On Tue, May 22, 2012 at 8:03 PM, <rhuij...@apache.org> wrote:
>...
> +++ subversion/trunk/build/transform_sql.py Wed May 23 00:03:06 2012
> @@ -110,10 +110,35 @@ class Processor(object):
> for line in input.split('\n'):
> line = line.replace('"', '\\"')
>
> + # IS_STRICT_DESCENDANT_OF()
> +
> + # A common operation in the working copy is determining descendants of
> + # a node. To allow Sqlite to use its indexes to provide the answer we
> + # must provide simple less than and greater than operations.
> + #
> + # For relative paths that consist of one or more components like
> 'subdir'
> + # we can accomplish this by comparing local_relpath with 'subdir/' and
> + # 'subdir0' ('/'+1 = '0')
> + #
> + # For the working copy root this case is less simple and not strictly
> + # valid utf-8/16 (but luckily Sqlite doesn't validate utf-8 nor
> utf-16).
> + # The binary blob x'FFFF' is higher than any valid utf-8 and utf-16
> + # sequence.
> + #
> + # So for the root we can compare with > '' and < x'FFFF'. (This skips
> the
> + # root itself and selects all descendants)
> + #
> + ### RH: I implemented this first with a user defined Sqlite function.
> But
> + ### when I wrote the documentation for it, I found out I could just
> + ### define it this way, without losing the option of just dropping the
> + ### query in a plain sqlite3.
> +
> # '/'+1 == '0'
> - line = re.sub(r'IS_STRICT_DESCENDANT_OF[(]([A-Za-z_.]+),
> ([?][0-9]+)[)]',
> - r"((\2) != '' AND ((\1) > (\2) || '/') AND ((\1) < (\2)
> || '0')) ",
> - line)
> + line = re.sub(
> + r'IS_STRICT_DESCENDANT_OF[(]([A-Za-z_.]+), ([?][0-9]+)[)]',
> + r"(((\1) > (CASE (\2) WHEN '' THEN '' ELSE (\2) || '/' END))" +
> + r" AND ((\1) < CASE (\2) WHEN '' THEN X'FFFF' ELSE (\2) || '0'
> END))",
> + line)
Rather than using the CASE logic, couldn't you just do something like:
r"(((\2 = '') AND (\1 != '')) OR (... old condition ...))"
Seems simpler to me. Does it somehow invalidate the usage of the index?
Cheers,
-g
