If we run a query,what all happens in background/what are phases of query processesing.?

Question

Hi Friends,
if we run a query,what all happens in background/what are phases of query processesing.?
Many thanks
Shashikala

Answer 1

It has to go through
Parsing-on this stage it perform basic check on code (T-SQL,
Binding(Algebrizer Stage)-on this stage does more parsing and perform query tree,
Optimize- on this stage take query tree from Binding and parsing and find a better way to return the result that you need so cost might apply here and then
Execute 
To know about transaction Log we have to know first how Transaction log file internally works: when you are trying to make change in data as Insert, Update, Delete requests
from applications using T-SQL or on object explorer, SQL Server will load (load) to the corresponding page data memory where we call this memory area as DATA CACHE.  Then the data in the data cache are changed which is also known as known as DIRTY PAGE.
Next all changes we made by running query will be recorded in the transaction log file so they called the write-ahead log. At final stage, a process known as CHECK POINT PROCESS will check and write all the transaction has been committed AND completed to your
hard drive by flushing the page.
So simply put here are the steps
Data modification sent by application
Data pages are located in or read into, cache and modified
Modification is recorded in transaction log on DISK
Checkpoint writes committed transactions to database
I hope this helps a bit in answering your question good luck.