Re: Slow update

[Herouth Maoz <herouth@xxxxxxxxxxxxx>]

Marc Mamin wrote:

Hello,

 

- did you vacuum your tables recently ?

 

- What I miss in your query is a check for the rows that do not need to be udated:

 

AND NOT (service = b.service

               AND status = b.status

              AND has_notification = gateway_id NOT IN (4,101,102)

              AND operator = COALESCE( b.actual_target_network_id,  b.requested_target_network_id   )

 

 

depending on the fraction of rows that are already up to date, the might fasten your process quite a lot...

I don't see why it would. As far as I know, the high saving in update time is done by using the indices. All the other conditions that are not on indices are all checked using a sequential scan on the rows that were brought from the index, so adding more conditions wouldn't make this a lot faster - maybe even slower because more comparisons are made.

In any case, the logic of the database is that the records that have delivered = 0 are always a subset of the records that are changed in this query, so querying on delivered=0 - which is an indexed query - actually make the above redundant.

Thanks for your response,
Herouth