Hey Community, I think I have got the answer to my query.
This statement about *copyFields <https://lucene.apache.org/solr/guide/8_0/copying-fields.html>*: *The copyField command can use a wildcard (*) character in the dest > parameter only if the source parameter contains one as well. copyField uses > the matching glob from the source field for the dest field name into which > the source content is copied.* So, the glob here means the *something_** pattern. copyField doesn't support chaining and similarly, does *NOT support copying into multiple destinations from a single or multiple field*. The whole point of supporting wildcard in dest when it is also present in source is to actually make *one-to-one mapping* from the matching glob. For example, consider having this config: <copyField src=“title_*” dest=“text_*”/> and these fields in the schema: <field name="title_en" .../> > <field name="title_fr" .../> > <field name="title_tr" .../> > <field name="text_en" .../> > <field name="text_fr" .../> > <field name="text_tr" .../> And if you index some information for title_*en*, it will be copied into text_*en* ONLY. Note the one-to-one mapping here: > *title_fr to text_fr**title_tr to text_tr* Note that information of title_*en *will *NOT* copy into text_*fr*. I guess Erick and Chris were actually making me understand this. I have tried my best to explain this to any possible uninformed. Thank you, everyone! :) On Thu, 24 Oct 2019 at 12:50, Paras Lehana <paras.leh...@indiamart.com> wrote: > Hey Chris, > > Awesome explanation. > > ...then solr has no idea what full field name to use as the destination >> when it seees values in a field "foo" ... should it be "1_bar" ? >> "aaa_bar" ? ... "zzzzzzzzzzzzzzzzzzzzzzzzz_bar" ? all three? > > > But how does Solr get the idea what full field name to use as the > destination when we provide wildcard in source as well? Seems I'm missing > something. > > > but using a wildcard in the dest only woks with a one-to-one mapping > > > So, I think, this restriction could be more related to the source code > flow instead of a logical reason. I'll try to understand the code about > this. > > I was actually curious if there's any logical restriction that I had been > missing. > > Many thanks. :) > > On Thu, 24 Oct 2019 at 03:47, Chris Hostetter <hossman_luc...@fucit.org> > wrote: > >> >> : Documentation says that we can copy multiple fields using wildcard to >> one >> : or more than one fields. >> >> correct ... the limitation is in the syntax and the ambiguity that would >> be unresolvable if you had a wildcard in the dest but not in the source. >> >> the wildcard is essentially a variable. if you have... >> >> source="foo" desc="*_bar" >> >> ...then solr has no idea what full field name to use as the destination >> when it seees values in a field "foo" ... should it be "1_bar" ? >> "aaa_bar" ? ... "zzzzzzzzzzzzzzzzzzzzzzzzz_bar" ? all three? >> >> : Yes, that's what hit me initially. But, "*_x" while indexing (in XMLs) >> : doesn't mean anything, right? It's only used in dynamicFields while >> : defining schema to let Solr know that we would have some undeclared >> fields >> >> use of wildcards in copyField is not contstrained to only >> using dynamicFields, this would be a perfectly valid copyField using >> wildcards, even if these are the only fields in the schema, and it had >> no dynamicFields at all... >> >> <field name="title_en" .../> >> <field name="title_fr" .../> >> <field name="title_tr" .../> >> >> <field name="text_en" .../> >> <field name="text_fr" .../> >> <field name="text_tr" .../> >> >> <copyField source="title_*" dest="text_*" /> >> >> : having names like this. Also, according to the documentation, we can >> have >> : dest="*_x" when source="*_x" if I'm right. In this case, there's support >> : for multiple destinations when there are multiple source. >> >> correct. there is support for copying from one field to another >> via a *MAPPING* -- so a single copyField declaration can go from multiple >> sources to multiple destiations, but using a wildcard in the dest >> only woks with a one-to-one mapping when the wildcard also exists in the >> source. >> >> on the flip side however, you have have a many-to-one mapping by using a >> wildcard *only* in the source.... >> >> <field name="title_en" .../> >> <field name="title_fr" .../> >> <field name="title_tr" .../> >> >> <field name="text" .../> >> >> <copyField source="title_*" dest="text" /> >> >> >> >> -Hoss >> http://www.lucidworks.com/ >> > > > -- > -- > Regards, > > *Paras Lehana* [65871] > Development Engineer, Auto-Suggest, > IndiaMART Intermesh Ltd. > > 8th Floor, Tower A, Advant-Navis Business Park, Sector 142, > Noida, UP, IN - 201303 > > Mob.: +91-9560911996 > Work: 01203916600 | Extn: *8173* > -- -- Regards, *Paras Lehana* [65871] Development Engineer, Auto-Suggest, IndiaMART Intermesh Ltd. 8th Floor, Tower A, Advant-Navis Business Park, Sector 142, Noida, UP, IN - 201303 Mob.: +91-9560911996 Work: 01203916600 | Extn: *8173* -- IMPORTANT: NEVER share your IndiaMART OTP/ Password with anyone.
