[jira] [Created] (IGNITE-6983) SQL: optimize CREATE INDEX and BPlusTree interaction

["Vladimir Ozerov (JIRA)" <ji...@apache.org>]

Vladimir Ozerov created IGNITE-6983:
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             Summary: SQL: optimize CREATE INDEX and BPlusTree interaction
                 Key: IGNITE-6983
                 URL: https://issues.apache.org/jira/browse/IGNITE-6983
             Project: Ignite
          Issue Type: Task
          Components: cache, sql
            Reporter: Vladimir Ozerov
             Fix For: 2.4


Currently index is built as follows:
1) Get next entry from partition's tree
2) Read it's key (copy to heap)
3) Acquire lock on {{GridCacheMapEntry}}
4) Lookup the same key in the tree from the top
5) Read it's value (copy to heap)
6) Add to index.

This is very complex flow. We can optimize two things - tree lookup and value deserialization as follows:
1) Every data page will have update counter, which is incremented every time anything is changed.
2) When lock on {{GridCacheMapEntry}} is acquired, we will acquire lock on the data page and re-check update counter. 
3) If page was changed between iterator read and lock acquisition then use old flow. 
4) Otherwise - set read lock on the page, read value as *offheap* object, apply it to index.



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