Alessandro Solimando created CALCITE-7174:
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Summary: Improve detection of lossless casts from INT family to
DOUBLE/REAL/DECIMAL
Key: CALCITE-7174
URL: https://issues.apache.org/jira/browse/CALCITE-7174
Project: Calcite
Issue Type: Improvement
Components: core
Affects Versions: 1.40.0
Reporter: Alessandro Solimando
Assignee: Alessandro Solimando
[RexUtil.java#isLossLessCast|https://github.com/apache/calcite/blob/calcite-1.40.0/core/src/main/java/org/apache/calcite/rex/RexUtil.java#L1692]
doesn't handle casts from the INT family to non-INT numeric are not covered at
all and always considered lossy.
This ticket proposes to detect the following additional cases as being lossless:
- INTEGER-family (excluding BIGINT) → DOUBLE
- SMALLINT/TINYINT → REAL
- INTEGER-family → DECIMAL(p,s) is lossless iff the integer part capacity (p -
s) is large enough (10 for INTEGER, 19 for BIGINT, etc.)
The method has been introduced in Calcite 1.22 and it's still marked as
experimental despite being [in
use|https://github.com/search?q=repo%3Aapache/calcite%20isLosslessCast&type=code]
for years now in several key components, this ticket also proposes promote it
to "stable".
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