Fill RDB$FIELDS.RDB$COMPUTED_SOURCE for view fields [CORE6179]

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Submitted by: Valdir Stiebe Junior (ogecrom)

Votes: 2

Every RDB$FIELDS.RDB$COMPUTED_SOURCE are null except for the ones from table computed fields.
Views with subqueries or expressions as fields should also have the correct computed source.

I've found this because I would like to pinpoint fields from views and try to execute statement the view source with only selected fields.

This is the sql query I was trying to build.

select
RF.RDB$FIELD_POSITION,
coalesce(trim(VR.RDB$CONTEXT_NAME) || '.' || trim(RF.RDB$BASE_FIELD), F.RDB$COMPUTED_SOURCE)
from
RDB$RELATION_FIELDS RF left join
RDB$VIEW_RELATIONS VR on RF.RDB$RELATION_NAME = VR.RDB$VIEW_NAME and RF.RDB$VIEW_CONTEXT = VR.RDB$VIEW_CONTEXT left join
RDB$FIELDS F on F.RDB$FIELD_NAME = RF.RDB$FIELD_SOURCE
where
RF.RDB$RELATION_NAME = 'VIEW_NAME'
order by
RF.RDB$FIELD_POSITION

[firebird-automations]

Commented by: F.D.Castel (fdcastel)

I did like the idea of having access to the view column source. However, I don't know if RDB$COMPUTED_SOURCE would be the best place for it.

Alternative suggestion: to add a new RDB$VIEW_SOURCE column into RDB$FIELDS. Only used for view fields.

This way we could keep the RDB$COMPUTED_SOURCE and RDB$COMPUTED_BLR fields just for COMPUTED BY fields.

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Commented by: @dyemanov

System tables are for the engine to operate and for extracting the source code as DDL. These tasks work fine without this new feature. So far I don't see any good rationale why this is necessary.