For those confused as to whether ETL or ELT is ultimately more appropriate for you… almost everyone is really just doing ETLTLTLT or ELTLTLTL anyways. The distinction is really moot.
Maybe my understanding is incorrect, but expansion on the distinction.
Assumptions -- We're talking about two separate systems (source and destination) with non-neglible transfer time (although perhaps "quick")
ETL -- Performing the transform before/during the load, such that fields in the destination are not guaranteed to have existed in the source (i.e. 2 db model)
ELT -- Performing a 1:1 copy of source into an intermediary table/db (albeit perhaps with filtering), then performing a transform on the intermediary table/db to generate the destination table/db (either realized or materialized at query time), with the intermediary table/database history retained (i.e. 3 table/db model)
In short distinction, if regeneration or altering the destination is required, ETL relies on history being available in the upstream source.
ELT pulls control of that to the destination-owner, as they're retaining the raw data on their side.
Assumptions -- We're talking about two separate systems (source and destination) with non-neglible transfer time (although perhaps "quick")
ETL -- Performing the transform before/during the load, such that fields in the destination are not guaranteed to have existed in the source (i.e. 2 db model)
ELT -- Performing a 1:1 copy of source into an intermediary table/db (albeit perhaps with filtering), then performing a transform on the intermediary table/db to generate the destination table/db (either realized or materialized at query time), with the intermediary table/database history retained (i.e. 3 table/db model)
In short distinction, if regeneration or altering the destination is required, ETL relies on history being available in the upstream source.
ELT pulls control of that to the destination-owner, as they're retaining the raw data on their side.