sql/schemachanger: Enable column type changes for virtual computed columns #135315
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…lumns This update introduces support for altering the column type of virtual computed columns in the declarative schema changer (DSC). Previously, such operations were not allowed. A key characteristic of virtual columns is that type changes never require a backfill or column rewrite, as their values are computed dynamically during access. This change includes adjustments to handle type changes that would typically involve a rewrite as simple metadata updates instead. Additionally, the USING expression in ALTER TABLE statements is now explicitly disallowed for virtual columns, as no data rewriting occurs. Attempts to use this option will result in an error. Epic: CRDB-25314 Closes: cockroachdb#125840 Release note: none
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This update introduces support for altering the column type of virtual computed columns in the declarative schema changer (DSC). Previously, such operations were not allowed.
A key characteristic of virtual columns is that type changes never require a backfill or column rewrite, as their values are computed dynamically during access. This change includes adjustments to handle type changes that would typically involve a rewrite as simple metadata updates instead.
Additionally, the USING expression in ALTER TABLE statements is now explicitly disallowed for virtual columns, as no data rewriting occurs. Attempts to use this option will result in an error.
Epic: CRDB-25314
Closes: #125840
Release note: none