Re: [Fwd: Re: [HACKERS] pg_dump additional options for performance]

Added to July patch queue. Thanks.

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Simon Riggs wrote:
> Re-sending post as discussed with Bruce...
>
> On Sun, 2008-03-23 at 12:45 -0300, Alvaro Herrera wrote:
> > Bruce Momjian wrote:
> > >
> > > Added to TODO:
> > >
> > > o Allow pre/data/post files when dumping a single object, for
> > > performance reasons
> > >
> > > http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
> >
> > "When dumping a single object"?? Do you mean database?
>
> It would be for whatever set of objects are specified through the use of
> databases, table include/exclude switches.
>
> I've written a patch that implements these new switches on the commands
> as shown
>
> pg_dump --schema-pre-load
> pg_dump --schema-post-load
>
> pg_restore --schema-pre-load
> pg_restore --schema-post-load
>
> I have not implemented --schema-pre-file=xxx style because they don't
> make any sense when using pg_restore in direct database connection mode.
> On reflection I don't see any particular need to produce multiple files
> as output, which just complicates an already horrendous user interface.
>
> This is a minimal set of changes and includes nothing at all about
> directories, parallelisation in the code etc..
>
> This has the following use cases amongst others...
>
> * dump everything to a file, then use pg_restore first --schema-pre-load
> and then --data-only directly into the database, then pg_restore
> --schema-post-load to a file so we can edit that file into multiple
> pieces to allow index creation in parallel
>
> * dump of database into multiple files by manually specifying which
> tables go where, then reload in parallel using multiple psql sessions
>
>
> The patch tests OK after some testing, though without a test suite that
> probably isn't more than a few percentage points of all the possible
> code paths. There are no docs for it, as yet.
>
> ---
>
> Further thinking on this....
>
> Some further refinement might replace --data-only and --schema-only with
> --want-schema-pre
> --want-data
> --want-schema-post
> --want-schema (same as --want-schema-pre --want-schema-post)
>
> These could be used together e.g. --want-schema-pre --want-data
> whereas the existing --data-only type switches cannot.
>
> Which would be a straightforward and useful change to the enclosed
> patch.
>
> That way of doing things is hierarchically extensible to include further
> subdivisions of the set of SQL commands produced, e.g. divide
> --want-post-schema into objects required to support various inter-table
> dependencies and those that don't such as additional indexes. I don't
> personally think we need that though.
>
>
> Comments?
>
> --
> Simon Riggs
> 2ndQuadrant http://www.2ndQuadrant.com

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--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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