Jira babel 3755

[ParikshitSarode]

Description

Improve performance of "simple expressions" in pltsql

1. An optimisation on the Postgres engine was done that reduced the query time execution for simple queries. Simple queries are the queries that do not refer to a relation (say, "x + 1" or "x > 0")
2. A similar optimisation is adopted for babelfish.
3. After doing the optimisations, an improvement of around 11% is noticed in simple queries.

Issues Resolved

Performance of simple queries is improved by 11%

Test Scenarios Covered

Currently few tests are failing as the error messages changed.
Ex:
-ERROR (Message: Transaction count after EXECUTE indicates a mismatching number of BEGIN and COMMIT statements. Previous count = 1, current count = 0.)
+ERROR (Message: Transaction count after execution indicates a mismatch number of BEGIN and COMMIT statements. Previous count 1 current count 0)

Check List

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