TRY_CONVERT

[robozmey]

Extension TRY_CONVERT adds function TRY_CONVERT

TRY_CONVERT was made to use like TRY_CAST from SQL-Server

Due polymorphism have strange signature (some_type, anyelement) -> anyelement

First parament is SOURCE_VALUE

Second parameter is DEFAULT_VALUE::TARGET_TYPE

TRY_CONVERT('42'::text, NULL::int2) -- returns 42::int2
TRY_CONVERT('42d'::text, NULL::int2) -- returns NULL::int2
TRY_CONVERT('42d'::text, 1234::int2) -- returns 1234::int2

We cannot have (any1, any2) -> any2 signature with different anyelement types, but we can create multiple (_, any) -> any functions in contrib/try_convert/try_convert--1.0.sql or use select add_type_for_try_convert('date'::regtype); to add types.

In init we can add all supported types, but with add_type_for_try_convert user can add whatever type he wants

ERROR HANDLING

Error handles by PG_TRY() PG_CATCH()

But better way is use "soft" error handling from Postgres 17 (postgres/postgres@ccff2d2) it also realising OPENGPDB (open-gpdb/gpdb@21be368). Of course it needs to convert datatype function to support "soft" error handling

Fixes #ISSUE_Number

What does this PR do?

Type of Change

• Bug fix (non-breaking change)
• New feature (non-breaking change)
• Breaking change (fix or feature with breaking changes)
• Documentation update

Breaking Changes

Test Plan

• Unit tests added/updated
• Integration tests added/updated
• Passed make installcheck
• Passed make -C src/test installcheck-cbdb-parallel

Impact

Performance:

User-facing changes:

Dependencies:

Checklist

• Followed contribution guide
• Added/updated documentation
• Reviewed code for security implications
• Requested review from cloudberry committers

Additional Context

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