Hi Stewart,
Thanks for the great info.
I've added some blueprints to track my progress.
For some of the questions, e.g. locking strategy, I've not come up with
an elegant solution,
I'll think a little more and discuss with you later.
--zimin
On 08/06/2010 9:02 AM, Stewart Smith wrote:
(CC'd drizzle-discuss in case anybody else has some thoughts too)
On Mon, 07 Jun 2010 18:58:56 +0800, Zimin<[email protected]> wrote:
lp:~ziminq/drizzle/filesystem-storage-engine
A few things:
- it looks like you haven't merged from trunk in a while, you should try
to keep rather up to date with trunk.
- in ha_filesystem::open
- the table message is already loaded by the upper layer, so you can
access it through table->share (see table_share.h)
- It looks as though you're not trying to open the actual file there?
- you should probably try to open the file there and report back
errors
- in doStartTableScan
- instead of using cerr for errors, use something like
push_warning_printf:
(for example, from embedded_innodb):
if (innodb_err != DB_SUCCESS)
{
push_warning_printf(&session, DRIZZLE_ERROR::WARN_LEVEL_ERROR,
ER_CANT_CREATE_TABLE,
_("Cannot create table %s. InnoDB Error %d (%s)\n"),
innodb_table_name.c_str(), innodb_err,
ib_strerror(innodb_err));
return HA_ERR_GENERIC;
}
- in rnd_next()
- Don't use drizzled::String, instead use std::string.
- have so you have a row separator as well as a column separator
e.g. a CSV file has ROW_SEPARATOR='\n', COLUMN_SEPARATOR=','
- you should set each field not null using Field instead of using
memset.
- position() and rnd_pos()
- you will need to implement these (check out my rnd_pos test for
embedded_innodb).
- they should be pretty easy. store the position in the file, seek to
it.
- you will need to set ref_length in ::open (see embedded_innodb for example)
- info()
- you'll need some things here, but shouldn't be hard.
- locking
- you probably want to write out the locking strategy.
- possible have options? fcntl locks?
- you have a table share (that isn't used), so the locking doesn't
work :)
- keep in mind that Drizzle is very much about removing horrible table
level locks, so this is the responsibility of the engine.
- insert/update row
- you need to operate on the buffer you're given. this means using
move_field_offset and that awful API (i've written a blog post on
this recently)
I would like to know whether such approach is OK or not.
and I use iostream file operation, is it ok? I know that getline() is
slow on big files.
In theory it should be okay - but what about the case where rows are not
delimited by newlines?
to delete and update a line, I used a temp file and rename the temp file
to the original one, it's kind of ugly.
I think it'd be great if you also:
- added more blueprints for each feature
- targeted these blueprints for a series (Dexter)
- targeted these blueprints for milestones (i.e. dates where you aim to
have code with that functionality merged into the main tree)
I do really like that there are tests there too!
great work so far, hopefully the above helps!
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