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  1. MariaDB Server
  2. MDEV-38

NOT EXISTS to IN (part of exists2in transformation for 10.0)

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Details

    • Task
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Fixed
    • 10.0.2
    • None
    • None

    Description

      Transform queries like:

      ... WHERE EXISTS (SELECT 1 FROM inner_table WHERE inner_table.field = 
      2*outer_table.field AND maybe_something_else)...

      and

      ... WHERE NOT EXISTS (SELECT 1 FROM inner_table WHERE inner_table.field = 
      2*outer_table.field AND maybe_something_else)...

      into

      ... WHERE 2*outer_table.field IN (SELECT inner_table.field FROM inner_table 
      WHERE 1 = 1 AND maybe_something_else)..
      		 

      ... WHERE NOT( 2*outer_table.field IS NOT NULL AND NOT 2*outer_table.field IN 
      (SELECT 
      inner_table.field FROM inner_table WHERE inner_table.field IS NOT NULL AND 
      maybe_something_else)...

      To allow optimizations made for IN/ALL/ANY subqueries.

      Conversion is possible only if:
      1)real NULL is not important (top element of WHERE/ON AND/OR list, i.e. NULL
      equal to FALSE)
      2a)subquery has dependences in the WHERE clause and they are equalities and in is not "NOT EXISTS" (this kind of queries could be converted to semijoin)
      OR
      2b)subquery has the only dependences (after bringing them out subquery become independent) in the WHERE clause and they are equalities (could be materialized)
      3)the subquery is simple (has no aggregate function, GROUp BY, ORDER BY, LIMIT
      HAVING and so on)

      For NOT EXISTS conversion the subquery should be marked that its left part can't
      be NULL.

      Note: Number of equalities could be limited by already allocated space for select list for current implementation.

      Attachments

        Issue Links

          includes

          Bug - A problem which impairs or prevents the functions of the product. MDEV-3903 Exists2In: Server crashes in Item_cond::fix_fields on 2nd execution of a prepared stmt with exists_to_in+materialization+semijoin, EXISTS subquery, STRAIGHT_JOIN

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-3904 Exists2In: Assertion `in_subs->has_strategy()' failed in JOIN::choose_subquery_plan on 2nd execution of PS with exists_to_in+semijoin, EXISTS subquery, MERGE view or FROM subquery

          • Major - Major loss of function.
          • Closed
          is blocked by

          Bug - A problem which impairs or prevents the functions of the product. MDEV-159 Exists2In: Assertion `!table || (!table->read_set || bitmap_is_set(table->read_set, field_index))' failed in String* Field_varstring::val_str(String*, String*)

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-160 Exists2In: Crash in in hp_movelink with subquery_cache=ON

          • Major - Major loss of function.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-245 Exists2In: Wrong result (extra rows) with exists_to_in=ON, materialization=OFF, NOT EXISTS subquery

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-403 Exists2In: Wrong result (missing rows) with subquery in EXISTS and an OR condition outside

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-404 Exists2In: Wrong result (extra rows) with STRAIGHT_JOIN, EXISTS subquery, NOT NULL column

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-3906 Exists2In: Server crashes in Dependency_marker::visit_field on 2nd execution of PS with exists_to_in and NOT EXISTS subquery

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-243 Exists2In: Wrong result (extra or missing rows) with exists_to_in + materialization, EXISTS subquery

          • Major - Major loss of function.
          • Closed
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              sanja Oleksandr Byelkin
              ratzpo Rasmus Johansson (Inactive)
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              Dates

                Created:
                Updated:
                Resolved:

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