Cost model ORM implemenation (#24)

* Add implementation for create_new_epoch

* implement get_stats methods

* Initial draft of update_stat

* Small optimization

* Basic error handling

* Finish update_stats and store_expr_stats_mappings

* Fix clippy

* integrate w nullable columns

* Update test_create_new_epoch

* add: cost methods

* add update_stats_from_catalog

* Add test_update_stats_from_catalog

* feat: enable unit test with every table intialized

* Fix clippy

* fix description

* Modify update_stat and add one related test

* refine test infra and track init.db

* add more initial data into stat-related tables

* add new line at eof

* refine variant tag in init

* use json for stat type

* add test_get_stats_for_table

* minor fixes

* add test_get_stats_for_single_attr and test_get_stats_for_multiple_attrs

* remove unused comments

* add: cost related tests

* Fix update_stats and add all tests

* Rebase on main

---------

Co-authored-by: Lan Lou <[email protected]>
Co-authored-by: Yuanxin Cao <[email protected]>

Author: 3 people

.gitignore

@@ -7,5 +7,8 @@ target/
 **/*.rs.bk
 
 **/*.db
+!init.db
 
 .DS_Store
+
+optd-persistent/sql/

optd-persistent/Cargo.lock

@@ -21,3 +21,4 @@ trait-variant = "0.1.2"
 async-trait = "0.1.43"
 async-stream = "0.3.1"
 strum = "0.26.1"
+lazy_static = "1"