babelfish-for-postgresql / babelfish_extensions / 15178427729

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Use Index Scan for EXACT and PREFIX pattern matches for LIKE for Const node inside CollateExpr (#3770)

With this commit: e119968, babelfish now use Index Scans for the following cases:

-- CASE 1
SELECT COL FROM TAB WHERE COL LIKE 'ab'

-- CASE 2
SELECT COL FROM TAB WHERE COL LIKE 'a%'

However if there is a Collate clause with the right operand :

-- CASE 1
SELECT COL FROM TAB WHERE COL LIKE 'ab' COLLATE DATABASE_DEFAULT

-- CASE 2
SELECT COL FROM TAB WHERE COL LIKE 'a%' COLLATE DATABASE_DEFAULT

then Babelfish does NOT use Index Scan.

This commit enables Index scan for such cases. We do this by removing CollateExpr on both operands as those are
redundant and the OpExpr (LIKE) operator is already aware of the collation it needs to use.

Task: BABEL-5077
Signed-off-by: Shameem Ahmed <shmeeh@amazon.com>

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