topic Re: How do you achieve a UNION or UNION ALL using the tELT components in talend? in Talend Studio

How do you achieve a UNION or UNION ALL using the tELT components in talend?

mdeeter — Tue, 21 May 2019 17:14:58 GMT

Hi, can someone explain how to accomplish UNION and UNION all in the tELT components in Talend?

My use case is to merge 2 tables into 1 that will have a sparse presentation.

e.g. Table A has ID and String1, String2 and Table B has ID and String1, String3.

The desired output table is ID, String1, String2, String3 with sparse results in String2 and String3.

The query in SQL looks like this:

SELECT ID, String1, String2, null as String3

UNION ALL

SELECT ID, String1, null, String3

Re: How do you achieve a UNION or UNION ALL using the tELT components in talend?

Anonymous — Mon, 27 May 2019 08:02:31 GMT

Hello,

Are your two tables from one database or not when you are using ELT components?

For UNION or UNION ALL operations, it can be implemented by doing a join on tMap.

Best regards

Sabrina

Re: How do you achieve a UNION or UNION ALL using the tELT components in talend?

dhazarihazari — Mon, 01 Feb 2021 12:44:06 GMT

Hi ,

Are you sure that Union/ union All can be implemented in tELTMap component?

Can you please share any sample job tELT Hive component design with union all please? I'm really not finding any relevent answer anywhere else?

Thanks,

Deepti

Re: How do you achieve a UNION or UNION ALL using the tELT components in talend?

Anonymous — Tue, 02 Feb 2021 08:52:05 GMT

Hello,

For UNION or UNION ALL operations, it can be implemented by doing a join on tMap component instead of tELTMap component.

The three ELT components are closely related, in terms of their operating conditions. Such as, tELTXXXInput, tELTMap and tELTXXXOutput.

Best regards

Sabrina

Re: How do you achieve a UNION or UNION ALL using the tELT components in talend?

Anonymous — Wed, 21 Sep 2022 12:07:25 GMT

@Xiaodi Shi Hi, i'm now trying to do a union of two large tables with same structure but using tMap would be very slow. Any chance to use tELT components to achieve this ?

Want to keep the metadata of tables, hence DBRow or similar wont work.