Re: App very unresponsive while performing simple update - Mailing list pgsql-performance
From | Brendan Duddridge |
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Subject | Re: App very unresponsive while performing simple update |
Date | |
Msg-id | 09F270C9-7DF8-4574-AC70-CD7F9DA2C020@clickspace.com Whole thread Raw |
In response to | Re: App very unresponsive while performing simple update ("Jim C. Nasby" <jnasby@pervasive.com>) |
Responses |
Re: App very unresponsive while performing simple update
|
List | pgsql-performance |
>> You should realize this will produce a lot of garbage records and >> mean you'll >> have to be running vacuum very frequently. You might consider >> instead of >> updating the main table inserting into a separate clickstream >> table. That >> trades off not getting instantaneous live totals with isolating the >> maintenance headache in a single place. That table will grow large >> but you can >> prune it at your leisure without impacting query performance on >> your main >> tables. We actually already have a table for this purpose. product_click_history > > Actually, you can still get instant results, you just have to hit two > tables to do it. Well, not really for our situation. We use the click_count on product to sort our product listings by popularity. Joining with our product_click_history to get live counts would be very slow. Some categories have many tens of thousands of products. Any joins outside our category_product table tend to be very slow. We'll probably have to write a process to update the click_count from querying our product_click_history table. ____________________________________________________________________ Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@clickspace.com ClickSpace Interactive Inc. Suite L100, 239 - 10th Ave. SE Calgary, AB T2G 0V9 http://www.clickspace.com On May 31, 2006, at 12:23 AM, Jim C. Nasby wrote: > On Sun, May 28, 2006 at 07:20:59PM -0400, Greg Stark wrote: >> Brendan Duddridge <brendan@clickspace.com> writes: >> >>> We do have foreign keys on other tables that reference the >>> product table. >>> Also, there will be updates going on at the same time as this >>> update. When >>> anyone clicks on a product details link, we issue an update >>> statement to >>> increment the click_count on the product. e.g. update product >>> set click_count >>> = click_count + 1; >> >> You should realize this will produce a lot of garbage records and >> mean you'll >> have to be running vacuum very frequently. You might consider >> instead of >> updating the main table inserting into a separate clickstream >> table. That >> trades off not getting instantaneous live totals with isolating the >> maintenance headache in a single place. That table will grow large >> but you can >> prune it at your leisure without impacting query performance on >> your main >> tables. > > Actually, you can still get instant results, you just have to hit two > tables to do it. > >> More likely you were blocking on some lock. Until that other query >> holding >> that lock tries to commit Postgres won't actually detect a >> deadlock, it'll >> just sit waiting until the lock becomes available. > > Wow, are you sure that's how it works? I would think it would be > able to > detect deadlocks as soon as both processes are waiting on each other's > locks. > -- > Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com > Pervasive Software http://pervasive.com work: 512-231-6117 > vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 > > ---------------------------(end of > broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings >
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