Performance improvement for queries having join between TABLE_CONSTRAINTS and KEY_COLUMN_USAGE views

[sumitj824]

Description

This commit addresses poor performance issues in queries that join the TABLE_CONSTRAINTS and KEY_COLUMN_USAGE views. The problem was caused by inaccurate row estimates resulting from a CASE expression in the TABLE_CONSTRAINTS view, leading to suboptimal query plans.

Signed-off-by: Sumit Jaiswal sumiji@amazon.com

Issues Resolved

Task: BABEL-5427

Test Scenarios Covered

Test are already present for modified views.

Performance Result

1. Improvement for query having join between TABLE_CONSTRAINTS and KEY_COLUMN_USAGE:

Objects	Before (ms)	After (ms)	Improvement %
1181 tables and primary key constraints	4781	87	98.18%
3000 tables and primary key constraints	33011	98	99.70%
3000 tables, primary key, unique and check constraints	14173	116	99.18%

2 Improvement for different queries:

Objects	Query	Before (ms)	After (ms)	Improvement %
1181 tables and primary key constraints	SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS	29	32.2	-11.03%
^	SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_NAME = 't456'	38	33.6	11.58%
^	SELECT * from INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_SCHEMA = 'dbo'	13.8	16.8	-21.74%
^	SELECT * from INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE CONSTRAINT_TYPE = 'PRIMARY KEY'	24.4	16.6	31.97%
^	SELECT * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE	22	20.2	8.18%
^	SELECT * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_NAME = 't456'	8	6.4	20%
^	SELECT * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_SCHEMA = 'dbo'	21.4	19.2	10.28%
3000 tables, primary key, unique and check constraints	SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS	105.2	128	-21.67%
^	SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_NAME = 't456'	79.8	58.2	27.07%
^	SELECT * from INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_SCHEMA = 'dbo'	77.8	100.6	-29.31%
^	SELECT * from INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE CONSTRAINT_TYPE = 'PRIMARY KEY'	61.4	53.2	13.36%
^	SELECT * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE	71.4	65.6	8.12%
^	SELECT * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_NAME = 't456'	12	10	16.67%
^	SELECT * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_SCHEMA = 'dbo'	75.6	67.2	11.11%

NOTE: We don't observe ANY degradation if we have 100 user schemas

Check List

• Commits are signed per the DCO using --signoff

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[coveralls]

Pull Request Test Coverage Report for Build 12314271462

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1738 unchanged lines in 14 files lost coverage.
• Overall coverage increased (+0.1%) to 74.832%

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Files with Coverage Reduction	New Missed Lines	%
contrib/babelfishpg_tsql/src/schemacmds.c	2	92.54%
contrib/babelfishpg_tsql/src/pl_funcs-2.c	3	45.82%
contrib/babelfishpg_tsql/src/pl_funcs.c	4	18.95%
contrib/babelfishpg_tsql/src/session.c	5	97.41%
contrib/babelfishpg_tsql/src/procedures.c	62	88.76%
contrib/babelfishpg_tsql/src/pltsql_utils.c	67	92.12%
contrib/babelfishpg_tsql/src/multidb.c	77	82.69%
contrib/babelfishpg_tds/src/backend/tds/tdsutils.c	110	73.66%
contrib/babelfishpg_tsql/src/rolecmds.c	159	85.11%
contrib/babelfishpg_tsql/src/pl_exec-2.c	219	82.24%

Totals
Change from base Build 12278087977:	0.1%
Covered Lines:	46509
Relevant Lines:	62151

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💛 - Coveralls