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Well… the start of it :)

I’ve taken the approach of taking tiny incremental steps (and getting review for each step) in implementing a Storage Engine based on the Embedded InnoDB library. What hit lp:drizzle (the trunk branch, for the 2010-04-07 milestone tarball) is only a handful of these small steps, so this engine is not remotely ready for end users.

There should be more of my Embedded InnoDB work hitting the tree in the upcoming days/weeks, enough to get it to a satte that one could describe as functional :)

Using the Embedded InnoDB plugin I’m working on, you can use the INNODB_STATUS table function in the data_dictionary, you can do pretty neat things.

For example, we can see that each autocommit transaction causes an fsync and if you insert multiple rows ina  single statement, you still only get 1 fsync:

drizzle> SELECT * FROM DATA_DICTIONARY.INNODB_STATUS
    -> WHERE name="fsync_req_done";
+----------------+-------+
| NAME           | VALUE |
+----------------+-------+
| fsync_req_done |    25 |
+----------------+-------+
1 row in set (0 sec)

drizzle> insert into t1 values (1);
Query OK, 1 row affected (0.05 sec)

drizzle> SELECT * FROM DATA_DICTIONARY.INNODB_STATUS WHERE name="fsync_req_done";
+----------------+-------+
| NAME           | VALUE |
+----------------+-------+
| fsync_req_done |    26 |
+----------------+-------+
1 row in set (0 sec)

drizzle> insert into t1 values (1),(2),(3),(4);Query OK, 4 rows affected (0 sec)
Records: 4  Duplicates: 0  Warnings: 0

drizzle> SELECT * FROM DATA_DICTIONARY.INNODB_STATUS WHERE name="fsync_req_done";
+----------------+-------+
| NAME           | VALUE |
+----------------+-------+
| fsync_req_done |    27 |
+----------------+-------+
1 row in set (0 sec)

I am rather excited about being able to do awesome things such as this to get the current configuration of your server:

drizzle> SELECT NAME,VALUE
    -> FROM DATA_DICTIONARY.INNODB_CONFIGURATION
    ->  WHERE NAME IN ("data_file_path", "data_home_dir");
+----------------+-------+
| NAME           | VALUE |
+----------------+-------+
| data_file_path | NULL  |
| data_home_dir  | ./    |
+----------------+-------+
2 rows in set (0 sec)

drizzle> SELECT NAME,VALUE
    -> FROM DATA_DICTIONARY.INNODB_CONFIGURATION
    -> WHERE NAME IN ("data_file_path", "data_home_dir");
+----------------+-------+
| NAME           | VALUE |
+----------------+-------+
| data_file_path | NULL  |
| data_home_dir  | ./    |
+----------------+-------+
2 rows in set (0 sec)

drizzle> SELECT NAME,VALUE
    -> FROM DATA_DICTIONARY.INNODB_CONFIGURATION
    -> WHERE NAME = "io_capacity";
+-------------+-------+
| NAME        | VALUE |
+-------------+-------+
| io_capacity | 200   |
+-------------+-------+
1 row in set (0 sec)

Coming soon: status in a table.

(this is for the upcoming embedded_innodb plugin, which using the API provided by Embedded InnoDB to implement a Storage Engine for Drizzle)