Module mz_sql::plan::query

SQL Querys are the declarative, computational part of SQL. This module turns Querys into HirRelationExprs - a more explicit, algebraic way of describing computation. Functions named plan_* are typically responsible for handling a single node of the SQL ast. Eg plan_query is responsible for handling sqlparser::ast::Query. plan_* functions which correspond to operations on relations typically return a HirRelationExpr. plan_* functions which correspond to operations on scalars typically return a HirScalarExpr and a ScalarType. (The latter is because it’s not always possible to infer from a HirScalarExpr what the intended type is - notably in the case of decimals where the scale/precision are encoded only in the type). Aggregates are particularly twisty.

In SQL, a GROUP BY turns any columns not in the group key into vectors of values. Then anywhere later in the scope, an aggregate function can be applied to that group. Inside the arguments of an aggregate function, other normal functions are applied element-wise over the vectors. Thus SELECT sum(foo.x + foo.y) FROM foo GROUP BY x means adding the scalar x to the vector y and summing the results.

In HirRelationExpr, aggregates can only be applied immediately at the time of grouping.

To deal with this, whenever we see a SQL GROUP BY we look ahead for aggregates and precompute them in the HirRelationExpr::Reduce. When we reach the same aggregates during normal planning later on, we look them up in an ExprContext to find the precomputed versions.

Structs

• AggregateTableFuncVisitor 🔒
  This is used to collect aggregates and table functions from within an Expr. See the explanation of aggregate handling at the top of the file for more details.
• CastRelationError 🔒
• CteDesc
  Description of a CTE sufficient for query planning.
• ExprContext
  A bundle of unrelated things that we need for planning Exprs.
• MutRecBlockOptionExtracted
• PlannedQuery 🔒
• PlannedRootQuery
• QueryContext
  The state required when planning a Query.
• ReadThenWritePlan
  Common information used for DELETE, UPDATE, and INSERT INTO … SELECT plans.
• SelectOptionExtracted
• SelectPlan 🔒
  Describes how to execute a SELECT query.
• WindowFuncCollector 🔒

Enums

• ExpandedSelectItem 🔒
• QueryLifetime
  Specifies how long a query will live.

Constants

• IGNORE_NULLS_ERROR_MSG

Functions

• cast_relation 🔒
  Cast a relation from one type to another using the specified type of cast.
• check_col_index 🔒
• coerce_homogeneous_exprs
  Coerces a list of expressions such that all input expressions will be cast to the same type. If successful, returns a new list of expressions in the same order as the input, where each expression has the appropriate casts to make them all of a uniform type.
• expand_select_item 🔒
• extract_scalar_subscript_from_positions 🔒
• handle_mutation_using_clause 🔒
• invent_column_name 🔒
• plan_aggregate_common 🔒
  Common part of the planning of windowed and non-windowed aggregation functions.
• plan_and 🔒
• plan_array 🔒
  Plans an ARRAY expression.
• plan_array_subquery 🔒
• plan_as_of
  Plans an expression in the AS OF position of a SELECT or SUBSCRIBE, or CREATE MATERIALIZED VIEW statement.
• plan_case 🔒
• plan_cast 🔒
• plan_collate 🔒
• plan_copy_from
• plan_copy_from_rows
  Builds a plan that adds the default values for the missing columns and re-orders the datums in the given rows to match the order in the target table.
• plan_copy_item
• plan_ct_query
  TODO(ct2): Dedup this with plan_root_query.
• plan_ctes
  Creates plans for CTEs and introduces them to qcx.ctes.
• plan_default_expr
• plan_delete_query
• plan_exists 🔒
• plan_expr
• plan_expr_inner 🔒
• plan_expr_or_col_index 🔒
• plan_exprs 🔒
  Plans a slice of expressions.
• plan_field_access 🔒
• plan_function 🔒
• plan_function_order_by 🔒
  Plans the ORDER BY clause of a window function.
• plan_group_by_expr 🔒
  Plans an expression in a GROUP BY clause.
• plan_homogenizing_function 🔒
• plan_identifier 🔒
• plan_in_list 🔒
• plan_index_exprs
• plan_index_list 🔒
• plan_insert_query
• plan_is_expr 🔒
• plan_join 🔒
• plan_join_identity 🔒
• plan_like 🔒
• plan_list 🔒
• plan_list_subquery 🔒
• plan_literal 🔒
• plan_map 🔒
• plan_map_subquery 🔒
• plan_mutation_query_inner
• plan_nested_query
• plan_not 🔒
• plan_op 🔒
• plan_or 🔒
• plan_order_by_exprs 🔒
  Plans a slice of ORDER BY expressions.
• plan_order_by_or_distinct_expr 🔒
  Plans an expression that appears in an ORDER BY or DISTINCT ON clause.
• plan_parameter 🔒
• plan_params
• plan_query 🔒
• plan_query_inner 🔒
• plan_root_query
  Plans a top-level query, returning the HirRelationExpr describing the query plan, the RelationDesc describing the shape of the result set, a RowSetFinishing describing post-processing that must occur before results are sent to the client, and the types of the parameters in the query, if any were present.
• plan_row 🔒
• plan_rows_from 🔒
  Plans a ROWS FROM expression.
• plan_rows_from_internal 🔒
  Plans an expression coalescing multiple table functions. Each table function is followed by its row ordinality. The entire expression is followed by the coalesced row ordinality.
• plan_scalar_table_funcs 🔒
• plan_secret_as
  Plans an expression in the AS position of a CREATE SECRET.
• plan_set_expr 🔒
• plan_slice_list 🔒
• plan_solitary_table_function 🔒
  Plans a table function that appears alone, i.e., that is not part of a ROWS FROM clause that contains other table functions. Special aliasing rules apply.
• plan_subquery 🔒
• plan_subscript 🔒
• plan_subscript_array 🔒
• plan_subscript_jsonb 🔒
• plan_subscript_list 🔒
• plan_table_alias 🔒
• plan_table_factor 🔒
• plan_table_function_internal 🔒
  Plans a table function.
• plan_table_with_joins 🔒
• plan_up_to
  Plans an expression in the UP TO position of a SUBSCRIBE statement.
• plan_update_query
• plan_using_constraint 🔒
• plan_values 🔒
  Plans a VALUES clause that appears in a SELECT statement.
• plan_values_insert 🔒
  Plans a VALUES clause that appears at the top level of an INSERT statement.
• plan_vector_like_subquery 🔒
  Generic function used to plan both array subqueries and list subqueries
• plan_view_select 🔒
  Plans a SELECT query. The SELECT query may contain an intrusive ORDER BY clause.
• plan_webhook_validate_using
  Plans an expression in the CHECK position of a CREATE SOURCE ... FROM WEBHOOK.
• plan_window_frame 🔒
• plan_window_function_common 🔒
  The common part of the planning of all window functions.
• plan_window_function_non_aggr 🔒
  The common part of the planning of non-aggregate window functions, i.e., scalar window functions and value window functions.
• resolve_desc_and_nulls_last 🔒
  Creates a ColumnOrder from an OrderByExpr and column index. Column index is specified by the caller, but desc and nulls_last is figured out here.
• resolve_func
  Resolves the name to a set of function implementations.
• scalar_type_from_catalog
• scalar_type_from_sql
• try_push_projection_order_by 🔒
  Attempts to push a projection through an order by.
• window_frame_bound_ast_to_expr 🔒
• window_frame_unit_ast_to_expr 🔒