Hi, Thirunarayanan!
On Nov 13, Thirunarayanan Balathandayuthapani wrote:
> revision-id: a04c60e6c99097c9b52f582b2af891f48b8f662d
> (mariadb-10.2.18-40-ga04c60e6c99)
> parent(s): ab1ce2204e959bea596817494e932754ab5cbe88
> author: Thirunarayanan Balathandayuthapani <th...@mariadb.com>
> committer: Thirunarayanan Balathandayuthapani <th...@mariadb.com>
> timestamp: 2018-11-12 16:30:34 +0530
> message:
>
> MDEV-16849 Extending indexed VARCHAR column should be instantaneous
>
> Analysis:
> ========
> Increasing the length of the indexed varchar column is not an instant
> operation for
> innodb.
>
> diff --git a/mysql-test/suite/innodb/r/alter_varchar_change.result
> b/mysql-test/suite/innodb/r/alter_varchar_change.result
> new file mode 100644
> index 00000000000..b60bd7847db
> --- /dev/null
> +++ b/mysql-test/suite/innodb/r/alter_varchar_change.result
> @@ -0,0 +1,269 @@
...
> +CALL get_table_id("test/t1", @tbl1_id);
> +SELECT @tbl1_id - @tbl_id;
> +@tbl1_id - @tbl_id
> +1
That's a bit fragile, you test that table id was changed exactly by 1.
I don't think the exact difference matters here, so it'd be safer to
test for `SELECT @tbl1_id = @tbl_id` (here and everywhere).
> +SHOW CREATE TABLE t1;
> diff --git a/sql/sql_table.cc b/sql/sql_table.cc
> index 02780e7d1e0..b9668ad0979 100644
> --- a/sql/sql_table.cc
> +++ b/sql/sql_table.cc
> @@ -6687,18 +6687,29 @@ static bool fill_alter_inplace_info(THD *thd,
> key_part < end;
> key_part++, new_part++)
> {
> + new_field= get_field_by_index(alter_info, new_part->fieldnr);
> + old_field= table->field[key_part->fieldnr - 1];
> /*
> + If there is a change in index length due to column expansion
> + like varchar(X) changed to varchar(X + N) and has a compatible
> + packed data representation, we mark it for fast/INPLACE change
> + in index definition. InnoDB supports INPLACE for this cases
no tabs in the server code, please.
If you're using vim, I can show you my config that has different
formatting style for innodb and the rest of the server :)
> +
> Key definition has changed if we are using a different field or
> - if the used key part length is different. It makes sense to
> - check lengths first as in case when fields differ it is likely
> - that lengths differ too and checking fields is more expensive
> - in general case.
> + if the user key part length is different.
> */
> - if (key_part->length != new_part->length)
> + if (key_part->length != new_part->length &&
> + new_field->field != NULL &&
can new_field->field be NULL here? when?
> + old_field->pack_length() < new_field->pack_length &&
Do you need it? I believe IS_EQUAL_PACK_LENGTH includes this check.
> + (key_part->field->is_equal((Create_field*) new_field)
> + == IS_EQUAL_PACK_LENGTH))
> + {
> + ha_alter_info->handler_flags |=
> + Alter_inplace_info::ALTER_COLUMN_INDEX_LENGTH;
> + }
> + else if (key_part->length != new_part->length)
> goto index_changed;
>
> - new_field= get_field_by_index(alter_info, new_part->fieldnr);
> -
Regards,
Sergei
Chief Architect MariaDB
and secur...@mariadb.org
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