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Re: NODE_DATA (2nd iteration)

From: Julian Foad <julian.foad_at_wandisco.com>
Date: Tue, 03 Aug 2010 10:12:11 +0100

On Mon, 2010-08-02, I (Julian Foad) wrote:
> Hi Erik.
>
> Would you or anybody volunteer to draw a diagram of how these table rows
> look in various simple-ish WC states?

Maybe I can help by drawing my best interpretation of it and getting
your feedback. I'll have a go.

- Julian

> I feel stupid saying this, but I haven't yet got much of an idea at all
> about how a set of database rows will represent a particular collection
> of repository nodes and local changes in the new scheme. I know roughly
> what the aim is (to be able to represent nested tree changes more
> flexibly), and I can read what elements of data will be stored in each
> table, but I am missing the part that says how those are connected.
>
> At this point we might as well assume it's a single DB - I think that
> will be clearest.
>
> Thanks.
>
> - Julian
>
>
> On Mon, 2010-07-12 at 23:23 +0200, Erik Huelsmann wrote:
> > After lots of discussion regarding the way NODE_DATA/4th tree should
> > be working, I'm now ready to post a summary of the progress. In my
> > last e-mail (http://svn.haxx.se/dev/archive-2010-07/0262.shtml) I
> > stated why we need this; this post is about the conclusion of what
> > needs to happen. Also included are the first steps there.
> >
> >
> > With the advent of NODE_DATA, we distinguish node values specifically
> > related to BASE nodes, those specifically related to "current" WORKING
> > nodes and those which are to be maintained for multiple levels of
> > WORKING nodes (not only the "current" view) (the latter category is
> > most often also shared with BASE).
> >
> > The respective tables will hold the columns shown below.
> >
> >
> > -------------------------
> > TABLE WORKING_NODE (
> > wc_id INTEGER NOT NULL REFERENCES WCROOT (id),
> > local_relpath TEXT NOT NULL,
> > parent_relpath TEXT,
> > moved_here INTEGER,
> > moved_to TEXT,
> > original_repos_id INTEGER REFERENCES REPOSITORY (id),
> > original_repos_path TEXT,
> > original_revnum INTEGER,
> > translated_size INTEGER,
> > last_mod_time INTEGER, /* an APR date/time (usec since 1970) */
> > keep_local INTEGER,
> >
> > PRIMARY KEY (wc_id, local_relpath)
> > );
> >
> > CREATE INDEX I_WORKING_PARENT ON WORKING_NODE (wc_id, parent_relpath);
> > --------------------------------
> >
> > The moved_* and original_* columns are typical examples of "WORKING
> > fields only maintained for the visible WORKING nodes": the original_*
> > and moved_* fields are inherited from the operation root by all
> > children part of the operation. The operation root will be the visible
> > change on its own level, meaning it'll have rows both in the
> > WORKING_NODE and NODE_DATA tables. The fact that these columns are not
> > in the WORKING_NODE table means that tree changes are not preserved
> > accros overlapping changes. This is fully compatible with what we do
> > today: changes to higher levels destroy changes to lower levels.
> >
> > The translated_size and last_mod_time columns exist in WORKING_NODE
> > and BASE_NODE; they explicitly don't exist in NODE_DATA. The fact that
> > they exist in BASE_NODE is a bit of a hack: it's to prevent creation
> > of WORKING_NODE data for every file which has keyword expansion or eol
> > translation properties set: these columns serve only to optimize
> > working copy scanning for changes and as such only relate to the
> > visible WORKING_NODEs.
> >
> >
> > TABLE BASE_NODE (
> > wc_id INTEGER NOT NULL REFERENCES WCROOT (id),
> > local_relpath TEXT NOT NULL,
> > repos_id INTEGER REFERENCES REPOSITORY (id),
> > repos_relpath TEXT,
> > parent_relpath TEXT,
> > translated_size INTEGER,
> > last_mod_time INTEGER, /* an APR date/time (usec since 1970) */
> > dav_cache BLOB,
> > incomplete_children INTEGER,
> > file_external TEXT,
> >
> > PRIMARY KEY (wc_id, local_relpath)
> > );
> >
> >
> > TABLE NODE_DATA (
> > wc_id INTEGER NOT NULL REFERENCES WCROOT (id),
> > local_relpath TEXT NOT NULL,
> > op_depth INTEGER NOT NULL,
> > presence TEXT NOT NULL,
> > kind TEXT NOT NULL,
> > checksum TEXT,
> > changed_rev INTEGER,
> > changed_date INTEGER, /* an APR date/time (usec since 1970) */
> > changed_author TEXT,
> > depth TEXT,
> > symlink_target TEXT,
> > properties BLOB,
> >
> > PRIMARY KEY (wc_id, local_relpath, oproot)
> > );
> >
> > CREATE INDEX I_NODE_WC_RELPATH ON NODE_DATA (wc_id, local_relpath);
> >
> >
> > Which leaves the NODE_DATA structure above. The op_depth column
> > contains the depth of the node - relative to the wc root - on which
> > the operation was run which caused the creation of the given NODE_DATA
> > node. In the final scheme (based on single-db), the value will be 0
> > for base and a positive integer for WORKING related data.
> >
> > In order to be able to implement NODE_DATA even without having a fully
> > functional SINGLE_DB yet, a transitional node numbering scheme needs
> > to be devised. The following numbers will apply: BASE == 0,
> > WORKING-this-dir == 1, WORKING-any-immediate-child == 2.
> >
> >
> > Other transitioning related remarks:
> >
> > * Conditional-protected experimentational sections, just like with SINGLE_DB
> > * Initial implementation will simply replace the current
> > functionality of the 2 tables, from there we can work our way through
> > whatever needs doing.
> > * Am I forgetting any others?
> >
> > Bye,
> >
> > Erik.
>
>
Received on 2010-08-03 11:12:53 CEST

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