Hi Tim,

Updates can be run in parallel if the name of the database is directly
specified in the query [1]:

  jobs:eval('delete node db:open("db1")//abc'),
  jobs:eval('delete node db:open("db2")//def')

In a future version of BaseX, we might split up our compilation phase
into multiple ones. After this, we could statically detect that a
passed on variable will be the name of a database.

Until then, you could try to build a query string that included
hard-coded database names.

Hope this helps,
Christian

[1] https://docs.basex.org/wiki/Transaction_Management#XQuery



On Wed, Feb 10, 2021 at 1:56 AM Tim Thompson <timathom@gmail.com> wrote:
>
> Thank you, Christian, for the detailed explanation!
>
> One more question, if I may. Is it possible to run updating jobs on different databases in parallel? Or can database update operations only be run sequentially, one db at a time? I have a query that calls a function to perform a series of operations:
>
> for $i in (0 to 9)
> return (
>   jobs:eval('
>     declare variable $iter external;
>     local:add-uris("marc.exp.20210115."||$iter)
>   ', map {"iter": $i})
> )
>
> The function:
>
> opens a database
> iterates through its records
> performs lookups against an index
> inserts any matches into the database
> calls file:append-text-lines() to write the results of the lookups
>
> Based on some simple tests, it doesn't seem possible to run the jobs in parallel, but I thought I would ask--to see whether there was something I was missing.
>
> Thanks again,
> Tim