01.06.2015 12:22, liviuslivius wrote:
>
> i do not know if this is related to CORE-4809 or should i report this as
> new ticket in tracker?
> for query
> SELECT
> *
> FROM
> RDB$RELATION_FIELDS RF
> left join RDB$RELATIONS R on R.RDB$FIELD_ID+0 = RF.RDB$FIELD_POSITION
> WHERE
> RF.RDB$RELATION_NAME='RDB$RELATIONS'
> we got
> PLAN JOIN (RF INDEX (RDB$INDEX_4), R NATURAL)

Correct.

> and stats are
> RDB$RELATION_FIELDS - 17 indexed reads
> RDB$RELATIONS - 4505 sequential reads
> but should this be as a HASH JOIN? to limit 4505 reads to only few?

Hash/merge algorithms are not supported for outer joins (yet).


Dmitry


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