topic Re: ApplyMap in QlikView

ApplyMap

vanderson009 — Wed, 25 Nov 2020 16:16:04 GMT

Difference between ApplyMap and Join.

How applymap work internally in qlikview.

Thanks,

Villyee.

Re: ApplyMap

marcus_sommer — Tue, 03 Jul 2018 12:20:22 GMT

A join is a merging of tables in regard to the specified key-fields, the used join-type (left, right, inner, outer) and the values within the key-fields (how they relate to eachother - 1:1, 1:n, n:n - and/or if there are missing ones). It's a complex process and could require large amounts of resources, especially RAM and time.

A mapping with applymap() is instead a kind of a lookup - quite similar to the Excel function lookup() - which is used to add, replace or filter values within a table. It's much simpler and faster as a join and there is no risks to change the number of records unintentionally.

Also see: Don't join - use Applymap instead

- Marcus

Re: ApplyMap

sujan24s — Tue, 03 Jul 2018 12:59:56 GMT

Hi,

please refer Below link that may helpful for you

https://community.qlik.com/servlet/JiveServlet/previewBody/3412-102-4-3894/Joins%20and%20Lookups.pdf

Re: ApplyMap

BalaBhaskar_Qlik — Tue, 03 Jul 2018 17:33:05 GMT

Avoid using join as far as possible and use applymap instead, even where several applymap are required.

Missing records can be given a name. Like 'Missing' . Or can be used to group records. So an excel spreadsheet will have the Focus Customers and the rest will be grouped as 'Other

In single mapping, performance is almost the same for both methods. But if there are a lot of fields to map in one table, better are ApplyMap functions. Datamodel decreased after reload.

Joins may cause data to be inadvertently duplicated and can be slow during reloads.

Left/Right join" both tables affected on record level - number of records of left/right table may grow and/or double records both tables may be withdraw. Datamodel get complexity.

ApplyMap do not affects records at all.