diff options
Diffstat (limited to 'src/query_planner.erl')
| -rw-r--r-- | src/query_planner.erl | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/src/query_planner.erl b/src/query_planner.erl index e6f2324..9d9d2bc 100644 --- a/src/query_planner.erl +++ b/src/query_planner.erl @@ -7,8 +7,7 @@ %%% == Query DSL Syntax == %%% %%% The DSL uses nested tuples to represent relational operations: -%%% -%%% ``` +%%% <pre> %%% % Scan relation (base case) %%% {scan, employees} %%% @@ -16,7 +15,7 @@ %%% {relation, employees} %%% %%% % Selection (filter) -%%% {select, {scan, employees}, fun(T) -> maps:get(age, T) > 30 end} +%%% {select, {scan, employees}, fun(T) -> maps:get(age, T) > 30 end} %%% %%% % Projection %%% {project, {scan, employees}, [name, age]} @@ -28,10 +27,10 @@ %%% {theta_join, %%% {scan, employees}, %%% {scan, departments}, -%%% fun(L, R) -> maps:get(dept_id, L) =:= maps:get(id, R) end} +%%% fun(L, R) -> maps:get(dept_id, L) =:= maps:get(id, R) end} %%% %%% % Sort -%%% {sort, {scan, employees}, fun(A, B) -> maps:get(age, A) =< maps:get(age, B) end} +%%% {sort, {scan, employees}, fun(A, B) -> maps:get(age, A) =< maps:get(age, B) end} %%% %%% % Take (limit) %%% {take, {scan, employees}, 10} @@ -46,23 +45,22 @@ %%% {scan, employees}, %%% {scan, departments}, %%% dept_id}, -%%% fun(T) -> maps:get(age, T) > 30 end}, +%%% fun(T) -> maps:get(age, T) > 30 end}, %%% [name, dept_name]} -%%% ``` +%%% </pre> %%% %%% == Usage == -%%% -%%% ``` +%%% <pre> %%% % Prepare a query plan %%% Plan = query_planner:prepare({select, {scan, employees}, -%%% fun(T) -> maps:get(age, T) > 30 end}). +%%% fun(T) -> maps:get(age, T) > 30 end}). %%% %%% % Execute and get iterator %%% Iter = query_planner:execute(DB, Plan). %%% %%% % Collect all results %%% Results = query_planner:collect(DB, Plan). -%%% ``` +%%% </pre> %%% %%% @author Nekoma Team %%% @copyright 2025 @@ -236,8 +234,18 @@ compile_to_iterator(DB, {sort, SubPlan, Comparator}) -> operations:sort_iterator(SubIter, Comparator); compile_to_iterator(DB, {take, SubPlan, N}) -> - SubIter = compile_to_iterator(DB, SubPlan), - operations:take_iterator(SubIter, N); + %% Use relational take operator when possible (for scans) + case SubPlan of + {scan, RelationName} -> + %% Direct scan: use relational take operator + {DB2, TakeRelation} = operations:take(DB, RelationName, N), + %% Get iterator from the take relation (now properly registered) + operations:get_tuples_iterator(DB2, TakeRelation#relation.name, #{}); + _ -> + %% Complex plan: fall back to iterator-based take for composition + SubIter = compile_to_iterator(DB, SubPlan), + operations:take_iterator(SubIter, N) + end; compile_to_iterator(DB, {rename, OldAttr, NewAttr, SubPlan}) -> SubIter = compile_to_iterator(DB, SubPlan), |