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MDEV-5067: Valgrind warnings (Invalid read) in QPF_table_access::print_explain

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- Query plan footprint (in new terms, "EXPLAIN structure") should always keep 
  a copy of key_name.  This is because the table might be a temporary table which
  may be already freed by the time we use query plan footprint.
This commit is contained in:
Sergey Petrunya
2013-09-26 14:42:30 +04:00
parent 7d60030c02
commit 0b69c44e94
6 changed files with 65 additions and 50 deletions
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23
sql/sql_select.cc
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@ -22599,8 +22599,7 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
QPF_table_access *qpt= new (output->mem_root) QPF_table_access;
qp_sel->add_table(qpt);
qpt->key.key_name= NULL;
qpt->key.key_len= (uint)-1;
qpt->key.set(thd->mem_root, NULL, (uint)-1);
qpt->quick_info= NULL;
/* id */
@ -22694,13 +22693,12 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
if (tab->select && tab->select->quick && tab_type != JT_CONST)
{
qpt->quick_info= new QPF_quick_select;
tab->select->quick->save_info(qpt->quick_info);
tab->select->quick->save_info(thd->mem_root, qpt->quick_info);
}
if (key_info) /* 'index' or 'ref' access */
{
qpt->key.key_name= key_info->name;
qpt->key.key_len= key_len;
qpt->key.set(thd->mem_root, key_info->name, key_len);
if (tab->ref.key_parts && tab_type != JT_FT)
{
@ -22723,8 +22721,9 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
if (tab_type == JT_HASH_NEXT) /* full index scan + hash join */
{
qpt->hash_next_key.key_name= table->key_info[tab->index].name;
qpt->hash_next_key.key_len= table->key_info[tab->index].key_length;
qpt->hash_next_key.set(thd->mem_root,
table->key_info[tab->index].name,
table->key_info[tab->index].key_length);
}
if (key_info)
@ -22763,14 +22762,8 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
key_name_buf.append(tmp_buff, strlen(tmp_buff), cs);
}
size_t len;
if ((len= key_name_buf.length()))
{
char *ptr= (char*)thd->alloc(len+1);
memcpy(ptr, key_name_buf.c_ptr_safe(), len+1);
qpt->key.key_name= ptr;
qpt->key.key_len= -1;
}
if (key_name_buf.length())
qpt->key.set(thd->mem_root, key_name_buf.c_ptr_safe(), -1);
}
qpt->ref_set= false;
}