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EXPLAIN FORMAT=JSON: support join buffering

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- Basic support for JOIN buffering
- The output is not polished but catches the main point:
  tab->select_cond and tab->cache_select->cond are printed separately.
- Hash join support is poor still.

- Also fixed identation in JOIN_TAB::save_explain_data
This commit is contained in:
Sergei Petrunia
2014-11-27 23:10:44 +03:00
parent 37c444e1a0
commit 461dbd80d2
5 changed files with 97 additions and 12 deletions
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39
sql/sql_explain.cc
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@@ -903,8 +903,18 @@ void Explain_table_access::tag_to_json(Json_writer *writer, enum explain_extra_t
write_item(writer, pushed_index_cond);
break;
case ET_USING_WHERE:
writer->add_member("attached_condition");
write_item(writer, where_cond);
if (where_cond)
{
writer->add_member("attached_condition");
/*
We are printing the condition that is checked when scanning this
table.
- when join buffer is used, it is cache_cond.
- in other cases, it is where_cond.
*/
Item *item= bka_type.is_using_jbuf()? cache_cond: where_cond;
write_item(writer, item);
}
break;
case ET_USING_INDEX:
writer->add_member("using_index").add_bool(true);
@@ -912,8 +922,8 @@ void Explain_table_access::tag_to_json(Json_writer *writer, enum explain_extra_t
case ET_USING:
// index merge: case ET_USING
break;
case ET_USING_JOIN_BUFFER:
// TODO TODO
case ET_USING_JOIN_BUFFER:
/* Do nothing. Join buffer is handled differently */
break;
default:
DBUG_ASSERT(0);
@@ -925,6 +935,12 @@ void Explain_table_access::print_explain_json(Json_writer *writer,
bool is_analyze)
{
Json_writer_nesting_guard guard(writer);
if (bka_type.is_using_jbuf())
{
writer->add_member("block-nl-join").start_object();
}
writer->add_member("table").start_object();
writer->add_member("table_name").add_str(table_name);
@@ -1018,6 +1034,21 @@ void Explain_table_access::print_explain_json(Json_writer *writer,
tag_to_json(writer, extra_tags.at(i));
}
if (bka_type.is_using_jbuf())
{
writer->end_object();
writer->add_member("buffer_type").add_str(bka_type.incremental?
"incremental":"flat");
writer->add_member("join_type").add_str(bka_type.join_alg);
if (bka_type.mrr_type.length())
writer->add_member("mrr_type").add_str(bka_type.mrr_type);
if (where_cond)
{
writer->add_member("attached_condition");
write_item(writer, where_cond);
}
}
writer->end_object();
}