Alena0704 opened a new pull request, #1872:
URL: https://github.com/apache/cloudberry/pull/1872
Feature: add TRY_CONVERT extension
TRY_CONVERT(source_value, default_value) casts source_value to the type of
default_value and returns default_value whenever the cast fails, which is the
behaviour of TRY_CAST in SQL Server. Without it a single malformed value makes
the whole query fail, and the plpgsql workarounds that catch the error per row
are several times slower.
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
The conversion to use is resolved the same way the parser resolves an
explicit cast in coerce_type(): a pg_cast entry, an I/O conversion or a
binary-compatible relabel, followed by the length coercion of the target type.
Casts between array types and casts to domain types are not supported and are
reported as query errors, the same as a cast that does not exist at all; only a
failure caused by the converted data is turned into the default value.
The cast itself runs inside a PG_TRY() block, since the datatype input
functions of Cloudberry cannot yet report a conversion failure without throwing.
The extension is marked trusted, so the owner of a database can install it
without being a superuser.
Co-authored-by: Vladimir Rachkin <[email protected]>
See: PR#901 <https://github.com/apache/cloudberry/pull/901>
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Fixes #ISSUE_Number
### What does this PR do?
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### 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
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### Test Plan
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- [ ] Unit tests added/updated
- [ ] Integration tests added/updated
- [ ] Passed `make installcheck`
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### Impact
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**Dependencies:**
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### Checklist
- [ ] Followed [contribution
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- [ ] Added/updated documentation
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