John Arbash Meinel wrote:
Is there a reason to use varchar(1) instead of char(1). There probably is 0 performance difference, I'm just curious.
No, not at all. I'm just not used to char().
Well, with cursors you can also do "FETCH ABSOLUTE 1 FROM <cursor_name>", which sets the cursor position, and then you can "FETCH FORWARD 30". I honestly don't know how the performance will be, but it is something that you could try.
This is science for me at this moment :-)
For display of single page consisting of 30 rows. The reason I query
all rows is that this is one of the filters users can use. User can
display just bigboards or billboards (or specify more advanced
filters) but he/she can also display AdDevices without any filter
(page by page). Before I select the 30 row, I need to order them by a
key and after that select the records, so this is also the reason why
to ask for all rows. The key for sorting might be different for each run.
How are you caching the information in the background in order to support paging? Since you aren't using limit/offset, and you don't seem to be creating a temporary table, I assume you have a layer inbetween the web server and the database (or possibly inside the webserver) which keeps track of current session information. Is that true?
I just need three information:
1) used filter (stored in session, identified by filter index in query string)
2) page length (static predefined)
3) what page to display (in query string)
In fact, on MySQL I didn't see any slow reactions so I didn't measure and inspect it. But I can try it if I figure out how to copy the database from PostgreSQL to MySQL.
I figured you still had a copy of the MySQL around to compare to. You probably don't need to spend too much time on it yet.
It's not so simple because there are some differences between MySQL and PostgreSQL in how they handle case sensitivity etc. The database table structures are not the same too because of different data types support and data values support.
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---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match