Dear Fabrice,

First, could you tell me how I can get only the query plan of a query, without running it ?

You can modify the "serialize" option to deactive the serialization of your query, using the following database commands:

set serialize off; xquery <your query>

Alternatively, to avoid evaluation for all queries, you need to get one level deeper, using e.g. the following code snippets (didn't test this, but I think it's correct):

// create database context Context ctx = new Context(); // activate query info ctx.prop.set(Prop.QUERYINFO, true); // alternative for activating query info // new Set("serialize", false).execute(ctx); // create query processor instance QueryProcessor qp = new QueryProcessor("your query", ctx); // compile query qp.compile(); // close instance qp.close(); // dump query info System.out.println(qp.info()); // close database context ctx.close();

Last, is there a way to call, in a same cross db/collection query, basex:index function on each of the dbs/collections ?

Yes, that's possible – but (as I just noticed) not in all cases. I've modified our code to support queries of the following kind (please get the latest version from our SVN or wait for basex-6.3.jar, which will be online in a few days):

for $i in 1 to 10 let $n := concat('database', $i) return doc($n)/basex:index('and', 'text')

Christian