Merge mysql.com:/home/svoj/devel/mysql/BUG21310/mysql-4.1-engines (2efb6576) · Commits · Software / OSDI20 Artifacts / mariadb

mysql-test/r/myisam.result

+16 −0

Original line number	Diff line number	Diff line
		@@ -1621,3 +1621,19 @@ select * from t1;
		a
		42
		drop table t1;
		CREATE TABLE t1(a VARCHAR(16));
		INSERT INTO t1 VALUES('aaaaaaaa'),(NULL);
		UPDATE t1 AS ta1, t1 AS ta2 SET ta1.a='aaaaaaaaaaaaaaaa';
		SELECT * FROM t1;
		a
		aaaaaaaaaaaaaaaa
		aaaaaaaaaaaaaaaa
		DROP TABLE t1;
		CREATE TABLE t1(a INT);
		INSERT INTO t1 VALUES(1),(2);
		UPDATE t1,t1 AS t2 SET t1.a=t1.a+2 WHERE t1.a=t2.a-1;
		SELECT * FROM t1 ORDER BY a;
		a
		2
		3
		DROP TABLE t1;

mysql-test/t/myisam.test

+19 −0

Original line number	Diff line number	Diff line
		@@ -1004,4 +1004,23 @@ connection default;
		select * from t1;
		drop table t1;

		#
		# BUG#21310 - Trees in SQL causing a "crashed" table with MyISAM storage
		# engine
		#

		# A simplified test case that reflect crashed table issue.
		CREATE TABLE t1(a VARCHAR(16));
		INSERT INTO t1 VALUES('aaaaaaaa'),(NULL);
		UPDATE t1 AS ta1, t1 AS ta2 SET ta1.a='aaaaaaaaaaaaaaaa';
		SELECT * FROM t1;
		DROP TABLE t1;

		# A test case that reflect wrong result set.
		CREATE TABLE t1(a INT);
		INSERT INTO t1 VALUES(1),(2);
		UPDATE t1,t1 AS t2 SET t1.a=t1.a+2 WHERE t1.a=t2.a-1;
		SELECT * FROM t1 ORDER BY a;
		DROP TABLE t1;

		# End of 4.1 tests

sql/sql_update.cc

+62 −76

Original line number	Diff line number	Diff line
		@@ -25,8 +25,6 @@
		#include "sp_head.h"
		#include "sql_trigger.h"

		static bool safe_update_on_fly(JOIN_TAB join_tab, List<Item> fields);

		/* Return 0 if row hasn't changed */

		static bool compare_record(TABLE *table, query_id_t query_id)
		@@ -1041,27 +1039,72 @@ int multi_update::prepare(List<Item> &not_used_values,
		for (i=0 ; i < table_count ; i++)
		set_if_bigger(max_fields, fields_for_table[i]->elements);
		copy_field= new Copy_field[max_fields];
		DBUG_RETURN(thd->is_fatal_error != 0);
		}


		/*
		Mark all copies of tables that are updates to ensure that
		init_read_record() will not try to enable a cache on them
		Check if table is safe to update on fly

		SYNOPSIS
		safe_update_on_fly()
		thd Thread handler
		join_tab How table is used in join
		all_tables List of tables
		fields Fields that are updated

		NOTES
		We can update the first table in join on the fly if we know that
		a row in this table will never be read twice. This is true under
		the following conditions:

		The problem is that for queries like
		- We are doing a table scan and the data is in a separate file (MyISAM) or
		if we don't update a clustered key.

		- We are doing a range scan and we don't update the scan key or
		the primary key for a clustered table handler.

		- Table is not joined to itself.

		When checking for above cases we also should take into account that
		BEFORE UPDATE trigger potentially may change value of any field in row
		being updated.

		UPDATE t1, t1 AS t2 SET t1.b=t2.c WHERE t1.a=t2.a;
		WARNING
		This code is a bit dependent of how make_join_readinfo() works.

		the row buffer may contain things that doesn't match what is on disk
		which will cause an error when reading a row.
		(This issue is mostly relevent for MyISAM tables)
		RETURN
		0 Not safe to update
		1 Safe to update
		*/
		for (table_ref= leaves; table_ref; table_ref= table_ref->next_leaf)

		static bool safe_update_on_fly(THD thd, JOIN_TAB join_tab,
		TABLE_LIST all_tables, List<Item> fields)
		{
		TABLE *table=table_ref->table;
		if ((tables_to_update & table->map) &&
		unique_table(thd, table_ref, update_tables))
		table->no_cache= 1; // Disable row cache
		TABLE *table= join_tab->table;
		if (unique_table(thd, table, all_tables))
		return 0;
		switch (join_tab->type) {
		case JT_SYSTEM:
		case JT_CONST:
		case JT_EQ_REF:
		return TRUE; // At most one matching row
		case JT_REF:
		case JT_REF_OR_NULL:
		return !is_key_used(table, join_tab->ref.key, *fields);
		case JT_ALL:
		/* If range search on index */
		if (join_tab->quick)
		return !join_tab->quick->is_keys_used(fields);
		/* If scanning in clustered key */
		if ((table->file->table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX) &&
		table->s->primary_key < MAX_KEY)
		return !is_key_used(table, table->s->primary_key, *fields);
		return TRUE;
		default:
		break; // Avoid compler warning
		}
		DBUG_RETURN(thd->is_fatal_error != 0);
		return FALSE;
		}


		@@ -1099,7 +1142,7 @@ multi_update::initialize_tables(JOIN *join)
		table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
		if (table == main_table) // First table in join
		{
		if (safe_update_on_fly(join->join_tab, &temp_fields))
		if (safe_update_on_fly(thd, join->join_tab, all_tables, &temp_fields))
		{
		table_to_update= main_table; // Update table on the fly
		continue;
		@@ -1150,63 +1193,6 @@ multi_update::initialize_tables(JOIN *join)
		DBUG_RETURN(0);
		}

		/*
		Check if table is safe to update on fly

		SYNOPSIS
		safe_update_on_fly
		join_tab How table is used in join
		fields Fields that are updated

		NOTES
		We can update the first table in join on the fly if we know that
		a row in this table will never be read twice. This is true under
		the following conditions:

		- We are doing a table scan and the data is in a separate file (MyISAM) or
		if we don't update a clustered key.

		- We are doing a range scan and we don't update the scan key or
		the primary key for a clustered table handler.

		When checking for above cases we also should take into account that
		BEFORE UPDATE trigger potentially may change value of any field in row
		being updated.

		WARNING
		This code is a bit dependent of how make_join_readinfo() works.

		RETURN
		0 Not safe to update
		1 Safe to update
		*/

		static bool safe_update_on_fly(JOIN_TAB join_tab, List<Item> fields)
		{
		TABLE *table= join_tab->table;
		switch (join_tab->type) {
		case JT_SYSTEM:
		case JT_CONST:
		case JT_EQ_REF:
		return TRUE; // At most one matching row
		case JT_REF:
		case JT_REF_OR_NULL:
		return !is_key_used(table, join_tab->ref.key, *fields);
		case JT_ALL:
		/* If range search on index */
		if (join_tab->quick)
		return !join_tab->quick->is_keys_used(fields);
		/* If scanning in clustered key */
		if ((table->file->table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX) &&
		table->s->primary_key < MAX_KEY)
		return !is_key_used(table, table->s->primary_key, *fields);
		return TRUE;
		default:
		break; // Avoid compler warning
		}
		return FALSE;
		}


		multi_update::~multi_update()
		{