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Re: Literals in wc SQLite queries

From: Greg Stein <gstein_at_gmail.com>
Date: Fri, 7 Dec 2012 18:13:17 -0500

That sounds like a great idea! +1

It shouldn't be hard to tweak transform_sql.py. If you have a specific
prefix for the "token" symbols (eg TOKEN_BASE_DELETED), then we can
have the transform script simply look for lines like you suggest in
(say) wc_db.h. If the search regex is strong enough, then it will have
no problem finding them. And if transform_sql.py sees TOKEN_FOO that
it does NOT recognize, then it should throw an error. Either somebody
forgot the mapping, or the syntax was not conformant -- both are
"errors".

I would be near -1 on putting short numeric values into the db; I
chose the tokens for debuggability, and think that is quite important.
I like your improvement on the strengthening the db/token system.

Cheers,
-g

On Fri, Dec 7, 2012 at 12:54 PM, Philip Martin <philip_at_codematters.co.uk> wrote:
> Columns such as nodes.kind, nodes.presence, etc. have strings that
> should be one of a discrete set of values. When we bind these columns
> in C code we use something like:
>
> svn_sqlite__bindf("t", presence_map, svn_wc__db_status_normal);
>
> This means we only use known values (svn_wc__db_status_normal) and the
> map converts it to the correct discrete string. This checking happens
> at build time.
>
> We also have queries where the strings are defined as literals in
> wc-queries.sql like:
>
> DELETE FROM nodes
> WHERE wc_id = ?1
> AND IS_STRICT_DESCENDANT_OF(local_relpath, ?2)
> AND (op_depth < ?3
> OR (op_depth = ?3 AND presence = 'base-deleted'))
>
> There is no checking of these literals to catch errors such as
> 'base-delete'.
>
> I've been thinking that transform_sql.py should do some checking.
> Perhaps we could move the maps into a know header, annotate them:
>
> { "base-deleted", svn_wc__db_status_base_deleted }, /* MAP_DELETED */
>
> and then have transform_sql.py parse the header and convert:
>
> OR (op_depth = ?3 AND presence = MAP_DELETED))
>
> into
>
> OR (op_depth = ?3 AND presence = 'base-deleted'))
>
> --
> Philip
Received on 2012-12-08 00:13:50 CET

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