Re: RM #1250 Collection node counts - Mailing list pgadmin-hackers

On Mon, Aug 8, 2016 at 1:18 PM, Akshay Joshi <akshay.joshi@enterprisedb.com> wrote:

On Mon, Aug 8, 2016 at 5:33 PM, Dave Page <dpage@pgadmin.org> wrote:

Hi

On Mon, Aug 8, 2016 at 11:39 AM, Akshay Joshi <akshay.joshi@enterprisedb.com> wrote:

Hi All

I have fixed the RM#1250 "Collection node counts". To fix this RM I need to do following changes

• Move "check_precondition" function from module's view class to global level within that python file itself, so that module class will use it. 
• Modified "get_nodes" function of each module's class, run the sql query to count the number of objects and pass the count to "generate_browser_collection_node" function to display the collection count.
• Reuse SQL queries which is used to fetch nodes. Make that query as inner query like "SELECT count(*) FROM( <node's> query  ) AS collection_count". For that I'll have to remove semicolon's from some of the SQL queries.

One case is not handled with this patch and that is on "Refresh" of collection node, count is not updated. If user refresh the parent node then it will be updated. I'll create a separate RM for that.

 

Sorry Akshay, but I really don't like the way you've done this. It seems like an unnecessarily large patch, and if I'm reading the patch correctly, it doubles the amount of SQL queries run against the database when navigating the tree, and introduces race conditions where the count displayed could be different from the actual number of nodes.

I was expecting to see this implemented by watching for tree events (e.g. 'added' and 'removed') and using those events to update the label on the parent node, if that node is a collection. That should just be a few lines, and should be correct at all times right?

   With current implementation children's of any collection node will be fetched/added when user will expand that collection node, in that case we will update the label once the node gets expanded. For example initially we will show "Databases"  and when it gets expanded then we will update it to "Databases (5)".      

Right, but you also need to allow for removal and addition of children when the node is already expanded, and refreshes. Plus my other comments are still valid I believe - race condition, double the SQL and a very large change late in the beta cycle which isn't ideal.

 

 

Attached is the patch file. Please review it and let me know the review comments.           

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Akshay Joshi

Principal Software Engineer 

Phone: +91 20-3058-9517
Mobile: +91 976-788-8246

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Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

--

Akshay Joshi

Principal Software Engineer 

Phone: +91 20-3058-9517
Mobile: +91 976-788-8246

--

Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company