Implement a server-side cursor to improve performance when fetching large volumes of data. #5797

[khushboovashi]

No description provided.

[akshay-joshi]

GUI-related comments:

1. Select 'Use server cursor' from the query tool. Run "select 1" query. Clicking on the Commit button gets the error message " the cursor is closed" and on Rollback "DECLARE "CURSOR:CONN:961921" CURSOR FOR ROLLBACK;" Disable those buttons in server cursor mode.
2. Set "Execute with server side cursor?" To true. Select any table and click on View/Edit data. It executes the query, but again commit and rollback buttons get enabled. Now try following:

• Try to close the tab. It will not.
• Pagination shows Page no 1 of 0.
• Click on Next page or Previous page, nothing happens, and the data is lost.    

Code-related comments:

1. Add this new 'Use server cursor?" preference to the preferences.rst. The screenshot will be updated after Aditya's PR.
2. Fix 3 small code smells in sqleditor/init.py

[khushboovashi]

GUI-related comments:

1. Select 'Use server cursor' from the query tool. Run "select 1" query. Clicking on the Commit button gets the error message " the cursor is closed" and on Rollback "DECLARE "CURSOR:CONN:961921" CURSOR FOR ROLLBACK;" Disable those buttons in server cursor mode.

Fixed the issue. I have disabled the buttons right now in View/Edit data but that is debatable, we will discuss that in the review.

2. Set "Execute with server side cursor?" To true. Select any table and click on View/Edit data. It executes the query, but again commit and rollback buttons get enabled. Now try following:

• Try to close the tab. It will not.
  Fixed
• Pagination shows Page no 1 of 0.
  Fixed
• Click on Next page or Previous page, nothing happens, and the data is lost.
  Didn't reproduce

Code-related comments:

1. Add this new 'Use server cursor?" preference to the preferences.rst. The screenshot will be updated after Aditya's PR.
   Fixed
2. Fix 3 small code smells in sqleditor/init.py

[akshay-joshi]

Update the preferences screenshot.