Re: [basex-talk] Loading data

I may need to load hundreds of thousands of items each with dozens of sub-nodes.

I am looking for a solution that will not be at risk of running out of heap memory.

On Mon, Nov 20, 2017 at 12:44 PM, Kendall Shaw kendall.shaw@workday.com wrote:

Hi,

Just about building maps, in general: If you look at map:merge in http://docs.basex.org/wiki/Map_Module it shows a way to build a map with a for expression. If the question updating maps in a loop was about this, then it is probably preferable to have the result of the for expression be a map, rather than updating a map, iteratively.

Kendall

*From: *basex-talk-bounces@mailman.uni-konstanz.de on behalf of "E. Wray Johnson" wray.johnson@gmail.com *Date: *Sunday, November 19, 2017 at 5:15 AM *To: *Michael Seiferle ms@basex.org *Cc: *BaseX basex-talk@mailman.uni-konstanz.de *Subject: *Re: [basex-talk] Loading data

Thanks. I tried doing #2 inside the iteration and that did not work. I will try it your way and let you know if it works.

Wray Johnson

(m) 704-293-9008 <(704)%20293-9008>

On Nov 19, 2017, at 6:30 AM, Michael Seiferle ms@basex.org wrote:

Dear Wray,

I tried to come up with a sketch of what–I think–might help you:

https://gist.github.com/micheee/8a8734a1713a7121cab15eb3dfb389d9 https://urldefense.proofpoint.com/v2/url?u=https-3A__gist.github.com_micheee_8a8734a1713a7121cab15eb3dfb389d9&d=DwMFaQ&c=DS6PUFBBr_KiLo7Sjt3ljp5jaW5k2i9ijVXllEdOozc&r=JgwnBEpN1c-DDmq-Up2QMq9rrGyfWK0KtSpT7dxRglA&m=0dY_XpYSlIufV9bPNvpZD4BvkOL2-P3MduC5WpG4FTc&s=Guzfb_5gXuH4sJ2goSUdevQcE_tYJ-A_zXytOn3yTPs&e=

Basically it boils down to:

1. Fetch the JSON

2. Convert that JSON to an XQuery item

3. Iterate over each array entry and explicitly construct the XML

representation you want

So in a nutshell, in XQuery 3.1, something like the following:

fetch:text('https://gist.githubusercontent.com/ Miserlou/c5cd8364bf9b2420bb29/raw/2bf258763cdddd704f8ffd3ea9a3e8 1d25e2c6f6/cities.json https://urldefense.proofpoint.com/v2/url?u=https-3A__gist.githubusercontent.com_Miserlou_c5cd8364bf9b2420bb29_raw_2bf258763cdddd704f8ffd3ea9a3e81d25e2c6f6_cities.json&d=DwMFaQ&c=DS6PUFBBr_KiLo7Sjt3ljp5jaW5k2i9ijVXllEdOozc&r=JgwnBEpN1c-DDmq-Up2QMq9rrGyfWK0KtSpT7dxRglA&m=0dY_XpYSlIufV9bPNvpZD4BvkOL2-P3MduC5WpG4FTc&s=oX2YSOYRvXFIiOp87Q6C_ev1UGt0DWVkaCFu0whK6GM&e= ')

=> parse-json() (: Convert to XQuery item representation :)

=> array:for-each(function($map){ (: For each entry in that array, do :)

element item { (: Construct an XML element named item :)

  $map => map:keys()

  => for-each(function($key){  (: For each key in the map, do: :)

    element { $key } {         (: Return an element named $key :)

      $map($key)               (: …and the value of $map($key) :)

    }

  })

}

})

=> array:flatten() (: Converts the array to a sequence :)

I assume you are using BaseX, so maybe the json:parse() function might be another option, that is based on our own implementation and will create an XML representation right away:

fetch:text('https://gist.githubusercontent.com/ Miserlou/c5cd8364bf9b2420bb29/raw/2bf258763cdddd704f8ffd3ea9a3e8 1d25e2c6f6/cities.json https://urldefense.proofpoint.com/v2/url?u=https-3A__gist.githubusercontent.com_Miserlou_c5cd8364bf9b2420bb29_raw_2bf258763cdddd704f8ffd3ea9a3e81d25e2c6f6_cities.json&d=DwMFaQ&c=DS6PUFBBr_KiLo7Sjt3ljp5jaW5k2i9ijVXllEdOozc&r=JgwnBEpN1c-DDmq-Up2QMq9rrGyfWK0KtSpT7dxRglA&m=0dY_XpYSlIufV9bPNvpZD4BvkOL2-P3MduC5WpG4FTc&s=oX2YSOYRvXFIiOp87Q6C_ev1UGt0DWVkaCFu0whK6GM&e= ')

=> json:parse()

For more info on our BaseX JSON-Module see: http://docs.basex.org/ wiki/JSON_Module https://urldefense.proofpoint.com/v2/url?u=http-3A__docs.basex.org_wiki_JSON-5FModule&d=DwMFaQ&c=DS6PUFBBr_KiLo7Sjt3ljp5jaW5k2i9ijVXllEdOozc&r=JgwnBEpN1c-DDmq-Up2QMq9rrGyfWK0KtSpT7dxRglA&m=0dY_XpYSlIufV9bPNvpZD4BvkOL2-P3MduC5WpG4FTc&s=Uia9oCJta1vQG3jvblV437dpVM5JvI9GsfmVjj2xssY&e=

As I can only guess what your XQuery code actually looks like I hope this comes somewhat close to what you want.

Hope this helps ;-)

Best from Konstanz

Michael

Am 19.11.2017 um 06:25 schrieb E. Wray Johnson wray.johnson@gmail.com:

I have a JSON file https://gist.githubusercontent.com/Miserlou/c5cd8364bf9b2420bb29/raw/ 2bf258763cdddd704f8ffd3ea9a3e81d25e2c6f6/cities.json https://urldefense.proofpoint.com/v2/url?u=https-3A__gist.githubusercontent.com_Miserlou_c5cd8364bf9b2420bb29_raw_2bf258763cdddd704f8ffd3ea9a3e81d25e2c6f6_cities.json&d=DwMFaQ&c=DS6PUFBBr_KiLo7Sjt3ljp5jaW5k2i9ijVXllEdOozc&r=JgwnBEpN1c-DDmq-Up2QMq9rrGyfWK0KtSpT7dxRglA&m=0dY_XpYSlIufV9bPNvpZD4BvkOL2-P3MduC5WpG4FTc&s=oX2YSOYRvXFIiOp87Q6C_ev1UGt0DWVkaCFu0whK6GM&e=

I want to load it into a database in a different XML format where I can use gml:Point in place of longitude and latitude as separate elements. However my for loop does not emit individual XML elements for each json object in the loaded array.