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--- oracle_sql_processing [2019/08/11 07:51] – andonovj
+++ oracle_sql_processing [2020/10/19 07:29] (current) – 86.49.253.137
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 =====Overview=====
+The SQL processing like any other processing of code. It comes from a human and needs to go back to a human :) The problem is, through how many stops it will pass
+Below you can see a basic representation on the possible wait times for any query:
+{{ :sqlprocessing.jpg?500 |}}
+This picture, clearly displays why it isn't ALWAYS A DATABASE FAULT :) Often the database is intermediary point between the User and the data.
+=====Calls=====
+Before we start speaking of SQL processing, we should discuss something very important and that is how ORACLE communicate and operate in general.
+Oracle kernel is using requests called "calls". These "calls" represent request to certain structures and are generally devided into two groups:
+DB Calls:
+  * Parse
+  * Execute
+  * Fetch
+Operation System (OS) Calls:
+  * WAIT
+  * STAT
+These calls are accomplished using different functions:
+{{ :sql_process_calls.gif?600 |}}
+=====SQL Processing =====
 SQL Processing is one of the biggest problems with any database because it is the hearth of performance tuning. In that chapter I will try to summarize, how Oracle processes an SQL.
 Firstly the statement has to be processed and there are several steps which should be executed.
+Below you can check a brief picture of Cursor Processing:
-Parse:
+{{ :cursorparsing.jpg?600 |}}
+[[oracle_sql_processing_parse| Parsing]]
   * Open Cursor
   * Syntax Check
   * Semmantic Check
-  * Shared Pool check
+  * [[oracle_sql_processing_shared_pool_check| Shared Pool check]]
   * Binding
   * *Optimization
   * *Row source generation
-Execute:
+[[oracle_sql_processing_execute| Execute]]
   * Execution
-Fetch:
+[[oracle_sql_processing_fetch| Fetching]]
   * Fetch results
   * Close Cursor
-*-Optional steps in case of hard parse
+*- Only when hard parse is needed
-Below you can check a brief picture of Cursor Processing:
-{{ :cursorparsing.jpg?600 |}}
-  - [[oracle_sql_processing_parse| Parsing]]
-  - [[oracle_sql_processing_execute| Execute]]
-  - [[oracle_sql_processing_fetch| Fetching]]