)
> return WRC_Abort;
> }
>
> - /* If there are no aggregate functions in the result-set, and no GROUP BY
> - * expression, do not allow aggregates in any of the other expressions.
> + /*
> + * If there are no aggregate functions in the
> + * result-set, and no GROUP BY or HAVING
> + * expression, do not allow aggregates in any
> + * of the other expressions.
> */
> assert((p->selFlags & SF_Aggregate) == 0);
> pGroupBy = p->pGroupBy;
> - if (pGroupBy || (sNC.ncFlags & NC_HasAgg) != 0) {
> + if ((pGroupBy != NULL || p->pHaving != NULL) ||
3. Why do you need the braces around
"pGroupBy != NULL || p->pHaving != NULL" ?
> + (sNC.ncFlags & NC_HasAgg) != 0) {
> assert(NC_MinMaxAgg == SF_MinMaxAgg);
> p->selFlags |=
> SF_Aggregate | (sNC.ncFlags & NC_MinMaxAgg);
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