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MXS-679: Correctly collect fields of WHERE

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qc_mysqlembedded used Item::next for traversing the fields of WHERE.
That is not correct as next is not intended for that purpose:

  /**
     Intrusive list pointer for free list. If not null, points to the next
     Item on some Query_arena's free list. For instance, stored procedures
     have their own Query_arena's.

     @see Query_arena::free_list
   */
  Item *next;

In pratice this meant that the fields in the SELECT part were reported
twice and that, depending on the query, all fields of WHERE were *not*
reported. For instance, the result for

    SELECT a from X WHERE b = 1 and c = 2;

would correctly be "a b c" (in fact, it would be "a b c a"), but
the result for

    SELECT a from X WHERE b = 1 and c = 2 and d = 3;

would also be "a b c".
This commit is contained in:
Johan Wikman 2016-04-21 11:19:40 +03:00
parent 9224249ae5
commit eb1a30e9ac
1 changed files with 43 additions and 11 deletions
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54
query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc
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@ -1320,6 +1320,48 @@ inline void add_str(char** buf, int* buflen, int* bufsize, char* str)
}
static void collect_where(Item* item, char** bufp, int* buflenp, int* bufsizep)
{
switch (item->type())
{
case Item::COND_ITEM:
{
Item_cond* cond_item = static_cast<Item_cond*>(item);
List_iterator<Item> ilist(*cond_item->argument_list());
item = (Item*) ilist.next();
for (; item != NULL; item = (Item*) ilist.next())
{
collect_where(item, bufp, buflenp, bufsizep);
}
}
break;
case Item::FIELD_ITEM:
if (item->name)
{
add_str(bufp, buflenp, bufsizep, item->name);
}
break;
case Item::FUNC_ITEM:
{
Item_func* func_item = static_cast<Item_func*>(item);
Item** items = func_item->arguments();
size_t n_items = func_item->argument_count();
for (size_t i = 0; i < n_items; ++i)
{
collect_where(items[i], bufp, buflenp, bufsizep);
}
}
break;
default:
break;
}
}
/**
* Returns all the fields that the query affects.
* @param buf Buffer to parse
@ -1375,19 +1417,9 @@ char* qc_get_affected_fields(GWBUF* buf)
}
}
if (lex->current_select->where)
{
for (item = lex->current_select->where; item != NULL; item = item->next)
{
itype = item->type();
if (item->name && itype == Item::FIELD_ITEM)
{
add_str(&where, &buffsz, &bufflen, item->name);
}
}
collect_where(lex->current_select->where, &where, &buffsz, &bufflen);
}
if (lex->current_select->having)