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I am using postgree 9.4 database and I have a table snapshots with 700+ million rows and I want to delete about 9 million rows. I have tried different queries to delete records, but no success.

Query to delete all records for a specific camera:

DELETE FROM snapshots where camera_id = 1248

Another query to delete recodes between snapshot_id:

DELETE from snapshots where snapshot_id >= '1248_201511010000000' and <= '1248_20151130235959000'

Suggest me what will be the fastest way of deleting records from 700+ millions records.

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  • Are there any foreign keys pointing at the snapshots table? Can you post an EXPLAIN ANALYZE of a slow DELETE? Dec 21, 2015 at 14:59
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    "no success" is neither a valid error message nor a useful description of the problem. Start by providing relevant details for your performance question as advised here: dba.stackexchange.com/tags/postgresql-performance/info Dec 21, 2015 at 15:09
  • There is no foreign key on table. It take too much time to executing query and at the end it gave message connection timeout. Dec 22, 2015 at 8:52

3 Answers 3

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Other than breaking the operation into chunks, I don't think there's a silver bullet method. This answer may come in handy

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  • My answer you refer to is only partly applicable since, in this case, only a small percentage of the whole table is deleted. Dec 21, 2015 at 15:12
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You can use something like pg_repack to keep the table clustered by camera_id, or snapshot_id whichever one is responsible is more problematic. This will make the marking of the rows as dead a much faster operation. It's probably better to use snapshot_id especially if that is chronological, and you're not inserting old snapshots.

On the other operation, you can use an index.

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Sometimes it is faster to create a new table and insert only the records you would like to keep.

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    This is unlikely to be faster when keeping ~691 million of ~700 million rows. Dec 21, 2015 at 14:50
  • It is true but maybe it will be easier to monitor the progress of insert
    – alonk
    Dec 21, 2015 at 15:11

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