revision-id: 0e62bfe92647ab4b5a2a8582979e4d161c43b105 (mariadb-10.6.1-358-g0e62bfe9264) parent(s): afa835568a1623991799830175039816b9ac2681 author: Sergei Petrunia committer: Sergei Petrunia timestamp: 2022-04-04 12:32:22 +0300 message: MDEV-28201: Server crashes upon SHOW ANALYZE/EXPLAIN FORMAT=JSON Fix it.(proper commit comment fill follow) --- mysql-test/suite/perfschema/r/nesting.result | 74 +++++++------- sql/item.cc | 20 +++- sql/mysqld.h | 4 + sql/sql_base.cc | 3 + sql/sql_class.cc | 3 - sql/sql_explain.cc | 145 +++++++++++++++++---------- sql/sql_explain.h | 104 +++++++++++-------- sql/sql_lex.cc | 3 +- sql/sql_parse.cc | 3 +- sql/sql_show.cc | 14 ++- 10 files changed, 232 insertions(+), 141 deletions(-) diff --git a/mysql-test/suite/perfschema/r/nesting.result b/mysql-test/suite/perfschema/r/nesting.result index 5fe515e2662..9e18e5ac272 100644 --- a/mysql-test/suite/perfschema/r/nesting.result +++ b/mysql-test/suite/perfschema/r/nesting.result @@ -128,11 +128,11 @@ relative_event_id relative_end_event_id event_name comment nesting_event_type re 11 11 stage/sql/Executing (stage) STATEMENT 0 12 12 stage/sql/End of update loop (stage) STATEMENT 0 13 13 stage/sql/Query end (stage) STATEMENT 0 -14 14 stage/sql/Commit (stage) STATEMENT 0 -15 15 stage/sql/closing tables (stage) STATEMENT 0 -16 16 stage/sql/Starting cleanup (stage) STATEMENT 0 -17 18 stage/sql/Freeing items (stage) STATEMENT 0 -18 18 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 17 +14 15 stage/sql/Commit (stage) STATEMENT 0 +15 15 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 14 +16 16 stage/sql/closing tables (stage) STATEMENT 0 +17 17 stage/sql/Starting cleanup (stage) STATEMENT 0 +18 18 stage/sql/Freeing items (stage) STATEMENT 0 19 19 wait/io/socket/sql/client_connection send STATEMENT 0 20 21 stage/sql/Reset for next command (stage) STATEMENT 0 21 21 wait/synch/mutex/sql/THD::LOCK_thd_data lock STAGE 20 @@ -152,11 +152,11 @@ relative_event_id relative_end_event_id event_name comment nesting_event_type re 35 35 stage/sql/Executing (stage) STATEMENT 24 36 36 stage/sql/End of update loop (stage) STATEMENT 24 37 37 stage/sql/Query end (stage) STATEMENT 24 -38 38 stage/sql/Commit (stage) STATEMENT 24 -39 39 stage/sql/closing tables (stage) STATEMENT 24 -40 40 stage/sql/Starting cleanup (stage) STATEMENT 24 -41 42 stage/sql/Freeing items (stage) STATEMENT 24 -42 42 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 41 +38 39 stage/sql/Commit (stage) STATEMENT 24 +39 39 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 38 +40 40 stage/sql/closing tables (stage) STATEMENT 24 +41 41 stage/sql/Starting cleanup (stage) STATEMENT 24 +42 42 stage/sql/Freeing items (stage) STATEMENT 24 43 43 wait/io/socket/sql/client_connection send STATEMENT 24 44 45 stage/sql/Reset for next command (stage) STATEMENT 24 45 45 wait/synch/mutex/sql/THD::LOCK_thd_data lock STAGE 44 @@ -176,11 +176,11 @@ relative_event_id relative_end_event_id event_name comment nesting_event_type re 59 59 stage/sql/Executing (stage) STATEMENT 48 60 60 stage/sql/End of update loop (stage) STATEMENT 48 61 61 stage/sql/Query end (stage) STATEMENT 48 -62 62 stage/sql/Commit (stage) STATEMENT 48 -63 63 stage/sql/closing tables (stage) STATEMENT 48 -64 64 stage/sql/Starting cleanup (stage) STATEMENT 48 -65 66 stage/sql/Freeing items (stage) STATEMENT 48 -66 66 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 65 +62 63 stage/sql/Commit (stage) STATEMENT 48 +63 63 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 62 +64 64 stage/sql/closing tables (stage) STATEMENT 48 +65 65 stage/sql/Starting cleanup (stage) STATEMENT 48 +66 66 stage/sql/Freeing items (stage) STATEMENT 48 67 67 wait/io/socket/sql/client_connection send STATEMENT 48 68 69 stage/sql/Reset for next command (stage) STATEMENT 48 69 69 wait/synch/mutex/sql/THD::LOCK_thd_data lock STAGE 68 @@ -203,12 +203,12 @@ select "With a third part to make things complete" as payload NULL NULL 84 84 stage/sql/Executing (stage) STATEMENT 72 85 85 stage/sql/End of update loop (stage) STATEMENT 72 86 86 stage/sql/Query end (stage) STATEMENT 72 -87 87 stage/sql/Commit (stage) STATEMENT 72 -88 88 stage/sql/closing tables (stage) STATEMENT 72 -89 89 stage/sql/Starting cleanup (stage) STATEMENT 72 -90 92 stage/sql/Freeing items (stage) STATEMENT 72 -91 91 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 90 -92 92 wait/io/socket/sql/client_connection send STAGE 90 +87 88 stage/sql/Commit (stage) STATEMENT 72 +88 88 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 87 +89 89 stage/sql/closing tables (stage) STATEMENT 72 +90 90 stage/sql/Starting cleanup (stage) STATEMENT 72 +91 92 stage/sql/Freeing items (stage) STATEMENT 72 +92 92 wait/io/socket/sql/client_connection send STAGE 91 93 110 statement/sql/select select "And this is the second part of a multi query" as payload; select "With a third part to make things complete" as payload NULL NULL 94 96 stage/sql/starting (stage) STATEMENT 93 @@ -222,12 +222,12 @@ select "With a third part to make things complete" as payload NULL NULL 102 102 stage/sql/Executing (stage) STATEMENT 93 103 103 stage/sql/End of update loop (stage) STATEMENT 93 104 104 stage/sql/Query end (stage) STATEMENT 93 -105 105 stage/sql/Commit (stage) STATEMENT 93 -106 106 stage/sql/closing tables (stage) STATEMENT 93 -107 107 stage/sql/Starting cleanup (stage) STATEMENT 93 -108 110 stage/sql/Freeing items (stage) STATEMENT 93 -109 109 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 108 -110 110 wait/io/socket/sql/client_connection send STAGE 108 +105 106 stage/sql/Commit (stage) STATEMENT 93 +106 106 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 105 +107 107 stage/sql/closing tables (stage) STATEMENT 93 +108 108 stage/sql/Starting cleanup (stage) STATEMENT 93 +109 110 stage/sql/Freeing items (stage) STATEMENT 93 +110 110 wait/io/socket/sql/client_connection send STAGE 109 111 129 statement/sql/select select "With a third part to make things complete" as payload NULL NULL 112 113 stage/sql/starting (stage) STATEMENT 111 113 113 wait/synch/mutex/sql/THD::LOCK_thd_data lock STAGE 112 @@ -239,11 +239,11 @@ select "With a third part to make things complete" as payload NULL NULL 119 119 stage/sql/Executing (stage) STATEMENT 111 120 120 stage/sql/End of update loop (stage) STATEMENT 111 121 121 stage/sql/Query end (stage) STATEMENT 111 -122 122 stage/sql/Commit (stage) STATEMENT 111 -123 123 stage/sql/closing tables (stage) STATEMENT 111 -124 124 stage/sql/Starting cleanup (stage) STATEMENT 111 -125 126 stage/sql/Freeing items (stage) STATEMENT 111 -126 126 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 125 +122 123 stage/sql/Commit (stage) STATEMENT 111 +123 123 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 122 +124 124 stage/sql/closing tables (stage) STATEMENT 111 +125 125 stage/sql/Starting cleanup (stage) STATEMENT 111 +126 126 stage/sql/Freeing items (stage) STATEMENT 111 127 127 wait/io/socket/sql/client_connection send STATEMENT 111 128 129 stage/sql/Reset for next command (stage) STATEMENT 111 129 129 wait/synch/mutex/sql/THD::LOCK_thd_data lock STAGE 128 @@ -263,11 +263,11 @@ select "With a third part to make things complete" as payload NULL NULL 143 143 stage/sql/Executing (stage) STATEMENT 132 144 144 stage/sql/End of update loop (stage) STATEMENT 132 145 145 stage/sql/Query end (stage) STATEMENT 132 -146 146 stage/sql/Commit (stage) STATEMENT 132 -147 147 stage/sql/closing tables (stage) STATEMENT 132 -148 148 stage/sql/Starting cleanup (stage) STATEMENT 132 -149 150 stage/sql/Freeing items (stage) STATEMENT 132 -150 150 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 149 +146 147 stage/sql/Commit (stage) STATEMENT 132 +147 147 wait/synch/mutex/sql/THD::LOCK_thd_kill lock STAGE 146 +148 148 stage/sql/closing tables (stage) STATEMENT 132 +149 149 stage/sql/Starting cleanup (stage) STATEMENT 132 +150 150 stage/sql/Freeing items (stage) STATEMENT 132 151 151 wait/io/socket/sql/client_connection send STATEMENT 132 152 153 stage/sql/Reset for next command (stage) STATEMENT 132 153 153 wait/synch/mutex/sql/THD::LOCK_thd_data lock STAGE 152 diff --git a/sql/item.cc b/sql/item.cc index c4ba402db49..c4606391d00 100644 --- a/sql/item.cc +++ b/sql/item.cc @@ -3125,10 +3125,11 @@ void Item_field::set_field(Field *field_par) base_flags|= item_base_t::FIXED; if (field->table->s->tmp_table == SYSTEM_TMP_TABLE) - { any_privileges= 0; - refers_to_temp_table= true; - } + + if (field->table->s->tmp_table == SYSTEM_TMP_TABLE || + field->table->s->tmp_table == INTERNAL_TMP_TABLE) + set_refers_to_temp_table(true); } @@ -7818,7 +7819,15 @@ Item_direct_view_ref::grouping_field_transformer_for_where(THD *thd, void Item_field::print(String *str, enum_query_type query_type) { - if (!refers_to_temp_table && field && field->table->const_table && + /* + If the field refers to a constant table, print the value. + (1): But don't attempt to do that if + * the field refers to a temporary (work) table, and + * temp. tables might already have been dropped. + */ + if (!(refers_to_temp_table && // (1) + (query_type & QT_DONT_ACCESS_TMP_TABLES)) && // (1) + field && field->table->const_table && !(query_type & (QT_NO_DATA_EXPANSION | QT_VIEW_INTERNAL))) { print_value(str); @@ -7826,7 +7835,8 @@ void Item_field::print(String *str, enum_query_type query_type) } /* Item_ident doesn't have references to the underlying Field/TABLE objects, - so it's safe to use the following even for a temporary table: + so it's safe to make the following call even when the table is not + available already: */ Item_ident::print(str, query_type); } diff --git a/sql/mysqld.h b/sql/mysqld.h index 3a8710f9a85..3b5bc62638d 100644 --- a/sql/mysqld.h +++ b/sql/mysqld.h @@ -903,6 +903,10 @@ enum enum_query_type // it evaluates to. Should be used for error messages, so that they // don't reveal values. QT_NO_DATA_EXPANSION= (1 << 9), + + // The temporary tables used by the query might be freed by the time + // this print() call is made. + QT_DONT_ACCESS_TMP_TABLES= (1 << 12) }; diff --git a/sql/sql_base.cc b/sql/sql_base.cc index a130cc53ad2..de4599b66a0 100644 --- a/sql/sql_base.cc +++ b/sql/sql_base.cc @@ -783,6 +783,9 @@ int close_thread_tables(THD *thd) int error= 0; DBUG_ENTER("close_thread_tables"); + if (thd->lex && thd->lex->explain) + thd->lex->explain->notify_tables_are_closed(); + THD_STAGE_INFO(thd, stage_closing_tables); #ifdef EXTRA_DEBUG diff --git a/sql/sql_class.cc b/sql/sql_class.cc index 214c06e06c5..60d5e4e151d 100644 --- a/sql/sql_class.cc +++ b/sql/sql_class.cc @@ -2241,9 +2241,6 @@ void THD::cleanup_after_query() thd_progress_end(this); - if (lex && lex->explain) - lex->explain->notify_item_objects_about_to_be_freed(); - /* Reset rand_used so that detection of calls to rand() will save random seeds if needed by the slave. diff --git a/sql/sql_explain.cc b/sql/sql_explain.cc index 31ba663eda6..a326a9016e2 100644 --- a/sql/sql_explain.cc +++ b/sql/sql_explain.cc @@ -39,8 +39,8 @@ const char *unit_operation_text[4]= const char *pushed_derived_text= "PUSHED DERIVED"; const char *pushed_select_text= "PUSHED SELECT"; -static void write_item(Json_writer *writer, Item *item); -static void append_item_to_str(String *out, Item *item); +static void write_item(Json_writer *writer, Item *item, bool no_tmp_tbl); +static void append_item_to_str(String *out, Item *item, bool no_tmp_tbl); Explain_query::Explain_query(THD *thd_arg, MEM_ROOT *root) : mem_root(root), upd_del_plan(nullptr), insert_plan(nullptr), @@ -157,18 +157,30 @@ void Explain_query::query_plan_ready() if (!apc_enabled) thd->apc_target.enable(); apc_enabled= true; +#ifndef DBUG_OFF + can_print_json= true; +#endif } -void Explain_query::notify_item_objects_about_to_be_freed() +void Explain_query::notify_tables_are_closed() { + /* + Disable processing of SHOW EXPLAIN|ANALYZE (because the query is about to + do cleanups which will make it difficult). + See sql_explain.h:ExplainDataStructureLifetime for details. + */ if (apc_enabled) { thd->apc_target.disable(); apc_enabled= false; +#ifndef DBUG_OFF + can_print_json= false; +#endif } } + /* Send EXPLAIN output to the client. */ @@ -184,7 +196,7 @@ int Explain_query::send_explain(THD *thd) int res= 0; if (thd->lex->explain_json) - print_explain_json(result, thd->lex->analyze_stmt); + print_explain_json(result, thd->lex->analyze_stmt, false /*is_show_cmd*/); else res= print_explain(result, lex->describe, thd->lex->analyze_stmt); @@ -227,25 +239,39 @@ int Explain_query::print_explain(select_result_sink *output, int Explain_query::print_explain_json(select_result_sink *output, bool is_analyze, + bool is_show_cmd, ulonglong query_time_in_progress_ms) { Json_writer writer; + +#ifndef DBUG_OFF + DBUG_ASSERT(can_print_json); +#endif + writer.start_object(); if (is_analyze && query_time_in_progress_ms > 0) writer.add_member("r_query_time_in_progress_ms"). add_ull(query_time_in_progress_ms); + /* + If we are printing ANALYZE FORMAT=JSON output, take into account that + query's temporary tables have already been freed. See sql_explain.h, + sql_explain.h:ExplainDataStructureLifetime for details. + */ + if (is_analyze) + is_show_cmd= true; + if (upd_del_plan) - upd_del_plan->print_explain_json(this, &writer, is_analyze); + upd_del_plan->print_explain_json(this, &writer, is_analyze, is_show_cmd); else if (insert_plan) - insert_plan->print_explain_json(this, &writer, is_analyze); + insert_plan->print_explain_json(this, &writer, is_analyze, is_show_cmd); else { /* Start printing from node with id=1 */ Explain_node *node= get_node(1); if (!node) return 1; /* No query plan */ - node->print_explain_json(this, &writer, is_analyze); + node->print_explain_json(this, &writer, is_analyze, is_show_cmd); } writer.end_object(); @@ -607,7 +633,8 @@ int Explain_union::print_explain(Explain_query *query, void Explain_union::print_explain_json(Explain_query *query, - Json_writer *writer, bool is_analyze) + Json_writer *writer, bool is_analyze, + bool no_tmp_tbl) { Json_writer_nesting_guard guard(writer); char table_name_buffer[SAFE_NAME_LEN]; @@ -650,12 +677,12 @@ void Explain_union::print_explain_json(Explain_query *query, //writer->add_member("dependent").add_str("TODO"); //writer->add_member("cacheable").add_str("TODO"); Explain_select *sel= query->get_select(union_members.at(i)); - sel->print_explain_json(query, writer, is_analyze); + sel->print_explain_json(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); } writer->end_array(); - print_explain_json_for_children(query, writer, is_analyze); + print_explain_json_for_children(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); // union_result writer->end_object(); // query_block @@ -713,7 +740,8 @@ bool is_connection_printable_in_json(enum Explain_node::explain_connection_type void Explain_node::print_explain_json_for_children(Explain_query *query, Json_writer *writer, - bool is_analyze) + bool is_analyze, + bool no_tmp_tbl) { Json_writer_nesting_guard guard(writer); @@ -733,7 +761,7 @@ void Explain_node::print_explain_json_for_children(Explain_query *query, } writer->start_object(); - node->print_explain_json(query, writer, is_analyze); + node->print_explain_json(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); } @@ -913,7 +941,8 @@ void Explain_select::add_linkage(Json_writer *writer) } void Explain_select::print_explain_json(Explain_query *query, - Json_writer *writer, bool is_analyze) + Json_writer *writer, bool is_analyze, + bool no_tmp_tbl) { Json_writer_nesting_guard guard(writer); @@ -935,7 +964,7 @@ void Explain_select::print_explain_json(Explain_query *query, message); writer->end_object(); - print_explain_json_for_children(query, writer, is_analyze); + print_explain_json_for_children(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); } else @@ -957,17 +986,17 @@ void Explain_select::print_explain_json(Explain_query *query, if (exec_const_cond) { writer->add_member("const_condition"); - write_item(writer, exec_const_cond); + write_item(writer, exec_const_cond, no_tmp_tbl); } if (outer_ref_cond) { writer->add_member("outer_ref_condition"); - write_item(writer, outer_ref_cond); + write_item(writer, outer_ref_cond, no_tmp_tbl); } if (pseudo_bits_cond) { writer->add_member("pseudo_bits_condition"); - write_item(writer, pseudo_bits_cond); + write_item(writer, pseudo_bits_cond, no_tmp_tbl); } /* we do not print HAVING which always evaluates to TRUE */ @@ -975,7 +1004,7 @@ void Explain_select::print_explain_json(Explain_query *query, { writer->add_member("having_condition"); if (likely(having)) - write_item(writer, having); + write_item(writer, having, no_tmp_tbl); else { /* Normally we should not go this branch, left just for safety */ @@ -998,7 +1027,8 @@ void Explain_select::print_explain_json(Explain_query *query, case AGGR_OP_FILESORT: { writer->add_member("filesort").start_object(); - ((Explain_aggr_filesort*)node)->print_json_members(writer, is_analyze); + auto aggr_node= (Explain_aggr_filesort*)node; + aggr_node->print_json_members(writer, is_analyze, no_tmp_tbl); break; } case AGGR_OP_REMOVE_DUPLICATES: @@ -1008,7 +1038,8 @@ void Explain_select::print_explain_json(Explain_query *query, { //TODO: make print_json_members virtual? writer->add_member("window_functions_computation").start_object(); - ((Explain_aggr_window_funcs*)node)->print_json_members(writer, is_analyze); + auto aggr_node= (Explain_aggr_window_funcs*)node; + aggr_node->print_json_members(writer, is_analyze, no_tmp_tbl); break; } default: @@ -1017,7 +1048,8 @@ void Explain_select::print_explain_json(Explain_query *query, started_objects++; } - Explain_basic_join::print_explain_json_interns(query, writer, is_analyze); + Explain_basic_join::print_explain_json_interns(query, writer, is_analyze, + no_tmp_tbl); for (;started_objects; started_objects--) writer->end_object(); @@ -1046,7 +1078,8 @@ Explain_aggr_filesort::Explain_aggr_filesort(MEM_ROOT *mem_root, void Explain_aggr_filesort::print_json_members(Json_writer *writer, - bool is_analyze) + bool is_analyze, + bool no_tmp_tbl) { char item_buf[256]; String str(item_buf, sizeof(item_buf), &my_charset_bin); @@ -1066,7 +1099,7 @@ void Explain_aggr_filesort::print_json_members(Json_writer *writer, { str.append(STRING_WITH_LEN(", ")); } - append_item_to_str(&str, item); + append_item_to_str(&str, item, no_tmp_tbl); if (*direction == ORDER::ORDER_DESC) str.append(STRING_WITH_LEN(" desc")); } @@ -1079,7 +1112,8 @@ void Explain_aggr_filesort::print_json_members(Json_writer *writer, void Explain_aggr_window_funcs::print_json_members(Json_writer *writer, - bool is_analyze) + bool is_analyze, + bool no_tmp_tbl) { Explain_aggr_filesort *srt; List_iterator<Explain_aggr_filesort> it(sorts); @@ -1088,19 +1122,19 @@ void Explain_aggr_window_funcs::print_json_members(Json_writer *writer, { Json_writer_object sort(writer); Json_writer_object filesort(writer, "filesort"); - srt->print_json_members(writer, is_analyze); + srt->print_json_members(writer, is_analyze, no_tmp_tbl); } } void Explain_basic_join::print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze) + bool is_analyze, bool no_tmp_tbl) { writer->add_member("query_block").start_object(); writer->add_member("select_id").add_ll(select_id); - print_explain_json_interns(query, writer, is_analyze); + print_explain_json_interns(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); } @@ -1109,7 +1143,7 @@ void Explain_basic_join::print_explain_json(Explain_query *query, void Explain_basic_join:: print_explain_json_interns(Explain_query *query, Json_writer *writer, - bool is_analyze) + bool is_analyze, bool no_tmp_tbl) { { Json_writer_array loop(writer, "nested_loop"); @@ -1122,7 +1156,7 @@ print_explain_json_interns(Explain_query *query, writer->start_array(); } - join_tabs[i]->print_explain_json(query, writer, is_analyze); + join_tabs[i]->print_explain_json(query, writer, is_analyze, no_tmp_tbl); if (join_tabs[i]->end_dups_weedout) { @@ -1131,7 +1165,7 @@ print_explain_json_interns(Explain_query *query, } } } // "nested_loop" - print_explain_json_for_children(query, writer, is_analyze); + print_explain_json_for_children(query, writer, is_analyze, no_tmp_tbl); } @@ -1531,7 +1565,7 @@ const char *String_list::append_str(MEM_ROOT *mem_root, const char *str) } -static void write_item(Json_writer *writer, Item *item) +static void write_item(Json_writer *writer, Item *item, bool no_tmp_tbl) { THD *thd= current_thd; char item_buf[256]; @@ -1541,23 +1575,27 @@ static void write_item(Json_writer *writer, Item *item) ulonglong save_option_bits= thd->variables.option_bits; thd->variables.option_bits &= ~OPTION_QUOTE_SHOW_CREATE; - item->print(&str, QT_EXPLAIN); + auto qtype= QT_EXPLAIN | (no_tmp_tbl? QT_DONT_ACCESS_TMP_TABLES : 0); + item->print(&str, (enum_query_type)qtype); thd->variables.option_bits= save_option_bits; writer->add_str(str.c_ptr_safe()); } -static void append_item_to_str(String *out, Item *item) +static void append_item_to_str(String *out, Item *item, bool no_tmp_tbl) { THD *thd= current_thd; ulonglong save_option_bits= thd->variables.option_bits; thd->variables.option_bits &= ~OPTION_QUOTE_SHOW_CREATE; - item->print(out, QT_EXPLAIN); + auto qtype= QT_EXPLAIN | (no_tmp_tbl? QT_DONT_ACCESS_TMP_TABLES : 0); + item->print(out, (enum_query_type)qtype); thd->variables.option_bits= save_option_bits; } -void Explain_table_access::tag_to_json(Json_writer *writer, enum explain_extra_tag tag) +void Explain_table_access::tag_to_json(Json_writer *writer, + enum explain_extra_tag tag, + bool no_tmp_tbl) { switch (tag) { @@ -1581,11 +1619,11 @@ void Explain_table_access::tag_to_json(Json_writer *writer, enum explain_extra_t break; case ET_USING_INDEX_CONDITION: writer->add_member("index_condition"); - write_item(writer, pushed_index_cond); + write_item(writer, pushed_index_cond, no_tmp_tbl); break; case ET_USING_INDEX_CONDITION_BKA: writer->add_member("index_condition_bka"); - write_item(writer, pushed_index_cond); + write_item(writer, pushed_index_cond, no_tmp_tbl); break; case ET_USING_WHERE: { @@ -1599,7 +1637,7 @@ void Explain_table_access::tag_to_json(Json_writer *writer, enum explain_extra_t if (item) { writer->add_member("attached_condition"); - write_item(writer, item); + write_item(writer, item, no_tmp_tbl); } } break; @@ -1712,7 +1750,7 @@ void Explain_rowid_filter::print_explain_json(Explain_query *query, void Explain_table_access::print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze) + bool is_analyze, bool no_tmp_tbl) { Json_writer_object jsobj(writer); @@ -1743,7 +1781,7 @@ void Explain_table_access::print_explain_json(Explain_query *query, } } writer->add_member("filesort").start_object(); - pre_join_sort->print_json_members(writer, is_analyze); + pre_join_sort->print_json_members(writer, is_analyze, no_tmp_tbl); } if (bka_type.is_using_jbuf()) @@ -1880,7 +1918,7 @@ void Explain_table_access::print_explain_json(Explain_query *query, for (int i=0; i < (int)extra_tags.elements(); i++) { - tag_to_json(writer, extra_tags.at(i)); + tag_to_json(writer, extra_tags.at(i), no_tmp_tbl); } if (full_scan_on_null_key) @@ -1901,7 +1939,7 @@ void Explain_table_access::print_explain_json(Explain_query *query, if (where_cond) { writer->add_member("attached_condition"); - write_item(writer, where_cond); + write_item(writer, where_cond, no_tmp_tbl); } if (is_analyze) @@ -1925,7 +1963,7 @@ void Explain_table_access::print_explain_json(Explain_query *query, { writer->add_member("lateral").add_ll(1); } - node->print_explain_json(query, writer, is_analyze); + node->print_explain_json(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); } if (non_merged_sjm_number) @@ -1935,7 +1973,7 @@ void Explain_table_access::print_explain_json(Explain_query *query, writer->add_member("unique").add_ll(1); Explain_node *node= query->get_node(non_merged_sjm_number); node->connection_type= Explain_node::EXPLAIN_NODE_NON_MERGED_SJ; - node->print_explain_json(query, writer, is_analyze); + node->print_explain_json(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); } if (sjm_nest) @@ -1943,7 +1981,7 @@ void Explain_table_access::print_explain_json(Explain_query *query, /* This is a non-merged semi-join table. Print its contents here */ writer->add_member("materialized").start_object(); writer->add_member("unique").add_ll(1); - sjm_nest->print_explain_json(query, writer, is_analyze); + sjm_nest->print_explain_json(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); } @@ -2249,7 +2287,8 @@ int Explain_delete::print_explain(Explain_query *query, void Explain_delete::print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze) + bool is_analyze, + bool no_tmp_tbl) { Json_writer_nesting_guard guard(writer); @@ -2264,7 +2303,7 @@ void Explain_delete::print_explain_json(Explain_query *query, writer->end_object(); // query_block return; } - Explain_update::print_explain_json(query, writer, is_analyze); + Explain_update::print_explain_json(query, writer, is_analyze, no_tmp_tbl); } @@ -2367,7 +2406,8 @@ int Explain_update::print_explain(Explain_query *query, void Explain_update::print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze) + bool is_analyze, + bool no_tmp_tbl) { Json_writer_nesting_guard guard(writer); @@ -2532,7 +2572,7 @@ void Explain_update::print_explain_json(Explain_query *query, if (where_cond) { writer->add_member("attached_condition"); - write_item(writer, where_cond); + write_item(writer, where_cond, no_tmp_tbl); } /*** The part of plan that is before the buffering/sorting ends here ***/ @@ -2544,7 +2584,7 @@ void Explain_update::print_explain_json(Explain_query *query, writer->end_object(); // table - print_explain_json_for_children(query, writer, is_analyze); + print_explain_json_for_children(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); // query_block } @@ -2574,7 +2614,8 @@ int Explain_insert::print_explain(Explain_query *query, } void Explain_insert::print_explain_json(Explain_query *query, - Json_writer *writer, bool is_analyze) + Json_writer *writer, bool is_analyze, + bool no_tmp_tbl) { Json_writer_nesting_guard guard(writer); @@ -2583,7 +2624,7 @@ void Explain_insert::print_explain_json(Explain_query *query, writer->add_member("table").start_object(); writer->add_member("table_name").add_str(table_name.c_ptr()); writer->end_object(); // table - print_explain_json_for_children(query, writer, is_analyze); + print_explain_json_for_children(query, writer, is_analyze, no_tmp_tbl); writer->end_object(); // query_block } diff --git a/sql/sql_explain.h b/sql/sql_explain.h index f00d6bcf029..983cc820e9e 100644 --- a/sql/sql_explain.h +++ b/sql/sql_explain.h @@ -27,9 +27,8 @@ Query optimization produces two data structures: produce output of SHOW EXPLAIN, EXPLAIN [FORMAT=JSON], or ANALYZE [FORMAT=JSON], without accessing the execution data structures. -(the only exception is that Explain data structures keep Item* pointers, -and we require that one might call item->print(QT_EXPLAIN) when printing -FORMAT=JSON output) +The exception is that Explain data structures have Item* pointers. See +ExplainDataStructureLifetime below for details. === ANALYZE data === EXPLAIN data structures have embedded ANALYZE data structures. These are @@ -135,12 +134,13 @@ class Explain_node : public Sql_alloc virtual int print_explain(Explain_query *query, select_result_sink *output, uint8 explain_flags, bool is_analyze)=0; virtual void print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze)= 0; + bool is_analyze, bool no_tmp_tbl)= 0; int print_explain_for_children(Explain_query *query, select_result_sink *output, uint8 explain_flags, bool is_analyze); void print_explain_json_for_children(Explain_query *query, - Json_writer *writer, bool is_analyze); + Json_writer *writer, bool is_analyze, + bool no_tmp_tbl); bool print_explain_json_cache(Json_writer *writer, bool is_analyze); virtual ~Explain_node(){} }; @@ -174,10 +174,10 @@ class Explain_basic_join : public Explain_node int print_explain(Explain_query *query, select_result_sink *output, uint8 explain_flags, bool is_analyze); void print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze); + bool is_analyze, bool no_tmp_tbl); void print_explain_json_interns(Explain_query *query, Json_writer *writer, - bool is_analyze); + bool is_analyze, bool no_tmp_tbl); /* A flat array of Explain structs for tables. */ Explain_table_access** join_tabs; @@ -261,7 +261,7 @@ class Explain_select : public Explain_basic_join int print_explain(Explain_query *query, select_result_sink *output, uint8 explain_flags, bool is_analyze); void print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze); + bool is_analyze, bool no_tmp_tbl); Table_access_tracker *get_using_temporary_read_tracker() { @@ -304,7 +304,8 @@ class Explain_aggr_filesort : public Explain_aggr_node Explain_aggr_filesort(MEM_ROOT *mem_root, bool is_analyze, Filesort *filesort); - void print_json_members(Json_writer *writer, bool is_analyze); + void print_json_members(Json_writer *writer, bool is_analyze, + bool no_tmp_tbl); }; class Explain_aggr_tmp_table : public Explain_aggr_node @@ -325,7 +326,8 @@ class Explain_aggr_window_funcs : public Explain_aggr_node public: enum_explain_aggr_node_type get_type() { return AGGR_OP_WINDOW_FUNCS; } - void print_json_members(Json_writer *writer, bool is_analyze); + void print_json_members(Json_writer *writer, bool is_analyze, + bool no_tmp_tbl); friend class Window_funcs_computation; }; @@ -378,7 +380,7 @@ class Explain_union : public Explain_node int print_explain(Explain_query *query, select_result_sink *output, uint8 explain_flags, bool is_analyze); void print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze); + bool is_analyze, bool no_tmp_tbl); const char *fake_select_type; bool using_filesort; @@ -417,36 +419,54 @@ class Explain_insert; /* Explain structure for a query (i.e. a statement). - This should be able to survive when the query plan was deleted. Currently, - we do not intend for it survive until after query's MEM_ROOT is freed. It - does surivive freeing of query's items. - - For reference, the process of post-query cleanup is as follows: + This should be able to survive when the query plan was deleted. Currently, + we do not intend for it survive until after query's MEM_ROOT is freed. + + == ExplainDataStructureLifetime == >dispatch_command | >mysql_parse - | | ... - | | lex_end() - | | ... - | | >THD::cleanup_after_query - | | | ... - | | | free_items() - | | | ... - | | <THD::cleanup_after_query + | | ... + | | + | | explain->query_plan_ready(); // (1) + | | + | | some_join->cleanup(); // (2) + | | + | | explain->notify_tables_are_closed(); // (3) + | | close_thread_tables(); // (4) + | | ... + | | free_items(); // (5) + | | ... | | | <mysql_parse | - | log_slow_statement() - | + | log_slow_statement() // (6) + | | free_root() - | + | >dispatch_command - - That is, the order of actions is: - - free query's Items - - write to slow query log - - free query's MEM_ROOT - + + (1) - Query plan construction is finished and it is available for reading. + + (2) - Temporary tables are freed. After this point, + we need to pass QT_DONT_ACCESS_TMP_TABLES to item->print(). Since + we don't track when #2 happens for each temp.table, we pass this + flag whenever we're printing the query plan for a SHOW command. + Also, we pass it when printing ANALYZE (?) + + (3) - Notification about (4). + (4) - Tables used by the query are closed. One known consequence of this is + that the values of the const tables' fields are not available anymore. + We could use the same approach as in QT_DONT_ACCESS_TMP_TABLES to work + around that, but instead we disallow producing FORMAT=JSON output at + step #3. We also processing of SHOW command. The rationale is that + query is close to finish anyway. + + (5) - Item objects are freed. After this, it's certainly not possible to + print them into FORMAT=JSON output. + + (6) - We may decide to log tabular EXPLAIN output to the slow query log. + */ class Explain_query : public Sql_alloc @@ -479,14 +499,14 @@ class Explain_query : public Sql_alloc bool print_explain_str(THD *thd, String *out_str, bool is_analyze); int print_explain_json(select_result_sink *output, bool is_analyze, + bool is_show_cmd, ulonglong query_time_in_progress_ms= 0); /* If true, at least part of EXPLAIN can be printed */ bool have_query_plan() { return insert_plan || upd_del_plan|| get_node(1) != NULL; } void query_plan_ready(); - - void notify_item_objects_about_to_be_freed(); + void notify_tables_are_closed(); MEM_ROOT *mem_root; @@ -510,6 +530,9 @@ class Explain_query : public Sql_alloc is unacceptable. */ longlong operations; +#ifndef DBUG_OFF + bool can_print_json= false; +#endif }; @@ -853,14 +876,15 @@ class Explain_table_access : public Sql_alloc uint select_id, const char *select_type, bool using_temporary, bool using_filesort); void print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze); + bool is_analyze, bool no_tmp_tbl); private: void append_tag_name(String *str, enum explain_extra_tag tag); void fill_key_str(String *key_str, bool is_json) const; void fill_key_len_str(String *key_len_str, bool is_json) const; double get_r_filtered(); - void tag_to_json(Json_writer *writer, enum explain_extra_tag tag); + void tag_to_json(Json_writer *writer, enum explain_extra_tag tag, + bool no_tmp_tbl); }; @@ -943,7 +967,7 @@ class Explain_update : public Explain_node virtual int print_explain(Explain_query *query, select_result_sink *output, uint8 explain_flags, bool is_analyze); virtual void print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze); + bool is_analyze, bool no_tmp_tbl); }; @@ -969,7 +993,7 @@ class Explain_insert : public Explain_node int print_explain(Explain_query *query, select_result_sink *output, uint8 explain_flags, bool is_analyze); void print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze); + bool is_analyze, bool no_tmp_tbl); }; @@ -996,7 +1020,7 @@ class Explain_delete: public Explain_update virtual int print_explain(Explain_query *query, select_result_sink *output, uint8 explain_flags, bool is_analyze); virtual void print_explain_json(Explain_query *query, Json_writer *writer, - bool is_analyze); + bool is_analyze, bool no_tmp_tbl); }; diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc index 58aae66cda1..77b5483b772 100644 --- a/sql/sql_lex.cc +++ b/sql/sql_lex.cc @@ -5834,7 +5834,7 @@ bool st_select_lex::is_merged_child_of(st_select_lex *ancestor) } /* - This is used by SHOW EXPLAIN. It assuses query plan has been already + This is used by SHOW EXPLAIN|ANALYZE. It assumes query plan has been already collected into QPF structures and we only need to print it out. */ @@ -5854,6 +5854,7 @@ int LEX::print_explain(select_result_sink *output, uint8 explain_flags, query_time_in_progress_ms= (now - start_time) / (HRTIME_RESOLUTION / 1000); res= explain->print_explain_json(output, is_analyze, + true /* is_show_cmd */, query_time_in_progress_ms); } else diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc index d6a15f340d8..00f357de0f3 100644 --- a/sql/sql_parse.cc +++ b/sql/sql_parse.cc @@ -6207,7 +6207,8 @@ static bool execute_sqlcom_select(THD *thd, TABLE_LIST *all_tables) result->remove_offset_limit(); if (lex->explain_json) { - lex->explain->print_explain_json(result, lex->analyze_stmt); + lex->explain->print_explain_json(result, lex->analyze_stmt, + false /* is_show_cmd */); } else { diff --git a/sql/sql_show.cc b/sql/sql_show.cc index 7be12ccd911..9f718203a6c 100644 --- a/sql/sql_show.cc +++ b/sql/sql_show.cc @@ -2999,14 +2999,24 @@ void Show_explain_request::call_in_target_thread() target_thd->query_charset()); DBUG_ASSERT(current_thd == target_thd); - set_current_thd(request_thd); + + /* + When producing JSON output, one should not change current_thd. + (If one does that, they will hit an assert when printing constant item + fields. + */ + if (!is_json_format) + set_current_thd(request_thd); + if (target_thd->lex->print_explain(explain_buf, 0 /* explain flags*/, is_analyze, is_json_format, &printed_anything)) { failed_to_produce= TRUE; } - set_current_thd(target_thd); + + if (!is_json_format) + set_current_thd(target_thd); if (!printed_anything) failed_to_produce= TRUE;