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Amit Khandekar
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WL#15040 Add system variable to control EXPLAIN format.
Introduce a system variable 'explain_format' to specify a default format to be used in EXPLAIN statement when the user does not specify the format in the EXPLAIN statement. The compiled-in default value is TRADITIONAL. This variable can be set either globally or in a session. With hypergraph optimizer on, no format specified in EXPLAIN, and explain_format set to TRADITIONAL, display the plan using TREE format. With EXPLAIN ANALYZE, no format specified in EXPLAIN, and explain_format set to TRADITIONAL, again use TREE format. This preserves the existing behaviour. Besides the usual format values, explain_format can have an additional value "TRADITIONAL_STRICT", only for the sake of mtr tests. The mtr tests would fail with hypergraph because of the silent conversion from TRADITIONAL to TREE since that would result in plan outputs that would differ in hypergraph. So in mtr now this variable explain_format will be set to TRADITIONAL_STRICT, so that tests continue to show existing behaviour of failing EXPLAIN statements with hypergraph and still managing to pass because this particular error is ignored. Change-Id: Ib6b1819ede619de94b3b551aae812caec418ba8e
1 parent 5381646 commit 44bfbbd

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+477
-67
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‎mysql-test/mysql-test-run.pl

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@@ -6244,6 +6244,11 @@ ($$$)
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mtr_add_arg($args, "--log-output=file");
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}
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# Force this initial explain_format value, so that tests don't fail with
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# --hypergraph due to implicit conversion from TRADITIONAL to TREE. Check the
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# definition of enum Explain_format_type for more details.
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mtr_add_arg($args, "--explain-format=TRADITIONAL_STRICT");
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# Indicate to mysqld it will be debugged in debugger
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if ($glob_debugger) {
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mtr_add_arg($args, "--gdb");

‎mysql-test/r/all_persisted_variables.result

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@@ -40,17 +40,17 @@ include/assert.inc [Expect 500+ variables in the table. Due to open Bugs, we are
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# Test SET PERSIST
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include/assert.inc [Expect 448 persisted variables in the table.]
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include/assert.inc [Expect 449 persisted variables in the table.]
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************************************************************
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* 3. Restart server, it must preserve the persisted variable
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* settings. Verify persisted configuration.
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************************************************************
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# restart
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include/assert.inc [Expect 448 persisted variables in persisted_variables table.]
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include/assert.inc [Expect 448 persisted variables shown as PERSISTED in variables_info table.]
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include/assert.inc [Expect 448 persisted variables with matching peristed and global values.]
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include/assert.inc [Expect 449 persisted variables in persisted_variables table.]
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include/assert.inc [Expect 449 persisted variables shown as PERSISTED in variables_info table.]
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include/assert.inc [Expect 449 persisted variables with matching peristed and global values.]
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************************************************************
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* 4. Test RESET PERSIST IF EXISTS. Verify persisted variable

‎mysql-test/r/explain_tree.result

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@@ -727,7 +727,7 @@ DROP TABLE t1;
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EXPLAIN ANALYZE FOR CONNECTION 1;
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ERROR 42000: This version of MySQL doesn't yet support 'EXPLAIN ANALYZE FOR CONNECTION'
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EXPLAIN ANALYZE FORMAT=TRADITIONAL SELECT 1;
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ERROR 42000: This version of MySQL doesn't yet support 'FORMAT=TRADITIONAL with EXPLAIN ANALYZE'
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ERROR 42000: This version of MySQL doesn't yet support 'EXPLAIN ANALYZE with TRADITIONAL format'
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EXPLAIN ANALYZE FORMAT=JSON SELECT 1;
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ERROR 42000: This version of MySQL doesn't yet support 'EXPLAIN ANALYZE with JSON format'
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EXPLAIN ANALYZE FORMAT=TREE SELECT 1;

‎mysql-test/r/mysqld--help-notwin.result

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@@ -378,6 +378,12 @@ The following options may be given as the first argument:
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options are set to nonzero values,
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binlog-expire-logs-seconds takes priority. Possible
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purges happen at startup and at binary log rotation.
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--explain-format[=name]
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The default format in which the EXPLAIN statement
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displays information. Valid values are TRADITIONAL
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(default), TREE, JSON and TRADITIONAL_STRICT.
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TRADITIONAL_STRICT is only used internally by the mtr
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test suite, and is not meant to be used anywhere else.
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--explicit-defaults-for-timestamp
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This option causes CREATE TABLE to create all TIMESTAMP
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columns as NULL with DEFAULT NULL attribute, Without this
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eq-range-index-dive-limit 200
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event-scheduler ON
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expire-logs-days 0
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explain-format TRADITIONAL
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explicit-defaults-for-timestamp TRUE
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external-locking FALSE
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flush FALSE

‎mysql-test/r/mysqld--help-win.result

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@@ -377,6 +377,12 @@ The following options may be given as the first argument:
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options are set to nonzero values,
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binlog-expire-logs-seconds takes priority. Possible
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purges happen at startup and at binary log rotation.
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--explain-format[=name]
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The default format in which the EXPLAIN statement
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displays information. Valid values are TRADITIONAL
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(default), TREE, JSON and TRADITIONAL_STRICT.
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TRADITIONAL_STRICT is only used internally by the mtr
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test suite, and is not meant to be used anywhere else.
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--explicit-defaults-for-timestamp
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This option causes CREATE TABLE to create all TIMESTAMP
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columns as NULL with DEFAULT NULL attribute, Without this
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eq-range-index-dive-limit 200
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event-scheduler ON
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expire-logs-days 0
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explain-format TRADITIONAL
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explicit-defaults-for-timestamp TRUE
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external-locking FALSE
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flush FALSE

‎mysql-test/suite/sys_vars/inc/explain_default_format.inc

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# WL15040: Add system variable to control EXPLAIN format
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# Save the original explain_format value.
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set @orig_explain_format=@@global.explain_format;
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# Test the initial value. It should be TRADITIONAL_STRICT.
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select @@explain_format, @@global.explain_format;
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# hypergraph with TRADITIONAL_STRICT should error out, rather than convert to TREE.
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--error 0, ER_HYPERGRAPH_NOT_SUPPORTED_YET
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explain select 1;
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set explain_format=traditional;
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--echo # With hypergraph and TRADITIONAL, EXPLAIN should use TREE format.
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explain select 1;
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--echo # Test that explain_format can be set to any of the scopes; i.e. session,
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--echo # global and persist.
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set persist explain_format=tree;
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select @@explain_format, @@global.explain_format;
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set global explain_format=json;
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select @@explain_format, @@global.explain_format;
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set explain_format=tree;
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select @@explain_format, @@global.explain_format;
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set explain_format=default;
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select @@explain_format, @@global.explain_format;
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set global explain_format=default;
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select @@explain_format, @@global.explain_format;
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set persist explain_format=default;
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select @@explain_format, @@global.explain_format;
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set explain_format=default;
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select @@explain_format, @@global.explain_format;
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reset persist explain_format; # Required to clear the conf file.
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select @@explain_format, @@global.explain_format;
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# Also delete the conf file to remote test foot-prints
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let $MYSQLD_DATADIR= `select @@datadir`;
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--remove_file $MYSQLD_DATADIR/mysqld-auto.cnf
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explain select 1;
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explain format=tree select 1;
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explain format=json select 1;
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set explain_format=tree;
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explain select 1;
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explain format=json select 1;
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set explain_format=json;
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explain format=tree select 1;
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explain select 1;
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set explain_format=default;
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explain select 1;
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explain format=tree select 1;
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set global explain_format=json; # Test that global setting does not interfere
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set explain_format=traditional;
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explain select 1;
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# Analyze should work with both traditional and traditional_strict, regardless
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# of hypergraph.
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set explain_format=traditional;
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--replace_regex /time=\d+\.\d+\.\.\d+\.\d+/time=N.NNN..N.NNN/
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explain analyze select 1;
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set explain_format=traditional_strict;
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--replace_regex /time=\d+\.\d+\.\.\d+\.\d+/time=N.NNN..N.NNN/
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explain analyze select 1;
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# But explicit use of unsupported format should error out.
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--error ER_NOT_SUPPORTED_YET
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explain analyze format=traditional select 1;
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# TRADITIONAL_STRICT value is only allowed in the sys variable; not in EXPLAIN.
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--error ER_UNKNOWN_EXPLAIN_FORMAT
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explain format=traditional_strict select 1;
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# Reset the global var to the original value
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set global explain_format=@orig_explain_format;
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select @@explain_format, @@global.explain_format;

‎mysql-test/suite/sys_vars/r/all_vars.result

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@@ -30,6 +30,8 @@ default_collation_for_utf8mb4
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default_collation_for_utf8mb4
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disabled_storage_engines
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disabled_storage_engines
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explain_format
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explain_format
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generated_random_password_length
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generated_random_password_length
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group_replication_consistency

‎mysql-test/suite/sys_vars/r/explain_default_format.result

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set @orig_explain_format=@@global.explain_format;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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TRADITIONAL_STRICT TRADITIONAL_STRICT
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explain select 1;
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select 1 AS `1`
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set explain_format=traditional;
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# With hypergraph and TRADITIONAL, EXPLAIN should use TREE format.
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explain select 1;
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select 1 AS `1`
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# Test that explain_format can be set to any of the scopes; i.e. session,
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# global and persist.
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set persist explain_format=tree;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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TRADITIONAL TREE
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set global explain_format=json;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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TRADITIONAL JSON
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set explain_format=tree;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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TREE JSON
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set explain_format=default;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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JSON JSON
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set global explain_format=default;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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JSON TRADITIONAL
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set persist explain_format=default;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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JSON TRADITIONAL
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set explain_format=default;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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TRADITIONAL TRADITIONAL
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reset persist explain_format;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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TRADITIONAL TRADITIONAL
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explain select 1;
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select 1 AS `1`
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explain format=tree select 1;
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EXPLAIN
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-> Rows fetched before execution (cost=0.00..0.00 rows=1)
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explain format=json select 1;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"message": "No tables used"
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}
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}
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Warnings:
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Note 1003 /* select#1 */ select 1 AS `1`
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set explain_format=tree;
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explain select 1;
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EXPLAIN
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-> Rows fetched before execution (cost=0.00..0.00 rows=1)
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explain format=json select 1;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"message": "No tables used"
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}
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}
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Warnings:
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Note 1003 /* select#1 */ select 1 AS `1`
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set explain_format=json;
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explain format=tree select 1;
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EXPLAIN
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-> Rows fetched before execution (cost=0.00..0.00 rows=1)
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explain select 1;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"message": "No tables used"
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}
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}
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Warnings:
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Note 1003 /* select#1 */ select 1 AS `1`
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set explain_format=default;
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explain select 1;
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select 1 AS `1`
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explain format=tree select 1;
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EXPLAIN
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-> Rows fetched before execution (cost=0.00..0.00 rows=1)
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set global explain_format=json;
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set explain_format=traditional;
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explain select 1;
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select 1 AS `1`
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set explain_format=traditional;
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explain analyze select 1;
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EXPLAIN
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-> Rows fetched before execution (cost=0.00..0.00 rows=1) (actual time=N.NNN..N.NNN rows=1 loops=1)
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set explain_format=traditional_strict;
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explain analyze select 1;
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EXPLAIN
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-> Rows fetched before execution (cost=0.00..0.00 rows=1) (actual time=N.NNN..N.NNN rows=1 loops=1)
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explain analyze format=traditional select 1;
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ERROR 42000: This version of MySQL doesn't yet support 'EXPLAIN ANALYZE with TRADITIONAL format'
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explain format=traditional_strict select 1;
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ERROR HY000: Unknown EXPLAIN format name: 'traditional_strict'
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set global explain_format=@orig_explain_format;
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select @@explain_format, @@global.explain_format;
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@@explain_format @@global.explain_format
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TRADITIONAL_STRICT TRADITIONAL_STRICT

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