MySQL 8.4.0
Source Code Documentation
Query_term_unary Class Reference

A <query primary> which is a parenthesized query expression (aka qe) body with order by clause and/or limit/offset clause and the qe body is not a binary set operation (union, except, intersect), but is viewed here as a degenerate set operation; i.e. More...

#include <query_term.h>

Inheritance diagram for Query_term_unary:

Public Member Functions

 Query_term_unary (MEM_ROOT *mem_root, Query_term *t)
 Constructor. More...
Query_term_type term_type () const override
 Get the node tree type. More...
const char * operator_string () const override
 Get the node type description. More...
void debugPrint (int level, std::ostringstream &buf) const override
 Print the tree rooted at this node to buf. More...
- Public Member Functions inherited from Query_term_set_op
Query_blockquery_block () const override
 Getter for m_block, q.v. More...
bool set_block (Query_block *b)
 Setter for m_block, q.v. More...
size_t child_count () const override
 Get the number of children this node has. More...
bool open_result_tables (THD *thd, int level) override
 Open tmp tables for the tree of set operation query results, by recursing. More...
void cleanup (bool full) override
 Reset resources used. More...
void destroy_tree () override
 Destroy the query term tree structure. More...
bool has_mixed_distinct_operators ()
 Check if this set operation has a mix of DISTINCT and ALL. More...
bool is_unary () const
 Check if this term is a unary set operation. More...
Mem_root_array< MaterializePathParameters::Operandsetup_materialize_set_op (THD *thd, TABLE *dst_table, bool union_distinct_only, bool calc_found_rows)
 Sets up each(*) query block in this query expression for materialization into the given table by making a materialization parameter for each block (*) modulo union_distinct_only. More...
- Public Member Functions inherited from Query_term
Query_termpushdown_limit_order_by (Query_term_set_op *parent=nullptr)
 Called after contextualization to simplify query, c.f. More...
bool validate_structure (const Query_term *parent, int depth=0) const
 Return true if structure is too deep, i.e. More...
std::pair< bool, bool > redundant_order_by (Query_block *block, int level)
 Determine if we have a redundant ORDER BY in block. More...
virtual ~Query_term ()=default
 Node destructor. More...
Query_term_set_opparent () const
 Getter for m_parent, q.v. More...
void printPointers (std::ostringstream &buf) const
 Print the pointer of this node and its parent to buf. More...
void set_setop_query_result (Query_result *rs)
 Setter for m_setop_query_result, q.v. More...
Query_resultsetop_query_result ()
 Getter for m_setop_query_result, q.v. More...
Query_result_unionsetop_query_result_union ()
 Getter for m_setop_query_result, q.v. Use only if we can down cast. More...
void cleanup_query_result (bool full)
 Cleanup m_setop_query_result, q.v. More...
void set_owning_operand ()
 Setter for m_owning_operand, q.v. More...
bool owning_operand ()
 Getter for m_owning_operand, q.v. More...
void set_result_table (Table_ref *tl)
 Setter for m_result_table, q.v. More...
Table_refresult_table ()
 Getter for m_result_table, q.v. More...
void set_fields (mem_root_deque< Item * > *fields)
mem_root_deque< Item * > * fields ()

Additional Inherited Members

- Static Public Member Functions inherited from Query_term
static void indent (int level, std::ostringstream &buf)
 Print blank space indentation (unit: two) to buf according to level. More...
static void print_order (const THD *thd, String *str, ORDER *ord, enum_query_type query_type)
 Print into str the order indicated in ord, using standard print_for_order Used by traditional explain. More...
- Public Attributes inherited from Query_term_set_op
mem_root_deque< Query_term * > m_children
 Tree structure. More...
int64_t m_last_distinct
 Index of last query expression which has <set-op> DISTINCT on its left. More...
int64_t m_first_distinct
 Presently only needed by EXCEPT set operator: the index of the first DISTINCT set operand: minimum legal value is 1. More...
bool m_is_materialized {true}
 true if the result of this set operation is materialized. More...
- Protected Member Functions inherited from Query_term_set_op
 Query_term_set_op (MEM_ROOT *mem_root)
void print (int level, std::ostringstream &buf, const char *type) const
 Common printing minion for set operations. More...
- Protected Attributes inherited from Query_term
Query_term_set_opm_parent {nullptr}
 Back pointer to the node whose child we are, or nullptr (root term). More...
Query_resultm_setop_query_result {nullptr}
 The query result for this term. More...
bool m_owning_operand {false}
 The operand of a n-ary set operation (that owns the common query result) has this set to true. More...
Table_refm_result_table {nullptr}
 Result temporary table for the set operation, if applicable. More...
mem_root_deque< Item * > * m_fields {nullptr}
 Used only when streaming, i.e. More...

Detailed Description

A <query primary> which is a parenthesized query expression (aka qe) body with order by clause and/or limit/offset clause and the qe body is not a binary set operation (union, except, intersect), but is viewed here as a degenerate set operation; i.e.

a "unary".

/// Example: (SELECT * FROM .. ORDER BY .. LIMIT n) ORDER BY .. LIMIT m
/// Tree:
///      Query_expression
///               | m_query_term
///      Query_term_unary
///      +--------------------+
///      |      m_block ------+---->      Query_block which holds outer
///      |        :           |           ORDER BY and LIMIT
///      |      m_children[0] |
///      +--------|-----------+
///               V
///        Query_block   holds inner SELECT and its ORDER BY/LIMIT

One extra Query_term_unary is added for each level of nesting with the top one representing the outermost ORDER BY/LIMIT/OFFSET

Constructor & Destructor Documentation

◆ Query_term_unary()

Query_term_unary::Query_term_unary ( MEM_ROOT mem_root,
Query_term t 


mem_rootthe mem_root to use for allocation
tthe child term

Member Function Documentation

◆ debugPrint()

void Query_term_unary::debugPrint ( int  level,
std::ostringstream &  buf 
) const

Print the tree rooted at this node to buf.

Call on top level with level==0

levellevel we are at in tree.
bufthe buffer to format output into

Implements Query_term.

◆ operator_string()

const char * Query_term_unary::operator_string ( ) const

Get the node type description.

descriptive string for each node type.

Implements Query_term.

◆ term_type()

Query_term_type Query_term_unary::term_type ( ) const

Get the node tree type.

the tree node type

Implements Query_term.

The documentation for this class was generated from the following files: