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From "Peer, Oded" <>
Subject RE: Updating only modified records (where lastModified < current date)
Date Wed, 13 May 2015 10:38:23 GMT
You can use the “last modified” value as the TIMESTAMP for your UPDATE operation.
This way the values will only be updated if lastModified date > the lastModified you have
in the DB.

Updates to values don’t create tombstones. Only deletes (either by executing delete, inserting
a null value or by setting a TTL) create tombstones.

From: Ali Akhtar []
Sent: Wednesday, May 13, 2015 1:27 PM
Subject: Updating only modified records (where lastModified < current date)

I'm running some ETL jobs, where the pattern is the following:

1- Get some records from an external API,

2- For each record, see if its lastModified date > the lastModified i have in db (or if
I don't have that record in db)

3- If lastModified < dbLastModified, the item wasn't changed, ignore it. Otherwise, run
an update query and update that record.

(It is rare for existing records to get updated, so I'm not that concerned about tombstones).

The problem however is, since I have to query each record's lastModified, one at a time, that's
adding a major bottleneck to my job.

E.g if I have 6k records, I have to run a total of 6k 'select lastModified from myTable where
id = ?' queries.

Is there a better way, am I doing anything wrong, etc? Any suggestions would be appreciated.

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