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https://issues.apache.org/jira/browse/HIVE-28449?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stamatis Zampetakis resolved HIVE-28449.
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Fix Version/s: Not Applicable
Resolution: Won't Fix
Resolving this as won't fix since there is no strong interest to push this
change forward and may cause other unintended breaking changes.
> Infer constant types from columns before strict type validation
> ---------------------------------------------------------------
>
> Key: HIVE-28449
> URL: https://issues.apache.org/jira/browse/HIVE-28449
> Project: Hive
> Issue Type: Improvement
> Components: Query Planning
> Environment:
> Reporter: Stamatis Zampetakis
> Assignee: Stamatis Zampetakis
> Priority: Major
> Labels: backwards-compatibility, pull-request-available
> Fix For: Not Applicable
>
>
> HIVE-2249 introduced some [specialized type inference
> logic|https://github.com/apache/hive/blob/5cbffb532a586226500abc498d6505722d62234d/ql/src/java/org/apache/hadoop/hive/ql/parse/type/TypeCheckProcFactory.java#L972]
> that kicks in when there are comparisons between columns and numeric
> constant expressions.
> Consider for instance a comparison between a BIGINT column and a STRING
> constant.
> {code:sql}
> SELECT * FROM table WHERE c_bigint = '9223372036854775807'
> {code}
> The type derivation logic will attempt to convert the STRING constant to
> BIGINT and evaluate the expression by comparing long values.
> Currently (commit 5cbffb532a586226500abc498d6505722d62234d), the query above
> throws the following ERROR/WARNING:
> {noformat}
> Comparing bigint and string may result in loss of information.
> {noformat}
> This is due to strict type checking (controlled via
> hive.strict.checks.type.safety property) that is now applied before the
> constant type inference logic described above.
> In this case, the ERROR/WARNING is a bit misleading since there is no real
> risk for losing precision/information since the STRING constant fits into a
> BIGINT (Java long) and the whole comparison can be evaluated without
> precision loss.
> For quite some time, strict type checking was performed *after* constant type
> inference (and not *before*) but the behavior was changed unintentionally by
> HIVE-23100.
> The goal of this change is to perform constant type inference before strict
> type validation (behavior before HIVE-23100) to restore backward
> compatibility and remove some unnecessary warnings/errors during compilation.
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