Re: [Wonder-disc] objectsWithFetchSpecification freezes during a slow call

[Jesse T. <jt...@oe...>]

well, I don’t know if there’s anything special going on there, but I have often seen similar reports --

indexes fail, thus causing certain fetches to become very long response without report of any failure.

you should check the database fetch plan where you can see report of the actual choices made in the database logic while interpreting your query.

that often reveals the broken indexes in my past experiences, because you can see how the index responds - so the idea just came to mind as you describe your situation.

if you suspect a specific index, drop and restore it maybe?




On Aug 8, 2013, at 1:22 PM, Mark Gowdy <ma...@go...> wrote:

> Hi, 
> 
> Have been trying to track down the cause of a very strange problem we have been having.
> 
> Using the MySQLPlugIn in Wonder, if we do a fetch (or anything SQL related), and it takes a while for MySQL to respond, the instance freezes (it does not get past the objectsWithFetchSpecification line).
> We originally thought it was something to do with the memory & tables becoming large, but now we are thinking it is a response time-out thing.
> 
> We can reproduce the problem quite easily now by specifying a sort ordering, we will give MySQL a bit of work to do (and slow down the response).
> 
> So, if we run the generated SQL directly in Sequel Pro:
> 
> (1) Including the slow field (CREATED_DATE)- Takes about 10 seconds for MySQL to return some values.
> SELECT RTRIM(t0.CONFIG), t0.CREATED_DATE, t0.IDENTIFIER_1, t0.IDENTIFIER_2, t0.IDENTIFIER_3, t0.IDENTIFIER_4, t0.ITEM_DATE, t0.MODIFIED_DATE, t0.QUEUE_DETAILS_FK, t0.QUEUE_ITEM_PK, t0.QUEUE_TAG, t0.STATUS FROM queue_item t0 WHERE (t0.QUEUE_TAG = 'mb:nui:RENDER_MEDIA' AND (t0.ITEM_DATE < '2013-08-08 16:46:17 Etc/GMT' OR t0.ITEM_DATE is NULL)) ORDER BY t0.CREATED_DATE ASC, t0.QUEUE_ITEM_PK ASC LIMIT 50
> 
> (2) Remove the slow sort field - Takes about 72ms for MySQL to return some values.
> SELECT RTRIM(t0.CONFIG), t0.CREATED_DATE, t0.IDENTIFIER_1, t0.IDENTIFIER_2, t0.IDENTIFIER_3, t0.IDENTIFIER_4, t0.ITEM_DATE, t0.MODIFIED_DATE, t0.QUEUE_DETAILS_FK, t0.QUEUE_ITEM_PK, t0.QUEUE_TAG, t0.STATUS FROM queue_item t0 WHERE (t0.QUEUE_TAG = 'mb:nui:RENDER_MEDIA' AND (t0.ITEM_DATE < '2013-08-08 16:46:17 Etc/GMT' OR t0.ITEM_DATE is NULL)) ORDER BY t0.QUEUE_ITEM_PK ASC LIMIT 50
> 
> Now, in our app, during the objectsWithFetchSpecification(..)
> (1) freezes the app totally.. no error messages, just frozen.
> (2) works fine.
> 
> Any thoughts?
> 
> Thanks, 
> 
> Mark
> 
> 
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