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MDEV-14820 System versioning is applied incorrectly to CTEs

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Make sure that SELECT_LEX_UNIT::derived, behaves as documented
(points to the "TABLE_LIST representing this union in the
embedding select"). For recursive CTE this was not necessarily
the case, it could've pointed to the TABLE_LIST inside the CTE,
not in the embedding select.

To fix:
* don't update unit->derived in mysql_derived_prepare(), pass derived
  as an argument to st_select_lex_unit::prepare()
* prefer to set unit->derived in TABLE_LIST::init_derived()
  to the TABLE_LIST in the embedding select, not to the recursive
  reference. Fail if there are many TABLE_LISTs in the embedding
  select with conflicting FOR SYSTEM_TIME clauses.

cleanup:
* remove redundant THD* argument from st_select_lex_unit::prepare()
This commit is contained in:
Sergei Golubchik
2018-04-18 14:29:48 +02:00
parent 0f956a0676
commit 531acda484
14 changed files with 431 additions and 69 deletions
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3
sql/sql_select.cc
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@ -25647,7 +25647,8 @@ bool mysql_explain_union(THD *thd, SELECT_LEX_UNIT *unit, select_result *result)
unit->fake_select_lex->type= unit_operation_text[unit->common_op()];
unit->fake_select_lex->options|= SELECT_DESCRIBE;
}
if (!(res= unit->prepare(thd, result, SELECT_NO_UNLOCK | SELECT_DESCRIBE)))
if (!(res= unit->prepare(unit->derived, result,
SELECT_NO_UNLOCK | SELECT_DESCRIBE)))
res= unit->exec();
}
else